Transmurality of scar influences the effect of a hybrid-intervention with autologous bone marrow cell injection and aortocoronary bypass surgery (MNC/CABG) in patients after myocardial infarction

Absolute Resting 13N-Ammonia PET Myocardial Blood Flow for Predicting Myocardial Viability and Recovery of Ventricular Function after Coronary Artery Bypass Grafting

OBJECTIVE

We aimed to evaluate the feasibility of resting myocardial blood flow (rMBF), quantified with dynamic 13 N-Ammonia (NH3) PET, for identifying myocardial viability and predicting improvement of left ventricular ejection fraction (LVEF) after coronary artery bypass grafting (CABG).

METHODS

Ninety-three patients with coronary artery disease (CAD) and chronic LVEF < 45%, scheduled for CABG, had dynamic 13NH3 PET and 18F-FDG PET imaging. The perfusion/metabolism polar maps were categorized in four patterns: normal (N), mismatch (M1), match (M2) and reverse mismatch (RM). The value of rMBF for identifying viable myocardium (M1, RM) and post CABG improvement of LVEF≥8% was analyzed by receiver operating characteristic (ROC) curves. Correlations of rMBF in segments to ΔLVEF post CABG were verified.

RESULTS

Mean rMBFs were significantly different (N=0.60±0.14; M1=0.44±0.07, M2=0.34±0.08, RM=0.53±0.09 ml/min/g, P<0.001). The optimal rMBF cutoff to identify viable myocardium was 0.42 ml/min/g (sensitivity=88.3%, specificity=82.0%) and 0.43 ml/min/g for predicting improvement of LVEF ≥8% (74.6%, 80.0%). The extent and rMBF of combined M1/RM demonstrated a moderate to high correlation to improved LVEF (r=0.78, 0.71, P<0.001).

CONCLUSION

Resting MBF, derived by dynamic 13NH3 PET, may be positioned as a supplement to 18F-FDG PET imaging for assessing the presence of viable myocardium and predicting potential improvement of LVEF after CABG.

Differential regenerative capacity of neonatal mouse hearts after cryoinjury

Neonatal mouse hearts fully regenerate after ventricular resection similar to adult zebrafish. We established cryoinjury models to determine if different types and varying degrees of severity in cardiac injuries trigger different responses in neonatal mouse hearts. In contrast to ventricular resection, neonatal mouse hearts fail to regenerate and show severe impairment of cardiac function post transmural cryoinjury. However, neonatal hearts fully recover after non-transmural cryoinjury. Interestingly, cardiomyocyte proliferation does not significantly increase in neonatal mouse hearts after cryoinjuries. Epicardial activation and new coronary vessel formation occur after cryoinjury. The profibrotic marker PAI-1 is highly expressed after transmural but not non-transmural cryoinjuries, which may contribute to the differential scarring. Our results suggest that regenerative medicine strategies for heart injuries should vary depending on the nature of the injury.

Transplantation of bone marrow stem cells during cardiac surgery

BACKGROUND

This systematic review with meta-analysis sought to determine the efficacy and safety of intramyocardial transplantation of bone marrow stem cells during coronary artery bypass graft surgery on postoperative cardiac functional parameters such as left ventricular ejection fraction and left ventricular end-diastolic volume.

METHODS

Medline/PubMed, Embase, Elsevier, Sciences online database, and Google Scholar literature search were searched. The effect sizes measured were risk ratio for categorical variables and weighted mean difference with 95% confidence interval for calculating differences between mean values of baseline and follow-up cardiac functional parameters. A value of p < 0.1 for Q test, or I(2 )> 50%, indicated significant heterogeneity among studies. The literature search retrieved 2900 studies from screened databases, of which 2866 (98.6%) were excluded and 34 (619 patients) were included for scoping review. The final analysis included 9 studies (335 patients).

RESULTS

Pooled effects estimates of left ventricular ejection fraction and left ventricular end-diastolic volume showed that bone marrow stem cell transplantation had a weighted mean difference of 4.06 (95% confidence interval: 0.41-7.72; p = 0.02) and 7.06 (95% confidence interval: -8.58-22.7; p = 0.3), respectively.

CONCLUSIONS

Intramyocardial transplantation of bone marrow stem cells improves cardiac functional parameters, significantly increasing left ventricular ejection fraction with a nonsignificant reduction in left ventricular end-diastolic volume. Also, this therapeutic method has no life-threatening complications and was therefore found to be an effective and safe method.