205 ST segment changes after external cardioversion using direct current shock: incidence, characteristics and predeictive factors

Abstract

DC shock is commonly used for external cardioversion of cardiac arrhythmias. Incidence, characteristics and predictive factors of transient ST-segment changes after DC shock are poorly known. 91 consecutive pts referred for external cardioversion of atrial fibrillation (AFib) (61 men, 69 ± 10 yo) were prospectively included. Duration and amplitude of ST elevation or depression were quantified on12 lead-ECG immediately after the first DC shock. Correlations with DC shock characteristics clinical variables, underlying heart disease, echocardiographic parameters, biological parameters, medications, anesthesic drugs as well with morphological features were made. 18 and 20 pts underwent 200 J or 300 J monophasic and 53 pts 200 J biphasic DC shocks. Immediate success rate was 95%.We found an incidence of 48% for ST segment changes: 35% for ST elevation (0,81 ± 0,44 mV) and 13% for ST depression (0,2 ± 0,07 mV, p<0,0001). ST changes were essentially seen in the right precordial leads. Major ST elevation was observed in 27% which could sometimes display Brugada-like pattern. ST changes durations were similar for ST elevation and ST depression (60 ± 43 vs 50 ± 26 sec, p=ns) and were correlated to the amplitude of ST changes. ST changes did not induce significant cardiac events or alter immediate or late AFib recurrences. ST changes were not related to energy but ST elevation was significantly more often induced by monophasic (76% vs 6%, p<0,0001) and ST depression by biphasic DC shocks (26% vs 3%, p=0,01). Using multivariate analysis, independent predictors for ST elevation were the use of monophasic DC shocks, use of propofol and increased CRP, while a low ejection fraction and use of biphasic DC hocks were independent predictors of ST depression. ST segment changes after external cardioversion with DC shock are common, short living and do not seem to carry clinical significance. They are related to the monophasic or biphasic configuration of DC shock, to the use of propofol, to the ejection fraction and to an increased CRP. Direct membrane injury by electroporation is suspected.