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 Epidemiologica) 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 (< or =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.