Blood Pressure Severity Modifies the Association Between Atrial Cardiopathy and Stroke Mortality

Background: Electrocardiographic (ECG) markers of atrial cardiopathy (AC) are associated with stroke mortality, but whether this association is modified by blood pressure (BP) is unknown. Methods: We analyzed 7,191 adults free of cardiovascular disease from the Third National Health and Nutrition Examination Survey who underwent baseline ECG. AC was defined by three ECG markers: prolonged P-wave duration 120 ms), abnormal P-wave axis (<0{degrees} or >75{degrees}), and deep terminal negativity of the P wave in V1 (<100 V). AC burden (per additional AC marker) and AC presence (1 vs. 0 markers) were examined in relation to stroke mortality using Cox proportional hazards models. Participants were stratified by BP as normal/elevated (<130/80 mmHg), stage 1-2 hypertension (130-159/80-99 mmHg), or severe hypertension (160/100 mmHg). Interaction by BP category was assessed. Results: During a median follow-up of 13.8 years, 183 stroke deaths occurred. In multivariable adjusted model, AC burden was associated with a 41% higher risk of stroke mortality (HR (95%CI): 1.41 (1.13-1.77)). This association was significantly modified by BP (interaction P=0.003). The HRs (95% CIs) per additional AC marker were 0.88 (0.52-1.49), 1.39 (1.03-1.88), and 2.94 (1.82-4.75) for normal/elevated BP, stage 1-2 hypertension, and severe hypertension, respectively. A similar pattern of associations was observed for AC presence, although the interaction with BP was not statistically significant. Conclusions: ECG-defined AC burden was independently associated with stroke mortality, with substantially stronger associations among individuals with severe hypertension, supporting BP as an important modifier of its prognostic significance.