Impaired left ventricular function is associated with increased recovery time dispersion in patients with previous myocardial infarction☆

Left ventricular (LV) dysfunction after myocardial infarction is associated with higher risk of serious ventricular arrhythmias and sudden death. We suspected that heterogeneity in ventricular repolarization contributes to these arrhythmias. To quantify this heterogeneity, we measured the recovery time (the interval between QRS onset and the time of maximum dV/dt in the ST-T segment) using an 87-lead body surface mapping electrocardiogram and estimated recovery time dispersion (the difference between maximum recovery time and minimum recovery time) in each lead. Differences between 110 patients with previous myocardial infarction and 31 healthy controls were compared. Recovery time dispersion [medians (25th, 75th percentiles)] was greatest in patients with a dilated LV {169 ms (154, 201) vs. 155 ms (137, 172), P < .005}, impaired ejection fraction {173 ms (155, 202) vs. 152 ms (138, 165), P < .0005} and LV dyskinesis {175 ms (159, 201) vs. 155 ms (137, 161), P < .0005}. This study suggests that LV dysfunction associated with myocardial infarction leads to heterogeneous ventricular repolarization and may provide the electrical substrate for ventricular arrhythmias.