Usefulness of extended holter ECG monitoring for serious arrhythmia detection in patients with heart failure and sleep apnea.

BACKGROUND: In patients with systolic heart failure (HF), coexisting sleep apnea may promote arrhythmia. Ambulatory Holter electrocardiogram (ECG) monitoring (AECG) is a method of arrhythmia and apnea evaluation. We hypothesized that 24-hour AECG in patients with HF who have a high risk of serious arrhythmia may be less accurate than AECG extended to 48 hours and that, moreover, arrhythmia may be related to apnea.
METHODS: Eighty-four recordings of 48-hour AECG in 84 patients with ischemic HF (mean ejection fraction 34 ± 7%) were analyzed. Day 1, Day 2 were checked for ventricular tachycardia (VT) and supraventricular tachycardia (SVT). Estimated apnea-hypopnea index (est.AHI) was calculated using Holter, monitoring where est.AHI >15 indicates apnea.
RESULTS: In 48-hour AECG, VT occurred in 34 patients (40.5%) whereas SVT in 17 patients (20.2%), and patients with est.AHI > 15 had higher VT occurrence. In two-sample one-sided test for proportions, 24-hour AECG from Day 1 showed a significantly lower percentage of patients with detected VT than 48-hour AECG-it was 23.8% (20 patients), meaning a significant underestimation with P = 0.0089. We assessed VT underestimation in the subgroups with regard to est.AHI, and found that it was present in Day 1 monitoring in the subgroups with est.AHI > 15. It was absent in the subgroups with est.AHI ≤ 15 and also in Day 2 monitoring.
CONCLUSIONS: In patients with systolic HF, 24-hour AECG may have insufficient sensitivity regarding serious arrhythmia occurrence. If significant apnea was detected in the first day, extending the monitoring may be recommended. ©2012, Wiley Periodicals, Inc.