In 22 patients with COPD, we studied the relationship between left ventricular function and cardiac arrhythmias. Ventricular arrhythmias were detected on a 24-h ECG recorded at the beginning of the observation period and after a stable improvement of RF. Left ventricular function was evaluated by equilibrium-gated radionuclide angiocardiography measuring LVEF, PER and PFR. We found a significant decrease in the arrhythmia score after improvement of RF; LVEF and PFR were slightly depressed in six and nine patients, respectively. A "step-up" multiple regression analysis revealed a significant inverse correlation between PFR and ventricular arrhythmias during worsened RF, whereas LVEF, arterial blood gases and clinical data were not significantly predictive variables. Thus, a depressed left ventricular diastolic performance seems to be a predictive factor for arrhythmias during RF from COPD. The poor definition of the statistical model suggests that other presently unknown factors contribute to the genesis of ventricular arrhythmias.