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ESC Congress 2024, Paris – The recent findings from the ABYSS trial have sparked significant debate in the cardiology community, raising concerns about the advisability of discontinuing long-term beta-blocker therapy in patients with a history of myocardial infarction (MI) and preserved left ventricular function. The trial’s results, presented at the European Society of Cardiology (ESC) Congress and simultaneously published in the New England Journal of Medicine, suggest that stopping beta-blockers might lead to a higher rate of cardiovascular hospitalizations, contradicting current guidelines that support discontinuation after one year in specific patient groups.
Study Overview and Key Findings
The ABYSS trial, an open-label, non-inferiority study, included 3,698 patients with a history of MI, all of whom had a left ventricular ejection fraction of at least 40% and were on long-term beta-blocker therapy. Participants were randomly assigned to either continue or discontinue their beta-blocker regimen. Over a median follow-up of three years, the trial aimed to assess a composite endpoint of death, MI, stroke, and cardiovascular hospitalization.
The results showed that 23.8% of patients in the discontinuation group experienced the primary endpoint, compared to 21.1% in the continuation group. This slight difference was primarily driven by an increase in cardiovascular hospitalizations in those who stopped taking beta-blockers (18.9% vs. 16.6%). Additionally, discontinuation was associated with a rise in both systolic and diastolic blood pressure, as well as an increased heart rate, without any observed improvement in quality of life.
“We anticipated that withdrawing beta-blockers would be safe and lead to improved quality of life. However, our findings indicate otherwise,” said Dr. Johanne Silvain, the lead investigator from Pitié-Salpêtrière University Hospital in Paris. “The trial not only failed to show the non-inferiority of stopping beta-blockers but also highlighted a safety signal with increased blood pressure and heart rate.”
Implications for Current Guidelines
Beta-blockers have been a cornerstone in the management of patients post-MI, particularly before the modern era of myocardial reperfusion and advanced pharmacotherapy, which have significantly reduced the risk of heart failure and mortality. The results of the ABYSS trial challenge the current guidelines, which suggest that beta-blockers may be discontinued after one year in certain patients with preserved ejection fraction and no other primary indications for beta-blocker use.
Dr. Silvain expressed surprise at the lack of improvement in quality of life among patients who discontinued beta-blockers, despite the common perception of beta-blockers having multiple side effects. “One potential reason could be that our trial participants had been on beta-blockers for several years and likely tolerated them well, while those with tolerance issues had already stopped using them.”
Comparisons with the REDUCE-AMI Trial
The ABYSS findings contrast with the recent REDUCE-AMI trial, which found no superiority of beta-blocker therapy over no therapy in acute MI patients with preserved ejection fraction. However, Dr. Silvain pointed out that the primary endpoint in REDUCE-AMI did not include cardiovascular hospitalizations, which were the main drivers of the differences observed in the ABYSS trial.
Dr. Jane Armitage of the University of Oxford, who discussed the trial results at the ESC HOTLINE session, acknowledged the importance of the findings but noted some limitations, including the open-label design that might introduce bias in hospitalization decisions. She also questioned whether a higher non-inferiority margin could have been more appropriate given the unexpected event rates.
Conclusion and Future Directions
The ABYSS trial’s results have led to a cautious approach among cardiologists regarding the discontinuation of beta-blockers in patients post-MI with preserved ejection fraction. Dr. Tomas Jernberg, in an accompanying editorial, emphasized the need for more data before updating guidelines, noting the potential risks of stopping beta-blockers, particularly concerning recurrent angina and the need for rehospitalization.
Until the results of ongoing trials are available, it may be prudent for clinicians to continue beta-blocker therapy in well-tolerated patients, despite emerging questions about the necessity of lifelong treatment in the modern era of cardiac care.
