Syndrome 'Z': A Predictor of Angiographic Severity of Coronary Artery Disease in Patients of Acute Coronary Syndrome.

Background: Owing to the growing evidence that the pathophysiology of obstructive sleep apnoea (OSA) and metabolic syndrome (MS) overlap considerably and both adversely impact cardiovascular health, we hypothesised that the presence of OSA with MS additively and adversely affect the severity of coronary artery disease (CAD). Exploration and understanding of this may have direct implications for the development of targeted, preventive strategies for CAD. Thus, this prospective study was aimed to determine the prevalence of 'Syndrome Z' in patients of MS who present with an acute coronary event and to correlate it with the angiographic severity of CAD in these patients.

Methods: The present study was a single centre, cross sectional study conducted in a university teaching hospital. In a span of 6 months, 922 patients with acute coronary syndromes (ACS) were screened for the study. Among these, 861 patients had no evidence of MS. The remaining 61 patients who were diagnosed to have MS were then subjected to an overnight sleep study. Only 58 had good sleep data so were included for further analysis. Angiographic parameters in terms of number of vessels involved and culprit lesions were noted and correlated with presence and absence of OSA and also with its severity based on the Apnoea/Hypopnoea Index (AHI).

Results: The prevalence of OSA positivity in patients with MS who presented with ACS was 34.5% (n=20). Most of the patients in the OSA negative group (78.9%, n=30) had disease limited to only one vessel while in the OSA positive group only a minority (15%, n=3) of patients had their disease limited to a single vessel (p=0.001). The number of lesions in the culprit vessel was also significantly less in the OSA negative group compared to the OSA positive group. While in the OSA negative group 68.4% (n=26) patients had a solitary lesion, followed by two and three lesions in 15.8% (n=6) of the patients each, multiple lesions were more common in OSA positive patients, involving 80% of cases (45.0%, n=9 with two lesions; 35.0%, n=7 with three lesions; only 20%, n=4 had a solitary lesion).

Conclusions: Prevalence of 'Syndrome Z' is high in patients having MS presenting with ACS and it correlates with the angiographic severity of CAD.