Ambulatory blood pressure monitoring early after acute myocardial infarction: development of a new prognostic index

Objectives The aim of our study was to assess the possible role of a prognostic index based on ambulatory blood pressure monitoring in a large cohort of patients with recent myocardial infarction. Methods The study population included 1335 consecutive patients admitted for ST elevation myocardial infarction and discharged alive from 48 Italian hospitals participating in the multicentric IMPRESSIVE (Infarto Miocardico, Pressione arteriosa e frequenza cardiaca. Studio Italiano di Valutazione Epidemiological) study. Ambulatory blood pressure monitoring was performed 3 weeks after discharge, with a clinical follow-up of 12 months. End-points included cardiac death and new admission for heart failure. A prognostic index was obtained from the ambulatory blood pressure monitoring variables according to the formula: (220 - age) - mean 24 h heart rate (m24hHR) + mean 24 h diastolic blood pressure (m24hDBP). Results Among many potential predictors only left-ventricular ejection fraction, creatinine levels, Killip class and the prognostic index were independently associated with events during the follow-up. In particular, higher values of the prognostic index were associated with a lower incidence of events, with an odds ratio of 0.958 (95% confidence intervals 0.943-0.974) and a 4% reduction in risk for each point of the prognostic index. Overall incidence of cardiac events was 6-fold higher in patients within the lowest quartile of the prognostic index (<= 148) compared with the other three quartiles (12 vs. 2, 1.4 and 2% respectively in the other three quartiles; P < 0.0001). Conclusions A simple prognostic index based on ambulatory blood pressure monitoring and age may be a useful tool in predicting cardiac death and heart failure in patients with recent myocardial infarction.