Long term risk stratification of patients with acute coronary syndromes: characteristics of troponin T testing and continuous ST segment monitoring

Usefulness of Serial 12-Lead Electrocardiograms in Predicting 30-Day Outcomes in Patients With Undifferentiated Chest Pain (the ASAP CATH Study)

An initial electrocardiogram (ECG) and serial troponin measurements are both independently and incrementally predictive of acute coronary syndrome in patients presenting with undifferentiated chest pain in the Emergency Department (ED). However, it is unclear if serial (ECGs) add significant to the contemporary diagnostic evaluation of this patient group. The ASAP CATH study was a single center, prospective study that enrolled patients presenting to an ED with undifferentiated chest pain. In addition to standard clinical evaluation, serial ECGs were performed at 90-minute intervals to evaluate whether serial changes suggestive of ischemia developed (Q waves, ST elevation or depression, or T-wave inversion). Total 365 subjects were enrolled from March 2014 to May 2015. Serial ECG changes developed in 6.6% (n = 24 of 365), the most common being the development of T-wave inversion (66.7%, n = 16 of 24). The sensitivity and positive predictive value of serial ECG changes were poor (<30%), with a less areas under the curve (0.55) compared with serial troponins alone (0.83). The addition of serial ECG changes to Thrombolysis In Myocardial Infarction risk scoring showed a decrease in the net reclassification index for major adverse cardiovascular events (-0.04, p <0.1) and was not significant for the prediction of major adverse cardiovascular events and/or acute coronary syndrome in 30 days (-0.003, p = 0.94). In conclusion, routine serial ECG evaluation for patients presenting with undifferentiated chest pain in the ED may not significantly improved diagnostic prognosis beyond current standard evaluation modalities.

National impact of the troponin diagnostic standard on the prevalence and prognosis of acute myocardial infarction in older persons

BACKGROUND

Consensus guidelines from the American College of Cardiology, the American Heart Association, and the European Society of Cardiology have made cardiac troponin central to the diagnosis of acute myocardial infarction (AMI). Although multiple studies have shown that the troponin diagnostic standard facilitates the identification of new AMI cases in the general population, and that elevations of troponin are associated with poor prognosis, questions remain regarding the impact of the troponin diagnostic standard on the prevalence and prognosis of AMI in older persons.

METHODS

Nationwide samples of eligible Medicare beneficiaries aged > or =65 years who were hospitalized (n = 71,120) with a primary discharge diagnosis of AMI between April 1998 and March 1999 (baseline cohort) or July 2000 and June 2001 (remeasurement cohort) were evaluated. The analysis was restricted to patients with clinically confirmed AMI who underwent testing for both CK-MB and troponin.

RESULTS

The majority of these patients (71.0%) were both CK-MB- and troponin-positive, but 17.8% were diagnosed with AMI based solely on positive troponin levels. Combining the CK-MB or both groups as a reference and troponin as a design variable to fit Cox proportional hazards models, troponin-only-positive patients had an unadjusted risk ratio (RR) of 1.14 (95% confidence interval [CI], 1.07-1.22) for the 30-day mortality and RR of 1.09 (95% CI, 1.03-1.15) for the 3-year mortality. However, after adjusting for patient demographics, clinical characteristics, physician specialties, and hospitals characteristics, troponin-only-positive patients had similar risk for early- and long-term mortality as the other 2 groups; the risk-adjusted RR for 30-day mortality was 0.96 (95% CI, 0.89-1.02) and for 3-year mortality was 0.95 (95% CI, 0.90-1.00).

CONCLUSION

The widespread application of cardiac troponins results in a substantial increase in AMI diagnoses in older patients. Contrary to the prevailing wisdom that troponin-only-positive AMIs are smaller "infarctlets" and likely to have better prognosis, older persons with troponin-only AMIs are at similar risk for early and long-term mortality compared with those with CK-MB-positive AMIs. Therefore, nationwide efforts should focus on the unique characteristics of this emerging patient population so as to improve quality of care provided to this high-risk cohort of patients with AMI.

Use and Misuse of Cardiac Troponins in Clinical Practice

Cardiac troponins are very sensitive and specific markers of myocardial injury. Elevated troponin levels in the setting of acute coronary syndrome are diagnostic of acute myocardial infarction and provide guidance to clinicians with regard to appropriate use of intensive medical and revascularization therapies. However, elevated troponin levels are commonly seen in several noncoronary ischemia presentations and create considerable confusion among clinicians in these settings. In this review article, we discuss the utility of troponins in various clinical settings and present a "common sense" approach to interpreting troponin elevation outside the setting of acute coronary syndrome.

Prognostic significance of ischemia-modified albumin in patients with acute coronary syndrome

To improve prognosis in acute coronary syndrome, new clinical applications in terms of diagnosis, risk stratification, and treatment strategies are still under investigation. Ischemia-modified albumin was one of the novel markers of myocardial ischemia. In our study, we aimed to determine the prognostic significance of the albumin cobalt binding capacity test in patients with acute coronary syndromes. We compared the ischemia-modified albumin levels of patients with acute coronary syndrome with those of patients with stable coronary artery disease and those of normal individuals and found them to be significantly higher in the first group (P<0.05). A cutoff value of ischemia-modified albumin of 477 U/ml was found by using receiver operating characteristic curve analysis. Mortality in groups of patients whose ischemia-modified albumin levels were above 477 U (50%) was found to be significantly higher than in those whose levels were below 477 U (8.3%) (P<0.05). The sensitivity and specificity of the cutoff value, 477 U/ml, for the 1-year mortality were found to be 70 and 82%, respectively. Using the Cox regression model the relation of albumin cobalt binding capacity test results with mortality was statistically significant (beta=1.013, confidence interval 95%, P=0.01) and independent of the existence of hypertension, diabetes, and advanced age. In conclusion, ischemia-modified albumin was found to be significantly related to 1-year mortality. Prognostic significance of ischemia-modified albumin should be evaluated in large populated and randomized study groups. Afterwards, ischemia-modified albumin could be used in risk stratification modality in patients with acute coronary syndrome.

Long-term prognostic value and therapeutic implications of continuous ST-segment monitoring in acute coronary syndrome

BACKGROUND

In patients with acute coronary syndromes (ACS), recurrent ischemia detected by continuous electrocardiographic monitoring portends a poor outcome. We sought to investigate (1) the additional long-term prognostic value of ST-segment monitoring beyond the validated Global Registry of Acute Coronary Events (GRACE) risk score in ACS and (2) whether ST-segment monitoring can identify patients who benefit from early revascularization.

METHODS

We determined the GRACE risk score (a validated predictor of inhospital mortality) in 681 non-ST-elevation ACS patients enrolled in the Integrilin and Enoxaparin Randomized Assessment of Acute Coronary Syndrome Treatment trial. Continuous ST-segment monitoring in the first 48 hours was analyzed by an automated algorithm and reviewed by a blinded cardiologist. Clinical outcomes were centrally adjudicated in a blinded fashion.

RESULTS

ST-segment shifts were present in 19.1% of 681 patients. After a median follow-up of 30 months, patients with ST-segment shifts had a higher risk of death (17.7% vs 5.8%, log-rank P < .001) and death or myocardial infarction (MI) (24.6% vs 11.1%, log-rank P < .001). In multivariable analysis adjusting for GRACE risk score, the presence of ST-segment shifts remained an independent predictor of death (adjusted hazard ratio = 2.37, 95% CI 1.38-4.09, P = .002) and death/MI (adjusted hazard ratio = 1.93, 95% CI 1.25-3.00, P = .003). Inhospital revascularization was independently associated with a lower risk of death/MI among patients with ST-segment shifts but not among those without (P for interaction = .02).

CONCLUSIONS

Continuous ST-segment monitoring provides incremental prognostic information beyond the validated GRACE risk score determined on presentation and identifies high-risk patients who benefit from early revascularization. This simple and valuable clinical tool may be useful in the routine management of ACS.

Sex and racial differences in outcomes and guideline-based management of troponin-only-positive acute myocardial infarction in older persons

Multiple studies have shown sex and racial differences in the management and outcomes of ischemic heart disease, but whether these sex and racial disparities persist in patients with troponin-only-positive acute myocardial infarction (AMI) is unknown. The authors evaluated a nationwide sample of eligible Medicare beneficiaries, 65 years or older, who were hospitalized (N=71,120) with a primary discharge diagnosis of AMI. Analysis was restricted to patients with troponin-only-positive AMI (n=5897) and was substratified into 4 groups: white men, white women, nonwhite men, and nonwhite women. The authors found that the traditional sex and racial disparities in the evidence-based medication prescriptions for ischemic heart diseases resolved in this cohort of older patients. Similarly, in settings of equal care, sex and race seem to have no impact on the outcomes for older patients with troponin-only-positive AM.

The association between hyperglycaemia and elevated troponin levels on mortality in acute coronary syndromes

Diabetes is associated with increased cardiovascular morbidity and mortality. We studied the relationship between hyperglycaemia, troponin I concentrations and one-year mortality in 498 subjects admitted to hospital with an acute coronary syndrome. The proportion of deaths was higher in those with hyperglycaemia (random glucose > 11.1 mmol/L) compared to those without (27% and 12%, respectively, Chi-squared test = 9.84, p=0.002). There was a difference in troponin I concentration on admission between those patients who were alive and dead (median and interquartile range 0.14 [0 to 3.90] and 2.98 [0.23 to 18.53] respectively, p<0.001) and the risk of death was elevated in those with a myocardial infarction compared to those without (relative risk = 1.85, 95% confidence intervals 1.55 to 2.21). Despite adherence to guidelines for the management of acute coronary syndromes, the presence of hyperglycaemia confers a significant long-term mortality disadvantage.

Risk stratification in acute coronary syndrome: focus on unstable angina/non-ST segment elevation myocardial infarction

Although there have been advances in the management of unstable angina/non-ST segment elevation myocardial infarction syndromes, the rate of cardiovascular mortality after discharge is still unacceptably high. With many therapeutic options available, the clinician is challenged to identify the safest and most effective treatment for long term survival of each individual patient