High-risk patients with acute coronary syndromes remain likely candidates for further cardiovascular events and death at 1-year follow-up despite receiving aggressive intervention, according to Kenneth W. Mahaffey, M.D., and his associates.
The short-term (30-day) results of the Superior Yield of the New Strategy of Enoxaparin, Revascularization, and Glycoprotein IIb/IIIa Inhibitors (SYNERGY) trial were widely reported in 2004. The study involved more than 10,000 patients with acute coronary syndromes (ACS) treated in 12 countries, who were randomly assigned to receive either low-molecular-weight heparin (enoxaparin) or unfractionated heparin, and who were also treated with an early invasive management strategy.
More than 70% of the patients underwent percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) surgery. Most (92%) also received aspirin, clopidogrel (54%), β-blockers (85%), ACE inhibitors (73%), and/or statins (81%), according to the discretion of their clinicians.
The SYNERGY investigators continued their follow-up and reported their long-term results. At the 6-month and 1-year marks, these patients remained at high risk for recurrent cardiovascular complications and death.
“Overall, nearly 18% died or experienced nonfatal MI [at] 6 months of follow-up, and 7% died by 1-year follow-up, despite aggressive coronary revascularization and high use of evidence-based therapies at the time of hospital discharge,” the researchers said (JAMA 2005;294:2594–600).
Outcomes were even worse for the highest-risk patients, defined as those aged 60 years or older, those with elevated levels of cardiac biomarkers, and those with adverse ECG changes. Among such patients, 21% had either died or sustained a nonfatal MI within 6 months of their initial ACS, and 10% had died within 1 year.
“These rates of morbidity and mortality are higher than those reported in virtually all contemporary non-ST-segment elevation ACS trials,” reported Dr. Mahaffey, of Duke Clinical Research Institute, Durham, N.C., and his associates.
“It is clear that patients with an ACS event with high-risk baseline features are at substantial risk for adverse cardiac events over time,” they noted.
Researchers found that the two anticoagulants performed equally well in the long term, as they had in the short term. There were no significant differences between patients who received enoxaparin and those who received unfractionated heparin in rates of hospital readmission (18% and 19.0%, respectively) or death (7.7% and 7.3%).
Stroke was a rare occurrence in both treatment groups, affecting 1.5% of those given enoxaparin and 1.6% of those given unfractionated heparin, the researchers reported.