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.