The electrocardiogram in asymmetric septal hypertropy.

Electrocardiograms and echocardiograms in 44 patients with asymmetric septal hypertrophy were reviewed. Patients with asymmetric septal hypertrophy had incidences of left ventricular hypertrophy (33 percent; 16/44) and left atrial hypertrophy (25 percent; 11/44) by ECG that were less than in a group of patients with significant aortic stenosis (70 percent [31/44] and 64 percent [28/44], respectively). Left ventricular hypertrophy on the ECG was associated with a greater septal-posterior wall thickness ratio in asymmetric septal hypertrophy. A small Q wave in lead V4 or a ratio of the R-wave to the S-wave amplitude (R/S ratio) of greater than 0.20 in lead V1 was found in 14 of 44 patients with asymmetric septal hypertrophy but in no patients with aortic stenosis. The mean corrected Q-T interval (Q-Tc) of patients with asymmetric septal hypertrophy was prolonged, and the mean Q-Tc of patients with aortic stenosis was normal. The distinctive findings of an R/S ratio of more than 0.2 in lead V1 and Q waves in lead V4 in asymmetric septal hypertrophy have clinical significance, and the prolonged Q-T interval may relate to sudden death.