Effectiveness of Implanted Cardiac Rhythm Recorders With Electrocardiographic Monitoring for Detecting Arrhythmias in Pregnant Women With Symptomatic Arrhythmia and/or Structural Heart Disease: A Randomized Clinical Trial.

Importance: Arrhythmias are an important cause of maternal morbidity and mortality but remain difficult to diagnose. Objective: To compare implantable loop recorder (ILR) plus 24-hour Holter electrocardiographic (ECG) monitoring with standard 24-hour Holter ECG monitoring alone in terms of acceptability, ability to identify significant arrythmias, and effect on management and pregnancy outcome in women who were symptomatic or at high risk of arrythmia because of underlying structural heart disease. Design, Setting, and Participants: This single-center, prospective randomized clinical trial recruited 40 consecutive patients from the Cardiac Disease and Maternity Clinic at Groote Schuur Hospital in Cape Town, South Africa. Pregnant patients with symptoms of arrhythmia and/or structural heart disease at risk of arrhythmia were included. Intervention: Patients were randomized to standard care (SC; 24-hour Holter ECG monitoring [n = 20]) or standard care plus ILR (SC-ILR; 24-hour Holter ECG monitoring plus ILR [n = 20]). Only 17 consented to ILR insertion, and the 3 who declined ILR were allocated to the SC group. Main Outcomes and Measures: Arrhythmias considered included atrial fibrillation, atrial flutter, premature ventricular complexes, supraventricular tachycardia, ventricular tachycardia, or ventricular fibrillation. Results: Among the 40 women in this trial, the mean (SD) age was 28.4 (5.5) years. Holter monitoring detected arrhythmias in 3 of 23 patients (13%) in the SC group and 4 of 17 patients (24%) in the SC-ILR group compared with 9 of 17 patients (53%) patients who had arrhythmias detected by ILR. Seven patients (4 with supraventricular tachycardia, 1 with premature ventricular complexes, and 2 with paroxysmal atrial fibrillation recorded by ILR) did not have arrhythmias detected by 24-hour Holter monitoring. Three of these 7 patients (43%) had a change in management as a result of their ILR recordings. There were no maternal deaths. However, the SC group had a significantly lower mean (SD) gestational stage at delivery (35 [5] weeks vs 38 [2], P = .04). Conclusions and Relevance: The ILR was better than 24-hour Holter monitoring in detecting arrhythmias, which led to a change in management for a significant proportion of patients. Our findings suggest that ILR may be beneficial for pregnant women at risk of arrhythmia. Trial Registration: ClinicalTrials.gov Identifier: NCT02249195.