Background:
Acute ischemic mitral regurgitation (MR) is a detrimental complication of ST elevation myocardial infarction (STEMI). We studied a) patient characteristics in acute ischemic MR in anterior versus inferior STEMI and b) its impact on outcomes.
Methods:
We retrospectively studied all patients presenting with STEMI complicated by acute ischemic MR to our center from 1994-2014. Patients were divided into two groups: anterior and inferior STEMI. Endpoints were 30-day and 1-year mortality. All cases with new development of > 2+ MR on baseline echo within 3 days of index MI were analyzed.
Results:
Out of 4005 STEMI patients, there were 221 patients (52.5% males) with acute MR at an incidence of 5.5% [74/1666 (4.4%) in anterior vs 147/2306 (6.4%) in inferior STEMI, p=0.02]. At baseline, there were no significant differences between anterior vs. inferior STEMI in age, co-morbidities or degree of MR (Table). Mean ejection fraction (EF) was 31±14 vs 45±13% (p<0.01). Median length of hospital stay was 6 vs 4 days (p<0.01). Overall 30-day mortality was 20 with anterior vs 10% (p=0.03) with inferior while 1-year mortality was 43 vs 24% (p<0.01) respectively. Overall 30-day mortality in 2+, 3+ and 4+ MR was 9, 19 and 29% while 1-year mortality was 23, 39 and 41% (p<0.01). Factors associated with 1-year mortality were older age (Hazards Ratio or (HR) 1.5, 95% CI 1.3-1.9, p<0.01), EF (HR 0.96, 95% CI 0.94-0.97, p<0.01), higher degree of MR (HR 4.6, 95% CI 1.6-11.7, p<0.01), DM (HR 2.4, 95% CI 1.4-3.9, p<0.01), shock on presentation (HR 2.3, 9% CI 1.3-4, p<0.01) and blood transfusion (HR 2.4, 95% CI 1.5-4, p<0.01). Kaplan-Meier survival curves for both groups and across grades of MR are shown in figure 1a and b.
Conclusion:
Acute ischemic MR is seen more commonly with inferior yet has worse outcomes in anterior STEMI with increased short and long term mortality. Further, old age, low EF, higher degree of MR, shock on presentation, and need for blood transfusion are associated with worse outcomes.