ImportanceLeft 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.ObjectiveTo determine the association between targeting intensive blood pressure (BP) control and the risk of developing left ventricular conduction disease.Design, Setting, and ParticipantsThis 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.InterventionParticipants 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 OutcomeThe 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.ResultsAmong 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 RelevanceIn 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.