Electrocardiographic changes in obstructive sleep apnoea syndrome.

Obstructive sleep apnoea syndrome (OSAS) has acute and chronic effects on the cardiovascular system. Both right and left sides of the heart are affected. Electrocardiographic pattern was studied in 190 OSAS patients. One or more of the following were found: persistent deep S in lateral chest leads V5, V6 (79%), left anterior hemiblock (71%), RS pattern with deep S wave in leads aVf, I, II and III (71, 55, 26 and 22% respectively), right axis (6%), right bundle branch block RBBB (5%), QRS voltage criteria of left ventricular hypertrophy (4%), QR pattern in V1 (4%) and none of the above (11%). The most common patterns were deep S wave in leads I, aVf, V6 with left axis (27%), deep S wave in leads II, III, aVf and V6 with left axis (12%), and deep S wave in leads I, II, III, aVf and V6 with left axis (11%). There was statistically significant difference in polysomnographic data and daytime PaO2 between OSAS patients with and without ECG findings. The latter had the mildest evidence of disease (P < 0.01). The findings suggest prevalence of late depolarization of hypertrophied right outflow tract and/or left anterior fascicular block. With progression of OSAS, there is evolution of an ECG pattern that is peculiar for the disease, and helpful in diagnosing OSAS patients when other disease entities are excluded.