Association of hypothyroidism with adverse events in patients with heart failure receiving cardiac resynchronization therapy.

Hypothyroidism is associated with an adverse prognosis in cardiac patients in general and in particular in patients with heart failure (HF). The aim of this study was to evaluate the impact of hypothyroidism on patients with HF receiving cardiac resynchronization therapy (CRT). Additionally, the impact of level of control of hypothyroidism on risk of adverse events after CRT implantation was also evaluated. We included consecutive patients in whom a CRT device was implanted from April 2004 to April 2010 at our institution with sufficient follow-up data available for analysis; 511 patients were included (age 68.5±12.4 years, women 20.4%); 84 patients with a clinical history of hypothyroidism, on treatment with thyroid hormone repletion or serum thyroid-stimulating hormone level≥5.00 μU/ml, were included in the hypothyroid group. The patients were followed for up to 3 years after implant for a composite end point of hospitalization for HF, left ventricular assist device placement, or heart transplant and cardiac death; 215 composite end point events were noted in this period. In a multivariate model, hypothyroidism (hazard ratio [HR] 1.46, 95% confidence interval [CI] 1.027 to 2.085, p=0.035), female gender (HR 0.64, 95% CI 0.428 to 0.963, p=0.032), and creatinine (HR 1.26, 95% CI 1.145 to 1.382, p<0.001) were significantly associated with occurrence of the composite end point; 53.6% of patients with hypothyroidism at baseline developed the composite end point compared with 39.8% of those with euthyroidism (p=0.02). In conclusion, hypothyroidism is associated with a worse prognosis after CRT implantation.