Rate of heart failure and 1-year survival for older people receiving low-dose β-blocker therapy after myocardial infarction

Background Many older people do not receive beta-blocker therapy after myocardial infarction or receive doses lower than those tested in trials, perhaps because physicians fear that beta-blockers may precipitate heart failure. We examined the relation between use of beta-blockers, the dose used, and hospital admission for heart failure and 1-year survival in a cohort of all older patients surviving myocardial infarction in Ontario, Canada. Methods We collected data on a cohort of 13 623 patients aged 66 years or older who were discharged from hospital after a myocardial infarction and who did not receive beta-blocker therapy or received low, standard, or high doses. We used Cox's proportional-hazards models to study the association of dose with admission for heart failure and survival with adjustment for factors including age, sex, and comorbidity. Findings Among 8232 patients with no previous history of heart failure, dispensing of beta-blocker therapy was associated with a 43% reduction in subsequent admission for heart failure (adjusted risk ratio 0.57 [95% CI 0.48-0.69]) compared with patients not dispensed this therapy. Among the 4681 patients prescribed beta-blockers, the risk of admission was greater in the high-dose than in the low-dose group (1.53 [1.01-2.31]). Among all 13 623 patients in the cohort, 2326 (17.1%) died by 1 year. Compared with those not dispensed beta-blocker therapy, the adjusted risk ratio for mortality was lower for all three doses (low 0.40 [0.34-0.47], standard 0.36 [0.31-0.42], high 0.43 [0.33-0.56]), Interpretation Compared with high-dose beta-blocker therapy, low-dose treatment is associated with a lower rate of hospital admission for heart failure and has a similar 1-year survival benefit. Our findings support the need for a randomised controlled trial comparing doses of beta-blocker therapy in elderly patients.