Noninvasive assessment of myocardial involvement in patients with systemic sclerosis: role of signal averaged electrocardiography.

Objective: To assess the role of late ventricular potentials (LVP) in detecting early myocardial involvement in patients with systemic sclerosis (SSc).

Methods: Seventy-seven patients with SSc (68 women, 9 men, mean age 50 +/- 13 yrs) and 33 control subjects (18 women, 15 men, mean age 46 +/- 10 yrs) underwent resting electrocardiogram (ECG), 24 h Holter monitoring, complete echocardiographic and Doppler echocardiographic examination, and signal averaged ECG at high pass setting of 40 Hz, with the low pass fixed at 250 Hz. Patients with SSc underwent resting myocardial scintigraphy and radionuclide angioventriculography.

Results: The prevalence of LVP at 40 Hz was 20.5%. Compared to control subjects, patients with SSc showed higher prevalence of septal infarction pattern (p = 0.05), complex ventricular arrhythmias (p = 0.03), pulmonary arterial hypertension (p < 0.001), and LVP (p = 0.02). Forty-four patients with SSc (57.1%) had resting perfusion defects by myocardial scintigraphy. Fourteen of 15 patients with LVP showed perfusion defects compared to 29 of 58 without LVP (p = 0.002). Linear regression analysis showed that myocardial perfusion defect score was significantly correlated to either the filtered QRS duration, or the duration of low amplitude signals < 40 microV of the terminal QRS, or the root mean square voltage of the last 40 ms of the QRS complex. After a mean followup period of 20 months, 8 patients died. In 2 patients who died suddenly, LVP were present.

Conclusion: Signal averaged ECG is a sensitive and inexpensive technique in the clinical assessment and followup of patients with SSc.