Risk Prediction of Atrial Fibrillation Based on Electrocardiographic Interatrial Block

Abstract

Background: The electrocardiographic interatrial block (IAB) has been associated with atrial fibrillation (AF). We aimed to test whether IAB can improve risk prediction of AF for the individual person.

Methods and results: Digital ECGs of 152 759 primary care patients aged 50 to 90 years were collected from 2001 to 2011. We identified individuals with P-wave ≥120 ms and the presence of none, 1, 2, or 3 biphasic P-waves in inferior leads. Data on comorbidity, medication, and outcomes were obtained from nationwide registries. We observed a dose-response relationship between the number of biphasic P-waves in inferior leads and the hazard of AF during follow-up. Discrimination of the 10-year outcome of AF, measured by time-dependent area under the curve, was increased by 1.09% (95% confidence interval 0.43-1.74%) for individuals with cardiovascular disease at baseline (CVD) and 1.01% (95% confidence interval 0.40-1.62%) for individuals without CVD, when IAB was added to a conventional risk model for AF. The highest effect of IAB on the absolute risk of AF was observed in individuals aged 60 to 70 years with CVD. In this subgroup, the 10-year risk of AF was 50% in those with advanced IAB compared with 10% in those with a normal P-wave. In general, individuals with advanced IAB and no CVD had a higher risk of AF than patients with CVD and no IAB.

Conclusions: IAB improves risk prediction of AF when added to a conventional risk model. Clinicians may consider monitoring patients with IAB more closely for the occurrence of AF, especially for high-risk subgroups.

Keywords: ECG; atrial fibrillation; epidemiology; interatrial; interatrial block; ischemic stroke; risk prediction.

© 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Figures

Figure 1

Examples of interatrial block as well as a normal ECG. IAB indicates interatrial block.

Figure 2

Multivariable‐adjusted hazard ratios for atrial fibrillation, ischemic stroke, conduction disorder, and all‐cause mortality by interatrial block. CI 95 indicates 95% confidence interval; IAB, interatrial block.

Figure 3

Differences in area under the curve for the 10‐year outcomes of atrial fibrillation and ischemic stroke obtained by adding interatrial block to conventional risk models for atrial fibrillation and ischemic stroke, respectively, stratified by the presence or absence of cardiovascular disease at baseline. AF indicates atrial fibrillation; AUC, area under the curve; CI, confidence interval; CVD, cardiovascular disease at baseline; IAB, interatrial block; noCVD, no cardiovascular disease at baseline.

Figure 4

Cumulative incidence curves of interatrial block for the outcome of atrial fibrillation in patients with and without cardiovascular disease at baseline and stratified into 10‐year age‐groups. Predictions were based on multivariable‐adjusted Cox models fitted within the respective age‐group and cardiovascular disease group (yes/no). AF indicates atrial fibrillation; CVD, cardiovascular disease; ECG, electrocardiogram; IAB, interatrial block.

Figure 5

Cumulative incidence curves of interatrial block for the outcome of ischemic stroke in patients with and without cardiovascular disease at baseline and stratified into 10‐year age‐groups. Predictions were based on multivariable‐adjusted Cox models fitted within the respective age‐group and cardiovascular disease group (yes/no). CVD indicates cardiovascular disease; ECG, electrocardiogram; IAB, interatrial block.

Figure 6

A, Violin plot displaying median, interquartile range, range, and probability density of left atrial end‐diastolic volume for normal P‐wave and interatrial block. IAB indicates inter‐atrial blockIAB‐1, interatrial block with one biphasic P‐wave in inferior leads; IAB‐2, interatrial block with 2 biphasic P‐waves in inferior leads. B, Receiving operator curve for the 2 models. In both models, interatrial block (yes/no) is outcome. AUC indicates area under the curve; LAEDV, left atrial end‐diastolic volume.