Impact of infarct location on left ventricular ejection fraction after correction for enzymatic infarct size in acute myocardial infarction treated with primary coronary intervention.

BACKGROUND: Left ventricular function and infarct size are strong predictors for prognosis after acute myocardial infarction (MI). Anterior MI is associated with greater reduction of left ventricular ejection fraction (LVEF) and worse prognosis. Our objective was to study whether the impact of infarct size on global LVEF is dependent of infarct location.
METHODS: We analyzed 888 patients treated with primary percutaneous coronary intervention for acute MI. Enzymatic infarct size and LVEF within 1 week were measured. In 490 patients (55%), LVEF was measured a second time at 6 months.
RESULTS: Every 1000 U/L of cumulative lactate dehydrogense release corresponded to a decrease of 4.7% (95% CI 4.1-5.3) in LVEF measured within 1 week post MI for left anterior descending coronary artery (LAD)-related infarcts and to a decrease of 2.4% (95% CI 1.7-3.1) in LVEF measured within 1 week post MI for non-LAD-related infarcts (P < .0001). Left ventricular ejection fraction measured 6 months post MI showed a decrease for every 1000 U/L cumulative lactate dehydrogense release of 4.8% (95% CI 4.2-5.3) for LAD and 2.4% (95% CI 1.7-3.1) for non-LAD-related infarcts (P < .0001). Multivariate correction for relevant clinical and angiographic data did not change these results.
CONCLUSION: In patients with a first acute MI treated with primary percutaneous coronary intervention, LAD-related infarcts show for a similar amount of myocardial necrosis as determined by enzymatic infarct size, a lower residual LVEF when compared with non-LAD-related infarcts.