In vivo MRI and ex vivo histological assessment of the cardioprotection induced by ischemic preconditioning, postconditioning and remote conditioning in a closed-chest porcine model of reperfused acute myocardial infarction: importance of microvasculature

BACKGROUND: Cardioprotective value of ischemic post- (IPostC), remote (RIC) conditioning in acute myocardial infarction (AMI) is unclear in clinical trials. To evaluate cardioprotection, most translational animal studies and clinical trials utilize necrotic tissue referred to the area at risk (AAR) by magnetic resonance imaging (MRI). However, determination of AAR by MRI' may not be accurate, since MRI-indices of microvascular damage, i.e., myocardial edema and microvascular obstruction (MVO), may be affected by cardioprotection independently from myocardial necrosis. Therefore, we assessed the effect of IPostC, RIC conditioning and ischemic preconditioning (IPreC; positive control) on myocardial necrosis, edema and MVO in a clinically relevant, closed-chest pig model of AMI. METHODS AND RESULTS: Acute myocardial infarction was induced by a 90-min balloon occlusion of the left anterior descending coronary artery (LAD) in domestic juvenile female pigs. IPostC (6 x 30 s ischemia/reperfusion after 90-min occlusion) and RIC (4 x 5 min hind limb ischemia/reperfusion during 90-min LAD occlusion) did not reduce myocardial necrosis as assessed by late gadolinium enhancement 3 days after reperfusion and by ex vivo triphenyltetrazolium chloride staining 3 h after reperfusion, however, the positive control, IPreC (3 x 5 min ischemia/reperfusion before 90-min LAD occlusion) did. IPostC and RIC attenuated myocardial edema as measured by cardiac T2-weighted MRI 3 days after reperfusion, however, AAR measured by Evans blue staining was not different among groups, which confirms that myocardial edema is not a measure of AAR, IPostC and IPreC but not RIC decreased MVO. CONCLUSION: We conclude that IPostC and RIC interventions may protect the coronary microvasculature even without reducing myocardial necrosis

Long-term outcome of combined (percutaneous intramyocardial and intracoronary) application of autologous bone marrow mononuclear cells post myocardial infarction: the 5-year MYSTAR study

OBJECTIVE: The long-term (5-year) outcome of early (3-6 weeks after acute myocardial infarction [AMI], BM-MNC Early group) and late (3-4 months after AMI, BM-MNC Late group) combined (percutaneous intramyocardial and intracoronary) delivery of autologous bone marrow mononuclear cells (BM-MNCs) was evaluated in patients with ejection fractions (EF) between 30-45% post-AMI. METHODS: Major adverse cardiac and cerebrovascular events (MACCE) and hospitalization were recorded. Left (LV) and right (RV) ventricular function were measured by transthoracic echocardiography. Cardiac magnetic resonance imaging (MRI) and myocardial single photon emission computed tomography was performed in a subgroup of patients. Pre-cell therapy myocardial voltage values of treated areas (assessed by NOGA mapping) were correlated with clinical outcome. RESULTS: Five-year MACCE incidences (7.4%. vs 24.1%) and the composite of all adverse events (11.1% vs 27.6%) were not different between the Early and Late treatment groups. The significant LV-EF increase at 1-year follow-up was preserved at the 5-year control (from baseline to 5-year: 5.3%, 95% CI:0.5-10.1, and 5.7%, 95% CI:1.7-9.6, p<0.05 in the Early and Late groups, respectively), with no significant changes between 1- and 5-year follow-ups. Similarly, RVEF increased significantly from baseline to the 5-year follow-up (Early group: 5.4%, 95% CI:1.0-9.6; and Late group: 8.4%, 95% CI:4.5-12.3). Lower baseline levels of myocardial viability of the treated cardiac area (6.3+/-2.4 vs 8.2+/-3.0 mV, p<0.05) were associated with incidence of MACCE. CONCLUSIONS: Percutaneous combined delivery of autologous BM-MNCs is feasible and safe after 5 years, and may result in sustained improvement of cardiac function at 5 years in patients with low EF post-AMI (Clinicaltrials.gov NCT01395212)