The electrocardiogram in systemic sclerosis (scleroderma). Study of 102 consecutive cases with functional correlations and review of the literature.

The electrocardiographic findings in 102 consecutive patients with scleroderma were reviewed to determine the frequency and nature of the electrocardiographic abnormalities associated with this disease. Septal infarction pattern unassociated with QRS prolongation was present in 10 percent, compared with none of 96 control subjects (p less than 0.001). Ventricular conduction abnormalities were present in 17 percent. A normal electrocardiogram was obtained in 49 percent. A subset of 48 patients underwent detailed cardiopulmonary evaluation including exercise thallium scintigraphy, rest and exercise radionuclide ventriculography, pulmonary function tests, and chest roentgenography. Functional correlations of the electrocardiographic findings were examined in this subset. Septal infarction pattern (five of 48) and ventricular conduction abnormalities (10 of 48) were both associated with septal or anteroseptal thallium perfusion abnormalities (10 of 15 versus six of 33 of the remainder, p less than 0.005), which were present despite normal coronary angiographic results. Thallium defect scores were greater in patients with septal infarction pattern or ventricular conduction abnormalities compared with the remainder (defect scores 3.0 +/- 2.6 versus 1.4 +/- 2.2, respectively, p less than 0.025). In patients with ventricular conduction abnormalities, both left bundle branch block and right bundle branch block with left anterior fascicular block were associated with abnormal left ventricular function, whereas isolated right bundle branch block or left anterior fascicular block was associated with normal left ventricular function. A normal electrocardiographic finding (19 of 48) was associated with normal left ventricular function at rest (19 of 19). However, 11 of 19 (58 percent) had thallium perfusion defects and four of 19 (21 percent) had an abnormal response to exercise, although in none was the peak ejection fraction less than 50 percent. It is concluded that both septal infarction pattern and ventricular conduction abnormalities are electrocardiographic abnormalities associated with scleroderma heart disease; they appear to be a result of myocardial fibrosis. Some degree of myocardial fibrosis may be present with a normal electrocardiographic result, but significant left ventricular dysfunction is unlikely. Septal infarction pattern and ventricular conduction abnormalities, when present, are indicators of more advanced fibrosis.