Biomarkers and imaging markers in ischemic heart disease¶
TL;DR — No circulating marker has replaced clinical assessment plus anatomic or functional testing for chronic IHD, and lesion-level prediction remains imprecise. High-sensitivity troponin is indispensable for detecting acute myocardial injury and also predicts risk in chronic coronary disease, but elevation is not specific for type 1 MI (Wereski 2023, PMID 37532417; Park 2017, PMID 29016754). hsCRP identifies inflammatory risk and enriched CANTOS, yet an hsCRP-guided treatment strategy has not been validated (Ridker 2017, PMID 28845751). Lp(a) is a largely inherited causal risk marker; Lp(a)HORIZON completed follow-up in July 2026, but live PubMed searches repeated on 2026-09-02 found no primary outcome report, while OCEAN(a)-Outcomes remains active without recruitment (NCT04023552; NCT05581303). Polygenic scores improve prediction modestly but face ancestry and actionability constraints (Marston 2023, PMID 36576811; Klarin 2022, PMID 34811547). Coronary calcium measures total calcified burden, whereas CCTA provides stenosis and plaque composition; low-attenuation plaque predicted MI in SCOT-HEART (Williams 2020, PMID 32174130). A useful biomarker must improve a decision and outcomes beyond established risk factors—not merely produce a significant association or AUC increment.
Biomarker roles¶
| Role | Example | Required proof |
|---|---|---|
| Diagnosis | hs-troponin in suspected MI | Sensitivity/specificity in a defined pathway |
| Prognosis | hs-troponin, hsCRP, plaque burden | Calibration and incremental discrimination |
| Treatment selection | hsCRP for cytokine trial enrichment | Interaction or strategy-trial benefit |
| Treatment monitoring | LDL-C after lipid therapy | Change linked to causal exposure and outcome evidence |
| Mechanistic readout | IL-6/hsCRP after ziltivekimab | Target engagement, not automatically clinical benefit |
Statistical association is the first rung. Clinical utility requires a changed action with net benefit.
High-sensitivity troponin¶
High-sensitivity cardiac troponin assays detect myocardial injury at low concentrations. Acute MI diagnosis requires a rise/fall plus clinical evidence of ischemia; chronic elevations occur with structural heart disease, CKD, heart failure, and other conditions (Park 2017, PMID 29016754).
In chronic coronary disease, higher hs-troponin concentrations predict cardiovascular events and can improve risk stratification (Wereski 2023, PMID 37532417). The marker may reflect ongoing myocyte injury and total disease burden rather than silent plaque rupture.
| Context | Valid inference | Invalid shortcut |
|---|---|---|
| Acute chest symptoms | Serial kinetics inform injury | One elevated value = type 1 MI |
| CKD | Persistent elevation is common and prognostic | Ignore all elevations as “renal” |
| Stable CAD | Higher level indicates higher risk | Routine angiography solely from biomarker |
| Women | Sex-specific thresholds alter detection | Symptoms are unnecessary once value rises |
CKD reduces specificity for acute MI but preserves prognostic information; deltas and clinical context are essential (Chuang 2020, PMID 32706208).
hsCRP and inflammatory markers¶
hsCRP is a standardized downstream marker of innate immune activity. CANTOS enrolled prior-MI patients with hsCRP ≥2 mg/L and showed IL-1β blockade reduced events without LDL change (Ridker 2017, PMID 28845751).
However:
- hsCRP is affected by infection, adiposity, smoking, and chronic inflammatory disease.
- It does not localize coronary inflammation.
- CIRT was neutral when the intervention did not lower IL-1β/IL-6/CRP (Ridker 2019, PMID 30415610).
- As of live PubMed and ClinicalTrials.gov searches repeated on 2026-09-02, no completed trial had shown that titrating colchicine to an hsCRP target improves outcomes. RIGHT registered an hsCRP-enriched randomized colchicine strategy (NCT06025071), but its record is stale (status unknown; last known not yet recruiting) and has no posted results.
Thus hsCRP is a risk/enrichment marker, not a stand-alone diagnosis of “residual inflammatory risk requiring therapy.”
Lipoprotein biomarkers¶
| Marker | What it approximates | Clinical use | Limitation |
|---|---|---|---|
| LDL-C | Cholesterol mass in LDL particles | Treatment target/threshold | Discordant with particle number in some states |
| Non-HDL-C | Cholesterol in all apoB particles | Secondary target, useful with triglycerides | Still cholesterol mass |
| ApoB | Number of atherogenic particles | Clarifies discordance | Assay/access and guideline variation |
| Lp(a) | Inherited LDL-like particle with apo(a) | Once-in-lifetime risk refinement; trial eligibility | Units/isoforms; no completed selective outcome proof |
| Triglycerides | Metabolic marker of remnant-rich state | Selects REDUCE-IT-like phenotype | Variable and not direct particle count |
FOURIER and ODYSSEY show event reduction with profound LDL lowering (Sabatine 2017, PMID 28304224; Schwartz 2018, PMID 30403574). Lp(a)HORIZON (NCT04023552) and OCEAN(a)-Outcomes (NCT05581303) were live-verified on ClinicalTrials.gov in this session and test whether selective Lp(a) lowering changes events.
Polygenic risk scores¶
CAD polygenic scores aggregate many common variants. In primary-prevention cohorts, scores improve risk classification beyond conventional variables, but clinical utility depends on ancestry-specific calibration and whether disclosure changes effective treatment (Marston 2023, PMID 36576811; Klarin 2022, PMID 34811547).
| Promise | Constraint |
|---|---|
| Stable from birth | Does not encode changing environment or treatment |
| Identifies high lifetime risk early | Most derivation cohorts overrepresent European ancestry |
| May motivate earlier prevention | Behavior-change benefit is unproven |
| Could refine family screening | Family history already captures some signal |
Healthy lifestyle is associated with lower coronary risk even at high genetic risk, so a high score is not deterministic (Khera 2016, PMID 27959714).
Coronary calcium¶
CAC is a robust measure of total calcified atherosclerotic burden and refines primary-prevention risk. A CAC score of zero predicts low short-term event risk in many stable chest-pain populations but does not exclude non-calcified plaque or microvascular disease (Wang 2019, PMID 31168373; Koopman 2022, PMID 35081649).
In established IHD, CAC rarely changes the diagnosis that systemic prevention is required; heavy calcification may instead inform procedural complexity and CT interpretability.
CCTA plaque biomarkers¶
CCTA reports stenosis, total plaque burden, composition, remodeling, and high-risk features. In SCOT-HEART, low-attenuation noncalcified plaque burden strongly predicted subsequent MI, adding information beyond stenosis and CAC (Williams 2020, PMID 32174130).
Semi-quantitative CCTA scores also carry prognostic information (SCOT-HEART analysis, PMID 37673712). AI-enabled plaque/physiology models may improve prediction, but external validation and strategy trials are required before prophylactic PCI or drug escalation is triggered (Koo 2024, PMID 38752951).
| Imaging marker | Biological interpretation | Decision status |
|---|---|---|
| Total plaque burden | Cumulative atherosclerosis | Prognostic; prevention intensity |
| Low attenuation | Lipid-rich component | Prognostic, not a routine PCI indication |
| Positive remodeling | Outward plaque expansion | High-risk association |
| Spotty calcification | Active mixed plaque phenotype | Association; limited specificity |
| Perivascular fat attenuation | Local inflammatory signal | Investigational |
| FFR-CT | Modeled lesion physiology | Helps select invasive evaluation/PCI |
Validation checklist¶
- Define intended use and population before selecting a cutoff.
- Compare with a strong clinical base model.
- Report calibration, discrimination, reclassification, and decision curves.
- Validate externally across sex, ancestry, kidney function, and treatment era.
- Show that biomarker-guided action improves outcomes.
- Include cost, false positives, incidental findings, and downstream procedures.
Reporting standards for candidate biomarkers¶
| Domain | Minimum report |
|---|---|
| Analytic validity | Assay platform, precision, detection limits, batch handling |
| Population | Recruitment, prevalence, treatment and missingness |
| Base model | Established clinical predictors and calibration |
| Increment | ΔC-statistic, calibration, reclassification and decision utility |
| Threshold | Prespecified cutoff and consequences of false results |
| Replication | External cohort and subgroup calibration |
| Action | Exact management change triggered |
| Outcome | Strategy-level benefit, harm and cost |
Many biomarker papers stop at discrimination. For chronic IHD, the decisive experiment is whether marker-guided action improves outcomes beyond readily available risk and imaging data (Marston 2023, PMID 36576811; Koo 2024, PMID 38752951).
Quantitative validation landmarks and failure modes¶
| Marker/test | Quantified evidence | Remaining limitation |
|---|---|---|
| ESC hs-cTn 0/1-hour algorithm | Meta-analysis supports high diagnostic performance across contemporary hs-cTn assays (Burgos 2021, PMID 32597681). | Performance is assay-, prevalence-, symptom-time-, and subgroup-dependent; “rule-out” is not zero risk. |
| Presentation hs-cTn rule-out | HiSTORIC (31,492 patients, stepped-wedge across hospitals) shortened length of stay and raised direct discharge from 50% to 71%; the 30-day safety outcome did not formally meet noninferiority (upper 1-sided 95% CI 0.70% versus a 0.50% margin; P=0.068) although observed rates favored the early pathway (0.4% versus 0.3%) (Anand 2021, PMID 33752439). | Cluster implementation evidence does not validate use before assay-specific minimum symptom duration. |
| Chronic hs-cTn | Detectable concentrations stratify risk in chronic CAD, including values below acute-MI rule-in ranges (Wereski 2023, PMID 37532417). | Prognostic association does not specify a new treatment. |
| CAC added to clinical factors | MESA-derived 10-year models improved risk classification when CAC was added and were externally tested in HNR and DHS cohorts (McClelland 2015, PMID 26449133). | CAC=0 does not exclude noncalcified plaque (Wang 2019, PMID 31168373). |
| CCTA low-attenuation plaque | In SCOT-HEART, low-attenuation plaque burden predicted subsequent MI beyond conventional measures (Williams 2020, PMID 32174130). | Lesion-level positive predictive value limits prophylactic focal treatment (Stone 2011, PMID 21247313; Ahn 2023, PMID 37271356). |
| Quantitative plaque plus physiology | AI-enabled plaque/hemodynamic analysis improves prediction in observational datasets (Koo 2024, PMID 38752951). | Calibration drift and prospective decision impact remain unproven. |
| Lp(a) | Participant-level and genetic analyses support risk independent of LDL-C (Bhatia 2025, PMID 39492722; Burgess 2018, PMID 29926099). | Association does not prove that a specific drug-induced reduction prevents events. |
| Polygenic score | CAD PRS can add modest prediction (Klarin 2022, PMID 34811547; Marston 2023, PMID 36576811). | Ancestry transferability and strategy-level benefit remain inadequate for routine equitable deployment. |
The risk-marker philosophy accepts a test if it improves discrimination and motivates established prevention; the strategy-trial philosophy requires evidence that measuring and acting improves outcomes. hs-cTn satisfies the latter for accelerated diagnostic pathways more convincingly than hsCRP, PRS, or plaque-AI currently do (Park 2017, PMID 29016754; Chuang 2020, PMID 32706208). CAC and CCTA sit between the philosophies because downstream testing, incidental findings, radiation/contrast, and treatment changes must be counted with events (Koopman 2022, PMID 35081649; Maclean 2023, PMID 37673712).
CANTOS demonstrated pathway causality after hsCRP enrichment, while CIRT showed that a nominally anti-inflammatory drug that did not lower IL-1β/IL-6/CRP did not reduce events (Ridker 2017, PMID 28845751; Ridker 2019, PMID 30415610). This supports target-engagement measurement but not routine hsCRP-guided treatment. PROSPECT and SCOT-HEART show plaque prognostic signal; PREVENT asks the harder strategy question of whether acting on a non-flow-limiting lesion improves outcomes (Stone 2011, PMID 21247313; Williams 2020, PMID 32174130; Ahn 2023, PMID 37271356).
Chest-pain guidance treats hs-cTn, CAC, and CCTA as components of pathways rather than freestanding answers (Gulati 2021, PMID 34709879). Genetic risk is similarly contextual: healthy lifestyle was associated with lower coronary risk across genetic strata, so PRS should not be framed as destiny (Khera 2016, PMID 27959714). Global LDL-attributable-burden modeling supplies population context but is not a patient-level biomarker validation study (GBD 2023 LDL Collaborators 2026, PMID 42525403).
ESC chronic-coronary guidance consequently positions biomarkers according to the decision they inform rather than recommending indiscriminate multimarker panels (Vrints 2024, PMID 39210710).
A marker can discriminate without improving care¶
Prospective validation of a 1-hour hs-cTnT algorithm placed 59.5% of 1,320 suspected-MI presentations in rule-out, with sensitivity 99.6% (95% CI 97.6%–99.9%) and NPV 99.9% (95% CI 99.3%–100%); 24.1% remained in an observation zone and therefore still required clinical adjudication (Reichlin 2015, PMID 25869867). High-STEACS then showed why diagnostic yield is not implementation success: sex-specific hs-cTnI thresholds increased detected injury by 42% in women versus 6% in men, yet women still received about half as much coronary treatment and their 1-year MI/CV-death outcome did not improve (adjusted HR 1.11, 95% CI 0.92–1.33) (Lee 2019, PMID 31623760).
Imaging markers similarly mix focal phenotype with total burden. In MESA, CAC ≥100 identified 21% of participants but 55% of cardiovascular events; rates were 22.7–29.5 per 1,000 person-years across lipid-abnormality strata, versus 2.7–5.9 with CAC=0 (Martin 2014, PMID 24141324). In SCOT-HEART, adverse plaque features predicted CHD death/nonfatal MI (4.1% vs 1.4%; HR 3.01, 95% CI 1.61–5.63), but the association was not independent of CAC, warning against treating a visually “vulnerable” plaque as separable from whole-patient plaque burden (Williams 2019, PMID 30678759).
Open questions¶
- Does serial hs-troponin-guided intensification improve outcomes in chronic CAD? (Wereski 2023, PMID 37532417)
- Can hsCRP guide anti-inflammatory therapy rather than merely enrich a trial? (Ridker 2017, PMID 28845751)
- Will Lp(a) reduction lower events, and what achieved reduction is necessary? (NCT04023552; NCT05581303)
- Can polygenic scores be recalibrated equitably and tested in treatment-strategy trials? (Klarin 2022, PMID 34811547)
- Does treatment triggered by low-attenuation plaque improve outcomes beyond intensive systemic prevention? (Williams 2020, PMID 32174130)
Related pages¶
- Lipid lowering — causal lipid targets.
- Inflammation and residual risk — hsCRP and cytokine trials.
- Pathophysiology and plaque biology — imaging phenotype and mechanism.
- Clinical trials landscape — marker-guided intervention trials.
References¶
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