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

Background — Many older people do not receive β-blocker therapy after myocardial infarction or receive doses lower than those tested in trials, perhaps because physicians fear that β-blockers may precipitate heart failure. We examined the relation between use of β-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 β-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 β-blocker therapy was associated with a 43% reduction in subsequent admission for heart failure (adjusted risk ratio 0·57 [95% C*** 0·48–0·69]) compared with patients not dispensed this therapy. Among the 4681 patients prescribed β-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 β-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 β-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 β-blocker therapy in elderly patients.