Abstract 3128: Nocturnal Non-Dipping of Pulse Rate Predicts Cardiovascular Events Independent of Non-Dipping of BP in Hypertensive/Diabetic Patients
Background Nocturnal non-dipping of BP is an established risk marker for future incidence of cardiovascular disease (CVD), but it is not established whether nocturnal non-dipping of pulse rate (PR) predicts CVD.
Objective To test the hypothesis that nocturnal non-dipping of PR predicts the risk of incident CVD independent of nocturnal BP dipping pattern.
Methods Ambulatory BP monitoring (ABPM) was performed without BP medications in 457 subjects who were seen in three clinics for the evaluation or assessment of diabetes or hypertension. They consisted of 200 diabetic and 257 hypertensive patients, all of whom were free from overt CVD at baseline; they were followed for an average of 72 ± 26 months. Non-dipper PR was defined as a night/day PR ratio greater than 0.90. Incident CVD was defined as either myocardial infarction, stroke, or sudden cardiac death, and its relationships to night/day PR ratio (continuous) and PR non-dipping status (binary) were investigated. Cox proportional hazard models were used to estimate hazard ratios (HR) and their 95% CI, before and after adjusting for age, sex, and BMI (Model 1), plus diabetes and serum creatinine (Model 2), plus 24-h SBP and nocturnal non-dipping of BP (Model 3).
Results The mean age was 66.9 ± 9.2 years; 38% were male; and 377 (82.5%) had a diagnosis of hypertension. In multivariable analyses, PR non-dipping status significantly predicted an increased risk of incident CVD in Model 1 (HR=2.46, 95% CI=1.24 – 4.88, P=0.01), Model 2 (HR=2.39, 1.20 – 4.74, P=0.01), and Model 3 (HR= 2.27, 1.15– 4.50, P=0.02). The result of Model 3 was the same when adjusted by riser pattern where nighttime BP exceeds daytime BP (HR= 2.28, 1.15– 4.54, P=0.02). The sleep/awake PR ratio also positively predicted CVD events in Model 1 (P=0.03) and was of borderline significance in Model 2 (P=0.06) and Model 3 (P=0.096). There was no evidence of an interaction in the effects of PR non-dipping status with either diabetes status (P=0.93) or ambulatory BP level (P=0.55) on CVD risk.
Conclusions The risk of future CVD was shown to be twice as great in those whose PR does not exhibit the typical nocturnal decline. The relationship was independent of non-dipping of BP and did not dependent on diabetes status or BP level.