Prediction of life-threatening arrhythmic events in patients with chronic myocardial infarction by contrast-enhanced CMR

OBJECTIVES: We hypothesized that infarct transmurality assessed with late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) predicts arrhythmic events in patients with chronic myocardial infarction. BACKGROUND: Patients with decreased left ventricular function due to chronic myocardial infarction are at increased risk for life-threatening arrhythmias related to infarcted tissue. LGE-CMR accurately detects infarct morphology. METHODS: We prospectively enrolled 52 patients with chronic myocardial infarction referred for primary preventive implantable cardioverter-defibrillator (ICD) implantation following MADIT (Multicenter Automatic Defibrillator Implantation Trial) study criteria. Using LGE-CMR, left ventricular volumes, function, and infarct morphology were assessed including calculation of total and relative infarct mass, infarct border, infarct border zone, and infarct transmurality. RESULTS: Patients were followed for 1,235 +/- 341 days. The primary combined endpoint including appropriate device therapy (ICD discharge or antitachycardia pacing) or death from cardiac cause occurred in 16 individuals resulting in an annual event rate of 4.7%. Six patients received an appropriate shock, 7 patients received recurrent appropriate antitachycardia pacing for sustained ventricular tachycardia, and 3 patients died of cardiac cause. There was a significant association to relative infarct mass (38 +/- 8% vs. 28 +/- 14%, p = 0.02), infarct transmurality (24 +/- 8 g vs. 16 +/- 12 g, p = 0.02), and relative infarct transmurality (RIT) (63 +/- 12% vs. 48 +/- 23%, p = 0.01). In separate logistic regression models, no variable emerged as significant when combined with RIT. As a single effect, RIT emerged as a predictor of the primary endpoint (p = 0.02). A RIT cutoff at 43% resulted in a sensitivity of 88%, a specificity of 50%, a positive predictive value of 44%, and a negative predictive value of 90%. CONCLUSIONS: In patients with chronic myocardial infarction scheduled for primary preventive ICD implantation, infarct transmurality as defined by LGE-CMR identifies a subgroup with increased risk for life-threatening arrhythmias and cardiac death