Association Between Intensive vs Standard Blood Pressure Control and Incident Left Ventricular Conduction Disease: A Post Hoc Analysis of the SPRINT Randomized Clinical Trial.

Importance: Left ventricular conduction disease predicts heart failure and death, and the only strategies to mitigate its effects involve implantation of a permanent pacemaker. There are currently no proven preventive strategies for this common condition. Objective: To determine the association between targeting intensive blood pressure (BP) control and the risk of developing left ventricular conduction disease. Design, Setting, and Participants: This was a post hoc analysis of the 2-arm multicenter Systolic Blood Pressure Intervention Trial (SPRINT), which recruited participants from 102 sites in the US and Puerto Rico and was conducted from November 2010 until August 2015. Adults 50 years and older with hypertension and at least 1 other cardiovascular risk factor were included. Participants with baseline left ventricular conduction disease, ventricular pacing, or ventricular pre-excitation were excluded for the current analysis. Data were analyzed from November 2021 to November 2022. Intervention: Participants were randomly assigned to a systolic BP target of less than 140 mm Hg (standard treatment group) or less than 120 mm Hg (intensive treatment group). Main Outcome: The primary outcome was incident left ventricular conduction disease, including any fascicular or left bundle-branch block, assessed by serial electrocardiography. Incident right bundle-branch block was examined as a negative control. Results: Among 3918 participants randomized to standard treatment and 3956 to intensive treatment (mean [SD] age, 67.6 [9.2] years; 2815 [36%] female) monitored for a median [IQR] 3.5 (0.02-5.2) years, 203 developed left ventricular conduction disease. Older age (hazard ratio per 10-year increase [HR], 1.42; 95% CI, 1.21-1.67; P < .001), male sex (HR, 2.31; 95% CI, 1.63-3.32; P < .001), and cardiovascular disease (HR, 1.46; 95% CI, 1.06-2.00; P = .02) were associated with a higher risk of left ventricular conduction disease. Assignment to intensive treatment was associated with a 26% lower risk of left ventricular conduction disease (HR, 0.74; 95% CI, 0.56-0.98; P = .04). These results persisted when incident ventricular pacing was included in the outcome and when considering all-cause death as a competing risk. In contrast, no association between randomization assignment and right bundle-branch block was observed (HR, 0.95; 95% CI, 0.71-1.27; P = .75). Conclusions and Relevance: In this study, targeting intensive BP control was associated with lower risk of left ventricular conduction disease in a randomized clinical trial, suggesting that clinically relevant conduction disease may be preventable. Trial Registration: ClinicalTrials.gov Identifier: NCT01206062.

Lifestyle habits associated with cardiac conduction disease.

AIMS: Cardiac conduction disease can lead to syncope, heart failure, and death. The only available therapy is pacemaker implantation, with no established prevention strategies. Research to identify modifiable risk factors has been scant. METHODS AND RESULTS: Data from the Cardiovascular Health Study, a population-based cohort study of adults ≥ 65 years with annual 12-lead electrocardiograms obtained over 10 years, were utilized to examine relationships between baseline characteristics, including lifestyle habits, and conduction disease. Of 5050 participants (mean age 73 ± 6 years; 52% women), prevalent conduction disease included 257 with first-degree atrioventricular block, 99 with left anterior fascicular block, 9 with left posterior fascicular block, 193 with right bundle branch block (BBB), 76 with left BBB, and 102 with intraventricular block at baseline. After multivariable adjustment, older age, male sex, a larger body mass index, hypertension, and coronary heart disease were associated with a higher prevalence of conduction disease, whereas White race and more physical activity were associated with a lower prevalence. Over a median follow-up on 7 (interquartile range 1-9) years, 1036 developed incident conduction disease. Older age, male sex, a larger BMI, and diabetes were each associated with incident conduction disease. Of lifestyle habits, more physical activity (hazard ratio 0.91, 95% confidence interval 0.84-0.98, P = 0.017) was associated with a reduced risk, while smoking and alcohol did not exhibit a significant association. CONCLUSION: While some difficult to control comorbidities were associated with conduction disease as expected, a readily modifiable lifestyle factor, physical activity, was associated with a lower risk.