Cardiomyopathy
Relation of Interatrial Block to New-Onset Atrial Fibrillation in Patients With Chagas Cardiomyopathy and Implantable Cardioverter-Defibrillators

https://doi.org/10.1016/j.amjcard.2014.02.036Get rights and content

Chagas cardiomyopathy is an endemic disease in Latin America. A significant proportion of patients develop atrial fibrillation (AF), which may result in stroke and increased morbidity or mortality. Interatrial block (IAB) has been associated with the development of AF in different clinical scenarios. The aim of our study was to determine whether IAB can predict new-onset AF in patients with Chagas cardiomyopathy and implantable cardioverter-defibrillators (ICDs). We conducted a retrospective study of patients with Chagas cardiomyopathy and ICDs from 14 centers in Latin America. Demographics, clinical, and device follow-up were collected. Surface electrocardiograms were scanned at 300 dpi and maximized ×8. Semiautomatic calipers were used to determine P-wave onset and offset. Partial IAB was defined as a P wave of >120 ms and advanced IAB as a P wave of >120 ms with biphasic morphology (±) in inferior leads. AF events and ICD therapies were reviewed during follow-up by 2 independent investigators. A total of 80 patients were analyzed. Mean age was 54.6 ± 10.4 years, and 52 (65%) were male. Mean left ventricular ejection fraction was 40 ± 12%. IAB was detected in 15 patients (18.8%), with 8 (10.0%) partial and 7 (8.8%) advanced. During a follow-up of 33 ± 20 months, 11 patients (13.8%) presented with new AF. IAB (partial + advanced) was strongly associated with new AF (p <0.0001) and inappropriate therapy by the ICD (p = 0.014). In conclusion, IAB (partial + advanced) predicted new-onset AF in patients with Chagas cardiomyopathy and ICDs.

Section snippets

Methods

The present study was a retrospective analysis of patients with Chagas cardiomyopathy and an ICD implanted for primary or secondary prevention at 14 Latin American centers included in the Fragmented ECG in Chagas Cardiomyopathy Study.11

The inclusion criteria were (1) Chagas cardiomyopathy diagnosed by positive serologic tests and classic criteria, including living in endemic areas, ECG, and chest x-ray criteria, (2) ICD implanted for primary or secondary prevention of sudden cardiac death, and

Results

A total of 94 patients were analyzed of whom 14 were unable to be enrolled (atrial pacing, permanent atrial arrhythmias, and illegible ECGs), leaving 80 patients suitable for inclusion in the study. Baseline characteristics and medications are summarized in Table 1. The indication for ICD was secondary prevention in 70% of patients. Devices implanted were single chamber in 31%, dual chamber in 65%, and resynchronization therapy in 4%.

Mean P-wave duration was 107.4 ± 12.6 ms, and IAB was

Discussion

The results of this study demonstrate that the presence of IAB in Chagas cardiomyopathy is associated with the development of new-onset AF. This is relevant considering that this arrhythmia is a major cause of stroke in this population12, 13 and an established predictor of poor prognosis.

Data regarding AF in Chagas cardiomyopathy are limited and heterogeneous, most of them from cross-sectional studies. In a large cohort of chagasic patients, Rassi et al3 found that AF or flutter was present on

Disclosures

The authors have no conflicts of interest to disclose.

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