SIGNAL VARIANCE ELECTROCARDIOGRAM - A TEST FOR EARLY DETECTION OF MYOCARDIAL INVOLVEMENT IN CYSTIC-FIBROSIS

1. Variance electrocardiography is a new resting procedure for the det ection of ischaemia-induced variability in the electrical expression o f the depolarization phase. The analysis is performed on 220 cardiac c ycles using high-fidelity ECG signals from 24 leads, and the electrica l variability is expressed as an electrical variability index ranging from 1 to 150. In this study, variance electrocardiography was employe d to detect cardiac involvement in 23 patients with cystic fibrosis. 2 . Patients with cystic fibrosis presented a significantly higher mean electrical variability index than control subjects, and their index va lues correlated inversely with the arterial oxygen partial pressure an d forced expiratory volume in 1.0s. Patients with a high electrical va riability index (>75) displayed a lower clinical score (Shwachman scor e) and a longer duration of chronic colonization with Pseudomonas aeru ginosa. Patients with conduction disturbances and patients with echoca rdiographic right ventricular pathology presented higher indices than those without. 3. Electrical variability index is increased in cystic fibrosis and correlates with other signs of cardiac and pulmonary dera ngement. Variance electrocardiography may therefore have the potential to be a sensitive and simple method for monitoring cardiac involvemen t in this disease.