Structural barriers can promote discordant action potential (AP) duration alternans, T wave alternans (TWA) and tachyarrhythmia in animal hearts and simulation studies. We hypothesized that heterogeneous scar (gray zone) and dense midwall scar (midwall core) would promote TWA in patients with cardiomyopathy by slowing conduction and uncoupling transmural APs, respectively. Scar core and gray zone were quantified in 40 cardiomyopathy patients using late gadolinium enhanced cardiac magnetic resonance imaging and related to the results of a clinically validated TWA test. The percentages of gray zone, epicardial core and midwall core were greater in the +TWA group, correlated with TWA magnitude and related to a lower heart rate onset for TWA. These specific scar patterns contribute to the genesis and severity of TWA in cardiomyopathy. Greater knowledge of the substrates that promote TWA in cardiomyopathy patients is valuable in determining those at risk of lethal ventricular arrhythmias.

Structural barriers can promote discordant action potential (AP) duration alternans, T wave alternans (TWA) and tachyarrhythmia in animal hearts and simulation studies. We hypothesized that heterogeneous scar (gray zone) and dense midwall scar (midwall core) would promote TWA in patients with cardiomyopathy by slowing conduction and uncoupling transmural APs, respectively. Scar core and gray zone were quantified in 40 cardiomyopathy patients using late gadolinium enhanced cardiac magnetic resonance imaging and related to the results of a clinically validated TWA test. The percentages of gray zone, epicardial core and midwall core were greater in the +TWA group, correlated with TWA magnitude and related to a lower heart rate onset for TWA. These specific scar patterns contribute to the genesis and severity of TWA in cardiomyopathy. Greater knowledge of the substrates that promote TWA in cardiomyopathy patients is valuable in determining those at risk of lethal ventricular arrhythmias.