Blood pressure and mortality among men with prior myocardial infarction
Flack JM., Neaton J., Grimm R., Shih J., Cutler J., Ensrud K., MacMahon S.
Background: The purpose of the present study was to describe the relation between blood pressure (systolic [SBP] and diastolic [DBP]) and death from coronary heart disease (CHD) and all causes for men with a history of myocardial infarction (MI). Methods and Results: The study cohort consisted of men aged 35 to 57 years screened for the Multiple Risk Factor Intervention Trial (MRFIT) in 1973 through 1975 and followed for survival for an average of 16 years through 1990. There were 5362 men who reported prior hospitalization for a heart attack of at least 2 weeks' duration at the initial screening of MRFIT. There was a J-shaped relation between SBP and DBP with both CHD and all-cause mortality during the first 2 years of follow-up in older (age, 45 to 57 years) men only. Risk nadirs for SBP were 152 and 145 mm Hg, respectively, for CHD death and all-cause mortality; corresponding DBP risk nadirs were 94 and 90 mm Hg. After the first 2 years, there was a positive association between SBP and death from CHD and all causes. By 15 years, cumulative CHD mortality percentages for men with screening SBP < 120, 120 to 139, 140 to 159, and ≥160 mm Hg were 19.7%, 21.3%, 27.5%, and 32.0%, respectively. When deaths only after year 2 were considered, although the linear DBP coefficient was significant, the quadratic term for DBP was no longer significant (P>.05). However, the relation still appeared J-shaped as cumulative mortality for those with DBP <70, 70 to 79, 80 to 89, 90 to 99, and ≥100 mm Hg was 24.3%, 20.8%, 21.1%, 25.5%, and 29.7%, respectively. When the joint relation of SBP and DBP was considered, there were no survival differences among the four cohorts (SBP ≥140 and DBP <80, SBP ≥140 and DBP ≥80, SBP ≤140 and DBP <80, and SBP ≤140 and DBP ≥80) during the first 2 years. After 2 years, both CHD and all-cause mortality rates were approximately 40% higher for participants with SBP ≥140 mm Hg versus <140 mm Hg regardless of DBP level (<80 or ≥80 mm Hg). Conclusions: In this large cohort of men with prior MI, the association of SBP and DBP with CHD and all- cause mortality varied over the 16-year follow-up period. During early follow-up, in older men only, J- or U-shaped relations were evident. However, after 2 years, these same relations had become positive and graded. Given the substantial excess mortality risk in this cohort associated with high blood pressure, particularly SBP, efforts to gradually lower blood pressure should receive high priority among hypertensive men with prior MI.