New England Journal of Medicine NOVEMBER 16, 2019

Efficacy and Safety of Low-Dose Colchicine After Myocardial Infarction (COLCOT)

Jean-Claude Tardif, Samer Kouz, David D. Waters, et al.

Bottom Line

In patients with a recent myocardial infarction, low-dose colchicine (0.5 mg daily) significantly reduced the composite risk of major ischemic cardiovascular events compared with placebo.

Key Findings

1. The primary composite endpoint occurred in 5.5% of the colchicine group compared to 7.1% in the placebo group, representing a significant 23% reduction in risk (hazard ratio 0.77; 95% confidence interval, 0.61 to 0.96; P=0.02).

2. The treatment effect was primarily driven by reductions in stroke (0.2% vs. 0.8%; HR 0.26) and urgent hospitalization for angina leading to coronary revascularization (1.1% vs. 2.1%; HR 0.50).

3. There was no statistically significant difference between groups regarding cardiovascular death (0.8% vs. 1.0%) or myocardial infarction alone (3.8% vs. 4.1%).

4. The incidence of diarrhea was similar between groups (9.7% vs. 8.9%), though serious adverse events including pneumonia were reported more frequently in the colchicine arm (0.9% vs. 0.4%, P=0.03).

Study Design

Design

RCT

Double-Blind

Sample

4,745

Patients

Duration

22.6 mo

Median

Setting

Multicenter, 12 countries

Population Patients who suffered a myocardial infarction within the previous 30 days and had completed all intended coronary revascularization.

Intervention Low-dose colchicine, 0.5 mg once daily.

Comparator Matching placebo once daily.

Outcome Composite of cardiovascular death, resuscitated cardiac arrest, myocardial infarction, stroke, or urgent hospitalization for angina leading to coronary revascularization.

Study Limitations

• The study had a relatively short median follow-up of 22.6 months, limiting understanding of the long-term safety and efficacy of colchicine.

• The primary endpoint was a composite heavily weighted by 'soft' outcomes like urgent revascularization for unstable angina, rather than hard outcomes like cardiovascular mortality.

• The study population was predominately male (81%), which may limit the generalizability of the findings to female patients.

• The trial was event-driven with a modest number of primary endpoints, and a small change in event status for a few patients could have rendered the result non-significant (fragility index).

Clinical Significance

The COLCOT trial provides evidence supporting the 'inflammatory hypothesis' of atherosclerosis, suggesting that low-cost, readily available anti-inflammatory therapy with colchicine can reduce recurrent ischemic events in patients post-MI when added to aggressive standard-of-care, including high-intensity statins.

Historical Context

Following the success of the CANTOS trial (using expensive monoclonal antibodies to target inflammation) and the failure of the CIRT trial (using methotrexate), COLCOT served as a pivotal investigation into whether an inexpensive, repurposed drug like colchicine could achieve similar clinical benefit in the post-MI setting.

Guided Discussion

High-yield insights from every perspective

Med Student

Medical Student

What is the primary mechanism by which low-dose colchicine is hypothesized to reduce major adverse cardiovascular events (MACE) following a myocardial infarction?

Key Response

Atherosclerosis is increasingly recognized as a chronic inflammatory disease. Colchicine inhibits tubulin polymerization and, more importantly in this context, inhibits the NLRP3 inflammasome. This prevents the release of pro-inflammatory cytokines like IL-1β and IL-18, which drive plaque instability and post-ischemic myocardial damage.

Resident

In the COLCOT trial, which specific component of the composite primary endpoint showed the most significant relative risk reduction, and how does this influence your counseling of a patient starting the medication?

Key Response

The most significant reduction was seen in the risk of stroke (hazard ratio 0.26) and urgent hospitalization for angina leading to revascularization (hazard ratio 0.50). While death from cardiovascular causes and MI were numerically lower, they did not reach individual statistical significance. Residents should counsel patients that the medication primarily reduces the risk of secondary ischemic events like stroke rather than immediately preventing mortality.

Fellow

The COLCOT trial initiated colchicine within 30 days of MI. How do the findings regarding the timing of initiation (early vs. late) in COLCOT's subgroup analysis compare to the results seen in the LoDoCo2 trial for chronic coronary disease?

Key Response

Subgroup analysis in COLCOT suggested a greater benefit when colchicine was started within the first 3 days post-MI. This aligns with the concept that the acute inflammatory burst following myocardial necrosis is a prime therapeutic target. In contrast, LoDoCo2 showed that the benefit persists in stable chronic coronary syndrome, suggesting that while early intervention is optimal post-event, the anti-inflammatory benefit is broadly applicable across the spectrum of coronary artery disease.

Attending

Despite the positive results for cardiovascular outcomes, COLCOT reported a higher incidence of pneumonia in the colchicine group. How should this finding impact your clinical decision-making for a post-MI patient with significant COPD or recurrent respiratory infections?

Key Response

Pneumonia occurred in 0.9% of the colchicine group vs 0.4% in the placebo group (p=0.03). This signal requires a personalized risk-benefit assessment. In patients with high baseline pulmonary risk, the small absolute risk reduction in cardiovascular events (1.6% absolute reduction in the primary endpoint) might be offset by the risk of infectious complications, necessitating shared decision-making.

Scholarly Review

Critical appraisal through the lens of expert reviewers and guideline development

PhD

COLCOT utilized a composite endpoint that included 'urgent hospitalization for angina leading to revascularization.' Critique the use of this specific endpoint regarding its susceptibility to bias and its impact on the study's statistical power.

Key Response

Urgent hospitalization for angina is considered a 'soft' endpoint because the decision to hospitalize and revascularize can be subjective and potentially influenced by unblinding (though the trial was double-blinded). While including this endpoint increases the total number of events and thus the statistical power to find a significant difference, it may dilute the perceived effect on more 'hard' clinical outcomes like cardiovascular death or large-scale MI.

Journal Editor

Considering the low absolute risk reduction (1.6%) and the lack of effect on all-cause mortality, what specific sensitivity analyses would you demand to ensure the robustness of the primary endpoint results?

Key Response

An editor would likely request a 'worst-case scenario' sensitivity analysis for missing data and a specific analysis excluding the softest endpoint (angina-related hospitalization). Furthermore, given the unexpected 74% reduction in stroke, a reviewer would scrutinize the baseline characteristics for imbalances in atrial fibrillation or carotid disease to ensure the stroke benefit was truly attributable to the drug's anti-inflammatory properties.

Guideline Committee

Based on the COLCOT and LoDoCo2 data, should colchicine be upgraded from a Class 2b to a Class 1 recommendation in secondary prevention guidelines, and what barriers prevent this upgrade?

Key Response

Current ESC and AHA/ACC guidelines generally list colchicine as Class 2b ('may be considered'). While COLCOT provides high-quality (Level A) evidence, the modest absolute risk reduction, the signal for increased non-cardiovascular death in some related trials (like LoDoCo2, though not COLCOT), and the increased risk of infection/GI side effects often prevent a Class 1 (strong) recommendation. Guidelines currently prioritize high-intensity statins and dual antiplatelet therapy (DAPT) which have larger effect sizes on mortality.

Clinical Landscape

Noteworthy Related Trials

2017

CANTOS Trial

n = 10,061 · NEJM

Tested

Canakinumab (anti-IL-1beta antibody)

Population

Patients with prior MI and elevated high-sensitivity C-reactive protein

Comparator

Placebo

Endpoint

Composite of nonfatal MI, nonfatal stroke, or CV death

Key result: Targeting the IL-1beta innate immunity pathway with canakinumab significantly reduced cardiovascular event rates.

2020

LoDoCo2 Trial

n = 5,522 · NEJM

Tested

Colchicine 0.5mg daily

Population

Patients with stable coronary artery disease

Comparator

Placebo

Endpoint

Composite of CV death, MI, ischemic stroke, or ischemia-driven coronary revascularization

Key result: Colchicine significantly reduced the risk of cardiovascular events compared to placebo in patients with chronic coronary disease.

2020

COPS Trial

n = 795 · Circulation

Tested

Colchicine 0.5mg twice daily for 1 month, then once daily for 11 months

Population

Patients with recent acute coronary syndrome

Comparator

Placebo

Endpoint

Composite of all-cause mortality, ACS, stroke, or urgent revascularization

Key result: The study showed a numerical reduction in events, though it did not reach statistical significance for the primary endpoint at 12 months.

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