IN HOSPITAL DAY-BY-DAY BLOOD PRESSURE VARIABILITY

Objective: Increased home day-by-day variability of blood pressure (BP), independently from its average value, results in increased risk of target organ damage and cardiovascular events in primary and secondary cardiovascular prevention. However, the association between in-hospital day-by-day BP variability and its prognostic value in secondary cardiovascular prevention has not yet been established. Design and method: We considered 1440 consecutive cardiac patients who underwent cardiovascular rehabilitation for at least 12 days after coronary artery bypass graft (CABG), valve surgery or both. In each rehabilitation day, trained nurses measured auscultatory BP in the morning and in the afternoon at the patient bed. Systolic BP variability (SBPv) was assessed as the standard deviation of the daily measures. Logistic regression analysis was calculated with endpoints the overall mortality, cardiovascular mortality, and major adverse cardiovascular and cerebrovascular events (MACCEs). Kaplan-Meier survival curves were calculated among SBPv tertiles. Results: Mean age was 68 ± 11 years. The prevalence of male gender was 72% and of hypertension was 61%; 807 patients (56%) underwent CABG, 475 (33%) valve surgery, 158 (11%) valve surgery+CABG. Ranges of SBPv tertiles were 4.1–9.1 mmHg, 9.2–11.5 mmHg, and 11.6–24.5 mmHg. In CABG patients, 1) the Kaplan-Meier curve showed worse survival free from overall mortality (p = 0.042) and MACCEs (p = 0.006) in the highest SBPv tertile, and 2) the logistic regression analysis showed significant positive correlations of SBPv with mortality and MACCEs (see Figure), with 12%, 11% and 10% increase of relative risk of overall mortality, cardiovascular mortality, and MACCEs for each mmHg increase of SBPv (overall mortality: HR = 1.12, p = 0.002; cardiovascular mortality: HR = 1.11, p = 0.014; MACCEs: HR = 1.10, p = 0.001). Logistic regression analysis remained significant also when calculated for the coefficient of variation, thus correcting the standard deviation by the mean SBP. Multivariate analysis separately adjusted for age, gender, hypertension, mean SBP, diabetes, glomerular filtration rate, left-ventricle ejection fraction and anti-hypertensive drugs, at discharge and follow-up, confirmed the correlation between SBPv and MACCEs or overall mortality. No association between SBPv and mortality or MACCEs was found in valve-surgery patients.Conclusions: In-hospital day-by-day SBPv predicts mortality and MACCEs for CABG patients in secondary cardiovascular prevention.