Holter monitoring versus conventional monitoring
Although the highest detection rate was observed during the first 24 hours following CV, a significant number of patients with QTc prolongation was detected thereafter. Furthermore, the maximum median QTc prolongation occurred during the second day (hour 44 post CV), which attenuated thereafter, returning to baseline QTc. Similar findings were reported in a study that tested the QT/RR relationship following ablation of the atrioventricular junction in patients with atrial fibrillation. It demonstrated that the highest change in QTc was documented on the second day [(516±51ms on second day vs 468±26ms baseline, p=0.02; in group I) and (497±37ms on second day vs 458±25ms baseline, p = 0.02; in group II)], afterwards the QTc normalizes with no statistical difference observed from days 3 to 7 at all heart rates (14). In light of our findings there might be a need for further monitoring beyond several hours post CV in some individuals. In the past, and in accordance with this concept, the ACC/AHA/ESC 2006 Guidelines for the Management of Patients with AF recommended in hospital QT interval monitoring for 24-48 h following CV in patients receiving drugs that prolong the QT interval. However, in the most recent AHA/ACC and ESC guidelines, the above-mentioned recommendation were omitted, and the monitoring time following CV in patient on antiarrhythmic drugs became undefined. Hence, we believe that monitoring or repeated ECGs are essential during the 48 hours post CV in some patients with persistent AF on antiarrhythmic drugs.