Time course of the ST segment changes after electrical cardioversion of chronic atrial fibrillation

Background: Electrocardiographic (ECG) abnormalities have been reported after transthoracic direct-current electrical cardioversion. The ST segment elevations are especially problematic and may indicate cardiac injury or even mimic the life-threatening Brugada syndrome Materials and We studied the evolution of 12-lead ECGs after transthoracic electrical cardio Methods: version for chronic atrial fibrillation in 27 consecutive patients, Countershocks were administered by incremental energy levels starting from 50, 100, 200, 300 to 400 Joules(J). The changes of 12-lead ECGs were recorded after successful conversion or the maximum of 400 J. Results: Acute ST segment elevation occurred in 23 (85%) of the 27 patients with a mean amplitude of 0.51 ± 0.52 mV (range 0 to 2.1 mV). The ECG leads with the elevated ST segments were precordial in 19 patients, anterolateral in 7 and inferior in 15. The ST segment change persisted for 50.7 ± 44.5 seconds (range 3 to 182 seconds). The peak (r = 0.35,p = 0.082) and duration (r = 0.37, p = 0.080) of the ST segment elevation escalated gradually in proportion to the energy required for cardioversion. The morphology of ST segment elevation after cardioversion manifested as either a high plateau or a dome shape in 15 patients. Whereas, a coved or saddleback-shaped ST elevation at VI, V2 or V3 leads was recorded in 8 other patients, mimicking that of Brugada syndrome. However, the post-cardioversion ST change was always widespread, never clustered only at V1 to V3 leads, and resolved rapidly within 44.2 ± 44.8 seconds (range 0 to 182 sec). On the other hand, the corrected QT interval became shorter in the post-cardioversion ST segment elevation phase (448.0 ± 55.7 ms, vs 496.4 ± 37.6 ms before cardioversion, p = 0.001) and in the ST segment recovery phase (467.9 ± 55.5 ms, p = 0.013, vs before cardioversion). There was no dispersion of the corrected QT interval nor the QRS interval after cardioversion. Conclusions: Postcardioversion transient ST elevation was usually manifested as a plateau or dome shape, less of a coved or saddle-back shape, and always disappeared within 3 minutes.