Value of early cardiac troponin I to predict long-term adverse events after coronary artery bypass graft surgery in patients presenting with acute coronary syndromes

Elevated troponin I is associated with a worse long-term prognosis in patients undergoing beating-heart coronary surgery

OBJECTIVES

The impacts of elevated troponin I levels after coronary artery bypass grafting (CABG) on long-term outcomes were investigated.

METHODS

A total of 996 patients who underwent elective isolated CABG for stable or unstable angina were enrolled. Patients were divided into higher and lower groups based on 80th percentile postoperative peak troponin I (ppTnI) levels. The relationship between ppTnI and long-term clinical outcomes was analysed.

RESULTS

The median ppTnI was 1.55 (2.74) ng/ml and was significantly higher in the conventional CABG subgroup than in the beating-heart CABG subgroup: 4.04 (4.71) vs 1.24 (1.99) ng/ml, P < 0.001. The 80th percentile of ppTnI was 3.3 ng/ml in the beating-heart CABG subgroup and 8.9 ng/ml in the conventional CABG subgroup. In the conventional CABG subgroup (n = 150), 10-year overall survival showed no significant difference between the higher (≥8.9 ng/ml) and lower (<8.9 ng/ml) ppTnI groups: 71% (10%) vs 76% (5%), P = 0.316. However, the beating-heart CABG subgroup (n = 846) showed significantly worse 10-year overall survival in the higher ppTnI group (≥3.3 ng/ml) than in the lower ppTnI group (<3.3 ng/ml): 64% (6%) vs 73% (3%), P = 0.010. In the beating-heart CABG subgroup, multivariable analysis showed that ppTnI exceeding the 80th percentile was a risk factor for overall death (hazard ratio: 1.505, 95% confidence interval: 1.019-2.225, P = 0.040).

CONCLUSIONS

Higher ppTnI over the 80th percentile was associated with worse long-term survival in beating-heart CABG, but not in conventional CABG.

N-Acetylcysteine for Cardiac Protection During Coronary Artery Reperfusion: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Coronary artery reperfusion is essential for the management of symptoms in the patients with myocardial ischemia. However, the benefit of reperfusion often comes at an expense of paradoxical injury, which contributes to the adverse events, and sometimes heart failure. Reperfusion is known to increase the production of reactive oxygen species (ROS). We address whether N-acetylcysteine (NAC) reduces the ROS and alleviates reperfusion injury by improving the clinical outcomes. A literature search for the randomized controlled trials (RCTs) was carried out in the five biomedical databases for testing the effects of NAC in patients undergoing coronary artery reperfusion by percutaneous coronary intervention, thrombolysis, or coronary artery bypass graft. Of 787 publications reviewed, 28 RCTs were identified, with a summary of 2,174 patients. A meta-analysis using the random effects model indicated that NAC administration during or prior to the reperfusion procedures resulted in a trend toward a reduction in the level of serum cardiac troponin (cTn) [95% CI, standardized mean difference (SMD) −0.80 (−1.75; 0.15), p = 0.088, n = 262 for control, 277 for NAC group], and in the incidence of postoperative atrial fibrillation [95% CI, relative risk (RR) 0.57 (0.30; 1.06), p = 0.071, n = 484 for control, 490 for NAC group]. The left ventricular ejection fraction or the measures of length of stay in intensive care unit (ICU) or in hospital displayed a positive trend that was not statistically significant. Among the nine trials that measured ROS, seven showed a correlation between the reduction of lipid peroxidation and improved clinical outcomes. These lines of evidence support the potential benefit of NAC as an adjuvant therapy for cardiac protection against reperfusion injury.

Improving the prediction of long-term readmission and mortality using a novel biomarker panel

OBJECTIVE

Several short-term readmission and mortality prediction models have been developed using clinical risk factors or biomarkers among patients undergoing coronary artery bypass graft (CABG) surgery. The use of biomarkers for long-term prediction of readmission and mortality is less well understood. Given the established association of cardiac biomarkers with short-term adverse outcomes, we hypothesized that 5-year prediction of readmission or mortality may be significantly improved using cardiac biomarkers.

MATERIALS AND METHODS

Plasma biomarkers from 1149 patients discharged alive after isolated CABG surgery from eight medical centers were measured in a cohort from the Northern New England Cardiovascular Disease Study Group between 2004 and 2007. We assessed the added predictive value of a biomarker panel with a clinical model against the clinical model alone and compared the model discrimination using the area under the receiver operating characteristic (AUROC) curves.

RESULTS

In our cohort, 461 (40%) patients were readmitted or died within 5 years. Long-term outcomes were predicted by applying the STS ASCERT clinical model with an AUROC of 0.69. The biomarker panel with the clinical model resulted in a significantly improved AUROC of 0.74 (p value <.0001). Across 5 years, the hazard ratio for patients in the second to fifth quintile predicted probabilities from the biomarker augmented STS ASCERT model ranged from 2.2 to 7.9 (p values <.001).

CONCLUSIONS

We report that a panel of biomarkers significantly improved prediction of long-term readmission or mortality risk following CABG surgery. Our findings suggest biomarkers help clinical care teams better assess the long-term risk of readmission or mortality.

Timing of coronary artery bypass surgery in patients with non-ST-segment elevation myocardial infarction and postoperative outcomes

INTRODUCTION

The aim of the study was to assess whether a cardiac troponin T (cTnT) level 1 ng/ml or below threshold is safe and to evaluate mid-term follow-up results in stable patients with non-ST-segment elevation after acute myocardial infarction.

MATERIAL AND METHODS

Among cTnT positive patients who presented to the emergency unit with chest pain and received coronary angiography, 100 patients who underwent isolated coronary artery bypass grafting (CABG) constituted the study group (group 1). The same number of patients (n = 100) who were cTnT negative and underwent an isolated CABG operation under elective conditions were selected as the control group (group 2).

RESULTS

Among preoperative criteria, group 1 had significantly higher smoking rates (74% vs. 41%, p = 0.0001), and significantly lower ejection fraction values (47.1 ±8.25, 54.69 ±8.73, p = 0.0001). There were no significant differences between the groups with respect to operative parameters. Postoperative follow-up periods were significantly longer in group 1 (23.25 ±14 vs. 17.55 ±7.95 months, p = 0.001). Average waiting time for cTnT to drop below the 1 ng/ml threshold value was 5.73 ±2.95 (1-12) days. Intra-aortic balloon pump use in Groups 1 and 2 was 3% and 1%, respectively. There were no hospital mortalities in either group. Mortality rates at mid term were 6% in both groups.

CONCLUSIONS

This study compared two groups positive and negative for preoperative cTnT. The findings show that it is safe to wait until cTnT levels decrease to the 1 ng/ml threshold value in cTnT positive patients having a stable course. This waiting period is not very long, which is significant with respect to potential complications.

The extent of coronary atherosclerosis is associated with increasing circulating levels of high sensitive cardiac troponin T

OBJECTIVE

This study explored the relationship between coronary atherosclerotic plaque burden and quantifiable circulating levels of troponin measured with a recently introduced high sensitive cardiac troponin T (hs-cTnT) assay.

METHODS AND RESULTS

Cardiac patients suspected of having coronary artery disease (CAD) but without acute coronary syndrome were studied. Cardiac troponin T levels were assessed using the fifth-generation hs-cTnT assay. All patients (n=615) underwent cardiac computed tomographic angiography (CCTA). On the basis of CCTA, patients were classified as having no CAD or mild (<50% lesion), moderate (50% to 70% lesion), severe (>70% lesion), or multivessel CAD (multiple >70% lesions). As a comparison, high-sensitivity C-reactive protein levels were measured. Progressively increasing hs-cTnT levels were found in patients with mild (median, 4.5 ng/L), moderate (median, 5.5 ng/L), severe (median, 5.7 ng/L), and multivessel (median, 8.6 ng/L) CAD compared with patients without CAD (median, 3.7 ng/L) (all P<0.01). For high-sensitivity C-reactive protein and N-terminal pro-B-type natriuretic peptide, no such relationship was observed. In patients without CAD, 11% showed hs-cTnT levels in the highest quartile, compared with 62% in the multivessel disease group (P<0.05). Multivariance analysis identified hs-cTnT as an independent risk factor for the presence of CAD.

CONCLUSIONS

In patients without acute coronary syndrome, even mild CAD is associated with quantifiable circulating levels of hs-cTnT.