Percutaneous mitral valve repair with the MitraClip appears to be a safe, effective, and life-saving new treatment for severe acute mitral regurgitation (MR) secondary to MI in surgical noncandidates, even when accompanied by cardiogenic shock, according to data from the international IREMMI registry.
“Cardiogenic shock, when adequately supported, does not seem to influence short- and mid-term outcomes, so the development of cardiogenic shock should not preclude percutaneous mitral valve repair in this scenario,” Rodrigo Estevez-Loureiro, MD, PhD, said in presenting the IREMMI (International Registry of MitraClip in Acute Myocardial Infarction) findings reported at the Transcatheter Cardiovascular Research Therapeutics virtual annual meeting.
Commentators hailed the prospective IREMMI data as potentially practice changing in light of the dire prognosis of such patients when surgery is deemed unacceptably high risk because medical management, the traditionally the only alternative, has a 30-day mortality of up to 50%.
Severe acute MR occurs in an estimated 3% of acute MIs, and in roughly 10% of patients who present with acute MI complicated by cardiogenic shock (CS). The impact of intervening with the MitraClip in an effort to correct the acute MR arising from MI with CS has previously been addressed only in sparse case reports. The new IREMMI study is easily the largest dataset to date detailing clinical and echocardiographic outcomes, Dr. Estevez-Loureiro of Alvaro Cunqueiro Hospital in Vigo, Spain, said at the meeting, sponsored by the Cardiovascular Research Foundation.
He reported on 93 consecutive patients who underwent MitraClip implantation for acute MR arising in the setting of MI, including 50 patients in CS at the time of the procedure. All 93 patients had been turned down by their surgical team because of extreme surgical risk. Three-quarters of the MIs showed ST-segment elevation. Only six patients had a papillary muscle rupture; in the rest, the mechanism of acute MR involved left ventricular global remodeling associated with mitral valve leaflet tethering. Percutaneous valve repair was performed at 18 expert valvular heart centers in the United States, Canada, Israel, and five European countries.
Procedural success
Time from MI to MitraClip implantation averaged 24 days in the CS patients and 33 days in the comparator arm without CS.
“These patients had been turned down for surgery, so the attending physicians generally followed a strategy of trying to cool them down with mechanical circulatory support and vasopressors. MitraClip wasn’t an option at the beginning, but after two or three failed weanings from all the possible therapies, then MitraClip becomes an option. This is one of the reasons why the time lapse between MI and the clip is so large,” the cardiologist explained.
Procedural success rates were similar in the two groups: 90% in those with CS and 93% in those without. However, average procedure time was significantly longer in the CS patients: 143 minutes versus 83 minutes in the patients without CS.
At baseline, 86% of the CS group had grade 4+ MR, similar to the 79% rate in the non-CS patients. Postprocedurally, 60% of the CS group were MR grade 0/1 and 34% were grade 2, comparable to the rates of 65% and 23% in the non-CS group.
At 3 months’ follow-up, 83.4% of the CS group had MR grade 2 or less, again not significantly different from the 90.5% rate in non-CS patients. Systolic pulmonary artery pressure was also similar: 39.6 mm Hg in the CS patients, 44 mm Hg in those without. While everyone was New York Heart Association functional class IV preprocedurally, 79.5% of the CS group were NYHA class I or II at 3 months, not significantly different from the 86.5% prevalence in the comparator arm.