Analysis suggests tweaking risk stratification for acute MI
Discharge heart rate may predict long-term mortality independently of and better than admission heart rate among acute MI patients, observational data suggested.
Three-year survival rates were approximately 91% among patients with discharge heart rates under 60 bpm and about 82% for those whose heart rates were at 90 bpm or higher, according to Jorge Kizer, MD, of San Francisco Veterans Affairs Heath Care System, and colleagues.
After statistical adjustment, all-cause deaths within 3 years were more strongly tied with heart rate at discharge (adjusted HR 1.14 per 10-bpm increase, 95% CI 1.07-1.21) than admission heart rate (adjusted HR 1.05 per 10-bpm increase, 95% CI 1.02-1.09; P=0.043 for comparison), the authors reported online in the Journal of the American Heart Association.
Yet people with faster heart beats at discharge had a lower mortality risk if they received beta-blockers when leaving the hospital (HR 1.10 per 10 bpm, 95% CI 1.03-1.17) versus if they didn't (HR 1.35 per 10 bpm, 95% CI 1.19-1.53; P=0.004 for interaction).
"The documented effect modification by β-blocker treatment suggests that post-acute MI patients leaving the hospital with higher heart rates (≥80 beats per minute and, especially, ≥90 beats per minute) may require closer follow-up, and underscores the importance of maximizing use of these medications after acute MI," according to Kizer's group.
In their study, 10.7% of patients did not receive beta-blockers at discharge.
"Beta-blocker therapy, which lowers heart rate among other mechanisms of cardioprotection, is already an evidence-based guideline-directed medical therapy. This study helps to further reinforce the benefits associated with beta-blockers in post-MI patients, which are incremental to other guideline-directed medical therapies," commented Gregg Fonarow, MD, of UCLA, who was not part of the study.
Fonarow pointed out that heart rate-lowering medication ivabradine (Corlanor) is only approved for use in patients with heart failure with reduced ejection fraction. The agent did not improve clinical outcomes in stable coronary artery disease in the SIGNIFY and BEAUTIFUL studies.
For Kizer's study, the researchers put together the PREMIER (2003-2004) and TRIUMPH (2005-2008) registries for their dataset. Included were 6,576 acute MI patients who survived to discharge (mean age 60 years, 33% women, 24% black).
Whereas admission heart rate has been included in risk calculators for acute MI such as GRACE and TIMI, because of its known association with short- and long-term mortality, discharge heart rate is "a potentially modifiable therapeutic target" that may also be important, Kizer and colleagues suggested.
"The present study is, to our knowledge, the largest to date to evaluate the association of discharge heart rate with mortality after acute MI. It is also the first to do so in a racially diverse U.S. population, and to account for a range of psychosocial, socioeconomic, and healthcare quality measures in addition to the demographic and clinical covariates considered in previous studies."
Nevertheless, residual confounding is a potential limitation to the analyses, the investigators said.
"The findings reflect practice patterns from 2003 to 2008, and may not be fully generalizable to contemporary practice," they also acknowledged. "We examined the effect of discharge heart rate, a single measure at one time point, on outcome over 3 years, and one could argue that this single measure may not be representative of patients' postdischarge heart rates."
The study should come as no surprise -- as higher heart rate is nearly always an adverse predictor of outcome -- and doesn't directly indicate need for increasing beta-blocker use or dosing, commented Eric Peterson, MD, of the Duke Clinical Research Institute in Durham, North Carolina.
The study was supported by CV Therapeutics and a grant from the Agency for Healthcare Research and Quality.
Kizer disclosed owning stock in Amgen, Gilead Sciences, Pfizer, and Johnson & Johnson.
Journal of the American Heart Association
Source Reference: Alapati V, et al "Discharge heart rate after hospitalization for myocardial infarction and long-term mortality in 2 US registries" J Am Heart Assoc 2019; DOI: 10.1161/JAHA.118.010855.
Read the original article on Medpage Today: High BPM at Discharge Spells Mortality Risk After Heart Attack