Use of sympathomimetic drugs leads to increased risk of hospitalization for arrhythmias in patients with congestive heart failure

Background: Sympathomimetic agents have a direct positive chronotropic effe ct on heart rate and may cause hypokalemia, even when administered by inhal ation. In selected patients (eg, patients with congestive heart failure [CH F]) this can lead to arrhythmias. Despite the potential adverse effects of these agents, they are used frequently in patients with CHF, due to a high incidence of respiratory comorbidity. This study investigates the effects o f sympathomimetics on the incidence of hospitalizations for arrhythmias in patients with CHF. Methods: In a cohort of 1208 patients with a validated hospital discharge d iagnosis of CHF, we identified 149 cases with a readmission for arrhythmias , and compared these in a nested matched case-control design with 149 contr ols from the remainder of the cohort with no hospital readmission for any c ardiac cause. Conditional logistic regression was used to calculate the ris k for hospitalization for arrhythmias associated with exposure to sympathom imetic agents, expressed as odds ratios. Results: Of 149 case patients, a total of 33 (22.1%) were treated with any sympathomimetic agent, and 6 patients (4.0%) were treated with systemic sym pathomimetics. The use of any sympathomimetic drug was associated with an i ncreased risk of admission for arrhythmia (odds ratio, 4.0; 95% confidence interval, 1.0-15.1). For systemic sympathomimetic drugs, the corresponding odds ratio was 15.7 (95% confidence interval, 1.1-228.0). Conclusions: The results of this study strongly suggest an increased risk o f hospitalization for arrhythmias in patients with CHF treated with sympath omimetic drugs. Sympathomimetics should be given under close surveillance t o patients with CHF.