[Evaluation of systolic intervals in Duchenne cardiomyopathy]

Patients with progressive muscular dystrophy rarely survive beyond the second or third decades: the commonest causes of death are respiratory failure and cardiac failure. An easily repeatable method for early recognition of cardiac dysfunction and its follow-up would therefore be valuable. We performed a polycardiographic study of systolic time intervals in 11 patients with dystrophy (each subject representing an age from 7 to 17 years) in a group comprising 10 of their mothers and in control groups matched for age and sex. The mean values of QS2, PEP and QS1 were significantly higher in patients compared to controls (QS2 : 543 +/- 26 msec compared to 519 +/- 19 msec; PEP : 142 +/- 21 msec compared to 123 +/- 18 msec, and QS1 : 105 +/- 22 msec compared to 75 +/- 12 msec) whilst mean ICT was shorter (36 +/- 11 msec, compared to 49 +/- 5 msec). Mean LVET was comparable in patients and control. These results indicate a reduction in compliance and an increase in end diastolic left ventricular tension. When the systolic time intervals were analysed in each child, an increase in PEP and reduction in LVET were characteristic of the more serious phases of the disease with cardiac failure. It is emphasized that early stages of the disease are characterised by restrictive changes resulting in a reduction in ICT whilst terminal stages with reduced cardiac output cause a reduction in LVET and an increase in PEP. No significant changes were found in the mothers of patients compared to the control group. These results indicate that systolic time intervals may be useful in following up patients with Duchenne's cardiomyopathy.