Background: Thyroid stimulating hormone (TSH) abnormalities have been associated with various cardiac arrhythmias. Effect of TSH abnormalities on mortality and implantable cardioverter defibrillators (ICD) behavior in patients with cardiomyopathy has not been investigated.
Methods: Our ICD database includes 1,445 patients between December 1997 and January 2008. TSH levels using the ultra sensitive assay were available in 371 patients. Patients were classified based on TSH levels as: High TSH (N = 102, TSH > 5) and Low TSH (N = 26, TSH < 0.4). TSH groups were compared for mortality, appropriate and inappropriate ICD therapies.
Results: A high or low TSH was an independent predictor of all-cause mortality: Hazard ratio (HR) 1.46 (95% CI 1.03-2.08), P = 0.033 and HR 1.76 (95% confidence interval 1.02-3.03), P = 0.043 respectively. TSH abnormalities were not associated with an increased incidence in appropriate or inappropriate ICD therapy.
Conclusion: A low or high TSH was associated with a higher mortality; however, neither were associated with appropriate or inappropriate ICD therapy after multivariate analysis. Univariate analysis demonstrated an association of high TSH and appropriate ICD therapy. However, multivariate analysis did not show this association. Therefore, we are concluding that TSH levels are predictors of all-cause mortality but not ICD therapy.