Distribution of QRST deflection areas in relation to repolarization and arrhythmias

QRST area maps were calculated from a computer model of propagated excitation with nonuniform cycle length-dependent recovery. Vulnerability was independently assessed as fibrillation threshold (FT). Separate effects of varied range and mean recovery durations on FT and QRST maps were determined. FT was inversely related to the range of recovery durations and that range was related to QRST area map features including magnitude, nonuniformity, and gradients. Mean recovery duration was directly related to FT but did not alter QRST maps unless changes of recovery duration were localized. Locally decreased mean duration resulted in decreased FT and increased magnitude and nonuniformity and gradients in QRST maps. Locally increased mean duration had similar effects on QRST maps, but FT was increased. Results support the validity of QRST map features as markers of vulnerability due to disparity of recovery duration or locally decreased mean recovery duration but not due to widespread changes of mean duration or locally increased duration.