Association between Serum Vitamin D Levels and Severity of Acute Coronary Syndrome: A Cross-Sectional Study among Hospitalized Patients in a Tertiary-Care Hospital, Northern India

Introduction: Acute coronary syndrome (ACS) is a leading cause of morbidity and mortality. Vitamin D deficiency has emerged as a potential non-traditional cardiovascular risk factor through its effects on inflammation, endothelial function and vascular calcification, but Indian data correlating it with ACS severity are limited. Objective: To assess serum vitamin D levels in hospitalized ACS patients and determine their association with disease severity. Methods: A hospital-based cross-sectional observational study was conducted in 500 patients with ACS. Demographic, biochemical, echocardiographic and coronary angiographic parameters were recorded. Serum 25-hydroxyvitamin D was categorised as deficient (<10 ng/mL), insufficient (10–20 ng/mL) or sufficient (>20 ng/mL); p<0.05 was significant. Unadjusted and adjusted odds ratios (OR) with 95% confidence intervals (CI) were estimated by logistic regression, with sufficient vitamin D as reference. Results: Mean age was 58.9±10.3 years and 67.2% were male. Deficiency and insufficiency were highly prevalent (17.6% and 38.2%). STEMI predominated and was commoner at lower vitamin D levels. Deficiency was significantly associated with reduced ejection fraction, diabetes and hypertension, and with severe stenosis or occlusion, higher Gensini score and higher mortality, but not with smoking, number of diseased vessels or TIMI flow. After adjustment for age, sex, diabetes, hypertension, smoking and BMI, deficiency remained independently associated with in-hospital death (adjusted OR 5.96, 95% CI 1.93–18.37) and with severe stenosis or occlusion (adjusted OR 6.02, 95% CI 3.32–10.93). Conclusion: Low serum vitamin D was significantly associated with greater ACS severity and adverse outcomes and may serve as a useful prognostic marker.