Predictive value of interatrial block for atrial fibrillation in elderly subjects enrolled in the PREDICTOR study.

AIMS: The principal aims of this prospective multicentre study were to relate the presence of interatrial block (IAB) with a late occurrence of atrial fibrillation (AF) and to demonstrate the independence of the IAB effect on risk of AF from structural cardiac alterations. METHODS: This prospective study was the follow-up of subjects included in the PREDICTOR cross-sectional population-based study. Subjects were divided into groups according to IAB status. Socio-demographic and health characteristic were collected during enrolment in the PREDICTOR along with ECGs, echocardiograms and NT-proBNP dosages. Follow up was performed on administrative data. The mean time of follow up was 6.6 years. RESULTS: 1626 subjects were included in the analysis. Four hundred-fifteen subjects out of 1626 (25.5%) had IAB. The survival analysis suggests an association between IAB alone and AF (HR = 1.50, p = 0.058) and, in normal-weight subjects, IAB strongly predicted AF indicating more than triple the risk (HR = 3.05; p = 0.002 95% CI: 1.51-6.18). The association seems to be independent of possible confounders such as history of IHD, left ventricular hypertrophy, CHA2DS2-VASc, left atrial dimension, or NT-proBNP dosage. CONCLUSION: Our analysis suggests that IAB is an electric condition that can increase the risk of AF independently of any structural cardiac alterations, at least in normal-weight subjects.

Interatrial block in prediction of all-cause mortality after first-ever ischemic stroke.

BACKGROUND: Interatrial block (IAB) is an ECG indicator of atrial fibrosis related to atrial remodeling and thrombus formation thus leading to embolic stroke and increasing mortality. We aimed to assess weather IAB predicted all-cause mortality during 10 years after ischemic stroke. METHODS: The study sample comprised 235 patients (median age 74 (interquartile range 25-75% 65-81) years, 95 female) included in the Lund Stroke Register in 2001-2002, who had sinus rhythm ECGs at stroke admission. IAB was defined as a P-wave duration ≥120 ms without = partial IAB (n = 56) or with = advanced IAB (n = 41) biphasic morphology (±) in the inferior ECG leads. All-cause mortality was assessed via linkage with the Swedish Causes of Death Register. RESULTS: During follow-up 126 patients died (54%). Advanced IAB, but not partial, was associated with all-cause mortality in univariate Cox regression analysis (hazard ratio (HR) 1.98, 95% CI 1.27-3.09, p = 0.003). After adjustment for age, gender, severity of stroke measured by NIHSS scale and smoking status in patients without additional comorbidities advanced IAB independently predicted all-cause mortality (HR 7.89, 95% CI 2.01-30.98, p = 0.003), while in patients with comorbidities it did not (HR 1.01 95% CI 0.59-1.72, p = 0.966). CONCLUSION: Advanced IAB predicted all-cause mortality after ischemic stroke, but mostly in patients without additional cardiovascular comorbidities.

Risk Prediction of Atrial Fibrillation Based on Electrocardiographic Interatrial Block.

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.