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Inflammation and residual cardiovascular risk

TL;DR — Residual risk after LDL lowering includes inflammatory risk, but “inflammation” is not one interchangeable target. CANTOS proved causality by reducing recurrent events with IL-1β blockade without changing LDL-C (Ridker 2017, PMID 28845751); CIRT then showed that low-dose methotrexate neither lowered IL-1β/IL-6/CRP nor reduced events (Ridker 2019, PMID 30415610). Colchicine reduced composite events after MI in COLCOT and in chronic disease in LoDoCo2, but CLEAR SYNERGY found no event benefit when colchicine was started routinely after acute MI, making timing, population, adherence, and mechanism genuine unresolved variables (Tardif 2019, PMID 31733140; Nidorf 2020, PMID 32865380; Jolly 2025, PMID 39555823). Infection and non-cardiovascular mortality signals constrain broad immune suppression. IL-6 inhibition with ziltivekimab strongly lowers inflammatory biomarkers; outcome trials, not biomarker response alone, determine whether it becomes therapy (Wada 2023, PMID 37211246; NCT06118281).

Residual risk is plural

After LDL, BP, smoking, diabetes, and thrombosis are treated, events still occur. The remaining risk can reflect persistent apoB exposure, Lp(a), inflammation, thrombogenicity, diabetes/adiposity, kidney disease, diffuse plaque burden, or poor adherence. Calling all of it “inflammatory residual risk” overstates what hsCRP can identify (Ajala 2020, PMID 32880743).

Residual-risk axis Candidate measure Established targeted outcome therapy?
LDL/apoB LDL-C, non-HDL-C, apoB Yes
Lp(a) Lp(a) mass or molar concentration Lp(a)HORIZON completed; no primary outcome report found in PubMed as of 2026-09-02; OCEAN(a)-Outcomes active, not recruiting (NCT04023552; NCT05581303)
Inflammation hsCRP; IL-6 pathway markers Colchicine in selected chronic/post-MI settings; cytokine therapy investigational
Thrombosis Clinical history; platelet/coagulation context Antithrombotic intensification in selected patients
Adiposity/metabolic BMI, waist, HbA1c GLP-1RA evidence in selected ASCVD populations
Behavioral/delivery Smoking, adherence, rehab attendance Yes, but implementation incomplete

CANTOS: pathway proof

CANTOS enrolled prior-MI patients with hsCRP ≥2 mg/L and randomized canakinumab. The 150-mg dose reduced the primary endpoint (HR 0.85) without lowering lipids, directly supporting the IL-1β inflammatory pathway (Ridker 2017, PMID 28845751).

The benefit came with more fatal infection and no significant all-cause mortality reduction. Canakinumab was not adopted as routine cardiovascular therapy because net benefit, cost, dosing, and safety were unfavorable despite mechanistic success.

CIRT: a negative mechanistic control

CIRT tested low-dose methotrexate in stable atherosclerosis plus diabetes or metabolic syndrome. It did not reduce IL-1β, IL-6, or CRP and did not reduce cardiovascular events (Ridker 2019, PMID 30415610).

The CANTOS–CIRT contrast is informative: anti-inflammatory reputation is insufficient; a therapy must engage a causal pathway in the treated population.

Cross-trial reviews emphasize that pathway engagement, disease phase, endpoint composition, and safety—not a generic drug-class label—must explain the CANTOS/CIRT/COLCOT/LoDoCo2 sequence (Samuel 2021, PMID 33687270).

Trial Population Intervention Primary result Mechanistic inference
CANTOS Prior MI, hsCRP ≥2 Canakinumab MACE HR 0.85 at 150 mg IL-1β pathway can reduce events
CIRT Stable CAD, diabetes/metabolic syndrome Methotrexate Neutral Did not suppress target cytokine/CRP pathway
COLCOT Recent MI Colchicine 0.5 mg HR 0.77 Post-MI benefit possible
LoDoCo2 Chronic coronary disease Colchicine 0.5 mg HR 0.69 Chronic-disease benefit possible
CLEAR SYNERGY Acute MI Colchicine 0.5 mg Neutral for CV composite Benefit not universal across acute-MI strategies

Colchicine: positive trials and a consequential negative trial

COLCOT randomized patients within 30 days after MI and reduced a composite of cardiovascular death, resuscitated arrest, MI, stroke, or urgent angina revascularization (5.5% vs 7.1%; HR 0.77), with pneumonia reported more often (Tardif 2019, PMID 31733140).

LoDoCo2 enrolled chronic coronary disease and reduced cardiovascular death, spontaneous MI, ischemic stroke, or ischemia-driven revascularization (6.8% vs 9.6%; HR 0.69). Non-cardiovascular death was numerically higher, an unresolved safety signal (Nidorf 2020, PMID 32865380).

CLEAR SYNERGY enrolled patients with acute MI undergoing PCI and found routine colchicine did not reduce the primary cardiovascular composite; diarrhea and tolerability affected exposure (Jolly 2025, PMID 39555823). This result prevents a simple class-wide statement that “colchicine works after every MI.”

Why might colchicine trials differ?

Candidate explanation Testable prediction
Timing after injury Benefit differs with immediate versus delayed initiation
Background therapy/revascularization Lower residual event rate reduces absolute and relative contribution
Adherence/tolerability On-treatment exposure predicts effect but introduces selection bias
Endpoint composition Urgent revascularization effects may dominate some composites
Population enrichment hsCRP, CKD, or clonal hematopoiesis identifies larger benefit
Chance/publication sequence Prospective replication attenuates early estimates

COLOCT assessed plaque stability by OCT after ACS, and LoDoCo2 imaging work examined pericoronary inflammation and plaque composition. Neither establishes a single local imaging mediator for the clinical outcomes (Yu 2024, PMID 39166327; Fiolet 2025, PMID 40393691).

hsCRP as marker versus treatment rule

hsCRP predicts risk and enriched CANTOS, but a marker can be causal, correlated, or both. Live PubMed and ClinicalTrials.gov searches repeated on 2026-09-02 found no completed strategy trial of hsCRP-targeted colchicine titration. RIGHT registered an hsCRP-enriched colchicine-versus-control trial in older adults with multivessel CAD (NCT06025071), but the registry record is stale: status is unknown, its last known status was not yet recruiting, and no results are posted.

Use of hsCRP Evidence status
Prognostic enrichment Supported across cohorts and CANTOS selection
Proof of IL-1β engagement Useful in cytokine trials
Diagnostic test for “inflamed plaque” Not specific
Routine trigger for colchicine Not prospectively validated
Serial treatment target Unproven

IL-6 inhibition

Ziltivekimab targets the IL-6 ligand. Phase 2 RESCUE programs in CKD and inflammation showed large hsCRP reductions, supporting pathway engagement (Wada 2023, PMID 37211246). Live ClinicalTrials.gov verification repeated on 2026-09-02 identified:

Trial NCT Population/status Enrollment
ZEUS NCT05021835 CVD + CKD + inflammation; completed 6,385 actual
ARTEMIS NCT06118281 Acute MI; recruiting 10,000 estimated
HERMES NCT05636176 HF + inflammation; active, not recruiting 4,899 actual
Plaque study NCT07301034 Post-MI coronary plaque; recruiting 332 estimated

Biomarker suppression is necessary but not sufficient: CANTOS showed that events and infections must be measured together. As of a live PubMed search on 2026-09-02, no primary outcome report from ZEUS had been published; the most recent ZEUS publication was its rationale, design and baseline-characteristics paper (Ridker 2026, PMID 41369941), so IL-6 ligand inhibition still rests on biomarker and mechanistic evidence.

Clonal hematopoiesis and precision inflammation

Somatic hematopoietic clones, especially TET2-related, may amplify IL-1β/IL-6 signaling and identify a biologically coherent inflammatory phenotype. A live ClinicalTrials.gov query verified a recruiting precision-colchicine study in TET2 clonal hematopoiesis (NCT07362966; 120 estimated enrollment). The key question is whether enrichment increases benefit more than it narrows applicability.

Practical boundaries

  • Do not substitute hsCRP lowering for outcomes evidence.
  • Exclude major infection, severe cytopenia, and important drug interactions before anti-inflammatory treatment.
  • Account for renal/hepatic function and CYP3A4/P-glycoprotein interactions with colchicine.
  • Separate relative MACE reduction from infection, intolerance, and non-cardiovascular death.
  • Continue LDL lowering and standard secondary prevention; inflammation therapy is additive, not a replacement.

Minimum design for a precision-inflammation trial

Design element Required specification
Enrichment hsCRP, IL-6, CKD, clonal hematopoiesis, or prespecified combination
Run-in LDL/adherence optimization and infection screening
Intervention Dose, target engagement, interaction management
Primary efficacy CV death, spontaneous MI, ischemic stroke; revascularization reported separately
Safety Serious/fatal infection, cytopenia, hepatic/muscle toxicity, GI intolerance
Competing events Non-CV and all-cause death
Mechanism Serial biomarkers plus imaging in a nested cohort
Strategy test Biomarker-guided initiation/continuation, not only drug versus placebo
Transportability Sex, ancestry, age, CKD stage and background therapy

The CANTOS/CIRT contrast requires documented target engagement; the COLCOT/LoDoCo2/CLEAR SYNERGY contrast requires prespecified replication across disease phase rather than retrospective explanation (Ridker 2017, PMID 28845751; Ridker 2019, PMID 30415610; Jolly 2025, PMID 39555823).

Causal triangulation and competing interpretations

Evidence type Signal Causal interpretation
Cytokine outcome trial CANTOS 150 mg reduced MACE (HR 0.85) without LDL lowering but increased fatal infection (Ridker 2017, PMID 28845751). Supports IL-1β-pathway causality, not indiscriminate immune suppression.
Negative mechanistic control CIRT neither reduced IL-1β/IL-6/CRP nor events (Ridker 2019, PMID 30415610). Failure to engage the pathway is consistent with clinical neutrality.
Mendelian randomization IL6R variants associated with reduced coronary risk provide lifelong genetic support for IL-6 signaling as a target (IL6R MR Collaboration 2012, PMID 22421340). Lifelong partial genetic modulation may not predict short-term pharmacologic efficacy or infection risk.
Phase 2 pharmacology Ziltivekimab produced dose-dependent hsCRP lowering in high-risk CKD (Ridker 2021, PMID 34015342), with similar pathway engagement in RESCUE-2 (Wada 2023, PMID 37211246). Biomarker movement is not an outcome and may overstate benefit if competing infection risk rises.
Colchicine outcomes COLCOT HR 0.77 and LoDoCo2 HR 0.69 contrast with neutral CLEAR SYNERGY (Tardif 2019, PMID 31733140; Nidorf 2020, PMID 32865380; Jolly 2025, PMID 39555823). The drug effect is not transportable across every post-MI timing and background-care context.
Imaging mediation COLOCT and LoDoCo2 imaging analyses did not establish one consistent local plaque mediator (Yu 2024, PMID 39166327; Fiolet 2025, PMID 40393691). Clinical benefit, where present, may reflect systemic thromboinflammation rather than measurable focal plaque change.
Clonal hematopoiesis CHIP links somatic hematopoietic mutations, inflammatory signaling, and ASCVD (Marnell 2021, PMID 34298011; Zuriaga 2023, PMID 34879980). Observational/genetic association does not yet identify who should receive colchicine or cytokine blockade.
Plaque immunology Human coronary plaque T cells show clonal expansion and cross-reactivity to viral and self antigens (Chowdhury 2022, PMID 35430876). Antigen specificity raises mechanistic hypotheses but not a safe current immunotherapy.

Residual inflammatory risk versus residual cholesterol risk

Inflammation and apoB exposure interact: retained lipoproteins initiate and sustain immune recruitment, while inflammation influences cap integrity, thrombogenicity, and repair (Ross 1999, PMID 9887164; Libby 2002, PMID 12490960). Statin and nonstatin therapy can regress or stabilize plaque while leaving hsCRP elevated (CTT 2010, PMID 21067804; Ueki 2024, PMID 39111840). Conversely, CANTOS reduced events without changing LDL-C. The evidence therefore rejects both extremes—“all residual risk is lipid” and “hsCRP identifies an independent disease”—in favor of interacting, measurable axes.

The practical controversy is whether to treat inflammation broadly or enrich. Broad colchicine is inexpensive but exposes many people to intolerance and interaction risk; hsCRP enrichment is simple but nonspecific; CKD and clonal hematopoiesis may identify larger pathway activity but also higher infection and competing mortality. A decisive strategy trial must compare test-and-treat against usual prevention, not merely active drug against placebo, and must prespecify CV death, spontaneous MI, stroke, infection, non-CV death, discontinuation, and cost (Ajala 2020, PMID 32880743; Samuel 2021, PMID 33687270).

Human plaque natural-history and CCTA studies provide a substrate layer: high-risk morphology predicts events but remains imprecise at the lesion level (Stone 2011, PMID 21247313; Williams 2020, PMID 32174130). PCSK9 inhibition and intensive LDL lowering reduce events and alter plaque biology without directly targeting cytokines (Sabatine 2017, PMID 28304224; Schwartz 2018, PMID 30403574; Ueki 2024, PMID 39111840). Conversely, low-dose methotrexate's neutrality despite its anti-inflammatory reputation shows why mechanism cannot be inferred from drug labels (Ridker 2019, PMID 30415610). These comparisons create a factorial research question: whether jointly lowering apoB and a measured inflammatory pathway produces additive, subadditive, or synergistic benefit and harm.

Residual risk also includes thrombosis and adiposity: COMPASS altered thrombotic risk while increasing bleeding, and SELECT reduced cardiovascular events in obesity without diabetes (Eikelboom 2017, PMID 28844192; Lincoff 2023, PMID 37952131). Neither result can be attributed to hsCRP without a prespecified mediation analysis.

Risk stratifiers are not interchangeable treatment selectors

In 13,129 UK Biobank participants with established ASCVD, CHIP prevalence was 5.1%; any CHIP predicted the composite of ASCVD events/all-cause death (adjusted HR 1.23, 95% CI 1.10–1.38), with stronger associations for large TET2 clones (HR 1.89, 95% CI 1.40–2.55) and large spliceosome-gene clones (HR 3.02, 95% CI 1.95–4.70) (Gumuser 2023, PMID 37197843). This establishes prognostic heterogeneity, not that clone screening improves selection for colchicine or cytokine blockade.

FOURIER demonstrates coexistence rather than competition between residual cholesterol and inflammation. Placebo-arm 3-year primary-event rates rose across hsCRP strata from 12.0% to 13.7% to 18.1%; evolocumab's relative effect was consistent, but absolute reductions increased from 1.6% to 1.8% to 2.6%, and hsCRP itself was unchanged (Bohula 2018, PMID 29530884). CLEAR Outcomes similarly found the highest versus lowest hsCRP quartile predicted the primary composite (HR 1.43, 95% CI 1.24–1.65) and all-cause death (HR 2.21, 95% CI 1.79–2.73), more strongly than LDL-C quartile, while bempedoic acid reduced both hsCRP and LDL-C about 21% (Ridker 2024, PMID 37929602).

A 2025 random-effects meta-analysis of 10 colchicine RCTs (22,532 participants) estimated MACE RR 0.73 (95% CI 0.57–0.95; NNT 52), MI RR 0.83 (95% CI 0.72–0.96), and revascularization RR 0.79 (95% CI 0.65–0.94), without significant mortality or serious-infection differences (Ballacci 2025, PMID 40530569). Its wide heterogeneity-compatible interval and inclusion of discordant acute/chronic trials argue for preserving trial-specific estimates alongside the pooled result.

Open questions

  • Which phenotype explains benefit in COLCOT/LoDoCo2 but neutrality in CLEAR SYNERGY? (Jolly 2025, PMID 39555823)
  • Should hsCRP or clonal hematopoiesis guide colchicine, and can a strategy trial prove net benefit? (NCT07362966)
  • Will IL-6 inhibition reduce hard outcomes without an infection or competing-mortality penalty? (NCT06118281)
  • What mediates colchicine benefit if plaque imaging changes are inconsistent? (Yu 2024, PMID 39166327; Fiolet 2025, PMID 40393691)
  • Can inflammation treatment be stopped after biomarker normalization, or is persistent suppression required?

References

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