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Ischemic heart disease — overview

TL;DR — Ischemic heart disease (IHD) comprises myocardial ischemia and its consequences, most often from coronary atherosclerosis but also including non-obstructive coronary mechanisms. It is the world's single largest killer: 254.3 million prevalent cases, 9.0 million deaths, and 188.4 million DALYs in 2021, and the leading cardiovascular cause of DALYs in GBD 2023 (Yang 2025, PMID 40841929; GBD CVD 2023 Collaborators 2025, PMID 40990886). For trial-eligible stable disease, a two-decade trial arc (COURAGE → ORBITA → ISCHEMIA) showed that routine initial PCI or an invasive strategy added to medical therapy did not reduce death or MI overall, although placebo-controlled PCI can relieve angina (Boden 2007, PMID 17387127; Maron 2020, PMID 32227755; Rajkumar 2023, PMID 38015442). Secondary prevention is the field's true engine: intensive LDL lowering, antithrombotic combinations, anti-inflammatory colchicine in selected settings, polypills, and cardiac rehabilitation each carry randomized mortality-or-MACE evidence (CTT 2010, PMID 21067804; Eikelboom 2017, PMID 28844192; Tardif 2019, PMID 31733140; Castellano 2022, PMID 36018037; Dibben 2023, PMID 36746187). Current anchors are the 2023 AHA/ACC chronic coronary disease guideline and the 2024 ESC chronic coronary syndromes guideline (Virani 2023, PMID 37471501; Vrints 2024, PMID 39210710). The central unresolved tension is route- and population-specific: routine PCI has not produced a survival benefit in stable severe ischemia or ischemic LV dysfunction, whereas CABG improved 10-year survival in selected ischemic cardiomyopathy (Maron 2020, PMID 32227755; Perera 2022, PMID 36027563; Velazquez 2016, PMID 27040723).

Definition and diagnostic anchors

  • IHD spans chronic coronary disease/syndromes (stable angina, post-ACS, ischemia with non-obstructive arteries) and acute coronary syndromes; contemporary taxonomy and diagnostic pathways are set by the 2023 AHA/ACC guideline (Virani 2023, PMID 37471501) and the 2024 ESC guidelines, which reframed the entity as "chronic coronary syndromes" (Vrints 2024, PMID 39210710).
  • Physiology-guided assessment (FFR/iFR) grades lesion significance; in placebo-controlled analysis these indices predict the true (placebo-subtracted) symptomatic response to PCI (Foley 2025, PMID 39462291).

Epidemiology and burden

Figure Value Source
Prevalent IHD cases, 2021 254.3 million (95% UI 221.4–295.5M) (Yang 2025, PMID 40841929)
IHD deaths, 2021 9.0 million (95% UI 8.3–9.5M) (Yang 2025, PMID 40841929)
IHD DALYs, 2021 188.4 million (Yang 2025, PMID 40841929)
Change in age-standardized IHD death rate 1990–2021 −31.6% (Yang 2025, PMID 40841929)
All-CVD deaths, 2023 19.2 million (up from 13.1M in 1990) (GBD CVD 2023 Collaborators 2025, PMID 40990886)
All-CVD prevalent cases, 2023 626 million (GBD CVD 2023 Collaborators 2025, PMID 40990886)
  • Age-standardized rates fall while absolute counts rise — population growth and aging outpace risk-factor progress; burden concentrates in low- and low-middle-SDI settings (GBD CVD 2023 Collaborators 2025, PMID 40990886).
  • Leading attributable risks are high systolic blood pressure and high LDL cholesterol (Yang 2025, PMID 40841929); elevated LDL-C burden is now tracked as its own GBD entity (GBD 2023 LDL Cholesterol Collaborators 2026, PMID 42525403).
  • Quality-of-care indices for IHD vary steeply by development level (Aminorroaya 2022, PMID 34041535).

Mechanism sketch

  • Atherosclerotic plaque limits flow (stable angina) or ruptures/erodes with thrombosis (ACS); residual risk after LDL lowering is partly inflammatory — IL-1β blockade (canakinumab) cut MACE 15% at the 150-mg dose with no lipid change, the proof-of-concept for the inflammatory hypothesis (Ridker 2017, PMID 28845751).
  • The stable-disease trial arc is consistent with systemic risk not being abolished by treating selected stenoses: PCI can relieve focal ischemic symptoms, while medical prevention treats risk across the arterial bed. COURAGE and ISCHEMIA do not by themselves identify the morphology of future culprit plaques (Boden 2007, PMID 17387127; Maron 2020, PMID 32227755).

Treatment landscape

Stable CAD: invasive vs conservative (the anchor trial arc)

Trial Population Result Source
COURAGE (2007) stable CAD PCI + OMT vs OMT: primary events 19.0% vs 18.5% (HR 1.05) — no reduction in death/MI (Boden 2007, PMID 17387127)
ORBITA (2018) single-vessel stable angina PCI vs placebo procedure: exercise-time gain +16.6 s, p=0.20 — no significant benefit on that endpoint (Al-Lamee 2018, PMID 29103656)
ISCHEMIA (2020) moderate–severe ischemia invasive vs conservative: 5-yr events 16.4% vs 18.2% (diff −1.8 pp, CI crosses 0); deaths 145 vs 144 (Maron 2020, PMID 32227755)
ISCHEMIA-EXTEND (2023) 7-yr follow-up all-cause mortality did not differ (12.7% vs 13.4%; adjusted HR 1.00, 95% CI 0.85–1.18); CV mortality was lower but non-CV mortality higher with the invasive strategy (Hochman 2023, PMID 36335918)
REVIVED-BCIS2 (2022) ischemic LV dysfunction (EF ≤35%) PCI vs OMT: death/HF hospitalization 37.2% vs 38.0% (HR 0.99) (Perera 2022, PMID 36027563)
ORBITA-2 (2023) stable angina on little/no antianginal therapy PCI vs placebo: angina symptom score 2.9 vs 5.6 (OR 2.21) — PCI relieves angina as standalone therapy (Rajkumar 2023, PMID 38015442)
  • Net reading in current guidelines: PCI in most stable disease is symptom-directed; selected anatomy and LV dysfunction require a separate CABG-versus-PCI prognostic assessment (Virani 2023, PMID 37471501; Vrints 2024, PMID 39210710). Symptom phenotype predicts placebo-controlled PCI benefit (Simader 2024, PMID 38759906); for refractory angina, the coronary-sinus reducer improved symptoms in the placebo-controlled ORBITA-COSMIC trial (Foley 2024, PMID 38604209).

Secondary prevention (the mortality engine) - Lipids — each 1.0 mmol/L LDL reduction cuts major vascular events ~22% (RR 0.78), with more-intensive statin regimens adding a further 15% (CTT 2010, PMID 21067804); ezetimibe adds benefit post-ACS (IMPROVE-IT; Cannon 2015, PMID 26039521); evolocumab on statin lowered LDL to a median 30 mg/dL and cut MACE (HR 0.85) (FOURIER; Sabatine 2017, PMID 28304224). - Antithrombotics — aspirin's secondary-prevention benefit is anchored in the ATT individual-participant meta-analysis (ATT 2009, PMID 19482214); adding low-dose rivaroxaban to aspirin cut MACE (HR 0.76) and death (HR 0.82) at the cost of more major bleeding (COMPASS; Eikelboom 2017, PMID 28844192). - Inflammation — colchicine 0.5 mg reduced MACE after MI (HR 0.77; COLCOT, Tardif 2019, PMID 31733140) and in chronic coronary disease (HR 0.69; LoDoCo2, Nidorf 2020, PMID 32865380). - Triglyceride-rich lipoproteins — icosapent ethyl cut events in hypertriglyceridemic statin-treated patients (REDUCE-IT; Bhatt 2019, PMID 30415628). - Adherence engineering — an aspirin/ramipril/atorvastatin polypill post-MI reduced MACE vs usual care (9.5% vs 12.7%, HR 0.76) (SECURE; Castellano 2022, PMID 36018037). - Cardiac rehabilitation — 85-RCT meta-analysis: CV mortality RR 0.74 (NNT 37), fewer hospitalizations, better quality of life (Dibben 2023, PMID 36746187; Cochrane: Dibben 2021, PMID 34741536). - Cardiometabolic drugs crossing over — semaglutide reduced MACE (HR 0.80) in patients with obesity and established CVD without diabetes (SELECT; Lincoff 2023, PMID 37952131).

Research frontier

  • Anti-inflammatory therapy beyond colchicine: targeting IL-6 and refining who benefits, after CANTOS proved the pathway but canakinumab was never brought to cardiology (Ridker 2017, PMID 28845751).
  • Placebo-controlled interventional cardiology as a method — the ORBITA family made sham control feasible and is redefining efficacy standards for devices (Rajkumar 2023, PMID 38015442; Foley 2024, PMID 38604209).
  • Closing the implementation gap: polypills and rehabilitation improve outcomes yet remain incompletely delivered; absolute burden is concentrated in settings with fewer resources for invasive and preventive care (Castellano 2022, PMID 36018037; GBD CVD 2023 Collaborators 2025, PMID 40990886).

Knowledge-map at full build

Domain Established anchor Main unresolved edge
Global burden 254.3M prevalent cases and 9.0M deaths in 2021 (Yang 2025, PMID 40841929) Which delivery bundles close SDI gradients?
Stable disease No routine death/MI benefit from initial PCI/invasive strategy (Boden 2007, PMID 17387127; Maron 2020, PMID 32227755) Predict individual symptom and rare prognostic benefit
Acute disease Time-critical reperfusion and risk-based complete revascularization Reduce delay and bleeding without losing ischemic protection
Ischemic LV dysfunction CABG benefit at 10 years; PCI neutral in REVIVED (Velazquez 2016, PMID 27040723; Perera 2022, PMID 36027563) Direct CABG-versus-PCI selection
Lipids ~22% fewer major vascular events per 1 mmol/L LDL reduction (CTT 2010, PMID 21067804) Lp(a) outcomes and lifetime very-low LDL safety
Inflammation IL-1β causal proof and selected colchicine benefit (Ridker 2017, PMID 28845751; Nidorf 2020, PMID 32865380) Explain CLEAR SYNERGY neutrality and identify responders
Rehabilitation CV mortality RR 0.74 (Dibben 2023, PMID 36746187) Scalable completion rather than referral alone
INOCA Endotype-guided care improves symptoms (Ford 2018, PMID 30266608) Hard outcomes and noninvasive endotyping
Patient experience Angina and psychological recovery are treatment outcomes Measures that capture function, uncertainty and burden

The resulting architecture is deliberately cross-linked: focal anatomy cannot be interpreted without systemic plaque biology; trial efficacy cannot be interpreted without delivery; and death/MI endpoints cannot replace symptom and functional outcomes.

Evidence-reading rules used across this condition

Rule Reason
Separate stable CAD from ACS Revascularization has different purposes and urgency
Separate PCI from CABG Route, completeness, hazard and evidence differ
Separate symptoms from death/MI One intervention may improve one but not the other
Report absolute and relative effects Baseline risk determines practical benefit
Show composite components Procedure MI, spontaneous MI, bleeding and revascularization differ
Preserve follow-up horizon Early hazard and late benefit can cross
Treat biomarkers as decisions, not associations Clinical utility requires an actionable strategy
Treat implementation as causal Prescribed therapy cannot work when unavailable or not taken

These rules explain apparently conflicting findings without forcing false consensus.

Cross-domain effect-size ledger

Domain Anchor estimate Interpretive boundary
Stable PCI prognosis COURAGE death/MI was 19.0% with PCI+OMT versus 18.5% with OMT (HR 1.05, 95% CI 0.87–1.27) (Boden 2007, PMID 17387127). Does not address left main disease, ACS, or symptom benefit in every phenotype.
Initial invasive stable strategy ISCHEMIA 5-year primary-event estimates were 16.4% versus 18.2% (difference −1.8 points, 95% CI −4.7 to 1.0), with no all-cause mortality benefit (Maron 2020, PMID 32227755). Procedural and spontaneous MI pull in opposite temporal directions.
Placebo-controlled symptom relief ORBITA exercise-time difference was 16.6 seconds (95% CI −8.9 to 42.0); ORBITA-2 favored PCI for daily angina score (OR 2.21, 95% CI 1.41–3.47) (Al-Lamee 2018, PMID 29103656; Rajkumar 2023, PMID 38015442). Background antianginal state and endpoint construction explain part of the apparent conflict.
LDL lowering Each 1 mmol/L further LDL-C reduction lowered major vascular events by about 22% (RR 0.78, 95% CI 0.76–0.80) (CTT 2010, PMID 21067804). Relative proportional benefit must be converted to absolute benefit for the patient's baseline risk and horizon.
Dual-pathway inhibition COMPASS reduced CV death/stroke/MI (HR 0.76) while increasing major bleeding (HR 1.70) (Eikelboom 2017, PMID 28844192). Benefit and harm must be displayed separately; full-dose anticoagulation is a different indication.
Inflammation CANTOS 150 mg reduced MACE (HR 0.85) but increased fatal infection; CIRT was biologically and clinically neutral (Ridker 2017, PMID 28845751; Ridker 2019, PMID 30415610). “Anti-inflammatory” is not a transferable drug-class effect.
Rehabilitation Contemporary randomized-trial meta-analysis supports lower cardiovascular mortality and hospitalization with exercise-based CR (Dibben 2023, PMID 36746187). Program dose, referral, uptake, and era determine real-world absolute impact.
Ischemic LV dysfunction CABG has long-term outcome support, whereas PCI did not reduce death/HF hospitalization in REVIVED (Velazquez 2016, PMID 27040723; Perera 2022, PMID 36027563). CABG and PCI cannot be pooled as “revascularization.”

IHD controversies often dissolve when the estimand is named: preventing spontaneous MI, accepting procedural MI, relieving angina, avoiding bleeding, extending survival, or improving function are different goals. Remaining disputes—left-main strategy, inflammatory enrichment, INOCA testing, Lp(a) lowering, beta-blocker duration, and implementation in low-resource systems—persist because the necessary populations, comparators, or time horizons have not yet been tested (Byrne 2023, PMID 37632766; Kelshiker 2022, PMID 34849697; Yndigegn 2024, PMID 38587241; Aminorroaya 2022, PMID 34041535).

Time horizon and delivery alter the disease portrait

Framingham's competing-risk analysis estimated lifetime CHD risk at age 40 as 48.6% (95% CI 45.8%–51.3%) for men and 31.7% (95% CI 29.2%–34.2%) for women; even at age 70, remaining lifetime risks were 34.9% and 24.2%, respectively (Lloyd-Jones 1999, PMID 10023892). These historical US estimates are not contemporary global prevalence, but they show why short-term risk and lifetime exposure answer different prevention questions.

Exposure history also matters biologically. Across 18,288 adults from four US cohorts, higher cumulative and time-weighted LDL-C through young/middle adulthood predicted later CHD after adjustment for the most recent midlife LDL-C (HR 1.57, 95% CI 1.10–2.23 and HR 1.69, 95% CI 1.23–2.31, respectively) (Zhang 2021, PMID 34550307). A single contemporary LDL value therefore cannot fully represent arterial exposure.

Treatment interpretation changes with estimand and health-system delivery. A Bayesian synthesis of seven contemporary stable-IHD RCTs (12,494 participants) centered the all-cause mortality absolute risk difference for revascularization plus medical therapy at −0.2 percentage points (95% credible interval −1 to +1), while favoring revascularization for MI/unstable angina and angina freedom at the cost of more stroke probability (Kumar 2022, PMID 35210188). In rural Iran, a 6,838-person cluster trial found a four-drug polypill reduced 5-year major cardiovascular events from 8.8% to 5.9% (adjusted HR 0.66, 95% CI 0.55–0.80), illustrating that scalable delivery can produce an effect distinct from choosing among individual drugs (Roshandel 2019, PMID 31448738).

Open questions

  • Is there any stable-CAD subgroup with a mortality benefit from revascularization? ISCHEMIA-EXTEND's split (lower CV death, higher non-CV death, net zero) keeps the question open (Hochman 2023, PMID 36335918).
  • Why did PCI fail even in ischemic LV dysfunction (REVIVED), where viability logic predicted benefit — is hibernating myocardium a flawed construct? (Perera 2022, PMID 36027563)
  • Who benefits from anti-inflammatory therapy — should hsCRP guide colchicine the way LDL guides statins, and why did colchicine's benefit not clearly extend to all-cause mortality? (Nidorf 2020, PMID 32865380; Ridker 2017, PMID 28845751)
  • How low should LDL go, and for whom — FOURIER's benefit at median achieved 30 mg/dL argues "lower is better" has no observed floor; the global burden of elevated LDL-C suggests massive undertreatment (Sabatine 2017, PMID 28304224; GBD 2023 LDL Cholesterol Collaborators 2026, PMID 42525403).
  • Can delivery innovations (polypill, rehab-at-scale, task-shifting) reverse the concentration of IHD mortality in low-SDI countries, where age-standardized death rates are falling slowest? (Castellano 2022, PMID 36018037; Yang 2025, PMID 40841929)

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