Clinical significance of late potential in patients with Duchenne muscular dystrophy.

The relationship between late ventricular potentials (LP) and myocardial ischemic changes or ventricular arrhythmias was investigated in patients with Duchenne muscular dystrophy (DMD). Twenty-six DMD patients aged 10-33 years (mean 18.2 years) and 27 age-matched healthy volunteers were studied. Ventricular arrhythmias were detected by 24-h Holter ECGs and LPs were determined using signal-averaged ECGs. In DMD patients filtered QRS duration, late duration, and low-amplitude signal under 40 microV were significantly prolonged compared with those of the controls. The root mean square voltage of the f-QRS complex in the last 40 ms was lower in DMD patients than in the controls. None of the control subjects had LP. However, LP was detected in 8 (31%) of the 26 DMD patients. The patients with LP had more frequent ST-T depression and ventricular arrhythmias than the patients without LP. LP had 60% sensitivity and 87% specificity for documented ventricular arrhythmias. It is concluded that LP in DMD patients indicates the presence of substrate for ventricular arrhythmias associated with local myocardial fibrosis, and is useful in identifying those at high risk for malignant ventricular arrhythmias.