Cardiac function in patients on chronic amiodarone therapy.

Antiarrhythmic agents may depress cardiac contractility and worsen heart failure. Few data are available describing the chronic effects of amiodarone on myocardial function. To assess the effects of amiodarone on cardiac function, we studied 41 consecutive patients with first-pass or equilibrium radionuclide angiography prior to and 3 months after drug therapy was initiated. The mean heart rate, systolic blood pressure (BP), and diastolic BP were not significantly altered by treatment. The mean ejection fraction was 36% +/- 19 (mean +/- 1 SD) at the time of drug initiation and 36% +/- 17 3 months later (p less than 0.05). Nineteen patients had an ejection fraction greater than 30% and 16 had an ejection fraction less than 30%. The mean change in ejection fraction for these two subgroups showed no statistically significant difference, although a decrease in EF greater than 10% was seen in three patients (symptomatic in two), necessitating an increase in diuretic dose. No correlation between amiodarone dose and change in ejection fraction (r = -0.12, p greater than 0.05) was noted. There was no correlation between baseline ejection fraction and change in ejection fraction over this 3-month period (r = -0.36, p greater than 0.05). In summary, amiodarone does not depress left ventricular function and as a result can be used safely in patients with mild to moderate impairment of left ventricular function. In patients with stable left ventricular function, serial tests of left ventricular function may not be necessary.