Temporal Relation of Myocardial Ischemia to Nocturnal Desaturation of Oxygen in Patients with Coronary Artery Disease

Purpose: Obstructive sleep apnea (OSA) is frequently associated with coronary artery disease. Causal relation of nocturnal respiratory disorders to the onset of myocardial ischemia has been discussed controversially. Methods: Patients with coronary artery disease (CAD) were enrolled in the present pilot study. Overnight polygraphy and 12-lead ECG were performed in all patients. Patients with nocturnal myocardial ischemia in the study night were eligible for analysis of breathing parameters preceding myocardial ischemia. Backwards from the first second of myocardial ischemia, a preceding period of 900 seconds was analysed for OSA and subsequent reduction of oxygen saturation. The frequency of respiratory events within this period was compared to frequency within the total time of sleep assessment. Results: We present data of 19 patients (4 women; 15 men) aged 45 to 79 years (mean 64.1 years; ± 9.4 (standard deviation)) with a mean body mass index (BMI) of 29.5 kg(m2)-1 ± 4.4. No patient had been diagnosed with OSA before study participation. In all patients an Apnea-Hypopnea-Index (AHI) ≥5/h (median 11/h; IQR: 8/25), in 9 patients (47%) an AHI of ≥15/h (median 25; IQR: 20/47.5) was calculated. Nocturnal myocardial ischemia was found in 8 patients and furthermore, one patient reported nocturnal chest pain. Preceding myocardial ischemia OSA was more frequent compared to the time without ischemia 100% (95%/100%) versus 66.8% (58%/75.9%); p= 0.012. Conclusion: The present study concludes that nocturnal myocardial ischemic events frequently occur with a temporal related accumulation of preceding OSA.