Lowering systolic blood pressure does not increase stroke risk: an analysis of the SPRINT and ACCORD trial data

Objective: Traditional neurology teaching states that when mean arterial pressure dips below a 60 mm Hg threshold, there is an increase in stroke risk due to cerebral hypoperfusion. The aim of this study was to determine whether intensive lowering of systolic blood pressure increases adverse cardiovascular outcomes by examining the association between achieved blood pressure values, specifically mean arterial pressure and pulse pressure, and risk of stroke. Methods: Data from participants in the Systolic Blood Pressure Intervention Trial (SPRINT) and the Action to Control Cardiovascular Risk in Diabetes (ACCORD) Blood Pressure (BP) trial were examined, using survival analysis to model minimal arterial pressure and average pulse pressure during the study period against risk of stroke, hypotension, and syncope, with death as a competing risk. Results: In both SPRINT and ACCORD participants, there was no increase in stroke risk with achieved mean arterial pressure values below 60 mm Hg. In SPRINT participants, achieved mean arterial pressure values greater than 90 mm Hg were associated with a 247% (HR: 3.47, 95% CI: 2.06-5.85) higher risk of stroke compared with participants in the 80-89 mmHg reference group. No association was found between low achieved pulse pressure values and greater stroke risk in either the SPRINT or ACCORD participants, as well as no association between mean arterial pressure and pulse pressure values and risk of syncope. Interpretation: Intensive lowering of systolic blood pressure does not increase risk of stroke in hypertensive patients, despite extremely low mean arterial pressure or pulse pressure values.