Relation of Variability of Low-Density Lipoprotein Cholesterol and Blood Pressure to Events in Patients With Previous Myocardial Infarction from the IDEAL Trial

Abstract

In patients with previous myocardial infarction (MI), aggressive hypertension control and low-density lipoprotein cholesterol (LDL-C) reduction are important secondary prevention measures. However, residual risk remains despite aggressive treatment. Whether variability in blood pressure (BP) and LDL-C can explain this residual risk is not known. Patients enrolled in the Incremental Decrease in End Points Through Aggressive Lipid-Lowering trial with at least 1 post-baseline measurement of LDL-C and blood pressure (BP) were included. Visit-to-visit LDL-C and BP variabilities were evaluated using various measures of variability. Primary outcome was any coronary event with the secondary outcomes of any cardiovascular event (CV), MI, stroke, death, and CV death. Among the 8,658 patients included, each 1-SD (10.8mg/dl) increase in LDL-C variability increased the risk of any coronary event (adjusted HR [HRadj] 1.07; 95% CI 1.04 to 1.11; p <0.0001), any CV event, MI, and death (HRadj 1.19; 95% CI 1.14 to 1.25; p <0.0001). Similarly, each 1-SD (7.2mm Hg) increase in systolic BP variability increased the risk of any coronary event (HRadj 1.15; 95% CI 1.10 to 1.20; p <0.0001), any CV event, MI, stroke, death (HRadj 1.28; 95% CI 1.18 to 1.38; p <0.0001), and CV death. Compared with the group with low variability for both LDL-C and systolic BP, the group with high variability for both had a significant increase in any coronary event (HRadj 1.48; 95% CI 1.30 to 1.70), any CV event (HRadj 1.43; 95% CI 1.27 to 1.61), and MI (HRadj 1.87; 95% CI 1.46 to 2.41). In conclusions, in patients with a history of MI, variabilities in LDL-C and BP are powerful and independent predictors of CV events including death.