Beta-blocker remedy past 1 12 months after myocardial infarction (MI) for sufferers with out heart failure or left ventricular systolic dysfunction was not related to improved cardiovascular outcomes in a brand new evaluation of a nationwide cohort of greater than 40,000 sufferers.
“The outcomes of our examine handle an current hole within the present proof and supply an perception into long-term optimum secondary prevention methods for a big proportion of MI survivors, specifically sufferers with no coronary heart failure or left ventricular systolic dysfunction who could have longer survival in contrast with those that develop such issues after an MI,” state the authors, led by Divan Ishak, MD, Uppsala College, Sweden.
The examine was published online in Coronary heart on Might 2.
The researchers clarify that scientific outcomes following MI have improved in recent times, partly due to the usage of evidence-based therapies together with well timed reperfusion and secondary prevention drugs. As such, extra sufferers are surviving MI with no coronary heart failure or left ventricular systolic dysfunction.
Beta-blockers are a longtime remedy for sufferers with coronary heart failure and/or left ventricular systolic dysfunction as a result of they cut back morbidity and mortality. For these with out coronary heart failure or left ventricular systolic dysfunction, proof helps the usage of beta-blockers within the early part after MI, however there may be uncertainty as as to if they need to be continued past the primary 12 months within the absence of different scientific indications.
In historic randomized trials, longer-term beta-blocker remedy has been proven to scale back mortality charges, however these trials have been performed earlier than the introduction of invasive reperfusion methods and antithrombotic brokers into routine MI care. More moderen research have been restricted by the inclusion of solely a subset of MI sufferers, comparatively small pattern dimension, or brief follow-up, the authors notice.
Whereas extra complete randomized trials are in progress, the good thing about beta-blockers within the power part past the primary 12 months would possibly stay unknown and the lengthy follow-up required to attract agency conclusions could also be difficult to attain.
The present examine subsequently aimed to analyze the affiliation between beta-blocker remedy and cardiovascular outcomes past the primary 12 months after MI in sufferers with out coronary heart failure or left ventricular systolic dysfunction utilizing real-world knowledge from the SWEDEHEART registry of sufferers with coronary heart disease in Sweden.
The examine included all 43,618 sufferers aged 18 years or over with MI, together with ST-elevation (STEMI) and non-STEMI, who had been hospitalized at one of many 74 cardiac care items in Sweden between 2005 and 2016.
Comply with-up began 1 12 months after hospitalization (index date). Sufferers with coronary heart failure or left ventricular systolic dysfunction up till the index date have been excluded. Sufferers have been allotted into two teams in keeping with beta-blocker remedy. The first consequence was a composite of all-cause mortality, MI, unscheduled revascularization, and hospitalization for coronary heart failure.
Outcomes confirmed that, general, 78.5% of sufferers obtained a beta-blocker and 21.5% didn’t take a beta-blocker on the index date 1 12 months following MI. The median age was 64 years, and 25.5% have been feminine. The median follow-up was 4.5 years.
Within the intention-to-treat evaluation, the unadjusted fee of main consequence was decrease amongst sufferers who obtained a beta-blocker versus those that didn’t (3.8 versus 4.9 occasions/100 person-years; hazard ratio [HR], 0.76; 95% confidence interval [CI], 0.73 to 1.04).
Nonetheless, following inverse propensity rating weighting and multivariable adjustment, the danger of the first consequence was not totally different in keeping with beta-blocker remedy (HR, 0.99; 95% CI, 0.93 to 1.04). These findings have been constant throughout particular person secondary endpoints and throughout affected person subgroups.
The authors say that that is the biggest examine to have evaluated beta-blocker remedy in sufferers with out coronary heart failure or left ventricular systolic dysfunction following MI. Though the design is observational, it contains a big pattern of sufferers, has a median follow-up of 4.5 years, and implements causal inference methods, they state.
Additionally they level out that the outcomes align with these of a current meta-analysis of up to date trials this query.
They notice that the potential mechanism of beta-blockers in enhancing cardiovascular outcomes following MI is attributed to the inhibition of the sympathetic overdrive, reducing coronary heart fee, and thus lowering myocardial oxygen consumption.
Nonetheless, routine and well timed coronary reperfusion, in addition to utilization of potent antiplatelet remedy, reduces infarct dimension, minimizing the upregulation of sympathetic exercise, notably in these people who don’t maintain substantial myocardial harm.
As well as, beta-blockers have been related to a number of unwanted effects, together with depression and fatigue, so figuring out whether or not they’re indicated past the primary 12 months after MI could have an effect on affected person health-related high quality of life, the authors counsel.
In an accompanying editorial, Tom Evans, MD, and Ralph Stewart, MD, Inexperienced Lane Cardiovascular Service, Auckland Metropolis Hospital, New Zealand, say the present examine raises an vital query immediately related to the standard of care: Do sufferers with a traditional left ventricular ejection fraction profit from long-term beta-blocker remedy after myocardial infarction?
They notice that the examine had a lot of strengths together with a big pattern dimension, a consultant examine inhabitants, detailed info on danger markers used for the propensity adjusted evaluation, and unbiased analysis of outcomes from administrative datasets as much as 12 years after the index MI.
However they warning that the potential for unrecognized confounding is a limitation, and subsequently extra proof from massive randomized scientific trials is required to reply this query.
This work was supported by grants from the Swedish Authorities.