Percutaneous Coronary Intervention Versus Coronary Artery Bypass Grafting in Multivessel Coronary Artery Disease

Definition and therapeutic rationale

Multivessel coronary artery disease (CAD) refers to clinically significant atherosclerotic disease affecting two or more major epicardial coronary arteries. It frequently coexists with left main coronary artery disease, diabetes mellitus, left ventricular dysfunction, peripheral vascular disease and other manifestations of diffuse atherosclerosis.

Percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) are revascularization procedures. Both can improve coronary flow, exercise capacity and angina-related health status, and both can reduce myocardial ischaemia during exertion or emotional stress. Neither procedure, however, reverses the underlying coronary atherosclerotic process. Their clinical effects therefore occur within the broader framework of guideline-directed medical therapy and secondary prevention.

PCI treats focal stenotic segments, whereas CABG provides a bypass beyond diseased segments. The latter may also protect against future proximal disease progression, while stents do not prevent the development of new proximal atherosclerosis. The choice between procedures therefore depends on the balance between:

• Anatomical completeness and complexity of revascularization

• Expected effects on death, myocardial infarction and stroke

• Likelihood of repeat revascularization

• Symptom burden and treatment goals

• Diabetes, left ventricular function and other comorbidities

• Surgical risk and contraindications to prolonged dual antiplatelet therapy

• Patient preferences, local expertise and operator or institutional experience

Assessment of coronary complexity

The SYNTAX score is used to characterize coronary anatomical complexity. It incorporates the number, location and complexity of coronary stenoses. Higher scores indicate more diffuse or technically complex disease and are associated with a greater relative advantage for CABG over PCI in multivessel disease.

A British Cardiovascular Intervention Society myocardial jeopardy score is an alternative method for estimating the extent and severity of CAD. It can help predict mortality after PCI and assess the completeness of revascularization, although the SYNTAX score is more widely used.

Anatomical assessment should be integrated with clinical variables rather than applied in isolation. A multidisciplinary heart team, including an interventional cardiologist and cardiac surgeon, is recommended when both revascularization strategies are feasible, particularly in complex multivessel or left main disease.

Clinical presentation and symptoms

The clinical presentation of multivessel CAD varies from stable angina or exertional limitation to acute coronary syndrome (ACS), ventricular arrhythmia, heart failure or cardiogenic shock.

In chronic coronary disease, the principal symptomatic indication for revascularization is angina that remains refractory despite medical therapy when significant stenoses are anatomically or physiologically suitable for treatment. Revascularization improves angina-related health status, but it should not be undertaken when symptoms are present without anatomical or physiological criteria supporting revascularization.

In less severe coronary disease, PCI generally offers more rapid recovery and lower initial morbidity than CABG, with lower stroke rates, but it is associated with less complete revascularization, less durable relief of angina in some patients and a greater likelihood of repeat PCI.

Multivessel disease in ACS is associated with an adverse prognosis. In STEMI, approximately half of patients undergoing primary PCI have multivessel disease. In ACS complicated by cardiogenic shock, multivessel disease is present in approximately 80% of patients.

Evaluation and clinical assessment

Clinical factors influencing treatment selection

The following characteristics favour CABG when clinically and anatomically appropriate:

• Diabetes mellitus, particularly with multivessel disease involving the LAD

• Left ventricular ejection fraction below 35%

• Mild-to-moderate LV systolic dysfunction when CABG can include a LIMA graft to the LAD

• Complex or diffuse multivessel disease, especially SYNTAX score >33

• Inability to achieve complete revascularization with PCI

• Diffuse in-stent restenosis

• Severe coronary calcification

• Contraindication to dual antiplatelet therapy

• The need for concomitant valve or aortic surgery

PCI may be favoured when:

• The patient is a poor surgical candidate

• Coronary anatomy is of low or moderate complexity

• Equivalent completeness of revascularization can be achieved

• A less invasive strategy and faster recovery are important

• CABG carries particularly high procedural risk

In left main disease, surgical risk may also influence the decision. PCI has been considered an alternative where anatomy is favourable and the predicted risk of adverse surgical outcomes is high.

Peripheral and cerebrovascular disease

Peripheral arterial disease is associated with more extensive atherosclerosis, greater end-organ damage and worse outcomes after CABG. In one database, in-hospital and long-term mortality after CABG were approximately twofold to 2.5-fold higher in patients with peripheral vascular disease than in those without it. Aortic atherosclerosis increases the risk of diffuse atheroembolism, perioperative death, stroke, neurocognitive dysfunction and multiorgan dysfunction.

When coronary and noncoronary vascular procedures are both required, elective vascular surgery can generally be deferred until unstable cardiac disease has been stabilized medically or by revascularization. Combined procedures may be required when both coronary and vascular disease are unstable. PCI can sometimes stabilize the coronary condition before definitive vascular repair.

The optimal management of concomitant carotid and coronary disease remains individualized. Neither combined nor staged carotid and coronary procedures has been established as universally superior. The decision depends on clinical stability, symptom status, coronary and carotid anatomy and institutional experience.

Diagnostic assessment

Coronary anatomy

Coronary angiography defines:

• The number of diseased vessels

• Left main involvement

• Proximal LAD involvement

• Lesion location and complexity

• Coronary calcification

• The feasibility of complete revascularization

• The suitability of distal targets for CABG

• The feasibility of native-vessel PCI in patients with previous CABG

Left main stenosis of 50% or greater is considered an indication for revascularization irrespective of symptoms or measured ischaemic burden. The large myocardial territory supplied by the left main coronary artery accounts for the poor prognosis associated with medical therapy alone.

In left main PCI, intravascular ultrasound or optical coherence tomography should be considered standard for procedural optimization. This is especially relevant to distal bifurcation disease, where more complex stenting strategies may be needed.

Physiological assessment

Physiological assessment can refine the significance of intermediate stenoses and guide PCI. In stable ischaemic disease, revascularization should not be performed solely to improve survival when a single coronary lesion is not anatomically or functionally significant, including a non-left-main stenosis <70% or fractional flow reserve (FFR) >0.80.

FFR-guided PCI is associated with fewer stents and lower repeat-revascularization rates than angiography-guided PCI. Nevertheless, in three-vessel disease without left main involvement, FFR-guided PCI with contemporary drug-eluting stents did not achieve non-inferiority compared with CABG in the FAME 3 trial.

After apparently successful PCI, approximately one-quarter of patients may retain residual ischaemia defined by FFR <0.80 or instantaneous wave-free ratio (iFR) ≤0.89. Additional post-dilatation or stenting may improve the pressure result, although residual abnormal physiology can persist.

Imaging and procedural planning

Coronary computed tomography angiography combined with FFR-CT can be used for non-invasive virtual PCI planning. This approach may provide anatomical information about the vessel wall and plaque in addition to physiological information. In the reported studies, virtual PCI planning modified the intended procedure in a substantial minority of lesions and patients.

Comparative outcomes of PCI and CABG

General multivessel disease

Randomized evidence generally favours CABG over multivessel PCI in patients with two- or three-vessel CAD, particularly when disease is complex or diffuse. CABG is associated with:

• Fewer repeat revascularizations

• Fewer spontaneous myocardial infarctions in many comparisons

• More complete revascularization

• Less recurrent angina in selected populations

• A survival advantage that becomes more evident with greater coronary complexity, diabetes and longer follow-up

PCI offers:

• Lower procedural invasiveness

• Faster recovery

• Lower early stroke risk in several comparisons

• Lower initial hospital costs

• Suitability for patients at high surgical risk or with unsuitable surgical anatomy

The main disadvantages of PCI in multivessel disease are more frequent spontaneous MI and repeat revascularization. CABG carries greater early procedural burden and a higher risk of perioperative stroke, wound infection, acute kidney injury, heart failure and death in selected high-risk populations.

In the SYNTAX trial, patients with triple-vessel disease had higher 5-year rates of major adverse cardiac and cerebrovascular events after PCI than after CABG. Mortality, MI and repeat revascularization all contributed to the difference, while stroke rates were similar. Among patients with low SYNTAX scores, overall event rates were more comparable, although repeat revascularization remained more frequent after PCI.

In the BEST trial, PCI with second-generation everolimus-eluting stents produced more frequent composite events than CABG during long-term follow-up. Mortality was similar, but spontaneous MI and repeat revascularization were higher with PCI.

In FAME 3, FFR-guided PCI for three-vessel CAD resulted in more major adverse cardiac or cerebrovascular events than CABG at both 1 and 3 years. The difference was largely attributable to greater rates of MI and repeat revascularization after PCI; death and stroke did not differ significantly.

Effect of anatomical complexity

The comparative effectiveness of PCI and CABG changes according to SYNTAX score:

• With low-complexity disease, outcomes may be similar for death, stroke and MI, although PCI generally requires more repeat revascularization.

• With intermediate or high-complexity disease, CABG provides better protection from major cardiovascular events.

• With SYNTAX scores ≥33, CABG remains the standard strategy in appropriate candidates.

• With SYNTAX scores <33, PCI can remain an acceptable alternative after heart-team assessment and shared decision-making.

At 10 years in the SYNTAX extended follow-up, mortality was higher after PCI among patients with complex multivessel disease, whereas the difference was less evident in left main disease.

Diabetes mellitus

Diabetes is a major determinant of revascularization choice. Patients with diabetes experience worse outcomes after both procedures, but recurrent cardiovascular events are particularly frequent after PCI. CABG is associated with higher risks of wound infection, acute kidney injury, heart failure, stroke and death in the perioperative period, yet it generally provides better long-term protection from death, MI and repeat revascularization in diabetic multivessel disease.

In the FREEDOM trial, patients with type 2 diabetes and multivessel disease had a lower composite risk of death, MI or stroke after CABG than after PCI. The reduction was driven largely by lower mortality and MI with CABG, while stroke was more frequent after CABG. Repeat revascularization was also substantially more common after PCI.

Pooled individual-patient analyses likewise found lower all-cause mortality with CABG than PCI in patients with diabetes and multivessel disease. The benefit was present across SYNTAX categories in the FREEDOM analysis and was especially relevant in younger patients during extended follow-up.

CABG with a left internal mammary artery graft to the LAD is recommended in appropriate patients with diabetes, multivessel disease and LAD involvement. PCI remains appropriate for diabetic patients who require revascularization but are poor surgical candidates. In diabetic left main disease with low- or intermediate-complexity disease elsewhere, PCI may be considered as an alternative.

Left ventricular systolic dysfunction

CABG has a particularly important role when multivessel disease coexists with LV dysfunction:

• In suitable patients with multivessel CAD and LVEF <35%, CABG is recommended to improve survival.

• In selected patients with LVEF 35%–50%, CABG including a LIMA-to-LAD graft is reasonable to improve survival.

The source material does not provide comparable detailed treatment recommendations for PCI in severe LV dysfunction.

Left main coronary disease

Left main disease carries a poor prognosis with medical therapy because it jeopardizes a large proportion of the myocardium. CABG has traditionally been the standard treatment.

Randomized comparisons in selected patients suitable for either procedure show broadly similar long-term mortality between PCI and CABG, including at 5- and 10-year follow-up. Important differences remain:

• CABG produces fewer spontaneous MIs.

• CABG requires fewer repeat revascularizations.

• PCI has a lower early stroke risk.

• PCI is less invasive and may have lower early procedural morbidity.

• PCI outcomes are less favourable with complex or diffuse disease, particularly when left main disease is combined with extensive multivessel involvement.

In patients with low-complexity left main disease, particularly SYNTAX score ≤22, PCI is an acceptable alternative when equivalent completeness of revascularization can be achieved. CABG remains preferred overall for left main disease because of its lower rates of spontaneous MI and repeat revascularization. In high-complexity left main disease, CABG is recommended over PCI to improve survival.

True distal left main bifurcation lesions have worse outcomes than nonbifurcation lesions. Intracoronary imaging is important for optimization, and complex two-stent strategies may be required.

Single- and two-vessel disease

Randomized data show generally similar rates of death, stroke and MI after PCI and CABG in one- or two-vessel disease, with or without proximal LAD involvement. CABG is more invasive and involves longer hospitalization and recovery, while complex LAD disease may carry a greater risk of late repeat revascularization after PCI.

In stable disease with normal LV function:

• The survival benefit of revascularization for isolated proximal LAD disease is uncertain.

• Revascularization is not recommended solely to improve survival in one- or two-vessel disease not involving the proximal LAD.

Treatment and management

Chronic coronary disease

The initial framework is guideline-directed medical therapy, with revascularization added when symptoms or prognosis justify an invasive approach.

Revascularization is recommended for significant stenoses amenable to treatment when angina remains refractory despite medical therapy. It should not be performed in patients with angina but no anatomical or physiological basis for revascularization.

Routine revascularization solely to reduce perioperative cardiovascular events is not recommended in patients with non-left-main, noncomplex CAD undergoing noncardiac surgery.

When both CABG and PCI are technically feasible, the heart team should assess:

• Coronary anatomical complexity and SYNTAX score

• The possibility of complete revascularization

• Diabetes and other comorbidities

• LV systolic function

• Surgical and PCI procedural risks

• The anticipated need for repeat intervention

• Patient priorities regarding invasiveness, recovery, stroke, MI and durability

Acute coronary syndrome

STEMI

Rapid reperfusion of the infarct-related artery is the central treatment strategy.

In stable patients presenting 12–24 hours after symptom onset, PCI is reasonable. When PCI is not feasible or unsuccessful and a large myocardial territory is at risk, urgent or emergency CABG may provide reperfusion.

PCI remains appropriate irrespective of the time from symptom onset when STEMI is complicated by ongoing ischaemia, acute severe heart failure or life-threatening arrhythmia. Conversely, PCI should not be performed in asymptomatic stable patients with a totally occluded infarct artery more than 24 hours after symptom onset when there is no evidence of severe ischaemia.

After successful primary PCI, staged treatment of significant non-infarct artery stenoses is recommended in selected haemodynamically stable patients to reduce death or MI. Elective CABG can be considered for complex multivessel non-infarct disease. PCI of a low-complexity non-infarct lesion at the time of primary PCI may be considered in selected stable patients.

Routine non-infarct artery PCI during the primary procedure should not be performed in STEMI complicated by cardiogenic shock because of increased risks of death or renal failure. Routine aspiration thrombectomy before primary PCI is not useful.

NSTE-ACS

Patients at elevated risk for recurrent ischaemic events who are appropriate candidates for revascularization should undergo an invasive strategy with intent to revascularize.

• Immediate invasive management is indicated for refractory angina or haemodynamic or electrical instability.

• In initially stabilized high-risk patients, an invasive strategy within 24 hours is reasonable.

• In intermediate- or low-risk patients, invasive evaluation before discharge is reasonable.

• In cardiogenic shock, emergency revascularization is recommended.

• Emergency CABG is reasonable after failed PCI when ongoing ischaemia, haemodynamic compromise or threatened occlusion places substantial myocardium at risk and the patient is a surgical candidate.

• Routine same-setting multivessel PCI should not be performed in NSTE-ACS complicated by cardiogenic shock.

In very-high-risk NSTE-ACS requiring immediate revascularization, PCI is generally preferred unless mechanical complications require surgery.

Cardiogenic shock

Patients with ACS and cardiogenic shock should be transferred promptly to a tertiary centre with an experienced shock team. Immediate coronary angiography and PCI of the infarct-related artery are recommended when feasible. If anatomy is unsuitable for PCI, emergency CABG is recommended.

In multivessel disease with shock, culprit-only PCI during the index procedure is preferred, with possible staged treatment of other vessels. Compared with immediate multivessel PCI, this approach reduces the combined risk of death or renal replacement therapy at 30 days. The benefit is mainly driven by lower early mortality.

Radial access is preferred over femoral access for diagnostic angiography and PCI when feasible because of its greater safety. CABG is used in a minority of shock cases, mainly when PCI cannot address the coronary anatomy.

PCI-specific considerations

Drug-eluting stents

Drug-eluting stents are preferred to bare-metal stents during PCI because they reduce restenosis, MI and acute stent thrombosis.

Calcified lesions

In fibrotic or heavily calcified lesions, rotational atherectomy can improve procedural success. Orbital atherectomy, balloon atherectomy, laser angioplasty or intracoronary lithotripsy may also be considered.

Saphenous vein graft disease

When PCI is required in a diseased saphenous vein graft, an embolic protection device is reasonable when technically feasible. If PCI of the native coronary artery is possible, it is preferred to PCI of a severely diseased vein graft.

A chronically occluded saphenous vein graft should not undergo percutaneous revascularization. CTO PCI may improve symptoms in selected patients with refractory angina, but its effect on broader clinical outcomes remains uncertain.

After prior CABG and SVG failure, PCI of the native coronary artery is generally preferred to SVG PCI because of lower complication rates and better long-term patency. Redo CABG carries substantially greater operative risk than first-time surgery.

Haemodynamic support

In selected high-risk patients, elective insertion of an appropriate haemodynamic support device may be reasonable as an adjunct to complex PCI to prevent haemodynamic compromise.

CABG-specific and hybrid strategies

Arterial grafting, particularly use of the LIMA to the LAD, improves graft durability. Multiple arterial grafting may reduce graft occlusion and prolong the effectiveness of revascularization.

Hybrid revascularization, such as minimally invasive LIMA-to-LAD bypass combined with PCI of other vessels, may be considered in selected patients, including some at moderate-to-high surgical risk. However, it is uncommon, comparative evidence is limited and registry data have reported more bleeding, renal failure, MI and heart failure than with PCI alone.

Guideline-based recommendations

Chronic coronary disease and multivessel CAD

Acute coronary syndromes

Prognosis and follow-up

CABG generally offers greater durability in complex multivessel disease, diabetes and diffuse atherosclerosis, with fewer spontaneous MIs and repeat revascularizations than PCI. Its advantages in survival become more apparent with increasing anatomical complexity and longer follow-up. PCI has lower procedural invasiveness, faster recovery and lower early stroke risk in several settings, but the need for repeat intervention is consistently greater.

In left main disease, long-term mortality may be similar after PCI and CABG in appropriately selected patients, particularly when anatomical complexity is low. CABG nevertheless reduces spontaneous MI and repeat revascularization, while PCI reduces early stroke risk.

Following PCI, surveillance should account for the possibility of residual ischaemia, restenosis, stent-related events and recurrent disease in untreated vessels. Following CABG, late symptoms may result from saphenous vein graft failure or progression of native-vessel disease. Redo CABG has greater mortality and operative complexity than initial CABG, and PCI—preferably of the native coronary artery—is increasingly used when technically feasible.

The available material does not specify a universal schedule for clinical review, routine stress testing or repeat angiography. Follow-up should therefore be individualized according to symptoms, ventricular function, completeness of revascularization, procedural complications, recurrence of ischaemia and the long-term need for secondary prevention. In patients who have undergone CABG after ACS and do not require long-term oral anticoagulation, dual antiplatelet therapy should be resumed and continued for 12 months after the ACS.