Serial lung function testing in patients treated with Amiodarone: A prospective study

Abstract purpose: Amiodarone has proven to be effective in many cases of cardiac arrhythmias, refractory ventricular tachycardia, and ventricular fibrillation. Pulmonary toxicity is a possible side effect of the drug, with a reported incidence of 2 to 15 percent per year. To determine the effect of amiodarone on lung function, we prospectively studied serial lung function tests in a cohort of 91 patients with refractory cardiac arrhythmias treated with this agent. patients and methods: Spirometry and carbon monoxide diffusing capacity (DL CO ) were measured at zero, three, six, 12, 18, and 24 months, with a mean follow-up of 351 days. results: For the whole population taking a mean dose of amiodarone of 367 mg daily (range: 136 to 512 mg), there was no accelerated rate of decline in spirometric induces or DL CO . Analysis of lung function changes by multivariate analysis demonstrated that an accelerated decline in DL CO values occurred in elderly patients (p CO of greater than 20 percent. All four patients recovered after the drug was stopped. Another 15 patients, without clinical evidence of pulmonary toxicity, had a sustained decline in DL CO of greater than 20 percent. These 15 patients remained assymptomatic over the next 11 months without interruption of therapy. A greater than 20 percent fail in DL CO was a sensitive test for clinically evident amiodarone pulmonary toxicity, but had a positive predictive value of only 21 percent. conclusion: An isolated fall in DL CO in the absence of clinical evidence of toxicity, does not necessitate stopping amiodarone. An unchanged DL CO value appears to be a reliable negative predictor of pulmonary toxicity.