Is preoperative myocardial viability testing warranted before deciding between percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG)?

Preoperative Myocardial Viability Testing Before PCI vs CABG Decision

Preoperative myocardial viability testing is NOT routinely warranted when choosing between PCI and CABG for chronic coronary syndrome, as current ESC guidelines do not require viability assessment for revascularization decisions and recent evidence shows viability does not predict differential survival benefit between these strategies.

Guideline-Based Decision Framework

The 2024 ESC guidelines for chronic coronary syndromes 1 provide a clear algorithmic approach to choosing between PCI and CABG based on anatomical complexity (SYNTAX score), disease extent, diabetes status, and left ventricular ejection fraction—notably absent is any requirement for viability testing.

Decision Algorithm Without Viability Testing:

For Left Main Disease:

• SYNTAX score 0-22: PCI is recommended as equivalent to CABG 1
• SYNTAX score 23-32: PCI should be considered 1
• SYNTAX score ≥33: CABG is preferred; PCI is not recommended 1

For Multivessel Disease with Diabetes:

• Three-vessel disease with SYNTAX 0-22: PCI may be considered 1
• Three-vessel disease with SYNTAX >22: PCI is not recommended 1

For Reduced LVEF (≤35%):

• One- or two-vessel disease: PCI should be considered as alternative to CABG when complete revascularization achievable 1
• Three-vessel disease: PCI should be considered based on Heart Team evaluation of anatomy, completeness of revascularization, diabetes, and comorbidities 1

For Proximal LAD Involvement:

• Single or double-vessel with proximal LAD: Both CABG and PCI are recommended 1
• Complex disease less amenable to PCI: CABG is recommended over PCI 1

Why Viability Testing Is Not Required

The 2021 EACVI expert consensus 2 identifies specific scenarios where viability testing may be considered, but these are narrow circumstances: patients presenting late with heart failure and occluded arteries, or those with chronic total occlusions before complicated PCI procedures. Importantly, this consensus explicitly states that viability-based algorithms "conflict with current ESC guidelines" and cannot be endorsed without newer scientific evidence on health outcomes 2.

Recent high-quality evidence strongly supports this guideline position:

• A 2025 study of 106 patients undergoing CABG found that CMR-assessed myocardial viability did not predict LVEF improvement or 3-year survival, concluding that nonviable myocardium should not be a contraindication to CABG in otherwise appropriate candidates 3

• A 2024 analysis concluded that presence of myocardial viability does not provide differential survival advantage for CABG over medical therapy, and that careful patient selection based on age, exercise tolerance, frailty, and renal function is more important than viability results 4

• A 2019 review noted that viability and ischemia detection have been unable to accurately predict treatment effects of CABG or PCI, questioning the revascularization mechanism for improving survival 5

The Contradictory Older Evidence

There is conflicting older evidence suggesting benefit from viability testing. A 2010 study of 476 patients with ischemic cardiomyopathy (LVEF ≤0.35) showed that PET-guided patient selection reduced in-hospital mortality (1.3% vs 10.1%, P=0.018) and improved long-term survival 6. However, this predates current guideline recommendations and more recent negative studies.

The critical distinction: This older evidence addressed whether to perform CABG versus medical therapy in severe LV dysfunction, not whether to choose PCI versus CABG. The current question is about revascularization strategy selection, where guidelines provide clear anatomical criteria.

Clinical Pitfalls to Avoid

1. Do not delay revascularization decisions waiting for viability studies when anatomical criteria clearly favor one approach
2. Do not use viability testing as a substitute for Heart Team evaluation of anatomical complexity and completeness of revascularization
3. Do not exclude patients from CABG based solely on nonviable myocardium when they meet other surgical criteria 3
4. Do not confuse the question of "revascularize vs medical therapy" with "PCI vs CABG"—viability may inform the former in severe LV dysfunction, but not the latter

When Viability Testing May Be Considered

The narrow exceptions where viability assessment might inform decisions 2:

• Chronic total occlusions before complicated PCI procedures
• Late presentation with heart failure and occluded vessels where late revascularization is questioned
• Mixed valvular and coronary disease (ischemic mitral regurgitation, low-flow low-gradient aortic stenosis)

Even in these scenarios, viability testing informs whether to revascularize at all, not which revascularization method to choose.

The Bottom Line

Base your PCI versus CABG decision on SYNTAX score, disease extent (left main, multivessel, proximal LAD involvement), diabetes status, LVEF, and completeness of achievable revascularization 1. Involve the Heart Team for complex cases. Reserve viability testing for the rare patient where you question whether any revascularization should be performed, not for choosing between revascularization strategies.