Cardiac rhythm disturbances in the obstructive sleep apnea syndrome - Effects of nasal continuous positive airway pressure therapy

Study objectives: A high incidence of nocturnal cardiac rhythm disturbances among patients with obstructive sleep apnea (OSA) syndrome has been descri bed in some reports, but not in others. We wished to examine the prevalence of significant cardiac rhythm disturbance in patients,vith established mod erate to severe OSA syndrome and, in particular, to assess the impact of na sal continuous positive airway pressure (nCPAP) therapy. Design and setting : A prospective study of consecutive eligible patients i n a dedicated sleep disorders unit of a university teaching hospital. Measurements and results: Holter monitoring was performed for 18 h in 45 pa tients with previously diagnosed OSA syndrome (mean [SD] apnea/hypopnea fre quency [AHI] of 50 [23]/h) and repeated within 2 to 3 days after institutio n of nCPAP therapy, Investigators were blinded to the patients' treatments during data analysis, Thirty-five patients were found to have some cardiac rhythm disturbance, but only 8 had pathologically significant disturbances (ventricular tachycardia or fibrillation, complex: ventricular ectopy, new- onset supraventricular tachycardia other than sinus tachycardia, pauses of > 2 s, and second- or third-degree heart block). Significant rhythm disturb ances occurred only during the nighttime, and there was a significant corre lation between OSA severity and the severity of rhythm disturbance (p = 0.0 4, r = 0.301). No significant correlation was found between OSA severity an d any other anthropometric parameter measured, nCPAP therapy resulted in ab olition of rhythm disturbance in seven of these eight patients; the eighth patient was found to have coexisting severe aortic valve disease requiring valve replacement. Conclusion: The data indicate that OSA syndrome predisposes to clinically s ignificant cardiac rhythm disturbances that can be successfully controlled by nCPhP therapy.