Small RNA Dynamic Evaluation Of Myocardial Injury And Perioperative Myocardial Infarction, Heart Failure Early Warning Studies Predict Survival & Ventilation Effectiveness

Circulating miRs provide dynamic evaluation of myocardial injury and early warning for perioperative myocardial infarction Rationale:Perioperative myocardial infarction (PMI) is the most common cause of serious complications for cardiovascular surgery, especially in coronary artery bypass graft surgery (CABG). PMI makes postoperative morbidity and mortality increased, it will significantly increase the length of hospital stay and costs. With an aging population, more high-risk cardiovascular patients will undergo surgical procedures, PMI has become a major problem. Nonetheless, in the early postoperative period, PMI is still very difficult to diagnose, because patients under sedation have no obvious symptoms, ECG’s performance is transient and non-specific. Although elevated troponin I (cTnI) levels can now facilitate diagnosis to24-48hours after surgery, there remains a need for earlier diagnosis to further reduce mortality.MicroRNAs (miRNAs, miRs) are a class of19-25nucleotides long non-coding RNAs which inhibit mRNA translation or induce its degradation, by specifically binding to the mRNA3’-UTR. miRNAs play key roles in diverse biological and pathological processes, including the regulation of proliferation, apoptosis and cellular differentiation. Although the function of miRNA has not been fully elucidated, there is clearly some tissue-specific miRNAs. Recent studies have found circulating miRNAs in the blood, and have shown that changes in circulating miRNAs could reflect myocardial damage in acute myocardial infarction patients, however, whether circulating miRNA can be a marker of myocardial injury in cardiac surgery is still unclear.In our study, cardiac-specific miRs were screened out to find good ones correlated significantly with myocardial injury. Then we perform diagnostic tests for PMI, and further validating the relationship of miRs and protein markers. Multivariate logistic analysis was used to determine whether miRs could be independent risk factors for PMI.Objectives:The present study aims to determine release patterns of miRNAs in cardiac surgery and to analyze the diagnostic power of miRs to early predict perioperative myocardial infarction in patients undergoing coronary artery bypass graft (CABG) surgery.Methods and results:Part I:Dynamic evaluation of circulating miRs for myocardial injury after cardiac surgeryThirty on-pump CABG patients and thirty off-pump OPCAB patients were recruited in this study, and we selected miR-208a, miR-208b, miR-499, miR-133a and miR-133b as candidates. Serial plasma samples from patients were collected at7perioperative time points (preoperatively, and1,3,6,12,24, and48h after declamping), and were tested for cardiac troponin I (cTnI) and miRs levels. Taqman probe real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect miRs levels, the value was expressed as2-△Ct value or fold change.1.The fold change of miRsCompared with the preoperative control, in CABG group, miR-499at1,3,6,12and24h after declamping was23-fold,72-fold,25-fold,8-fold, and14-fold, respectively(P <0.01); miR-133a at1,3,6and12h was28-fold,23-fold,6-fold,7-fold, respectively (P <0.01); miR-133b at1,3,6and24h was8-fold,19-fold,3.6-fold,4-fold (P＜0.01); miR-208a increased only at3h (7-fold, P＜0.01); there’s no significant changes in miR-208b (P>0.05). In OPCAB group, miR-499at1,3, and6h was13-fold,11-fold,8-fold (P<0.01); miR-133a began to increase at1h (6-fold, P<0.01), peaked at3h (10-fold, P<0.01), and gradually return to normal at6h (P>0.05); miR-133b elevated at lh(6-fold, P<0.01), gradually returned to preoperative levels at3h(P>0.05); miR-208a and miR-208b increased, but not statistically significant (P>0.05). MiRs are higher in the CABG group than in the OPCAB group (P<0.05),but that miR-208b was no significant difference(P>0.05).2.The release profile of miRs and cardiac markersMiRs, cTnI and CK-MB were measured from the same plasma samples. Various markers showed a clear trend that they increased from baseline values to postoperative peak, and gradually returned to preoperative levels after48h. Overall, all three markers were consistent in their time course. In CABG group, miRs rose fast, reached their peak as early as1-3h after declamping, decreased significantly at6h, had a small peak at12-24h, and returned to baseline levels at48h. While cTnI peaked at6h, later than miRs. CK-MB reached a peak at3h, but declined slowly before12h. In OPCAB group, cTnI and CK-MB peaked at3h, also later than miRs.3. The correlation between miRs and traditional protein markers.In CABG group, circulating miRs significantly correlated with peak cTnI (miR-499, r=0.583, P=0.001; miR-133a, r=0.514, P=0.006; miR-133b, r=0.437, P=0.05;), but miR-208a or miR-208b was not related(miR-208a, r=0.258, P=0.194; miR-208b, r=0.031, P=0.878). MiRs were also found significant correlation with peak CK-MB levels(miR-499, r=0.579, P=0.002; miR-133a, r=0.527, P=0.005; miR133b, r=0.397, P=0.04), but miR-208a or miR-208b was not (miR-208a, r=0.127, P=0.528; miR-208b, r=-0.132, P=0.512). Thus, among the candidates of miRs, miR-499and miR-133a can best reflect myocardial injury. In OPCAB group, cTnI correlated with miR-133b, but not statistically significant (r=0.322, P=0.193), the remaining miRs were not correlated with cTnI or CK-MB.Part II:Circulating microRNA provide early warning for perioperative myocardial infarction in cardiac surgeryWe recruited120cases of on-pump CABG patients according to the inclusion and exclusion criteria, three patients were excluded. According to2012ESC/ACCF/AHA/WHF criteria for the diagnosis of type5myocardial infarction, among117cases of patients,28patients had defined perioperative myocardial infarction a week postoperatively, and89cases did not, the rate was23%. Plasma biomarkers were measured at6h postoperatively, including cTnI, CK-MB, h-FABP, miR-499, and miR-133a. We performed ROC curve analysis, pearson correlation analysis between markers and Logistic regression model to determine diagnostic ability of miRs and analyze perioperative risk factors of PMI.1. Analysis of the diagnostic test resultsROC curve analysis showed that miR-499at6h postoperatively is able to diagnose PMI. The sensitivity85.7%, specificity93.3%, area under the curve (AUC)(95%confidence interval) was0.939(0.880-0.975), the cut-off threshold of miR-499is△Ct<18.7477; whereas miR-133a has89.3%sensitivity and67.4%specificity, AUC was0.845(0.767-0.905), the cut-off threshold of miR-133a is△Ct<13.6417; for cTnI, the cut-off value>2.98ng/ml, the sensitivity was only64.3%, specificity86.5%, the area under the ROC curve was0.787(0.702-0.858); CK-MB cut-off value>11.3ng/ml, sensitivity78.6%, specificity73.0%, the area under the ROC curve was0.800(0.716-0.869); h-FABP cut-off value>14.57ng/ml, sensitivity75.0%, specificity75.3%, the area under the ROC curve was0.797(0.713-0.866). According cut-off value, we calculated the positive likelihood ratio+LR and its95%confidence interval, respectively.[miR-499:12.71(10.8-14.9) vs. miR-133a:2.74(2.3-3.3) vs.cTnI:4.77(3.6-6.4) vs.CK-MB:2.91(2.3-3.7) vs. h-FABP:3.03(2.4-3.9)].2.Comparison between the two groupsIn addition to preoperative ejection fraction, the remaining differences of baseline data do not exist between the two groups of patients with and without PMI. Cardiopulmonary bypass time, aortic clamping time, and postoperative mechanical ventilation time, were significantly higher in PMI group than those in the group without PMI; protein markers of myocardial necrosis were significantly higher in PMI group.(cTnl:4.82±0.74vs2.00±0.15ng/ml, CK-MB:22.10±3.46vs10.43±0.40ng/ml, h-FABP:.27.44±3.25vs11.09±0.88ng/ml)(P＜0.0001).△Ct value of the miRs in the PMI group was significantly lower than the group without PMI (miR-133a:12.25±0.32vs.14.18±0.1; miR-499:17.17±0.38vs.20.61±0.17), indicating that miRs level in PMI group was much higher than the group without PMI (P＜0.0001).3. Correlation analysis between markersThe circulating miR-499level at6h postoperatively was significantly associated with protein markers (cTnI, r=0.379, P=0.000; CK-MB, r=0.518, P=0.000; h-FABP, r=0.348, P=0.000). Circulating miR-133a levels and protein levels of each marker were also found significant correlation (cTnI, r=0.315, P=0.001; CK-MB, r=0.474, P=0.000; h-FABP, r=0.280, P=0.002).4. Multiple regression analysis of risk factors for PMILogistic regression using dichotomous was analyzed in117patients, to screen independent risk factors associated with PMI. In univariate analysis, preoperative left ventricular ejection fraction, cardiopulmonary bypass time, aortic clamping time, and postoperative mechanical ventilation time were associated with PMI; with variables of P <0.2, cTnI, CK-MB, h-FABP, miR-499and miR-133a included in the multivariate logistic regression analysis, we found that only miR-499is an independent risk factor for PMI.Conclusion:Our results demonstrate that plasma cardiac-specific miRs, especially miR-499and miR-133a, peak earlier than troponin I, and correlate positively with the traditional markers cTnI or CK-MB, and can reflect myocardial injury. MiRs’release in CABG group, is mainly due to the whole heart ischemia-reperfusion injury. The levels of miR-499at6h postoperatively provide an early indication of PMI, and show a high sensitivity and specificity; miR-499is an independent risk factor for perioperative myocardial infarction after coronary artery bypass graft surgery. Ventilatory efficiency parameters predict survival in patients with heart failureBackgroud:Comparisons of ventilation (VE) to carbon dioxide output (V CO2), which measure ventilatory efficiency, have been shown to be even more useful than peak O2uptake in assessing patients with chronic heart failure (CHF). Because both the ratios (V E/V CO2) and slopes (VE-vs-VC02) over differing durations can be used, we thought it worthwhile to compare multiple ways of assessing ventilatory efficieny and survival in a large cohort of patients with CHF.Methods:271CHF patients with NYHA class Ⅱ-Ⅳ underwent incremental cardiopulmonary exercise testing (CPET) and were followed for a median duration of479days. Four different linear regression V E-vs-V co2slopes were calculated from data of exercise onset, to180s; to anaerobic threshold (AT); to the ventilatory compensation point (VCP); and to end of exercise. Five VE/V CO2ratios were calculated at rest (60-180s), warmup330-360s, AT (60s), lowest value (90s), and peak exercise (30s). Death or heart transplant were considered end-points. Multiple statistical analyses were performed.Results:CHF patients had increased the lowest V E-vs-V CO2(41.0±9.2,141±30%predicted) and V E-vs-V CO2slope (37.6±12.1,126±41%predicted). The best predictor of survival was lower the lowest VE/VCO2(<41,<141%predicted); the lowest V E-vs-V CO2was better than other ratios and V E-vs-V CO2slope was better than other slopes. For6-months survival,%predicted values were superior; for long-term survival, absolute values were superior.Conclusions:A decreased lowest V E/V CO2, which is easily identified and simple to measure, is the superior index for assessing ventilatory efficiency and CHF survival.