Prevalence of postural T wave changes in mitral valve prolapse: a quantitative study.

The abnormal ECG T wave changes associated with mitral valve prolapse (MVP) were studied and quantitated in a group of 36 asymptomatic individuals with MVP and compared with a 27-member control group. The mean frontal plane T wave axis shifted markedly leftward on standing, with T wave axis less than or equal to 0 degrees in 16 (44%) of the subjects with MVP vs. only 2 (7.4%) of the control group, while the QRS-T angle widened to more than 60 degrees in 18 (50%) of those with MVP. Marked left axis deviation of the T wave on standing with T wave axis less than or equal to -30 degrees was found only in subjects with MVP, and their QTc interval was longer, P less than 0.05. In 11 subjects with mitral valve bowing or rounding on the echocardiogram (i.e., less than 2 mm posterior mitral valve displacement), intermediate grades of T wave axis shifts were seen.