Signal-Averaged Electrocardiogram in Physically Healthy, Recently Abstinent Chronic Cocaine Users

Objectives: Cocaine use is associated with cardiac arrhythmias. Markers of ventricular late potentials, which may be a precursor to malignant ventricular arrhythmias, can be detected by signal-averaged electrocardiography (SA-ECG) but not by standard ECG. Methods: We evaluated SA-ECG parameters in 60 medically screened, physically healthy, recently abstinent cocaine users (53 males, mean [SD] age, 34.0 [4.6] years; 10.1 [6.0] years of use) and 54 nondrug-using controls (21 males, mean [SD] age 28.4 [7.8] years). SA-ECGs were done periodically for <= 12 weeks of monitored abstinence in 25 cocaine users. We analyzed 3 SA-ECG parameters considered markers of ventricular late potentials: duration of filtered QRS complex, duration of low-amplitude potentials during terminal 40 ms of QRS complex (LAS40), and root mean square voltage during terminal 40 ms of QRS complex (RMS40). Results: Cocaine users differed significantly from controls in filtered QRS complex (118.5 [11.2] ms versus 111.9 [11.4] ms; P = 0.03) but not in LAS40 (28.9 [8.2] ms versus 30.8 [8.3] ins; P = 0.40) or RMS40 (40.0 [19.8] mu V versus 30.2 [20.1] mu V; P = 0.06) values. The proportion of subjects with abnormal SA-ECG parameters did not differ significantly between male cocaine users and male controls. There were no significant changes over time in either the mean values or proportion of subjects with abnormal values for any SA-ECG parameter. There were significant gender differences among controls but not among cocaine users. Conclusion: These findings suggest that chronic cocaine use is not associated with a higher prevalence of abnormal SA-ECG parameters in physically healthy users.