Severe mitral regurgitation complicating acute myocardial infarction. Clinical and angiographic differences between patients with and without papillary muscle rupture.

AIMS: To assess the differential clinical and angiographic characteristics of patients with severe mitral regurgitation related (n = 31) or unrelated (n = 16) to papillary muscle rupture complicating acute myocardial infarction. METHODS AND
RESULTS: The clinical and angiographic features of patients with myocardial infarction and severe mitral regurgitation were evaluated. Patients with papillary muscle rupture were older (67 vs 60 years, P < 0.005) and had a lower rate of diabetes (7% vs 38%, P < 0.005) and of previous angina or infarction (24% vs 50%, P < 0.05). Frequency of inferior infarction was high and comparable in both groups (papillary muscle rupture, 72% vs non-papillary muscle rupture, 88%, ns) whereas in-hospital rate of angina/infarct extension prior to mitral regurgitation, also high, tended to be higher in patients without than in those with papillary muscle rupture (67% vs 39%, ns). Incidence of multivessel disease tended to be higher in patients without papillary muscle rupture (87% vs 56%, P < 0.06) and they had a lower ejection fraction (46 +/- 15 vs 61 +/- 14%, P < 0.03), whereas the culprit artery was mainly the right or the circumflex coronary artery in both groups (papillary muscle rupture, 100% vs non papillary muscle rupture, 93%, ns). Valve replacement was performed earlier in patients with papillary muscle rupture (1 (1; 14) vs 25 (5; 45) days, median, P < 0.002) but was associated with a similar mortality (papillary muscle rupture 11/24, 46% vs non-papillary muscle rupture, 7/15, 47%, ns). The main cause of death was cardiogenic shock in patients without papillary muscle rupture (5/7, 71%), and respiratory insufficiency--sepsis in those with papillary muscle rupture (7/11, 64%).
CONCLUSIONS: Severe mitral regurgitation in myocardial infarction with or without papillary muscle rupture is mostly related to inferior infarction and often follows reinfarction, particularly in non-papillary muscle rupture cases. The main contributors to surgical mortality appear to be respiratory insufficiency in patients with papillary muscle rupture and cardiogenic shock, facilitated by a lower ejection fraction, a higher frequency of diabetes and more extensive coronary disease, in patients without papillary muscle rupture.