IMPACT OF SUBCLINICAL HYPOTHYROIDISM ON FREQUENCY OF PREMATURE VENTRICULAR CONTRACTIONS IN ELDERLY PATIENTS WITHOUT STRUCTURAL HEART DISEASE

摘要

Introduction: Premature ventricular contractions (PVCs) are common arrhythmias, most of them requiring no follow-up or treatment. Subclinical hypothyroidism (SH) is defined as normal levels of free triiodothyronine (FT3) and free thyroxine (FT4), with elevation of serum thyroid stimulating hormone (TSH) levels (4.2 mIU/l). We aimed to demonstrate the association of SH with the frequency of PVCs in elderly patients without structural heart disease. Materials and Method: We included 327 consecutive elderly patients who underwent 24-hour Holter monitoring for the frequency of PVCs. The patients were initially divided into two groups with respect to the presence of SH. Later, the patients were divided into three groups with respect to the frequency of PVCs, with groups 1, 2 and 3 representing PVCs (1,000/day), (1,000?5,000/day) and (10,000/day), respectively. Results: A total of 28 patients had SH. Number of PVCs was significantly higher in patients with SH (13104.7 ± 7007 vs 9286.7 ± 7724, p = 0.012) than in those without SH. On comparing the groups based on the frequency of PVCs, TSH levels were significantly higher in group 3 patients (10,000 PVCs/day) than those in the others (p 0.001). The percentage of patients with SH was significantly higher in group 3 (p = 0.005). According to univariate and multivariate analysis, SH was found to be an independent predictor of PVCs. Conclusion: We found that SH is independently associated with frequent PVCs. We concluded that serum TSH concentration has a role in the frequency of PVC, therefore, SH may lead to a predisposition to ventricular arrhythmias.