WASHINGTON -- Colchicine does not protect against major cardiovascular adverse events after an acute myocardial infarction, according to a multinational placebo-controlled trial of more than 7000 patients.
The CLEAR SYNERGY (OASIS 9) study, called "the largest trial ever of colchicine in acute MI," showed no hint of benefit in an adverse event curve for colchicine relative to placebo over 5 years, which suggests that the role of this drug after myocardial infarction (MI) "is uncertain," Sanjit Jolly, MD, an interventional cardiologist at Hamilton Health Sciences and a professor of medicine at McMaster University in Hamilton, Ontario, Canada, reported here at Transcatheter Cardiovascular Therapeutics (TCT) 2024.
For the primary composite outcome -- cardiovascular death, MI, stroke, and ischemia-driven revascularization -- the event curves in the colchicine and placebo groups remained essentially superimposed over 5 years of follow-up, with only a slight separation after 4 years. The hazard ratio for the primary endpoint showed a 1% difference in favor of colchicine (hazard ratio [HR], 0.99; P = .93).
There were no meaningful differences in any of the individual endpoint components; all 95% CIs straddled the line of unity. Rates of cardiovascular death (3.3% vs 3.2%) and stroke (1.4% vs 1.2%) were numerically higher in the colchicine group than in the placebo group. Rates of MI (2.9% vs 3.1%) and ischemia-driven revascularization (4.6% vs 4.7%) were numerically lower in the colchicine group.
No adverse outcomes, including all-cause death (4.6% vs 5.1%), approached significance, with the exception of noncardiovascular death (13.0% vs 1.9%). For this outcome, the 95% CI stopped just short of the line of unity (HR, 0.68; 95% CI, 0.46-0.99).
Rates of adverse events (31.9% vs 31.7%; P = .86), serious adverse events (6.7% vs 7.4%; P = .22), and serious infections (2.5% vs 2.9%; P = .85) were similar in the colchicine and placebo groups, but diarrhea, a known side effect of colchicine, was higher in the colchicine group (10.2% vs 6.6%; P < .001).
Given these results, a panelist questioned the use of the word "uncertain" to describe the findings during the late-breaker session in which these results were presented.
"I think you are selling yourself short," said J. Dawn Abbott, MD, director of the Interventional Cardiology Fellowship Training Program at the Lifespan Cardiovascular Institute, Brown University in Providence, Rhode Island. Based on the size and conduct of this trial, she called the results "definitive" and suggested that the guidelines should be adjusted.
In OASIS 9, 3528 patients were randomized to colchicine, and 3534 were randomized to placebo. A second randomization in both groups was to spironolactone or placebo; these results will be presented at the upcoming American Heart Association (AHA) 2024 meeting. Both analyses will be published in The New England Journal of Medicine at that time, Jolly reported.
The study involved 104 sites in Australia, Egypt, Europe, Nepal, and North America. Follow-up in both groups exceeded 99%. Most patients had an ST-elevation MI (STEMI), but about 5% of those enrolled had a non-STEMI. Less than 10% of patients had experienced a previous MI.
Less than 5% of patients were discharged on sodium-glucose cotransporter 2 therapy, and more than 95% were discharged on aspirin and a statin. Nearly 80% were discharged on an angiotensin-converting enzyme inhibitor, and most patients received an anticoagulant. More than 95% of patients were implanted with a drug-eluting stent.
At month 3, C-reactive protein levels were significantly lower in the colchicine group than in the placebo group. C-reactive protein is a biomarker for the anti-inflammatory effect that is considered to be colchicine's primary mechanism of action. An anti-inflammatory effect has been cited as the probable explanation for the positive results shown in the COLCOT and LODOCO2 trials, published in 2019 and 2020, respectively.
In COLCOT, which randomized 4745 patients who experienced an acute MI in the previous 30 days, colchicine was associated with a 23% reduction in a composite major cardiovascular adverse events endpoint relative to placebo (HR, 0.77; P = .02). In LODOCO2, which randomized 5522 patients with chronic coronary disease, colchicine was associated with a 31% reduction in an adverse event composite endpoint (HR, 0.68; P < .0001).
However, two more recent trials -- CONVINCE and CHANCE-3 -- showed no difference between colchicine and placebo for the endpoint of recurrent stroke at 90 days. CONVINCE, with approximately 3000 patients, was relatively small, whereas CHANCE-3 randomized more than 8000 patients and showed no effect on the risk for stroke (HR, 0.98; 95% CI, 0.83-1.16).
Of these trials, COLCOT was the most similar to OASIS 9, according to Jolly. Among the differences, OASIS 9 was initiated earlier and was larger than the other trials, so it had more power to address the study question.
Given the absence of benefit, Jolly indicated that OASIS 9 might disrupt both the joint American College of Cardiology and AHA guidelines, which gave colchicine a class 2b recommendation in 2023, and the European Society of Cardiology guidelines, which gave colchicine a 2a recommendation.
"This is a big deal for me," said Ajay J. Kirtane, director of the Interventional Cardiovascular Care program at Columbia University in New York City. As someone who is now using colchicine routinely, these data have changed his opinion, he said.
The previous data supporting the use of colchicine "were just so-so," he explained. "Now I have a good rationale" for foregoing the routine use of this therapy.
Jolly said that he had put his own father on colchicine after an acute MI on the basis of the guidelines, but immediately took him off this therapy when the data from OASIS 9 were unblinded.
"The only signal from this trial was an increased risk of diarrhea," Jolly said. The results, at the very least, suggest that colchicine "is not for everyone" after an acute MI, although he emphasized that these results do not rule out the potential for benefit from anti-inflammatory therapy. Ongoing trials, including one targeting interleukin 6, a cytokine associated with inflammation, remain of interest, he added.