Is cardiac magnetic resonance one of cardiology's magic crystal balls?

Rational transplant timing and dose of mesenchymal stromal cells in patients with acute myocardial infarction: a meta-analysis of randomized controlled trials

Background

Mesenchymal stromal cells (MSCs) are considered to have a modest benefit on left ventricular ejection fraction (LVEF) in patients with acute myocardial infarction (AMI). However, the optimal injection timing and dose needed to induce beneficial cardiac effects are unknown. The purpose of this meta-analysis was to identify an optimal MSC transplantation time and cell dose in the setting of AMI to achieve better clinical endpoints.

Methods

The authors conducted a systematic review of studies published up to June 2016 by searching PubMed, EMBASE, MEDLINE, and the Cochrane Library for relevant randomized controlled trials (RCTs).

Results

Eight prospective RCTs with 449 participants were included. The pooled results revealed that patients in the MSC group had no significant increase in LVEF from baseline compared with that in the control group (1.47% increase, 95% confidence interval (CI) −4.5 to 7.45; I² = 97%; P > 0.05). A subgroup analysis was conducted to explore the results according to differences in transplantation time and dose of MSCs injected. For transplantation timing, the LVEF of patients accepting a MSC infusion within 1 week was significantly increased by 3.22% (95% CI 1.31 to 5.14; I² = 0; P < 0.05), but this increase was insignificant in the group that accepted an MSC infusion after 1 week (−0.35% in LVEF, 95% CI −10.22 to 9.52; I² = 99%; P > 0.05). Furthermore, patients accepting a MSC dose of less than 10⁷ cells exhibited an LVEF improvement of 2.25% compared with the control (95% CI 0.56 to 3.93; I² = 9%; P < 0.05). Combining transplantation time and cell dose indicates that a significant improvement of LVEF of 3.32% was achieved in the group of patients injected with <10⁷ MSCs within 1 week (95% CI 1.14 to 5.50; I² = 0; P = 0.003).

Conclusions

Transplantation time and injected cell dose are key factors that determine the therapeutic effect of stem cell therapy. The injection of no more than 10⁷ MSCs within 1 week for AMI after percutaneous coronary intervention might improve left ventricular systolic function. Further studies on the mechanism and the effectiveness of MSCs for long-term therapy are warranted.

Prediction of long-term major events soon after a first ST-segment elevation myocardial infarction by cardiovascular magnetic resonance

BACKGROUND

Cardiovascular magnetic resonance (CMR) predicts combined clinical events in post-ST-segment elevation myocardial infarction (STEMI) patients. However, its contribution to predicting long-term major events (ME: cardiac death and non-fatal myocardial infarction [MI]) is unknown. We aimed to assess whether CMR predicts long-term MEs when performed soon after STEMI.

METHODS AND RESULTS

We prospectively recruited 546 STEMI patients between 2004 and 2012. The Left ventricular (LV) ejection fraction (LVEF,%), infarct size (IS), edema, hemorrhage, microvascular obstruction, and myocardial salvage were quantified by CMR at pre-discharge. During a mean follow-up of 840 days, 57 ME events (10%; 23 cardiac deaths, 34 non-fatal MIs) were documented. Patients with MEs has more depressed LVEFs (p<0.001), larger ISs (p<0.001), more extensive edema, hemorrhage, and microvascular obstruction, and lower myocardial salvage (p<0.05). CMR indexes were dichotomized according to the best cutoff values for predicting ME. In a comprehensive multivariate model, a LVEF<40% (HR: 2.3; 95% CI [12, 43]; p= 0.009) and an IS>30% of LV mass (HR: 2.4; 95% CI [13, 44]; p= 0.007) independently doubled the ME risk. The ME risk rates were 6%, 14%, and 30%, respectively (p<0.001) in patients with both the LVEF≥40% and an IS≤30% of LV mass (n=393), those with only one altered value (n=84), and in cases with both the LVEF<40% and an IS>30% of LV mass (n=69). Similar tendencies were observed regarding cardiac deaths (2%, 6%, 14%; p<0.001) and MI (4%, 8%, 16%; p < 0.001).

CONCLUSIONS

CMR performed soon after STEMI predicts long-term MEs. Combined analysis of CMR-derived LVEF and IS allows robust stratification of patient outcomes.