Mounting Use of 'Primary' TAVR in Shock from Aortic Stenosis

June 04, 2020

The buzz on transcatheter aortic valve replacement (TAVR) has long focused on its steady expansion to patients at progressively lower levels of surgical risk. But there are patients with aortic stenosis whose overall risk exceeds even the most severe that was addressed in the earliest major trials comparing TAVR with surgical aortic valve replacement.

The share of TAVR procedures performed in the United States within 24 hours of presentation in shock fell by more than one-half over a recent 4-year period that saw climbing TAVR use overall in lower-risk patients. But at the same time, the absolute number of TAVRs in shock attributed to aortic stenosis went up by more than a factor of three.

The analysis, published in the June 8 issue of JACC: Cardiovascular Interventions, not surprisingly showed their mortality at 30 days to be abysmal, even if improved by TAVR. But mortality seemed primarily driven by shock severity rather than any complications related to TAVR, conclude the authors, led by Luke Masha, MD, MPH, Oregon Health & Science University, Portland.

"Although our study signals the clear safety and benefit of an expedient TAVR for carefully selected patients in cardiogenic shock, we also demonstrate that much of the associated mortality is not addressed by resolving aortic stenosis alone," they write.

The analysis is based on patients in the Society of Thoracic Surgeons and the American College of Cardiology Transcatheter Valve Therapy (STS/ACC TVT) registry and Medicare claims data covering 2014 to 2017. Patients for whom shock preceded TAVR were compared with high-risk patients without shock.

Much discussion has centered on how early in the spectrum of disease patients with aortic stenosis can go to TAVR rather than surgical aortic replacement, "but there hasn't been a lot of focus, at this point, on what can we do for the patients who are the sickest at the time of TAVR," Masha observed for | Medscape Cardiology.

Most patients in cardiogenic shock aren't suitable for surgery, and the major TAVR trials excluded patients with severe hemodynamic compromise, so there's little evidence base to guide therapy. Yet without intervention, he said, the expectation is that virtually all patients in shock from aortic stenosis will die within 30 days.

With TAVR, mortality may be as low as 10% for such patients with the least severe shock, and up to 40% for the most severe cases, Masha said. "It can be really quite favorable if physicians are somewhat aggressive with these shock patients, although there's probably a point where the patient is too far gone."

And regardless of the severity of shock in patients going to TAVR, he cautioned, "we still really need to work on our outcomes with these patients."

"The results of this study support not only the feasibility but also the safety of TAVR in this particularly high-risk population. However, can we claim the use of TAVR as the first-line therapy in any patient admitted with cardiogenic shock and aortic stenosis?" asks an editorial accompanying the report.

The results are "encouraging" but should be seen in light of the study's limitations, write Marina Urena, MD, PhD, and Dominique Himbert, MD, both from Bichat Claude Bernard Hospital, Paris.

For example, as they and the report's authors note, the observational study is based on an American registry limited to TAVR patients, which likely biased the population toward those less sick and more likely to benefit from the intervention. Also, it may be "challenging" to determine that aortic stenosis is the main driver of shock. And, TAVR isn't available at many interventional centers that can instead perform balloon valvuloplasty.

"In light of these results, 'primary' TAVR might be the best strategy in selected patients with cardiogenic shock and aortic stenosis," they write. But balloon valvuloplasty "as bridge to a definitive therapy might be the preferable therapy in the sickest patients."

The prevalence of acute cardiogenic shock fell steadily in the TAVR registry from 8.2% in 2012 to 3.2% in 2017, for an average of 4.1%; their mortality dropped from 28% to 16.6%.

In the 2014-2017 analysis comparing 2,220 patients with shock and 12,851 high-risk patients without shock, median STS risk scores were comparable at 9.8 and 10.2, respectively.

In the absence of appropriate hemodynamic data, the group defined cardiogenic shock as "inotrope use within 24 h before TAVR, pre-procedural cardiac arrest, pre-procedural use of mechanical circulatory support or cardiopulmonary bypass."

All-cause mortality at 30 days, the primary outcome, averaged 19.1% during the period for patients with shock, compared with 4.9% in the other group. The adjusted hazard ratio (HR) was 3.7 (< .001). The risk for stroke was also significantly increased for patients with shock.

Hazard Ratio (HR) for End Points, Shock vs No Shock, Multivariate Analysis*
End Point HR (95% CI) P Value
30-day mortality 3.73 (3.11–4.48) <.001
30-day stroke 1.69 (1.32–2.16) <.001
1-year mortality 1.83 (1.61–2.07) <.001
1-year stroke 1.37 (1.11–1.68) .003
*Adjusted for factors including demographics, body surface area, LVEF, hemoglobin, platelets, renal function, coronary anatomy, history of MI or stroke, endocarditis, carotid or peripheral artery disease, smoking, diabetes, NYHA class, atrial fibrillation, chronic lung disease, home oxygen, access site, pacemaker, cardiac surgical history, valve insufficiency, mean and peak AV gradient, and use of circulatory support device.

Mortality appeared to be proportional to shock severity. For example, 30-day mortality was 9.9% for patients put on inotropic agents only, 15.9% for those put on pre-TAVR mechanical circulatory support, 17.0% for those with previous cardiac arrest, but 41.0% for those put on cardiopulmonary bypass support.

It's clear why TAVR is growing in patients at low surgical risk, Masha said, "but it wasn't actually clear to us why the highest-risk population is growing as well."

Perhaps, he speculated, cardiology has rapidly come to routinely view TAVR as a go-to treatment option and, in the absence of clinical-trial guidance, is increasingly comfortable seeing selected patients with aortic stenosis in cardiogenic shock as suitable candidates.

Masha reports no relevant conflicts; disclosures for the other authors are in the report. Himbert discloses serving as a proctor for Edwards Lifesciences and Abbott. Urena had no relevant disclosures.

J Am Coll Cardiol Intv. 2020;13:1314-1325, 1326-1328. Abstract, Editorial

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