Cardiogenic Shock Spells Poor Outcomes Despite Successful TAVR

TAVR is feasible and associated with high success rates in patients with severe aortic stenosis who present with acute cardiogenic shock, but mortality remains much higher in this group than in the broader high-risk TAVR population, registry data show.

Mortality at 30 days was 19.1% in patients who had presented with cardiogenic shock and 4.9% in patients who were considered high risk but did not have shock (adjusted HR 3.7; 95% CI 3.1-4.5), despite a similar TAVR result in both groups in terms of postprocedural mean gradient, according to researchers led by Luke Masha, MD (Oregon Health & Science University, Portland).

Though shock patients had more procedural complications, those accounted for only a small part of the observed mortality difference. Much of the disparity instead seemed to be driven by the severity of preprocedural shock, the investigators report in a study published online ahead of the June 8, 2020, issue of JACC: Cardiovascular Interventions.

“There is a clear point where the patient is so significantly ill that even a successful TAVR is unlikely to change their 1-month or 3-month outcome. And physicians need to be well aware of that and need to do pretty much everything in their power to avoid referring patients for TAVR when it’s well too late,” Masha told TCTMD.

Still, the study should alleviate some of the concerns physicians have about performing TAVR in critically ill patients, he said, pointing to the high rate of procedural success in the shock cohort and the roughly 20% mortality rate at 30 days. That’s high, Masha acknowledged, but he said it indicates that TAVR is having a benefit in a group of very sick patients in which mortality would be much higher without an intervention.

There is a clear point where the patient is so significantly ill that even a successful TAVR is unlikely to change their 1-month or 3-month outcome. Luke Masha

Commenting for TCTMD via email, Christian Frerker, MD (Heart Center of the University of Cologne, Germany), said the study confirms that TAVR is a treatment option for patients with cardiogenic shock due to severe aortic stenosis. He noted that the first TAVR performed by Alain Cribier, MD, in 2002 was done in a patient with cardiogenic shock who had undergone an emergency balloon valvuloplasty a week prior.

“However, despite these arguments for doing TAVR first, there are some arguments against this treatment option,” he added. “TAVR is not available at every hospital and these hemodynamically unstable patients could not be transferred to a TAVR center. For these patients, in which TAVR is [not an] option, balloon valvuloplasty could be a lifesaving procedure.”

Cardiogenic Shock-TAVR Population Growing

Physicians commonly encounter patients who present with acute cardiogenic shock and untreated severe aortic stenosis, but because these patients have been excluded from the pivotal TAVR trials, there are few data on which to base management decisions, Masha said.

To help fill the evidence gap, the investigators turned to the Society of Thoracic Surgeons/American College of Cardiology TVT Registry, also looking at claims data from the Centers for Medicare & Medicaid Services. Because of the lack of invasive hemodynamic data in the registry, cardiogenic shock was defined as inotrope use in the 24 hours before TAVR, preprocedural cardiac arrest, and preprocedural use of mechanical circulatory support or cardiopulmonary bypass.

From 2012 to March 2017, 4.1% of patients who underwent TAVR presented with acute cardiogenic shock. That proportion dropped from 8.2% in 2012 to 3.2% in 2017 due to the disproportionate growth in TAVR in lower-risk groups over that span, although the total number of patients with cardiogenic shock undergoing TAVR increased threefold. That “suggests to us that this is a population that really is quite ripe for study because it’s not going away. It’s only growing,” Masha said.

To explore outcomes in shock patients, Masha et al compared 2,220 patients with cardiogenic shock (median STS score 9.8) and 12,851 high-risk patients (median STS score 10.3) who underwent TAVR between 2014 and 2017. The analysis was limited to fee-for-service Medicare beneficiaries who were older than 65.

Procedural success, based on postprocedural mean gradient, was comparable in both groups.

Outcomes, however, were worse in the shock group. The mortality curves diverged early and continued separating up until about 3 months; after that point, rates of mortality were similar. At 30 days, cardiogenic shock patients also had a higher rate of stroke (4.0% vs 2.6%; adjusted HR 1.7; 95% CI 1.3-2.2). The excess risks of both outcomes associated with acute cardiogenic shock persisted at 1 year—mortality (HR 1.83; 95% CI 1.61-2.07) and stroke (HR 1.37; 95% CI 1.11-1.68).

Rates of various procedural complications, including new dialysis, valve reintervention, and unplanned cardiac surgery, were elevated in the shock group, so the investigators checked to see what impact that had on the observed mortality difference. “In our analysis, the absence of procedural complications by VARC-2 early safety criteria appeared to only minimally reduce the risk of death at 30 days,” they report.

Risk of death, they say, is more strongly related to the severity of shock before TAVR. Indeed, prior cardiac arrest and preprocedural use of inotropes, mechanical circulatory support, and cardiopulmonary bypass were all tightly linked to 30-day mortality.

Role of Balloon Valvuloplasty

In an accompanying editorial, Marina Urena, MD, PhD, and Dominique Himbert, MD (both Hospital Bichat-Claude Bernard, Paris VII University, France), say the study supports the feasibility and safety of TAVR in patients presenting with cardiogenic shock.

“However,” they add, “can we claim the use of TAVR as the first-line therapy in any patient admitted with cardiogenic shock and aortic stenosis? Although encouraging, these results should be interpreted while keeping in mind the shortcomings and limitations of the study.” Urena and Himbert point to selection bias in that only patients who underwent TAVR were included; the difficulty of confirming the causal role of valve disease in patients with cardiogenic shock; differences in management between groups, including less frequent use of CT and transfemoral access in the shock patients; the lack of information on the time from presentation to TAVR; and the fact that TAVR was futile in the patients who either died within a year or had poor quality of life after the procedure.

“Moreover, from a societal perspective, TAVR does not meet the commonly accepted thresholds for cost-effectiveness if life expectancy is < 2 years or if the quality of life remains poor after a successful procedure,” they write. “In the sickest patients, a less expensive intervention should probably be favored.”

Therefore, even though “‘primary’ TAVR might be the best strategy in selected patients with cardiogenic shock and aortic stenosis,” Urena and Himbert say, percutaneous balloon aortic valvuloplasty “as bridge to a definitive therapy might be the preferable therapy in the sickest patients yet to avoid futility.”

Frerker said balloon valvuloplasty might be an option for some patients, but added that “we know from the literature that patients after a valvuloplasty procedure still have a gradient across the aortic valve with a mostly still severe grade of aortic stenosis. In my opinion, particularly patients in cardiogenic shock should be treated optimally with respect to the correction of aortic stenosis. Another argument against doing a balloon valvuloplasty is the higher risk of significant postprocedural aortic regurgitation.”

On the other hand, TAVR and SAVR are not always available and transferring patients with cardiogenic shock is risky, Frerker said. “In such a setting and situation, balloon valvuloplasty should be discussed as a treatment option, especially as a bridge to TAVR or SAVR.”

Additional studies are needed to identify the best strategy, Urena and Himbert say. “However, even with a first-line definitive therapy, the risk of mortality of these patients remains high; thus, all efforts should be done not only to avoid any delay on their treatment, but also to prevent cardiogenic shock by early referral of patients with severe aortic stenosis.”