In Cardiogenic Shock, Edge-to-Edge Mitral Valve Repair Improves Outcome

Ted Bosworth

September 17, 2022

In patients with severe mitral regurgitation (MR) and cardiogenic shock, successful transcatheter edge-to-edge repair (TEER) is associated with a substantial reduction in all-cause mortality and lower morbidity at 1 year, according to an analysis of registry data.

The data from this analysis also confirm that "successful reduction of MR is achievable with TEER in most patients with cardiogenic shock," reported Mohamad A. Alkhouli, MD, an interventional cardiologist and professor of medicine at the Mayo Clinic, Rochester, Minnesota.

In those with device success, achieved in 85.6% of patients, all-cause mortality was about 21% lower (34.6% vs. 55.5%; P < .001) at 1 year than in those who were not successfully repaired, according to Dr. Alkhouli, who presented the findings at the Transcatheter Cardiovascular Therapeutics annual meeting in Boston. This translated into a reduction in the hazard ratio for death of nearly 50% (HR, 0.52; 95% confidence interval, 0.43-0.63).

A similar relative benefit was found for the composite endpoint of mortality and heart failure admissions at 1 year. Whether unadjusted (HR, 0.54; 95% CI, 0.45-0.66) or adjusted (HR, 0.51; 95% CI, 0.42-0.62), risk reductions with successful MR reduction, defined as ≥1 grade improvement and a final MR grade of ≤2+, indicated that major adverse outcomes are reduced by about half.

STS/ACC TCT Registry Data Queried

Drawn from the Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy Registry, 3,797 patients with cardiogenic shock underwent MR repair between November 2013 and December 2021. Outcomes at 1 year were evaluable in 2,773 of these patients. For inclusion, all had to meet at least one of the definitions of cardiogenic shock, such as inotrope use or mechanical circulatory support.

At baseline, 94.5% had a MR severity of at least 3+, and most of these had 4+. Thirty days after treatment, 88.8% had MR severity of 2+ or less, the majority of which had a severity of 1+.

These data address an important question not previously well studied, according to Dr. Alkhouli. In MR patients, cardiogenic shock is associated with a high risk of death, but there has been little evidence that valve repair does not exacerbate let alone modify this risk.

These data support the value of intervention, which was performed in almost all patients with MitraClipä (Abbott), the only device available for most of the period in which the registry was queried. However, Dr. Alkhouli cautioned that his data are best considered "hypothesis generating."

"We need a randomized trial," he said at the meeting, sponsored by the Cardiovascular Research Foundation. He pointed out that this is a complex population for which multiple variables might have skewed results when data are analyzed retrospectively. Not least, those MR patients with cardiogenic shock in the database considered for TEER might well have been relatively healthy and not representative of an unselected population with both MR and cardiogenic shock.

The question might be better answered by the multicenter Canadian trial CAPITAL MINOS, which has just started. Described in an article in the American Heart Journal, it has a planned enrollment of about 150 MR patients with cardiogenic shock randomized to TEER or medical therapy. Results are expected in about 1 year, according to Dr. Alkhouli.

But regarding the present analysis, Dr. Alkhouli did note that sensitivity analyses conducted within his data across risk factors, such as degenerative versus nondegenerative MR, low (<30%) versus higher left ventricular ejection fraction (LVEF), and presence or absence of an acute coronary syndrome (ACS), consistently supported a benefit from intervention.

Also, cardiogenic shock did not appear to be a factor in device failure, according to Dr. Alkhouli, addressing a potential criticism that cardiogenic shock was an underlying reason for device failure.

>90% in NYHA Class III or IV Heart Failure

In this study, the mean age was 73 years. More than 90% were in class III or IV heart failure in the 2 weeks prior to TEER. More than half had established coronary artery disease. Other concomitant cardiovascular morbidities, including atrial fibrillation or flutter (65%), prior MI (39%), and prior stroke or transient ischemic attach (>10%) were well represented.

When those with device success were compared to those with device failure, the risk profile was comparable. The predicted STS (Society of Thoracic Surgeons) mortality for mitral valve repair among these two groups was 14.8% vs. 15% (P = 0.97), respectively.

However, those with device failure did have a lower baseline left ventricular ejection fraction (40.7% vs. 42.9%; P = .009) and a greater prevalence of moderate-to-severe or severe MR (96.1% vs. 84.9%; P < 0.001).

The growing experience with TEER means that benefit has now been shown in several complicated MR groups, such as those with severe ventricular dysfunction, renal insufficiency, and obstructive lung disease. This was a rationale for looking at the impact or repairing MR in patients with cardiogenic shock.

It is a pressing question, according to Dr. Alkhouli. He cited studies suggesting that up to 20% of patients hospitalized for cardiogenic shock have at least moderate-to-severe MR. Conversely, cardiogenic shock is not an uncommon finding in patients with MR.

While Dr. Alkhouli acknowledged that the many variables influencing outcome in patients with MR and cardiogenic shock will make a randomized trial "challenging," many experts echoed this concern and even expressed some skepticism about the potential for an unbiased trial.

Data Confirm MR Repair Is Safe During Shock

"These data do show that repair of MR is safe in patients safe in patients with cardiogenic shock," said Anita W. Asgar, MD, an interventional cardiologist associated with the Montreal Heart Institute, Canada. She noted that there was a 5- to 6-day delay among the cardiogenic shock patients prior to undergoing MR repair in this analysis, potentially reflecting an elimination of those at very high risk. Similarly, she suggested that many interventionalists are likely to consider multiple variables before proceeding.

As a result, MR repair may not be amenable to randomization in a cardiogenic shock population, given that this decision is not typically undertaken out of the context of multiple variables.

"I am not sure that a clinical trial is ethical," she said. She would expect that clinicians enrolling patients would only do so on a selective basis.

Alexandra J. Lansky, MD, Director of the Yale Heart and Vascular Research Program, Yale University, New Haven, Connecticut, also emphasized the difficulty of controlling for variables, such as the duration of cardiogenic shock, that influence decision-making.

Nevertheless, she called the data "very important" in that they at least lend some objective data for deciding whether to intervene a group of "challenging" patients not uncommonly faced in clinical practice.

Dr. Alkhouli reports financial relationships with Abbott Vascular, Boston Scientific, Johnson & Johnson, and Phillips. Dr. Asgar reports financial relationships with Abbott Vascular, Edwards Lifesciences, W.L. Gore & Associates, and Medtronic. Dr. Lasky reports no potential conflicts of interest.

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