Limited prognostic value of myocardial viability assessment in patients with coronary artery diseases and severe left ventricular dysfunction

Background: Myocardial viability assessment is typically performed in patients with coronary artery disease (CAD) and severe left ventricular (LV) dysfunction to identify those who might benefit from revascularization and assist in decision making process. However, the prognostic value of myocardial viability testing remains a debating issue.

Methods: Positron Emission Tomography using ¹⁸F-fluorodeoxyglucose (¹⁸FDG-PET) was performed in 81 patients with ischemic LV dysfunction [ejection fraction (EF) ≤35%] for myocardial viability assessment prior to coronary artery bypass surgery. Fifty-three of them received finally coronary artery bypass grafting and were divided into two groups according to the extent of myocardial scar: one group with scar burden ≥10% (n=30) and the other with scar burden <10% (n=23). The remaining patients were contraindicated for CABG and received optimal medical treatment (OMT, n=28). All patients were followed up and the primary endpoint was all-cause mortality and the secondary endpoint was a composite of all-cause mortality and major adverse cardiovascular and cerebrovascular events (MACCE).

Results: ¹⁸FDG-PET revealed a different profile of myocardial viability among three groups with respect to the extent of myocardial scar, the hibernating myocardium (both P<0.01), some echocardiographic parameters such as left ventricular diastolic dimension (LVDD) and EF were also significantly different (both P<0.05). Nevertheless, the baseline prevalence of comorbidities and functional classifications were comparable. The per-procedural parameters were not significantly different between two CABG groups. In a median follow-up time of 32 months, Kaplan Meier analysis uncovered no significant difference in terms of overall survival (P=0.74) and MACCE-free survival (P=0.66) among three groups.

Conclusions: Myocardial viability assessment using ¹⁸FDG-PET is of limited prognostic value in patients with CAD and severe LV dysfunction. In patients with substantial myocardial scar burden despite the existence of considerable hibernating myocardium, functional recovery following surgical revascularization is not necessarily translated to survival benefits.