Effect of Intensive Blood Pressure Reduction on Left Ventricular Mass, Structure, Function, and Fibrosis in the SPRINT-HEART

Abstract

In observational studies, left ventricular mass (LVM) and structure are strong predictors of mortality and cardiovascular events. However, the effect of hypertension treatment on LVM reduction and its relation to subsequent outcomes is unclear, particularly at lower blood pressure (BP) targets. In an ancillary study of SPRINT (Systolic Blood Pressure Intervention Trial), where participants were randomly assigned to intensive BP control (target systolic BP target <120 mm Hg) versus standard BP control (<140 mm Hg), cardiac magnetic resonance imaging was performed at baseline and 18-month follow-up to measure: LVM, volumes, ejection fraction, and native T1 mapping for myocardial fibrosis. At baseline, 337 participants were examined (age: 64±9 years, 45% women); 300 completed the 18-month exam (153 intensive control and 147 standard control). In the intensive versus standard BP control group at 18 months, there was no difference in change in LVM (mean±SE =−2.7±0.5 g versus −2.3±0.7 g; P =0.368), ejection fraction, or native T1 ( P =0.79), but there was a larger decrease in LVM/end-diastolic volume ratio (−0.04±0.01 versus −0.01±0.01; P =0.002) a measure of concentric LV remodeling. There were fewer cardiovascular events in the intensive control group, but no significant association between the reduced events and change in LVM or any other cardiac magnetic resonance imaging measure. In SPRINT-HEART, contrary to our hypothesis, there were no significant between-group differences in LVM, function, or myocardial T1 at 18-month follow-up. These results suggests that mediators other than these LV measures contribute to the improved cardiovascular outcomes with intensive BP control.

A population-based phenome-wide association study of cardiac and aortic structure and function

“…This substantially extends earlier findings that heart size at birth has subtle but significant and persistent effects on cardiac structure into adulthood 50 . While the positive association between SBP and left ventricular mass is consistent with a previous interventional study 51 , it raises questions about the best interpretation of a more recent interventional study showing that intensive blood pressure (BP) control and standard BP control reduced left ventricular mass to a similar extent 52 . There was a negative association between diabetes and aortic area and distensibility, an observation that is useful for understanding observations such as the negative relationship of aortic distensibility to all cause mortality 53 .…”

Effect of Intensive Blood Pressure Control on Aortic Stiffness in the SPRINT-HEART

“…12,18 Participants were recruited from 4 clinics, and the CMRI exams were performed at Wake Forest School of Medicine. 15 The study was approved by the Institutional Review Board, and written informed consent was obtained.…”

“…12,13,18 SPRINT-HEART was a 337 participant ancillary study within the main SPRINT. 15 All methods and inclusion and exclusion criteria…”

“…We recently showed that intensive treatment did not significantly improve LV hypertrophy, LV function, or myocardial fibrosis compared with standard treatment. 15 This suggests that mediators other than these LV measures may contribute to the improvements in CVD events associated with intensive treatment. A recent secondary analysis of SPRINT showed that the intensive treatment was associated with improvements in estimated aortic stiffness at 12 months of follow-up and improved risk prediction for incident CVD events and mortality.…”

Risk-Benefit Assessment of Intense Blood Pressure Lowering

“…12 Furthermore, more intense blood pressure lowering did not reduce left ventricular mass or markers of cardiac fibrosis determined by magnetic resonance imaging. 13 The observation is counterintuitive given the known relationship between arterial hypertension and left ventricular hypertrophy, which predisposes to cardiac dysrhythmias, diastolic dysfunction, and overt heart failure. Obviously, we have to understand the mechanisms of how risks and benefits of more intense blood pressure lowering are mediated to inform clinical decisions.…”