Study Patients
From July 09, 2017 through August 27, 2018, we prospectively enrolled
consecutive patients with persistent AF who were admitted to the
cardiology ward at the Chaim Sheba Medical Center (Tel Hashomer, Israel)
for elective electric cardioversion. Our study inclusion criteria were:
1) age ≥ 18 years old, 2) symptomatic persistent AF/AFL (atrial
fibrillation or atrial flutter), 3) baseline QTc>300 msec,
4) no contraindication for ECV, and 5) no contraindication for
anticoagulation. Study exclusion criteria included: 1) recent initiation
of medication that is well known to prolong QTc, 2) recent increase in
dose of potentially prolonging medication (other than the medication
desired for the CV), 3) pregnancy, 4) patients with congenital long QT
syndrome, 5) baseline QTc>500 msec, and 6) history of
Torsade de pointes. Out of 136 consecutive patients, 100 patients agreed
to participate in the study. All enrolled patients were connected to a
7-day 3-lead Holter prior to CV (in order to monitor QTc during
AF)(Figure 1).
All patients underwent transesophageal echocardiography (TEE) if
effective anticoagulation status was not confirmed or upon physician
discretion. In addition, all underwent transthoracic echocardiography
(TTE) within three months prior to the study enrollment, or on the day
of CV. Of note, after connecting patients to Holter, ten patients (10%)
were withdrawn from the study due to left atrial appendage thrombus or
severe swirling in TEE (4 patients), Holter malfunction (3), failure to
cardiovert to sinus rhythm (2) and a patient who spontaneously converted
to sinus rhythm following TEE, who was mistakenly discharged without
further Holter monitoring. All remaining 90 patients were successfully
CV to sinus rhythm and were monitored according to the study protocol
using the Holter for 7 days.
The protocol was approved by the institutional review board of our
center. All patients provided written informed consent. The primary
hypothesis was that signifcant QTc prolongation can occur following ECV
during 7 days of prolonged ECG monitoring, and that the use of Holter
would be superior to the conventional protocol in detecting potentially
clinically significant QTc prolongation.