Key result
PET flow-metabolism mismatch predicts an ~11-point post-revascularization gain in regional EF, unlike myolytic viable myocardium.
Why the study?
This study aimed to identify hibernating myocardium in the clinical setting and predict functional outcome in patients with coronary artery disease after coronary revascularization.
Does preoperative characterization of hibernating myocardium using PET and equilibrium-gated nuclear angiography predict early recovery of regional ejection fraction after coronary bypass surgery in patients with coronary artery disease?
Cohort (n=50)
Does preoperative characterization of hibernating myocardium using PET and equilibrium-gated nuclear angiography predict early recovery of regional ejection fraction after coronary bypass surgery in patients with coronary artery disease?
Noninvasive preoperative identification of a low regional ejection fraction combined with high FDG metabolism accurately distinguishes true hibernating myocardium that recovers early after coronary bypass surgery from viable but myolytic myocardium that does not recover early.
Answers are grounded in this paper and cite their sources.
Recovery in hibernating myocardium may improve regional function after revascularization; leaves open whether viability imaging should guide decisions in CAD.
BACKGROUND: The aims of this study were to identify hibernating myocardium (hypocontractile, hypoperfused viable myocardium that regains contractility after revascularization) in the clinical setting and to predict functional outcome in patients with coronary artery disease after coronary revascularization. METHODS AND RESULTS: Preoperative data related to the anterior free wall of the left ventricle were collected in 50 coronary bypass surgery candidates (positron emission tomography [PET], [13N]NH3 for flow, and [18F]FDG for metabolism [MET]; equilibrium-gated nuclear angiography [EGNA] for regional ejection fraction [REF]; and histological data from myocardial biopsies for percentage fibrosis and viable myocytes). Three months after surgery, the patients had follow-up PET and EGNA investigations. A principal-components analysis identified four patient clusters. Cluster 1 (n = 9) had normal viable myocardium. Cluster 2 (n = 18) had viable hypocontractile myocardium (REF, 39 +/- 12%) showing a PET mismatch pattern. Cluster 3 (n = 16) had viable hypocontractile myocardium associated with morphological myocyte injury showing a matched moderate decrease in flow (66 +/- 11%) and MET (70 +/- 11%). Cluster 4 (n = 7) had hypocontractile myocardium with mainly scar tissue (fibrosis, 74 +/- 12%). After surgery, only cluster 2, with hibernating myocardium, showed significant improvement in REF (from 39 +/- 12% to 50 +/- 13%, P < .05). Cluster 3, with sites of morphological myocyte injury, showed no recovery. The stepwise logistic regression showed a combination of low preoperative REF and high MET to be the best predictor of functional recovery (P < .008). CONCLUSIONS: Multivariate analysis identifies hibernating myocardium showing early postrevascularization recovery, as opposed to viable but myolytic myocardium with no early recovery. Postrevascularization recovery can be predicted (combination of low REF and high MET) by noninvasive techniques.
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Shivalkar et al. (1996) conducted a cohort in Coronary artery disease undergoing coronary bypass surgery (n=50). Coronary bypass surgery and preoperative PET/EGNA/histological myocardial characterization vs. Comparison across four principal-component clusters (normal viable, hibernating mismatch, viable with myocyte injury, and scar tissue) was evaluated on Early recovery of regional ejection fraction (REF) 3 months after coronary revascularization (p=< .05). Hibernating myocardium with PET flow-metabolism mismatch showed early postoperative recovery in regional ejection fraction (from 39% to 50%, P<.05), whereas myolytic viable myocardium did not.
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