The influence of hypothyroidism on the course of coronary artery disease in patients with reduced left ventricular ejection fraction

Background. Thyroid hormones play a fundamental role in the homeostasis of the cardiovascular system. Cardiovascular diseases are among the most common diseases worldwide, causing a significant percentage of mortality, hospitalizations, and disability. The purpose of the study is to evaluate the impact of hypothyroidism on the course of atherosclerotic lesions of coronary arteries and major cardiovascular events in patients with heart fai­lure with reduced left ventricular ejection fraction after myocardial revascularization using percutaneous coronary intervention (PCI). Materials and methods. This prospective observational one-center study included 103 patients with ischemic cardiomyopathy, heart failure with reduced left ventricular ejection fraction, with and without hypothyroidism who underwent PCI. The result of revascularization was evaluated within 2 years. Inclusion criteria: age over 18 years, coronary artery disease, left ventricular ejection fraction less than 40 %. Results. Patients with hypothyroidism had a worse lipid profile and, as expected, a higher baseline thyroid-stimulating hormone (TSH). According to echocardiography, patients with hypothyroidism had thickening of the left ventricular myocardium walls, which is indicated by a probable increase in the dimensions of the left ventricular posterior wall (11.40 ± 0.98 mm; p < 0.001). In the first group, patients had higher myocardial mass indicators as one of the criteria for left ventricular hypertrophy (172.73 ± 12.72 g/m2; p < 0.001). After multivariate analysis using Cox proportional hazards regression, an elevated TSH level was still associated with significantly higher rates of cardiovascular mortality (risk ratio (RR) 0.85; 95% confidence interval (CI) 0.75–0.95; p < 0.001), repeat PCI (RR 0.75; 95% CI 0.65–0.85; p < 0.05) and decompensation due to heart failure (RR 0.88; 95% CI 0.78–0.96; p < 0.05). Conclusions. Hypothyroidism is associated with a higher incidence of the primary composite endpoint of repeat PCI, hospitalizations for decompensated heart failure, and the secondary endpoint of cardiovascular mortality compared to euthyroid patients over two years of follow-up. Maintaining adequate control of TSH in patients with coronary artery disease and heart failure with reduced ejection fraction is prognostically important for preventing cardiovascular events.