Blood Pressure at 6 Months After Acute Myocardial Infarction and Outcomes at 2 Years: The Perils Associated With Excessively Low Blood Pressures

Background: This study aimed to determine the association between achieved blood pressure at 6-month follow-up and cardiovascular outcomes at 2 years in patients treated with β-blockers and renin-angiotensin-aldosterone blockers after acute myocardial infarction (AMI). Methods: We analyzed data from 5503 patients enrolled in the national AMI registry. Patients with myocardial reinfarction (MrI), rehospitalization for heart failure (rHHF), or stroke before 6-month follow-up were excluded. Achieved blood pressures were categorized into 10-mm Hg increments. The primary outcome was all-cause death. The secondary outcome was a composite of all-cause death, MrI, and rHHF. Hazard ratios (HRs) were estimated with multivariable-adjusted Cox hazards models using 125- to 134-mm Hg systolic blood pressure (SBP) and 75- to 84-mm Hg diastolic blood pressure (DBP) subgroups as reference. Results: After a median follow-up of 2.1 years, SBP < 115 mm Hg was associated with increased risks for all-cause death (adjusted HR: 2.202 [1.158-4.188]) and for a composite outcome (HR: 1.682 [1.075-2.630]). Likewise, DBP < 75 mm Hg tended to be associated with an increase in all-cause death (HR: 2.078 [0.998-4.327] for DBP of 65 to 74 mm Hg; HR: 2.610 [1.256-5.423] for DBP < 65 mm Hg). Even in patients <75 years, the risk of a composite outcome was increased for DBP < 65 mm Hg (HR: 2.492 [1.401-4.434]). Conclusions: Low blood pressure achieved with β-blocker and renin-angiotensin-aldosterone blocker at 6 months was associated with an increased risk of all-cause mortality independently of confounding factors in patients with AMI. This finding suggests that caution should be taken for patients with AMI who use blood-pressure–lowering treatments.