A large study that has questioned the role of beta blockers post MI has found the drugs offer no survival benefit to patients with heart attack in the absence of heart failure.
Researchers in the UK who conducted the observational study said secondary therapy at hospital discharge might not need to include beta-blockers for this group of acute MI patients which they argued would reduce unnecessary cost, side effects and poor adherence in some patients who are being prescribed too many medications.
The study published in JACC earlier this month examined data from 179,810 patients hospitalised with acute MI without heart failure or left-ventricular systolic dysfunction.
According to the investigators after adjustment there was no statistical difference in mortality rates within a year of the patients suffering their heart attack between those who had been prescribed beta blockers and those who had not.
The findings were similar regardless of whether patients had STEMI or NSTEMI.
National Heart Foundation’s Chief Medical Advisor, Professor Garry Jennings told the limbic that it was reasonable to question the relevance of the drugs in this setting given that a lot of the data that led to the ‘beta-blockers for all’ recommendation predated the routine use of statins and the contemporary era where many patients undergo revascularisation for acute MI.
He said unlike the US and UK Australia has already acknowledged in its most recent Acute Coronary Syndromes guideline the growing body of evidence, which suggests the routine prescription of beta-blockers might not be indicated in patients with a normal ejection fraction or without heart failure after acute MI.
“The Australian ACS guidelines are very clear on the fact that people who have impaired ventricular function heart failure should be prescribed beta blockers but it is a lot more sanguine about the use of beta blockers for everyone,” he said noting that the current guideline incorporates much of the evidence that has cast doubt on whether beta blockers add any value to patients with MI but without heart failure.
“While the [2016 ACS guidelines] don’t say don’t use beta blockers in this group of patients – and it couldn’t on the basis of observational data which is all we have at the moment – it does imply that these drugs are going to be more beneficial in those at highest risk of a second MI – and those at higher risk are those that have got impaired ventricular function or heart failure.”
In an editorial accompanying the study researchers led by cardiologist Professor Borja Ibáñez, from Madrid, Spain raised concerns about the fact that the investigators used a threshold of systolic dysfunction of 30%, saying they “missed a great opportunity to present only patients with preserved LVEF (≥ 50%) or even to differentiate between patients with intermediate and good LVEF.”
Despite this they described the study as ‘important’ adding that it has highlighted the need to ‘reboot the system’.
“The role of beta blockers in post-MI patients without LVSD (LVEF >40%) needs to be evaluated from scratch,’’ they wrote.