Background: Atrial fibrillation is the most common clinically significant arrhythmia. It is now established that atrial high-rate episodes are highly correlated with atrial fibrillation.

Aims: To investigate the relation between diastolic electrocardiographic parameters and subclinical atrial fibrillation detected by cardiac implantable electronic devices.

Study Design: Ccross-sectional study.

Methods: A total of 203 patients who had a dual-chamber, rate-modulated pacing pacemaker implanted due to sinus node dysfunction were prospectively enrolled in this study. Atrial high-rate episodes were defined as any lasting more than 5 min with an atrial rate of ≥220 beats per minute during the previous year. Patient groups were categorized on the basis of pacemaker interrogation as the absence of atrial high-rate episodes [atrial high-rate episodes (-)] and the presence of atrial high-rate episodes [atrial high-rate episodes (+)]. Episodes related to atrial over sensing were excluded. Twelve-lead surface electrocardiography was independently analyzed by two experienced readers for the measurement of diastolic electrocardiography parameters.

Results: Among 203 patients (mean age: 67.5±9.1, 60.1% male), 51 (25.1%) with atrial high-rate episodes were defined as group 1 and 152 (74.9%) without atrial high-rate episodes were defined as group 2. Both groups were similar in terms of demographic characteristics and cardiovascular risk factors. Tend-Q and Tend-P were significantly longer in group 2. PQ interval was statistically longer in group 1. Corrected QT interval was significantly longer in group 1. Diastolic electrocardiography index, heart rate and PQ and QT intervals were the only independent predictors of atrial high-rate episodes in patients with dual pacemakers in multivariate analysis.

Conclusion: Abnormal diastolic electrocardiography parameters are powerful predisposing factors for the initiation of incident atrial fibrillation. Diastolic electrocardiography parameters and a novel diastolic index predict atrial high-rate episodes. Evaluating these parameters enables clinicians to identify patients who are at high risk and who may benefit from prophylactic treatment.