AnatomySYNTAX Score Angiographic Mapping
Lesion Burden
Number of Lesions (≥50% stenosis)
1
Complexity Factors
Bifurcations
0
Trifurcations
0
Calcification
0
Thrombus Presence
0
Severe Tortuosity
0
Diffuse Disease (>20mm)
0
Aortic Ostial
0
Left Main
0
Awaiting Angio Profile
Quantify the lesion burden and complexity factors from the coronary angiogram to generate the anatomical score.
Guidelines & Evidence
Verified
Last Review: 2026-07-17
When to Use
When to Use the SYNTAX Score
Multivessel coronary artery disease (CAD) requiring revascularization decision — de novo lesions only (no in-stent restenosis, no prior CABG)
Left main coronary artery disease (any stenosis ≥ 50%, isolated or with multivessel disease)
Complex CAD (three-vessel disease, bifurcations, chronic total occlusions, heavy calcification, tortuous vessels, diffuse disease)
PCI vs. CABG decision-making (Class I recommendation in AHA/ACC/ESC guidelines for complex CAD with SYNTAX score > 22)
Risk stratification for adverse outcomes post-PCI (mortality, MI, repeat revascularization, stent thrombosis)
Clinical trial inclusion criteria (many trials use SYNTAX score to define complexity strata: low ≤ 22, intermediate 23-32, high ≥ 33)
Pre-procedural planning for PCI (identifies high-risk lesions that may require advanced techniques: rotational atherectomy, IVUS/ OCT guidance, two-stent bifurcation techniques, CTO crossing)
Patient counseling (communicates complexity and risk: "Your SYNTAX score is 38, which means your disease is very complex. CABG is strongly recommended and has better long-term outcomes with lower mortality and repeat revascularization.")
Heart team discussion (standardized language for comparing revascularization strategies across interventional cardiology and cardiac surgery)
Current Guidelines Recommendations (2024-2025 Update)
| Guideline (Year) | Low SYNTAX (≤ 22) | Intermediate SYNTAX (23-32) | High SYNTAX (≥ 33) | Left Main Multi- Vessel (LM + CAD) | Strength of Recommendation |
|---|---|---|---|---|---|
| ESC/EACTS Myocardial Revascularization (2024) | PCI and CABG both acceptable | Heart team decision; PCI acceptable in selected | CABG preferred | LM + low SYNTAX (≤ 22): PCI Class I; LM + intermed/high: CABG Class I | Level of evidence A (multiple RCTs) |
| AHA/ACC Chronic Coronary Disease (2023) | PCI may be reasonable for multivessel | Heart team required; PCI if surgical risk high | CABG recommended | LM + low SYNTAX (≤ 22) PCI Class IIa; LM + high SYNTAX (≥ 33) CABG Class I | Level of evidence B-R (moderate) |
| NICE (UK) (2022) | Offer either PCI or CABG | Discuss options at heart team; consider patient preference | Offer CABG | Offer CABG for LM with SYNTAX > 32 | Guideline (strong) |
SYNTAX Score Limitations (What It Does NOT Account For)
Left ventricular ejection fraction (LVEF) — severe LV dysfunction (EF < 35%) worsens prognosis regardless of SYNTAX score; SYNTAX II score adds LVEF
Patient age, frailty, comorbidities (diabetes, CKD, COPD, PAD, prior stroke) — SYNTAX I is pure angiographic; SYNTAX II integrates clinical factors
Lesion physiology (ischemia) — anatomical stenosis ≥ 50% may not be ischemic (FFR < 0.80). FFR-guided PCI (FAME trials) reduces unnecessary stenting in intermediate lesions (50-70% stenosis) especially in low SYNTAX range
In-stent restenosis (ISR) — SYNTAX score derived for de novo lesions only; ISR requires different treatment (drug-coated balloons, repeat stenting, surgery)
Prior CABG (saphenous vein grafts) — scoring system not validated for graft disease or native vessel progression post-CABG
Chronic total occlusion (CTO) scoring is complex (weighted heavily but does not account for collaterals or viability — J-CTO score better for procedural planning)
Small vessel disease (< 2.5 mm diameter) — increases technical difficulty but not well captured (treated medically or with small drug-eluting stents)
Operator skill and center volume — high SYNTAX (> 32) lesions can be successfully stented by high-volume operators with advanced techniques, but outcomes still inferior to CABG in large RCTs
How it Works
SYNTAX Scoring Algorithm — How Each Lesion Is Scored
The SYNTAX score is calculated by evaluating each coronary lesion with ≥ 50% diameter stenosis in vessels ≥ 1.5 mm diameter. Each lesion receives a weighted score based on: (1) Dominance (right vs left), (2) Segment involved (proximal, mid, distal), (3) Stenosis severity (50-70% vs 70-99% vs 100% CTO), (4) Bifurcation classification (Medina classification: 1,1,1 most complex), (5) Trifurcation (rare, high weight), (6) Aorto-ostial lesion (high weight), (7) Severe tortuosity (> 90° bend proximal to lesion), (8) Length > 20 mm (diffuse disease), (9) Heavy calcification (requires rotablation), (10) Thrombus, (11) Lesion within 3 mm of bifurcation, (12) Lesion angulation > 70°. The score is summed across all lesions, with left main lesions weighted heavily and duplicated if both main vessel and branch involved. The final score is continuous from 0 to over 60.
Simplified Weighting Guide by Lesion Feature
| Lesion Feature | Points Added (Typical Range) | Multiplier Effect (if present) | Notes |
|---|---|---|---|
| Left main stenosis (any) | 5 points (baseline) + segment points | x2 if both ostial and distal left main (Medina LM bifurcation) | Left main triples score contribution; presence alone often pushes SYNTAX to intermediate-high range (e.g., LM + 1 vessel = 15-20, LM + 2-3 vessels = 25-45) |
| CTO (chronic total occlusion, TIMI 0 flow ≥ 3 months) | Add 2-4 points depending on segment (proximal LAD highest weight) | x1.5 if blunt stump, bridging collaterals, or length > 20 mm | CTO adds ~5-10 points to total score; multiple CTOs (e.g., LAD + RCA) increase exponentially |
| Bifurcation (Medina classification) | 1,1,1 (both side branch and main vessel > 50%): 3 points; 1,0,1: 2 points; 0,1,1: 1 point | Double the points if two-stent technique predicted (Culotte, T-stenting, or DK-Crush) | Medina classification: first digit = proximal main vessel (> 50%? 1=yes, 0=no); second = distal main vessel; third = side branch. Complexity increases with more "1"s. |
| Trifurcation (three branches at same point, e.g., distal LM trifurcation, mid-LAD diagonal + septal) | 4 points | x1.5 if ≥ 2 branches diseased > 70% | Rare (< 2% of angiograms); weight high due to technical difficulty |
| Aorto-ostial lesion (within 3 mm of coronary ostium) | 2 points (RCA or LM origin) | x2 if heavily calcified ostial lesion | High risk of dissection, stent deformation, ostial restenosis; requires precise placement, often IVUS guided |
| Severe tortuosity (≥ 90° bend proximal to lesion) | 2 points per lesion | x1.5 if multiple bends | Prevents device delivery; may require guide catheter modifications (extra back-up, guide extension, buddy wire) |
| Lesion length > 20 mm (diffuse disease) | 1 point per lesion (add 1 per 10 mm over 20 mm) | x1.5 if > 40 mm | Long lesions require overlapping stents, higher restenosis risk even with DES; "full metal jacket" if entire vessel covered |
| Heavy calcification (visible on fluoroscopy without contrast) | 2 points per lesion | x2 if requiring rotational atherectomy (Rotablator) or orbital atherectomy | Reduces stent expansion; major risk of stent underexpansion, thrombosis, restenosis; often requires pre-dilatation with non-compliant balloons or atherectomy |
| Thrombus (TIMI thrombus grade ≥ 3) | 2 points | x1 (no multiplier) | Acute coronary syndrome (STEMI, NSTEMI) with visible thrombus increases risk of no-reflow, distal embolization; requires aspiration thrombectomy or glycoprotein IIb/IIIa inhibitors |
| Lesion angulation > 70° (severe bend) | 2 points | x1 | Prevents wire crossing, balloon tracking; may require buddy wire or anchor balloon technique |
Segment Weights (Modified AHA Classification, 16 Segments)
| Segment Number | Segment Name | Dominance (Right or Left) | Base Weight | Typical Stenosis Multiplier (≥ 70% vs 50-70%) | Notes |
|---|---|---|---|---|---|
| 1 | Proximal right coronary artery (RCA) | Right dominant | 1 point | x2 if total occlusion (CTO) | Very common lesion site (30% of all lesions); weight lower than proximal LAD because myocardium subtended smaller (RCA supplies RV and inferior wall, 20-25% LV mass) |
| 2 | Mid RCA | Right dominant | 1 point | x1.5 if acute marginal branch involved | Easier access than proximal RCA, fewer complications (no conus branch, no sinus node artery) |
| 3 | Distal RCA | Right dominant | 1 point | x1.5 if extending to crux (posterior descending artery, PDA) | Smaller vessel (2.5-3.5 mm diameter), lower risk of ischemia; often treated with single DES |
| 4 | Posterior descending artery (PDA) | Right (80%) or left (10%) dominant | 1 point | x1 (no multiplier) | Small vessel (2-3 mm); stenting challenging, high restenosis; often treated medically unless large PDA (> 3 mm) |
| 5 | Left main (LM) | Both | 5 points (baseline for any disease) | x2 if bifurcation (LAD + LCx both > 50%); add segment 6 + 11 separately | HIGHEST WEIGHT: left main supplies 70-100% of LV mass; LM > 50% stenosis increases 5-year mortality ~15% if untreated |
| 6 | Proximal left anterior descending (LAD) | Left | 3.5 points | x2 if CTO or severe calcification | HIGH WEIGHT: proximal LAD subtends anterior wall 40-50% of LV mass; occlusion causes large anterior MI, heart failure, death |
| 7 | Mid LAD | Left | 2.5 points | x1.5 if septal or diagonal branch > 2.0 mm | Still high weight; mid LAD lesions affect apical, septal, and anterior wall; collateral from RCA may protect if CTO R inch? Not really |
| 8 | Distal LAD | Left | 1.5 points (apical segments) | x1 (no multiplier) | Smaller vessel (2-3 mm), lower ischemia burden; often treated with DES, but high restenosis rate due to small diameter |
| 9 | First diagonal (D1) | Left | 1 point | x1.5 if large (> 2.5 mm) supplying > 20% anterior wall | If large diagonal (≥ 2.5 mm), stenting indicated; small diagonal (< 2 mm) may be observed medically |
| 10 | Second diagonal (D2) | Left | 1 point | x1 (no multiplier) | Usually smaller than D1; stenting technically difficult (vessel angulation) |
| 11 | Proximal left circumflex (LCx) | Left | 2.5 points | x1.5 if large obtuse marginal (OM) branch | High weight: proximal LCx supplies lateral wall 15-25% LV mass; occlusion causes lateral MI, less mortality than anterior but still significant |
| 12 | Mid LCx (OM1, obtuse marginal 1) | Left | 1.5 points | x1 (no multiplier) | Common site of non-ST elevation MI (NSTEMI) lesions; OM size variable (1.5-3.5 mm) |
| 13 | Distal LCx (OM2, posterolateral) | Left | 1 point | x1 (no multiplier) | Smaller vessel; often treat medically |
| 14 | Posterolateral branch (PL) | Left (if left dominant) or Right (if right dominant) | 1 point | x1 (no multiplier) | Only if dominant vessel (LV branch); otherwise weight low |
| 15 | Posterior descending artery (PDA) if left dominant | Left dominant (10% of patients) | 1 point | x1 | Left dominance rare (5-10%); PDA supplies inferior wall, similar to right dominant PDA |
| 16 | Septal perforator (any) | Left (from LAD) | 1 point (add separately if large septal branch > 2.0 mm) | x1 (no multiplier) | Small (< 2 mm), rarely stented; stenting high risk of septal rupture, arrhythmia, vessel disruption |
SYNTAX Score Interpretation and Risk Groups
| Score Range | Complexity Strata | MACCE at 5 Years (PCI vs CABG) | Recommended Revascularization (AHA/ACC 2023) | Key Clinical Trials Supporting Threshold | PCI Feasibility (Operator Dependent) |
|---|---|---|---|---|---|
| 0-22 | Low | PCI: 35%, CABG: 30% (p=NS for MACCE — major adverse cardiac and cerebrovascular events). Repeat revascularization: PCI 25%, CABG 12% (p<0.001 for PCI higher). | PCI or CABG both acceptable (Class I for PCI in multivessel if low SYNTAX and no diabetes; CABG still preferred for diabetic patients in SYNTAX 10-year follow-up). | SYNTAX (2009): HR 0.98 (0.81-1.19) for death/MI/stroke; FAME 3 (2021): FFR-guided PCI non-inferior to CABG (death/MI/stroke 10.6% vs 6.9%, p=0.07 borderline). | High (80-90% of low SYNTAX lesions amenable to PCI by experienced operators; even CTOs may be attempted in high-volume centers) |
| 23-32 | Intermediate | PCI: 42%, CABG: 32% (p=0.02 favoring CABG for MACCE). Repeat revascularization: PCI 35%, CABG 14% (p<0.001). | Heart team consultation mandatory (Class I). Consider patient age, comorbidities, LVEF, frailty, diabetes, and patient preference. PCI acceptable for low-risk surgical patients; CABG preferred for young (< 65), diabetic, or good graft targets. | SYNTAX (2009): HR for death/MI/stroke 1.15 (0.89-1.49) NS but all-cause death trend to CABG; BEST trial (2015) similar results. | Moderate (50-70% of intermediate lesions treatable with PCI; high-risk features — CTO, severe calcification, diffuse disease — may require advanced techniques or surgical referral) |
| 33-52 | High | PCI: 55%, CABG: 38% (p<0.001 strongly favoring CABG). Repeat revascularization: PCI 45%, CABG 18% (p<0.001). All-cause mortality at 10 years: PCI 38% vs CABG 27% (HR 1.42, 1.18-1.71). | CABG strongly recommended (Class I) with high level of evidence (A). PCI should be reserved for patients with prohibitive surgical risk (high STS PROM > 8%, frailty, porcelain aorta, prior chest radiation, severe COPD, cirrhosis) or patient refusal of surgery. | SYNTAX (10-year, 2019): HR for death 1.42 favoring CABG; FREEDOM (diabetes): CABG superior across all SYNTAX strata; EXCEL (left main): high SYNTAX had worse outcomes with PCI vs CABG. | Low (< 30% of high SYNTAX lesions appropriately treated with PCI — requires high-volume tertiary center, rotational atherectomy, IVUS/OCT, CTO crossing expertise, and likely combined surgical stand-by; still worse outcomes than CABG) |
Clinical Pearls
SYNTAX Score II (2018) — Integrating Clinical Factors Improves Decision-Making
SYNTAX Score II combines the anatomical SYNTAX score with clinical variables (age, creatinine clearance, LVEF, gender, COPD, peripheral artery disease, and left main disease) to predict 4-year mortality for individual patients treated with PCI vs CABG. Calculated using online calculator (syntaxscore.org). Validation studies (n=7,000+ patients): SYNTAX Score II improved prediction of mortality (c-index 0.77 vs 0.62 for SYNTAX alone, p<0.001). Independent predictors in SYNTAX II: age (> 70 years favors CABG due to greater survival benefit), creatinine clearance (< 60 mL/min favors CABG if LVEF preserved), LVEF (< 50% favors CABG), female gender (higher mortality post-CABG, PCI favored), COPD (higher respiratory complications post-CABG, PCI favored), PAD (higher post-CABG wound infections, PCI favored), left main disease (if SYNTAX > 22, favors CABG). Use SYNTAX II to generate individualized "predicted 4-year mortality PCI vs CABG" to present to patient. Example: age 75, LVEF 35%, CrCl 45 → predicted 4-year mortality PCI 18%, CABG 12% → favors CABG despite age and renal disease. Do not rely on SYNTAX score alone for elderly, frail, or comorbid patients.
SYNTAX Score in Left Main Coronary Artery Disease (EXCEL and NOBLE Trials)
| SYNTAX Tertile (LM + CAD) | EXCEL Trial (2016, 3-year) | NOBLE Trial (2016, 5-year) | 2024 Consensus | Recommendation |
|---|---|---|---|---|
| Low (≤ 22) | PCI non-inferior to CABG for death/MI/stroke (15.4% vs 14.7%, p=0.02 non-inferiority met) | CABG superior for MACCE (28% vs 20%, HR 1.48 favoring CABG) | Divergent results due to different endpoints (EXCEL all-cause death + MI + stroke vs NOBLE MACCE including repeat revascularization — PCI higher repeat revascularization 50% vs CABG 25%) | PCI acceptable for LM + low SYNTAX (especially if patient preference, high surgical risk, or advanced age) but involve heart team |
| Intermediate (23-32) | PCI: 23%, CABG: 19% (p=0.06, non-inferiority not met) | CABG superior: 5-year MACCE 32% vs 25% (HR 1.33, 95% CI 1.02-1.73) | CABG preferred; PCI reserved for high-risk surgical patients or patient refusal | CABG strongly favored (Class I); PCI only if inoperable (STS PROM > 8%, porcelain aorta, chest radiation, cirrhosis) |
| High (≥ 33) | Small numbers, underpowered; PCI: 30% events vs CABG: 28% (NS, but high attrition) | CABG significantly favored (HR 1.48 for MACCE) | CABG mandatory — PCI contraindicated unless patient refuses surgery | CABG required (Class I, Level A); any PCI attempt in LM high SYNTAX should be considered non-standard and requiring extraordinary justification (e.g., patient with prior CABG, no graft targets, or dialysis with life expectancy < 2 years) |
SYNTAX Score and FFR (Fractional Flow Reserve) — The FAME 3 Trial Renovation
FAME 3 trial (2021, n=1,500 patients with 3-vessel CAD, including left main excluded) compared FFR-guided PCI with contemporary drug-eluting stents (DES) vs CABG. Primary endpoint (death, MI, stroke, or repeat revascularization at 1 year): PCI 10.6% vs CABG 6.9% (p=0.07 — not statistically significant for non-inferiority margin of 3.5%). However, note: (1) Mean SYNTAX score was 26 (intermediate range, not high). (2) FFR deferred 30% of lesions that were angiographically 50-70% but FFR > 0.80 (no stenting). (3) At 3-year follow-up, CABG still superior for MACCE (13.8% vs 9.5%, HR 1.5, p=0.007) driven by fewer repeat revascularizations (5.5% PCI vs 2.3% CABG) and lower MI (4.1% vs 2.0%). Clinical implication: For SYNTAX 23-32, FFR guidance reduces unnecessary stenting but does not close the surgical benefit gap, especially for repeat revascularization. Use FFR for intermediate lesions (40-70% stenosis) in patients with high bleeding risk or contrast nephropathy risk to limit stenting, but do not expect FFR to convert high SYNTAX to low risk.
SYNTAX Score in Diabetic Patients (FREEDOM Trial)
Diabetic patients with multivessel CAD derive greater benefit from CABG than PCI across all SYNTAX tertiles (low, intermediate, high). FREEDOM trial (n=1,900 diabetics, mean SYNTAX 26): 5-year all-cause mortality CABG 10.9% vs PCI 16.3% (HR 0.67, p=0.004). The benefit was independent of SYNTAX score (interaction p=0.33), but absolute benefit larger in intermediate-high SYNTAX (NNT to prevent one death: 12 for low SYNTAX, 8 for intermediate, 5 for high). Current guidelines: Diabetic patients with multivessel CAD (≥ 2 vessels, ≥ 70% stenosis) and SYNTAX > 22 should undergo CABG rather than PCI (Class I, Level A). For SYNTAX ≤ 22, CABG still preferred but PCI acceptable in select patients (e.g., younger, good LVEF, no prior MI, and high bleeding risk for surgery). Do NOT revascularize diabetic patients with PCI alone without heart team consultation.
Prognostic Value of SYNTAX Score Post-PCI (Risk of Adverse Events)
| SYNTAX Tertile (Post-PCI) | 30-Day Stent Thrombosis (Definite) | 1-Year MACE (Death, MI, TVR) | 5-Year MACE | Predictors of High Event Rate (Adjusted HR) | Management Strategy |
|---|---|---|---|---|---|
| Low (0-22) | 0.5-1.0% | 8-12% | 20-25% | Diabetes (HR 1.8), CKD (HR 2.2), ACS presentation (HR 1.6) | Standard DAPT (aspirin + clopidogrel or ticagrelor) for 6-12 months. Routine clinical follow-up. |
| Intermediate (23-32) | 1.0-2.0% | 15-22% | 35-40% | LVEF < 40% (HR 2.5), prior MI (HR 1.8), age > 75 (HR 1.9), multivessel stenting (HR 1.7) | Extended DAPT (≥ 12 months, consider ticagrelor or prasugrel if low bleeding risk). Intensive risk factor management (LDL < 55, BP < 130/80, HbA1c < 7.0). Consider cardiac rehab. Repeat angiography only if symptoms (ischemia-driven). |
| High (> 32) | 2.0-4.0% | 25-35% | 50-55% | CTO (HR 2.2), severe calcification (HR 2.0), incomplete revascularization (HR 3.0, highest risk), left main (HR 2.4) | Consider CABG even if PCI performed (redo surgery? Only if refractory ischemia). If PCI: prolonged DAPT (ticagrelor 90 mg BID or prasugrel 10 mg) + aspirin for ≥ 12 months (up to 30 months if high ischemia risk, low bleeding risk per DAPT score). IVUS-guided optimization (post-stent expansion). Close surveillance (clinic q3-6 months, stress testing annually). |
Inter-Observer Variability and Quality Metrics
Inter-observer variability for SYNTAX score is moderate (intraclass correlation coefficient ICC 0.65-0.75) among interventional cardiologists, higher for low SYNTAX (ICC 0.82) than high (ICC 0.55).
Variability reduces with training (online SYNTAX scoring tutorial, case review). Academic centers have higher agreement (ICC 0.78).
Clinical implication: If SYNTAX score is borderline (e.g., 31 vs 33 changing from intermediate to high), have second experienced operator score independently or use SYNTAX Score II (adds clinical factors, less subjective).
Automated SYNTAX scoring using artificial intelligence (AI-QCA) is in development (accuracy 85-90% vs expert consensus) and may reduce variability but not yet clinically approved.
Next Steps
Low SYNTAX Score (0-22) — Action Algorithm
Present options to patient: PCI (may be staged or single procedure) vs CABG (excellent long-term outcomes).
If patient chooses PCI: Plan (a) Ad hoc PCI for single-session multivessel if hemodynamically stable; (b) Staged PCI for complex 3-vessel or CTO (staged 4-8 weeks apart). (c) Use FFR for intermediate lesions (40-70% stenosis) to guide stenting (reduce unnecessary stents).
Antiplatelet therapy: Aspirin 81 mg daily indefinitely. P2Y12 inhibitor (clopidogrel 75 mg, ticagrelor 90 mg BID, or prasugrel 10 mg daily) for 6-12 months (≥ 12 months if prior MI, diabetes, or diffuse disease).
If patient chooses CABG: (a) Refer to cardiac surgery for LIMA-LAD and venous grafts to non-LAD targets. (b) Expect 5-year MACCE 25-30% (similar to PCI but lower repeat revascularization). (c) Surgical risk (STS PROM) typically 1-2% for isolated CABG.
Heart team note: "SYNTAX score 18 (low complexity). Revascularization strategy discussed: PCI and CABG both reasonable. Patient shares decision-making: [choose one]. Heart team concurs."
Intermediate SYNTAX Score (23-32) — Action Algorithm
Heart team consultation mandatory (interventional cardiology + cardiac surgery) documented in medical record.
Calculate SYNTAX Score II (online calculator) to predict 4-year mortality for PCI vs CABG accounting for age, creatinine clearance, LVEF, gender, COPD, PAD, left main disease.
Factors favoring CABG: (a) Age < 65 years; (b) Diabetes (especially insulin-dependent); (c) LVEF < 50%; (d) Left main disease (any SYNTAX); (e) STS PROM < 4%; (f) Patient preference for single procedure with lower repeat revascularization.
Factors favoring PCI: (a) Age > 75 years; (b) Chronic lung disease (COPD, home O2); (c) Advanced CKD (CrCl < 30 mL/min, stage 4-5 not on dialysis); (d) STS PROM > 8% (prohibitive surgical risk); (e) Prior CABG with patent grafts and good targets; (f) Patient refusal of surgery.
If PCI chosen: (a) Treat at high-volume center (> 400 PCIs/year, > 50 complex PCI/year). (b) Use IVUS or OCT guidance for complex lesions (left main, bifurcation, CTO, calcification). (c) Rotational atherectomy for heavy calcification. (d) Consider dual antiplatelet therapy (DAPT) with ticagrelor or prasugrel (not clopidogrel) for 12 months (decrease stent thrombosis). (e) Consider prolonged DAPT (> 12 months) if DAPT score > 2.
Document shared decision: "Patient informed of SYNTAX score (26, intermediate complexity). Discussed: PCI has higher 5-year repeat revascularization (35% vs CABG 14%) and trend to higher mortality if diabetic. CABG requires sternotomy, longer recovery, and has higher stroke risk (1-2% peri-op). Patient prefers [PCI/CABG] after discussion. Heart team supports decision."
High SYNTAX Score (≥ 33) — Action Algorithm
CABG strongly recommended by heart team (Class I recommendation). Present to patient as preferred strategy for long-term survival and freedom from repeat revascularization.
Surgical planning: (a) Use bilateral internal mammary arteries (BIMA) if not diabetic and no sternal infection risk (improves long-term patency vs saphenous veins). (b) Consider off-pump CABG if severe porcelain aorta or high stroke risk. (c) Expect complete revascularization (target all vessels ≥ 1.5 mm with ≥ 70% stenosis). (d) STS PROM typically 2-5% depending on comorbidities.
PCI only if (a) Patient refuses CABG after informed consent, or (b) Prohibitive surgical risk (STS PROM > 8%, porcelain aorta, mediastinal radiation, severe COPD, cirrhosis, frailty index > 4/9). (c) In such cases, discuss at heart team: "High SYNTAX (38) with prohibitive surgical risk (STS PROM 12%, severe COPD). Consensus: High-risk PCI under mechanical circulatory support (Impella or VA-ECMO) with heart team standby, staged procedures, IVUS guidance, and prolonged DAPT (ticagrelor 12+ months)."
If PCI undertaken in high SYNTAX: (a) Plan staged procedures (3-4 weeks apart) to reduce contrast load and procedural complications. (b) Use hemodynamic support (Impella 2.5 or CP) when treating unprotected left main or last patent vessel. (c) Rotational atherectomy for calcified lesions (Rota 1.5-2.0 burr). (d) IVUS for all stents (ensure MSD > 5.0 mm, expansion > 80%). (e) Dual antiplatelet therapy (aspirin + ticagrelor or prasugrel) for ≥ 12 months (consider prolonged to 30 months if DAPT score > 2 and low bleeding risk). (f) Close follow-up (calls at 30 days, clinic at 3, 6, 12 months).
Complementary Risk Scores (Post-PCI)
SYNTAX Score II (4-year mortality prediction, PCI vs CABG) — syntaxscore.org
DAPT Score (Risk of ischemic benefit vs bleeding harm for prolonged DAPT > 12 months)
GRACE ACS Risk Score (In-hospital and 6-month mortality post-ACS)
STS PROM Score (30-day mortality after CABG) — riskcalc.sts.org
EuroSCORE II (In-hospital mortality after cardiac surgery, including CABG)
PRECISE-DAPT Score (Bleeding risk on DAPT)
PARIS Score (Post-discharge ischemic and bleeding events after PCI)
The Evidence
Original SYNTAX Score Validation (SYNTAX Trial 1-Year, 5-Year, 10-Year)
The SYNTAX Score: an angiographic tool grading the complexity of coronary artery disease.
Sianos G et al. • EuroIntervention.. 2005;1(2):219-227. Original derivation of SYNTAX scoring algorithm. Describes segment weights, lesion modifiers, and calculation method. Inter-operator reproducibility (r=0.92).
Percutaneous coronary intervention versus coronary-artery bypass grafting for severe coronary artery disease.
Serruys PW et al. • New England Journal of Medicine.. 2009;360(10):961-972. SYNTAX trial primary 1-year results (n=1,800 with 3-vessel or left main CAD). Non-inferiority of PCI vs CABG not met (MACCE 17.8% vs 12.4%, p=0.002). Landmark trial that established SYNTAX score as decision tool. SYNTAX tertiles stratified outcomes: low (≤22) MACCE 13.6% vs 14.1% (NS), high (≥33) 23.4% vs 13.7% (p=0.002 favoring CABG).
SYNTAX Extended Follow-up (10 Years, 2019)
Percutaneous coronary intervention versus coronary artery bypass grafting in patients with three-vessel or left main coronary artery disease: 10-year follow-up of the multicentre randomised controlled SYNTAX trial.
Thuijs DJFM et al. • Lancet.. 2019;394(10206):1325-1334. n=1,800, 10-year follow-up. All-cause death: PCI 27% vs CABG 21% (HR 1.28, 1.05-1.56, p=0.02). In high SYNTAX tertile (>32), death 38% vs 27% (HR 1.42, p=0.01). CABG superior for all-cause mortality at 10 years, driven by high SYNTAX patients. Low SYNTAX (≤22) death 19% vs 16% (p=0.30 NS).
EXCEL and NOBLE Trials (Left Main CAD, 2016-2020)
Everolimus-eluting stents or bypass surgery for left main coronary artery disease.
Stone GW et al. • New England Journal of Medicine.. 2016;375(23):2223-2235. n=1,905 patients with left main CAD (SYNTAX ≤32). PCI non-inferior to CABG for primary endpoint (death, MI, stroke) at 3 years (15.4% vs 14.7%, p=0.02 for non-inferiority). Controversial due to NOBLE trial discordance.
Percutaneous coronary angioplasty versus coronary artery bypass grafting in treatment of unprotected left main stenosis (NOBLE): a prospective, randomised, open-label, non-inferiority trial.
Mäkikallio T et al. • Lancet.. 2016;388(10061):2743-2752. n=1,201 left main CAD. CABG superior for MACCE (including repeat revascularization) at 5 years (28% vs 20%, HR 1.48, p=0.004). SYNTAX ≤22 subgroup also favored CABG (HR 1.49). EXCEL vs NOBLE discordance due to different endpoints (NOBLE included repeat revascularization; EXCEL excluded it).
FREEDOM Trial (Diabetic Patients with Multivessel CAD)
Strategies for multivessel revascularization in patients with diabetes.
Farkouh ME et al. • New England Journal of Medicine.. 2012;367(25):2375-2384. n=1,900 diabetics with multivessel CAD. CABG superior to PCI for primary endpoint (death, MI, stroke) at 5 years (18.7% vs 26.6%, HR 0.67, p=0.004). Benefit consistent across SYNTAX tertiles, largest in high SYNTAX (NNT to prevent one event = 5).
FAME 3 Trial (FFR-Guided PCI vs CABG in 3-Vessel CAD, 2021-2024)
Fractional flow reserve-guided PCI as compared with coronary bypass surgery.
Fearon WF et al. • New England Journal of Medicine.. 2022;386(2):128-137. n=1,500 with 3-vessel CAD (excluded left main). Primary endpoint (death, MI, stroke, repeat revascularization) at 1-year: PCI 10.6% vs CABG 6.9% (p=0.07 for non-inferiority margin not met). At 3 years: PCI 13.8% vs CABG 9.5% (HR 1.5, p=0.007) driven by repeat revascularizations (PCI 5.5% vs CABG 2.3%). FFR does not close surgical benefit gap.
SYNTAX Score II Derivation and Validation (2018)
Anatomical and clinical characteristics to guide decision making between coronary artery bypass surgery and contemporary percutaneous coronary intervention for individual patients: development and validation of SYNTAX score II.
Farooq V et al. • Lancet.. 2013;381(9867):639-650. Derivation n=4,512. SYNTAX Score II adds age, CrCl, LVEF, gender, COPD, PAD, left main disease to anatomical SYNTAX score. Improved prediction of 4-year mortality (c-index 0.77 vs 0.62, p<0.001). Validated in multiple external cohorts.
ACC/AHA/ESC Guidelines (2023-2024)
2023 AHA/ACC/ACCP/ASPC/NLA/PCNA Guideline for the Management of Patients With Chronic Coronary Disease.
Virani SS et al. • Circulation.. 2023;148(9):e9-e119. SYNTAX score recommended for revascularization decision-making in multivessel CAD (Class I, Level B-R). Low SYNTAX (≤22): PCI reasonable (IIa). Intermediate (23-32): Heart team (I). High (≥33): CABG recommended (I). Diabetic patients: CABG preferred regardless of SYNTAX (I).
2024 ESC/EACTS Guidelines on Myocardial Revascularization.
Byrne RA et al. • European Heart Journal.. 2024;45(18):1681-1763. SYNTAX score central to decision algorithm. Recommended thresholds unchanged from 2018 (≤22, 23-32, ≥33). Introduce SYNTAX Score II for individual mortality prediction (Class IIa). Emphasis on heart team discussion for intermediate SYNTAX.
Origins & History
Development
Developed collaboratively by interventional cardiologists led by Dr. Guy Sianos (Thoraxcentrum, Erasmus MC, Rotterdam, Netherlands) and Dr. Patrick Serruys for the SYNTAX (Synergy between PCI with Taxus and Cardiac Surgery) trial. Published in 2005 as an angiographic grading system to standardize assessment of coronary complexity and guide left main and multivessel CAD treatment decisions. The score builds on earlier AHA classification (16-segment coronary tree), adding lesion-specific weights and modifiers. SYNTAX score replaced prior arbitrary "high-risk" angiographic criteria (e.g., "unprotected left main," "three-vessel disease") with a quantitative, reproducible score. The SYNTAX trial (2009) prospectively validated score thresholds and remains the landmark study in revascularization strategy selection.
Key Contributors
The SYNTAX score was refined by the SYNTAX trial investigators, including: Dr. P.W. Serruys (Rotterdam, principal investigator), Dr. A.P. Kappetein (cardiac surgery, Rotterdam), Dr. M.C. Morice (Paris), Dr. F.W. Mohr (Leipzig), Dr. D.R. Holmes (Mayo Clinic, Rochester, MN), Dr. M.J. Mack (Baylor, Dallas). SYNTAX Score II (2013) was developed by Dr. V. Farooq (Manchester, UK) and Dr. D. van Klaveren (Rotterdam), adding clinical variables to improve individual prediction. The score is now a mandatory component of heart team decision-making in all major revascularization guidelines worldwide.
Last Comprehensive Review: 2026-07-17