CMR quantification of infarct tissue heterogeneity and remote myocardial fibrotic burden during convalescent phase following acute myocardial infarction (MI) provided strong and complementary evidence of ventricular arrhythmogenicity from quantitative microvolt T-wave alternans testing (the NHLBI PROSPECT-CMR study)

In patients with recent MI, elevated fibrotic burden within the remote myocardium quantified by CMR is strongly associated with post-exercise heart rate variability (HRV) and QT dispersion (QTD). In contrast, infarct tissue heterogeneity demonstrated strong association with prolonged mean QRS duration at rest and during exercise. We postulate that these patterns of ischemic structural/arrhythmogenic affiliations during convalescent infarct healing, likely reflect differences in depolarization/repolarization characteristics of different post-ischemic myocardium and sympathetic innervation.