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Posts Tagged ‘aortic stenosis’

The FDA recently approved the first TAVI device for aortic stenosis.   Currently the device is only eligible for patients who are unable to withstand surgery.   But who will end up making that determination?  The cardiologist who will be implanting the device?  At present – the company manufacturing the Sapien aortic device is recommending that patients be evaluated by a heart surgeon – but if this follows the typical course, I am sure that this recommendation will be abandoned as a matter of course.

Hopefully, the industry (interventional cardiology) will proceed cautiously, after being ‘omce bitten, twice shy” in light of the epidemic overstenting catastrophies.

For more on Aortic stenosis, TAVI and the overstenting controversies – look under the cardiology and cardiac surgery tab.

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As many readers know, I advise caution to patients prior to pursuing TAVI (or transcatheter aortic valve implantation, primarily because there is no long-term data on durability or long-term effects.

One of these days, I may have to eat my words – and when that day comes; I will be happy to do so (and will do it with a 14-point font).  But that day is not today.

As reported by Reed Miller over at Heartwire, there are the first results of a very small Canadian study with average follow-up 3.7 years after implantation..  Unfortunately, its way too small of a sample – and mean follow-up falls short of the five-year mark.

But given the rate of implantation in Europe (Germany, in particular) and the fact that these valves are used in younger patients over there – we should have some large (thousands of patients enrolled) studies with five-year data in just a year or two.. One of two well designed studies with a large study population would sure make a lot of us over here (in the USA) feel a lot more comfortable about the safety and efficacy of these devices in our patients.

Now, I bet most of you have gotten pretty good at picking through these Heartwire articles to get to the bit of truth inside – and the experts quoted here do a much better job at providing straight forward answers (unlike the cast of characters quoted for many of the articles regarding the stent scandals.)

(I’ll re-post below so you can see for yourself.)  I’ve also included links to our little collection of TAVI articles here – or the ‘TAVI library” for first-time readers to catch up.

1.  Aortic Stenosis – more patients need surgery  – for some background on the issue (more articles on Aortic stenosis under cardiology)

2.  TAVI  – ‘a new stent scenario’ – discussing concerns with the widespread adoption of this therapy

3.  TAVI recommendations and guidelines –  the most recent established US guidelines for therapy

4.  TAVI – an overview – getting back to the basics

5.  TAVI – mortality data – this had some pretty frightening results, another reason for caution.

6. TAVI and FDA approval: what does it mean? – talking about the implications of FDA approval, and the history of FDA approval of medical devices.

CoreValve TAVI maintains durability out to four years in small study

(Reed Miller)

[Bold type from original article]

Paris, France – The longest follow-up of patients implanted with the CoreValve (Medtronic) transcatheter aortic-valve implantation (TAVI) device presented so far suggests that it is reliable and durable in high-risk patients, according to the study investigators [1].

“In due time, I’m sure we will see a gradual decrease in the average patient age, treating patients with less comorbidity than was done in the beginning, strengthened by these types of results showing the durability of the implants,” study lead-investigator Dr Peter den Heijer (Amphia Hospital, Breda, the Netherlands) told heartwire.

Here at the European Society of Cardiology 2011 Congress, den Heijer presented long-term follow-up results from 52 patients implanted with the second-generation version of CoreValve in 2005 and 2006 in Europe and Canada. All of the patients in the study were at least 80 years old with a logistic EuroSCORE over 20 or over 65 years old with at least one high-risk comorbidity. All of the patients had severe aortic stenosis and an aortic-valve annulus diameter between 20 mm and 24 mm. Two-thirds of the patients had NYHA class 3 heart failure and almost 20% had class 4 heart failure.

Four-year follow-up data was collected on 20 patients, but 26 patients died, including 13 cardiac deaths. Overall survival was 58.5% at two years and 45.1% at four years. At four years, the surviving patients showed significant improvement in heart-failure symptoms, with 61% in class 1 heart failure and 22% in class 2. Nearly a third of patients showed grade 2 or 3 aortic regurgitation at baseline, but after four years 57% showed no regurgitation and 43% showed grade 1 regurgitation. The mean valve gradient decreased from 41 mm Hg at baseline to 12 mm Hg at 30 days and 10 mm Hg at four years.

There were no strokes reported in the study population between three months and four years and no frame fractures, valve migrations, valve endocarditis, or structural valve deteriorations leading to stenosis or regurgitation. “That’s important, because the goal of this treatment is to provide patients with severe aortic stenosis, a severely life-limiting disease, with a better prognosis, and it appears to be not at all hampered by the structure of the valve,” den Heijer told heartwire.

In a 70-patient study by Dr Ronen Gurvitch (University of British Columbia, Vancouver) colleagues, the Sapien (Edwards Lifesciences) transcatheter aortic valve showed no structural valvular deterioration, stent fracture, deformation, or valve migration over a mean follow-up of 3.7 years [2].

CoreValve is available in Europe and is being tested in a major US clinical trial that Medtronic says will be completed in 2012. The FDA is expected to approve Edward’s Sapien TAVI device soon, following a positive appraisal by its advisory committee.

Still much too early to assess long-term TAVI results

Surgeon Dr Craig Miller (Stanford University, CA), one of the investigators of the pivotal PARTNER trial of Sapien, told heartwire that while the four-year results with CoreValve are “decent,” the clinical community will “need much larger numbers of patients followed at two, three, and four years for the hemodynamics to mean much.”

PARTNER investigator Dr Michael Mack (Medical City Dallas Hospital, TX) told heartwire, “Although it’s reassuring that there are now results out to four years and there’s no sign of structural valve deterioration, it really adds minimal information to what we know already.

“There’s only 20 patients alive at four years, so how do you know what happened to the other 30 patients [in the trial]? Some died of cardiac death and some died of unknown causes. How do you know they didn’t die of structural valve deterioration?” he said. “A better way of doing this study for all aspects is that all the information should be on matched patients.”

Mack said that the real long-term durability of transcatheter valves will become more clear with more data from the SOURCE registry and the long-term follow-up of PARTNER trial, which will include annual core-lab-adjudicated echocardiography follow-up out to five years.

In an email to heartwire, Dr Grayson Wheatley (Arizona Heart Institute, Phoenix) pointed out that although the study had a high percentage of cardiac-related deaths, the arrhythmia-related deaths were a smaller proportion than in some other recent studies. But Mack and Wheatley also pointed out that because there was no echocardiographic core lab in this study, the functional assessments of the valve may not have been always accurate.

Wheatley also pointed out that this study used an older version of the CoreValve, so “this study doesn’t relate too well to real-world use of the CoreValve due to new design changes in the valve system, but it does show that, in general, TAVI procedures can be used in high-risk cardiac patients and that there will be long-term survivors.”

 

TAVI overseas –

As mentioned above, TAVI has rapidly been implemented in Europe.  Latin American medicine has begun to embrace this emerging technology as well.  In fact, US physicians are travelling outside the country to perform this procedure on their patients (since it’s not FDA approved.)

From a statement by the University of Miami Medical School – International Medicine Institute: [verbatim]

“New Technology Treats Aortic Heart Valve Disease Without Surgery

 At 86, Dr. Isaac Hariton is back to walking three miles a day since getting a new aortic valve this past June. To avoid surgery, this retired surgeon traveled to Cali, Columbia, for his procedure.  Hariton’s doctor is Eduardo de Marchena from UHealth – University of Miami Health System, who traveled with him to implant a valve not FDA approved for use in this country.”

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More on TAVI: A newly published analysis of the existing/ reported data for peri-operative mortality after transcatheter aortic valve implantation looking at 12 previous studies was recently (June) published in the journal of Interventional Cardiology.  (While the study looks at the causes of death – we here at Cartagena Surgery – are going to talk about the rate of death in this study.)

Article information:

Causes of Peri-Operative Mortality After Transcatheter Aortic Valve Implantation: A Pooled Analysis of 12 Studies and 1,223 PatientsThe Journal of Invasive Cardiology 2011;23(5):180-184.

Raul Moreno, MD; Luis Calvo, MD; Pablo Salinas, MD; David Dobarro, MD; Jimenez Valero Santiago, MD; Angel Sanchez-Recalde, MD; Guillermo Galeote, MD; Luis Riera, MD; Isidro Moreno-Gomez, MD; Jose Mesa, MD; Ignacio Plaza, MD; Jose Lopez-Sendon, MD

Abstract re-posted below.

Background. In order to improve technique and to prevent serious procedural complications during transcatheter aortic valve implantation (TAVI), it is crucial to identify the causes of death of patients undergoing this procedure.
Objective. The objective of this study was to identify the causes of death during the procedure and at 1 month in patients with severe aortic stenosis undergoing TAVI.

Methods. 12 published studies with information about the causes of death in patients undergoing TAVI were selected. Overall, 1,223 patients were included in these studies, and 249 deaths were reported (119 at 1 month and 130 at > 1 month post-procedure).

Mortality during the procedure and at 1 month was 2.3% and 9.7%, respectively. The proportion of cardiac deaths was higher at < 1 month in comparison with > 1 month (56% versus 34%, respectively; p = 0.001). At 1 month, the most frequent causes of death were cardiac failure/multi-organ failure (24%), sudden death/cardiac arrest (17%), vascular and bleeding complications (17%), stroke (11%), sepsis (11%), and cardiac tamponade (10%). During the procedure, the most frequent causes of death were cardiac tamponade (39%), cardiac failure (21%), cardiac arrest (18%), and vascular and/or bleeding complications (18%).

In patients treated with the CoreValve system (Medtronic, Minneapolis, Minnesota) versus those treated with Edwards valves (Cribier-Edwards, Edwards-SAPIEN or SAPIEN XT valve, Edward Lifesciences, Irvine, California), deaths at 1 month due to vascular and bleeding complications were less frequent (3% versus 22%, respectively; p = 0.019), but those due to cardiac tamponade (26% versus 6%, respectively; p = 0.019), and because of aortic regurgitation (10% versus 0%, respectively; p = 0.03) were more frequent.

Conclusion. In this pooled analysis, mortality at 1 month after TAVI was 9.7%. The causes of death were widely variable, and of both cardiac and non-cardiac origin. There were some important differences between both devices in the cause of mortality.

How does this compare with conventional aortic valve replacement surgery (AVR)?

In cardiac surgery – surgeons use database calculators.  The most popular one is called the STS risk calculator to determine or estimate the surgical risk for specific patients.  This calculator is based on thousands and thousands of patients over decades of research to give approximate surgical risk of morbidity (post-operative complications) and mortality by looking at the planned procedure as well as patient risk factors (age, poor heart function, co-morbidities).  Other calculators include a European calculator called EUROscore, and a score used  by the VA (veteran’s hospitals.)

Well, how accurate are these calculators?

Interestingly enough – at the same time as the TAVI article, an article (Basreon et. al) discussing and comparing each of these calculators to actual results was published in the June 23 issue of the Annals of Thoracic Surgery.  (I’ve re-posted the abstract below.)

In their research – Basreon et. al. found the overall peri-operative mortality for aortic valve replacement surgery to be 5.9%  which is well under the 9.7% reported in the article by Moreno, et. al (re-posted above) for TAVI.

While the argument can be made that the higher than expected peri-operative mortality in the TAVI group may be secondary to other factors (patient condition at time of TAVI) without more information on patient demographics – it is hard to know.

I, for one, would like to know the average ages of patients in both groups – was the TAVI group made up of non-surgical fragile, 95 year-olds?  What specific factors raised their EUROscores? Was it overall heart function, or was it a specific co-morbidity?

It’s difficult to know since it’s a composite of other research data from multiple studies (and since TAVI is widely used in Europe, accounting for as many as 40% of all aortic procedures in Germany, for example) – this data may also reflect many of these patients (who are not frail elderly, for example.)

Reading through the Moreno study – there is little discussion of the actual patient population, except for one small paragraph (re-posted below). Both of these limitations are probably due to the nature of the study – where investigators were pooling the results of several different studies – which is a good strategy to get a wide overview.  However, this can make it impossible to go back and look at questions like ours, particularly if the investigators on the original, smaller studies didn’t record / report this information.

[my comments in brackets/ italics].  I have placed data within the article in bold or italics. 

“In this study, pooling the results of 12 series, mortality at 1 month in patients treated with TAVI was 9.7%, and mortality during the procedure was 2.3%. These data compare favorably with the predicted surgical mortality, since EuroSCOREs ranged from 12–28%.  [this is the risk calculator that Basreon et. al found that grossly overestimated risk in the study re-posted below.]

In the randomized PARTNER trial, a significant reduction (~20% absolute risk reduction) in the 1-year mortality was obtained for patients with severe aortic stenosis and considered not suitable for surgery due to a very high surgical risk when treated with TAVI in comparison with medical treatment. [as you know from previous discussions – medical treatment is exceedingly ineffective for this condition.  It would be more helpful if authors had better defined their ‘very high’ risk patient group since multiple studies show that cardiologists, etc. overestimate patient’s surgical risk.] 

Importantly, mortality significantly reduced through the years, from 2004 to 2010, probably reflecting not only the learning curve and the technical improvements, but also a better patient selection process. [meaning patients that are ineligible for surgery may also be ineligible for TAVI in some cases.]   This reduction in mortality over time has also been observed in single-center experiences.

Although not statistically significant, mortality at 30 days was higher in patients treated by transapical approach in comparison with transfemoral approach. Probably, the worse clinical profile of patients undergoing transapical TAVI justifies, at least in part, these findings.[7,12]

Ann Thorac Surg. 2011 Jun 23. [Epub ahead of print] Comparison of Risk Scores to Estimate Perioperative Mortality in Aortic Valve Replacement Surgery.

Source

Division of Cardiology, Veterans Administration Medical Center and University of Minnesota, Minneapolis, Minnesota.

Abstract  (bolding/ italics from original article)

BACKGROUND:

Transaortic valve implantation has recently been introduced as an alternative to aortic valve replacement (AVR) for high-risk patients with aortic stenosis. However, accurate assessment of surgical risk is critical for appropriate patient selection. We compared the accuracy of The Society of Thoracic Surgeons (STS) risk score, the European System for Cardiac Risk Evaluation (EuroSCORE), and the Veterans Administration (VA) risk score in predicting perioperative mortality after AVR.

METHODS:

We included 537 consecutive patients who underwent AVR for severe aortic stenosis at the Minneapolis VA Medical Center between 1997 and 2008. Observed and predicted perioperative (30-day) mortality rates were compared. Hosmer-Lemeshow goodness-of-fit test and receiver operating characteristic curves were performed to assess the performance of the scores.

RESULTS:

Perioperative mortality rate was 5.9% (n = 32). Predicted mortality rates for the EuroSCORE, STS score, and VA score were 15.6%, 3.6%, and 6.7%, respectively (p = 0.001). The EuroSCORE overestimated mortality in all patients, most notably among those with ejection fraction less than 35% (49% predicted versus 9% observed). The EuroSCORE had poor calibration (goodness-of-fit test p < 0.008), whereas the STS and the VA scores were well calibrated. However, all three scores displayed good discrimination characteristics per the areas under the receiver operating characteristic curves: STS score 0.73 (95% confidence interval: 0.69 to 0.77); VA score 0.66 (95% confidence interval: 0.62 to 0.70); and EuroSCORE 0.68 (95% confidence interval: 0.64 to 0.72; p > 0.05).

CONCLUSIONS:

The EuroSCORE substantially overestimates perioperative mortality risk in AVR, particularly in patients with low ejection fraction. These data have implications when deciding the appropriate intervention (transaortic valve implantation versus AVR) for high-risk aortic stenosis patients.

In general – the majority of the literature cites peri-operative mortality for AVR at 2.0 – 5.0% (but this is an average of ALL patients, making the calculators our best estimate of predicted risk.)

So what does this mean?

Clearly, when the data from Moreno et. al shows a thirty-day (peri-operative) mortality of almost 1 in 10 patients – it’s a signal we need to proceed with caution, and continue to follow the research.

1.  Since the authors report many of these patients at very high surgical risk (presumably due to cardiac status as well as co-morbidities) and 2. we know that in most people aortic stenosis progresses slowly  – it stands to reason that we need to consider intervening earlier in the course of the disease.  (Before the heart is significantly weakened).

For people with Aortic Stenosis – I’d want to get second/ third opinions from a cardiac surgeon before proceeding with any catheter based valve procedures.  I’d bring all of my information, and studies (echocardiogram results, lab results, medication lists) to have a serious talk to the surgeon about my surgical risk – (and ask him to calculate and show my risk based on the STS calculator).  I certainly wouldn’t let anyone make any decisions about my health/ care based on my age alone.  [we’ve talked about a ‘good 80’ versus a ‘bad 80’ or even a ‘bad 50’ before.]

Then, I would weigh all of the information – and do my best to make an informed decision.

Other posts about Aortic Stenosis/ TAVI/ AVR:

1. TAVI overview

2. TAVI: a stent scenario

3. TAVI recommendations

4. Aortic Stenosis and TAVI

5. Aortic Stenosis as Heinz 57

6. Aortic stenosis and surgery

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I am re-posting an article published in May on the heart.org by Reed Miller regarding the use of Transcutaneous Aortic Valve Intervention (TAVI).  TAVI is when a device is implanted in the cardiac cath lab (through an artery) to treat aortic stenosis.  Right now, this therapy is still in limited use in the United States, but is used more extensively in Europe where the guidelines are less restrictive.

I was a little disappointed here because I think some of his introductory language shows significant bias – but I think this article certainly adds to some of the discussions we’ve had here at Cartagena Surgery.  Even the title reflects a cardiology bias – cardiothoracic surgeons certainly aren’t the only ones who think we should be cautious about the overimplementation of new, experimental technologies in patients who are good candidates for existing (and proven) surgical treatments.   I would think that any prudent health care provider, or consumer would be hesitant to wholeheartedly embrace this therapy given the previous and recent cardiology lessons related to both carotid and cardiac stenting.

New technology is great – when it is selectively targeted to specific populations (high-risk surgical candidates such as extreme elderly (90+) or patients with multiple high risk co-morbidities) who would otherwise be ineligible for surgical intervention.  But let’s not put our patients at unnecessary risk by selling TAVI as an ‘easy’ fix to people who we know we benefit from aortic valve replacement surgery before we have all the data.

There are still multiple issues to be addressed with transcutaneous valve therapies – we don’t even know the durability of this technology (how long with they last?)  or the long-term complications..   Also when we compare ourselves to European practices, we need to remember that ‘acceptable thresholds’ may differ significantly.  At what level of risk of stroke are YOU willing to accept?  5 % ?  10% ?  25% ?  And doesn’t that depend on whether you are eligible to have other therapies, and what the risks of those therapies are?

Lastly, it’s important to note that the study in question – which revealed a higher than expected stroke rate was funded by the corporations that manufacture and supply these valves.  We’ve seen before how this can influence the practice of cardiology and cardiology guidelines.

Article re-post below: [my comments in brackets.]

Surgeons caution against

 overenthusiasm for TAVI in light of

PARTNER A stroke data

May 10, 2011            |            Reed Miller

Philadelphia, PA – The neurological injury data from the PARTNER cohort A trial of transcatheter aortic-valve intervention (TAVI) underscore the importance of the collaboration between surgeons and interventionalists when making decisions on how to treat patients in need of a new aortic valve, surgeons here at the American Association for Thoracic Surgery (AATS) 2011 Annual Meeting agreed.

As reported by heartwire, Dr Craig Miller (Stanford University, CA) presented new details on the neurological-event data from PARTNER cohort A, which included high-risk patients eligible for either surgery or TAVI. [‘high risk’ needs to be better defined if the patients were considered acceptable surgical candidates.] 

The data showed that the risk of neurological adverse events (transient ischemic attack [TIA] and stroke) was slightly higher with TAVI than surgery in the “as-treated” patients, especially in the patients who underwent transapical TAVI because their vessels were too small to accommodate a transfemoral implant, usually because they were obstructed with arteriosclerosis. Rates of major stroke, however, were not statistically different between the two groups in the as-treated analysis.  [numbers/ percents – I need hard data..]

Because of the added neurological risk, Miller believes TAVI should not replace surgery for most patients who can withstand surgery. So he is dismayed that it has grown so rapidly in some European countries where TAVI devices are commercially available, even though the durability of these devices has not been proven. “This is not going to be cost-effective, and civilization cannot afford this if they do not last a good amount of time, and a good amount of time would mean something different to a 95-year-old who is inoperable and to somebody under 70 with a very low surgical risk who should have 10- to 20-year life expectancy. So we have to look at valve durability,” he said.  [I wholeheartedly agree. All of Dr. Miller’s concerns are valid.]

“There are many [inoperable patients like] the people in PARTNER cohort B, who gained 1.9 quality-adjusted life-years, and it only cost $55K per QALY to achieve that. So for the inoperable cohort, it is cost-effective and actually provides meaningful rehabilitation, but the jury is out for the younger patients,” he said. “But the cost economics of the not-so-sick operable patients is going to be different; they’re still beaucoup sick and old in PARTNER A, but to take this down to younger, healthier patients is a huge question mark in my mind and in the FDA‘s mind, because we already have the gold standard of low-risk, durable, surgical [aortic-valve replacement],” Miller said.

Surgeon/interventionalist collaboration is critical

Miller thinks one reason that TAVI has become “a runaway train” in Europe is that in some countries there, interventionalists are able to decide to implant a transcatheter valve without consulting a surgeon or, in some cases, even having a surgeon on site. “The German Federal Ministry of Health didn’t have the backbone to stand up and legislate appropriate use, so it’s a free-for-all. But that would be wrong, especially since we don’t have durability data,” Miller said. Miller said he learned that about a quarter of aortic-valve replacements in 2010 in Germany were TAVI procedures, but Dr John Mayer (Children’s Hospital Boston, MA) reported at the meeting that the figure is now around 40%.

A good amount of time would mean something different to a 95-year-old who is inoperable and to somebody under 70 with a very low surgical risk who should have 10- to 20-year life expectancy.

Mayer and Dr Grayson Wheatley III (Arizona Heart Institute, Phoenix) echoed Miller’s concerns about overenthusiasm for TAVI during a staged luncheon debate on whether or not expensive technologies like TAVI ought to be somehow rationed to control healthcare costs. Mayer took the position of defending rationing and Wheatley argued against it, but they both agreed that physicians and their professional societies ought to work to ensure appropriate use of TAVI.

Wheatley said, “We’re probably going to see something along the carotid-stent paradigm, where it’s FDA approved, but [the Centers for Medicare & Medicaid Services] CMS has restricted [coverage] of an FDA-approved device, based on the data and economics, to the highest-risk patients. I see a lot of parallels there.”

“The Medicare national coverage decision process is going to undoubtedly come into play,” Mayer agreed. “That’s one way to control it, and that’s probably the biggest weapon in the arsenal.” Mayer said that the CMS is already discussing a future Medicare coverage policy for TAVI with the Society of Thoracic Surgeons (STS).

“But the other way to control it is to take the combined cardiology/cardiothoracic surgery approach to be careful about how this gets rolled out,” he said. The STS and the American College of Cardiology (ACC) are currently working on a joint position paper that will call for TAVI appropriateness guidelines based on the PARTNER results, Mayer pointed out. That paper will likely be published this summer. “That’s an extremely important step, and I think the government will understand and accept a lot of the recommendations in there.”

Meanwhile, the Society for Cardiac Angiography and Interventions (SCAI) will be contributing to the STS/ACC position paper and is also developing an expert consensus document with representatives from the AATS, STS, and ACC that will outline training and facility standards for performing TAVI. That document will be published prior to the TCT 2011 conference, according to SCAI.

“The difference between how this was rolled out in Europe and how the investigators in the PARTNER trial would like to roll it out in the United States is that a heart team with a surgeon and cardiologists—and not just the interventional cardiologists, but general cardiologists—make the decisions jointly. That is the model that we think should be imposed going forward,” Mayer said. This collaboration will “be a way of us fulfilling our professional responsibility and making sure that this gets rolled out with high quality and will have the side benefit of keeping it from going nuts like it has in Europe.”

While some may be better off undergoing surgery than transfemoral TAVI, there are also some patients whose risk of neurological injury is so high due to arteriosclerotic burden that they are probably not suitable for either surgery or TAVI, Miller said. “The only thing that’s going to change that is more rigorous patient selection and just saying no,” Miller told heartwire. “That might not go over well in the US where everybody demands everything yesterday, [but] since these are patient-disease-related predictors, more rigorous patient selection is the only thing that will reduce the late hazard of neuro events [in patients with very high arteriosclerotic burden].”

What does PARTNER cohort A reveal about the cause of strokes?

STS president and PARTNER investigator Dr Michael Mack (Medical City Dallas Hospital, TX) told heartwire, “There was an initial thought for the past few years that the transapical might be more neuroprotective than the transfemoral because you don’t transverse the aortic arch with the device, and I think this puts to bed that that was not the case. In fact, the stroke rate was higher in the transapical than in transfemoral, but the presentation showed that it was clearly related to the patient substrate.” The one-year stroke rate in the transfemoral-eligible surgery patients was 1.9%, while the one-year stroke rate for the same surgical procedure in transfemoral-ineligible patients was 9.7%, Mack pointed out. “That says they’re different patients [with] a higher atherosclerotic burden.”

[Collaboration will make] sure that [TAVI] gets rolled out with high quality and will have the side benefit of keeping it from going nuts like it has in Europe.

Mack pointed out that the version of the Sapien valve (Edwards Lifesciences) tested in PARTNER was a first-generation device that did not have the nose cone that newer versions will have, “so you basically had this snowplow that could go across the aortic arch and scrape stuff off; smaller delivery devices with nose-cone protection may be expected to be of benefit,” Mack said. However, previous studies with transcranial Doppler show that the majority of the emboli come from the valve during balloon valvuloplasty and deployment of the valve and not from the aortic arch. “[This is] why you don’t see a benefit of the transapical here, because you’re still blowing up that valve [inside the native valve].”

This explanation is consistent with the study’s finding that, in the first few weeks following the procedure, a smaller valve opening area, which is usually a sign of high calcification around the opening, was associated with a higher risk of neurological events in the TAVI patients. Embolic-protection devices, such as Edwards’s Embrella, may catch some of these emboli released during the valve deployment, Mack said, but clinical experience with these devices is very limited so far.

Better devices may stop a lot of the periprocedural events, but about half of the neurological events happened after the periprocedural period. In this period, the most important risk factor—other than undergoing TAVI instead of surgery or being transfemoral ineligible—was a stroke or TIA within the previous six to 12 months. Atrial fibrillation, which was predicted by some to possibly be a risk factor for strokes, was not associated with an increased risk of neurological events in the study. Dual antiplatelet therapy was recommended for all patients in the trial, but the trial could not track how compliant patients were with that therapy.

“We have absolutely no clue if these strokes were device related or not. We don’t know if the device is thrombogenic, or if all that calcium left in the aorta hanging out eventually breaks out, or if it’s a nidus for clot formation and that breaks off. We just don’t have any insight on that,” Mack said.

PARTNER was sponsored by Edwards Lifesciences. Miller has consulting arrangements with Medtronic CardioVascular, Abbott Vascular, and MitraClip. Mack consults for Edwards Lifesciences and Medtronic.

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“Aortic Stenosis as Heinz 57”

I apologize, but the best analogy I can use – is a squeeze ketchup bottle.

okay, it's not heinz.. but you get the picture..

In normal valve functioning, the three valve leaflets open and close fully to permit and control the flood of blood from the left ventricle to the aorta, where it is then circulated throughout the body.

normal valve diameter

During diastole (the filling phase) the leaflets are shut to prevent blood from leaking backwards from the aorta into the heart.  (When leaflets don’t close properly this is called aortic regurgitation.)

During systole, the ventricle contracts like a big fist,  squeezing the ketchup bottle to shoot blood out of the heart into the aorta.  (The force of this is measured in millimeters of mercury, and is the top number on your blood pressure cuff).  When the valve is working normally, it opens fully and the blood is ejected out to the aorta, and the whole cycle begins again.

In Aortic Stenosis – the valve leaflets have become fused together, either from age or disease.
(Some people are born with only two valve leaflets and this means that they are more likely to develop aortic stenosis as they age.)  As aortic stenosis progresses, the opening for blood to pass thru becomes smaller and smaller since the leaflets can not longer open fully,  In many people – at the time of surgery – this opening is about the size of the pinhole in the ketchup bottle that squirts ketchup.      (The normal sized opening is 2 to 3 centimeters).

average valve opening in severe aortic stenosis

Now, think about how hard a person has to squeeze that ketchup bottle to get some ketchup for hamburgers, fries (and all the other foods I usually scold about in other posts).
In the heart – this pressure is magnified (and can be measured in the cath lab during cardiac catheterization).

As this pressure gets higher and higher to compensate for the narrowed opening, the delicate structures of the heart become damaged, with the heart muscle becoming thicker and less flexible (just like any other muscle with exercise.)  Except unlike biceps, a big thick heart muscle is not a good thing, and can lead to heart failure, arrhythmias and sudden cardiac death.

Eventually, as the heart pushes against the increased pressure, over and over (at least sixty times per minute) the heart gets tired from working so hard.  As the heart fatigues, it is unable to keep up with demand and patients will begin to develop symptoms.

These symptoms include:

Syncope/ near syncope (fainting or near fainting) as not enough blood is pushed into central circulation and to the brain.

Chest pain – because not enough blood is pushed out to the coronary arteries during diastole.  (In a person with aortic stenosis, nitroglycerin can cause problems – as it lowers blood pressure  (and force of contraction even further in someone who needs the extra force.)

Heart failure – the weakened and thickened heart can no
longer keep up and blood begins to back up in the left ventricle.

What these symptoms predict:

Once these symptoms develop, doctors can readily estimate the approximate longevity for patients who do not subsequently have surgery.

From the natural history of aortic stenosis (from before we had surgery to treat it) we know that 50% of people with Syncope will die within 5 years.

Fifty percent of people with chest pain die within three years.

And ultimately, fifty percent of people with heart failure die within two years.

These numbers are important, and I want you to remember them for our subsequent discussions on aortic valve replacement because they need to be factored into a patient’s decision whether or not to pursue surgery.

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