Systolic time intervals in Duchenne muscular dystrophy: evaluation of left ventricular performance

The purpose of this study was to evaluate the prevalence of latent cardiac heart failure in Duchenne's muscular dystrophy (DMD). Systolic time intervals (STI) were measured in a cross-sectional study of a group of 177 patients 6-21 years old. Total electromechanical systole (QS2), left ventricular ejection time (LVET), and pre-ejection period (PEP), were corrected for heart rate by means of regression equations obtained from 33 normal subjects (QA2 I, LVET I, PEP I). Mean STI values were significantly different from those observed in an age-matched control group. PEP I was prolonged, LVET I was abbreviated, while QS2 I remained unaltered. STI varied significantly with age. Abnormal values were uncommon before age 10 years. The most critical period was 14-16 years, with an abrupt increase in prevalence from 35 to 72%. Such changes point to the practical use of the STI for clinical decision making especially for surgery.