Evidence of cardiac myolysis in severe nonischemic heart failure and the potential role of increased wall strain

Troponin elevation in heart failure prevalence, mechanisms, and clinical implications

Circulating biomarkers have become increasingly important in diagnosing and risk stratifying patients with heart failure (HF). While the natriuretic peptides have received much focus, there is increasing interest in the role of circulating cardiac troponin (cTn) in detecting myocardial injury (often subclinical) in those with HF. Accumulating evidence suggests that patients with chronic and acute HF may have measurable levels of circulating cTn, whose detection and magnitude may have prognostic implications. Furthermore, as new, more sensitive cTn assays are being developed, larger numbers of HF patients are found to have detectable cTn with a persistent relationship between magnitude and outcome. This knowledge improves our ability to understand the mechanism of worsening HF, improve risk stratification, and detect potential injury related to new therapeutics in HF. As investigators begin to understand the relationship of detectable cTn to HF outcomes, as well as temporal changes in its magnitude, and its relationship to other circulating biomarkers, more insight may be gained into the progressive nature of cardiac dysfunction and the transition from chronic compensated to acute decompensated HF. Ultimately, this information might allow physicians to guide therapy, choose appropriate therapeutics, and improve HF outcomes.

An update on cardiac troponins as circulating biomarkers in heart failure

Circulating troponins and natriuretic peptides are the only biomarkers specifically released from cardiac myocytes that can be determined with robust and sensitive analytical methods, even in healthy subjects. These intracellular proteins are released from reversibly or irreversibly damaged cardiac myocytes into the bloodstream by mechanisms that are not entirely clear. The recent introduction of a new generation of highly sensitive assays of cardiac troponin I or T has not only improved the early diagnosis of acute myocardial infarction but also suggested that there are several causes for troponin release other than acute coronary syndromes. Circulating troponins are elevated in patients with acute or chronic heart failure and are strongly associated with outcome, independently of natriuretic peptides, the benchmark biomarkers in heart failure. In the absence of further experimental evidences, the pathophysiologic basis for the elevation of circulating cardiac troponins in patients with stable chronic heart failure remains speculative.

Pseudo myocardial infarction - a condition in need to be redefined?

Since the introduction of cardiac plasma troponin measurements, a significant number of patients were seen with chest pain, elevated troponin levels but no significant coronary artery disease. Pulmonary embolism, aortic valve disease, myocarditis, sepsis, trauma, arrythmias, stress cardiomyopathy and dilated cardiomyopathy stand among possible causes for this syndrome. In some cases, myocardial strain could be the mechanism underlying this phenomenon, since it is known that the stimulation of stretch-responsive integrins may lead to the release of cardiac troponin I. In the present text, a case is made in favour of classifying this syndrome, of chest pain with increased values for plasma cardiac troponin, with or without ECG changes, in the absence of definite myocardial infarction or coronary artery disease, as pseudo myocardial infarction (PMI). This constitutes a new definition for a concept with decades, formerly centered on clinical and electrocardiographic changes mimicking infarct. The case is based on the search of scientific truth, on avoidance of unnecessary cardiac examinations, on avoidance of unnecessary drug therapy and on avoidance of unnecessary legal liability. PMI should be seen as a working diagnosis, since a more definitive diagnosis can be reached at all time. It should also be seen as a heterogeneous group of patients - several different diseases and conditions can lead to this phenomenon. But it must certainly not be seen as a benign condition, since published studies point in a totally different direction.

Prevalence and prognostic significance of incidental cardiac troponin T elevation in ambulatory patients with stable coronary artery disease: data from the Heart and Soul study

BACKGROUND

The significance of troponin elevation and clinical utility of troponin testing in ambulatory patients with coronary artery disease (CAD) have not been examined. We sought to investigate the prevalence and prognostic value of cardiac troponin T (cTnT) elevation in a population with stable CAD.

METHODS

We studied 987 patients with stable CAD enrolled in the Heart & Soul study who had plasma cTnT measurements before performing exercise treadmill testing.

RESULTS

Of the studied population, 58 patients or 6.2% had detectable cTnT levels, >or=0.01 ng/mL (0.01-0.72 ng/mL). During a mean follow-up period of 4.3 (0.1-6.5) years, 58.6% of participants with detectable cTnT had cardiovascular events compared with 22.5% of those without detectable cTnT (hazard ratio [HR] 3.8, 95% CI 2.6-5.4, P < .001). This association remained strong after adjustment for traditional risk factors and C-reactive protein (HR 2.0, 95% CI 1.3-3.1, P = .002). However, after further adjustment for N-terminal pro-B-type natriuretic peptide and echocardiographic parameters of left ventricular function, cTnT elevation was not an independent predictor of cardiovascular events (HR 1.3, 95% CI, 0.8-2.3, P = .28).

CONCLUSIONS

In ambulatory patients with stable CAD, the prevalence of cTnT elevation was 6.2%. Cardiac troponin T elevation detected using the conventional troponin assay was associated with increased risk of adverse cardiovascular outcomes, but its prognostic value was not incremental over N-terminal pro-B-type natriuretic peptide and echocardiographic evidence of cardiac abnormalities.

Serum cardiac troponin T in patients hospitalized with heart failure is associated with left ventricular hypertrophy and systolic dysfunction

BACKGROUND

Cardiac troponin T (cTnT) is a highly sensitive and specific marker of acute myocardial infarction. Serum cTnT is also slightly elevated in patients with severe heart failure and is associated with left ventricular hypertrophy (LVH) in patients treated with haemodialysis. In this study serum cTnT concentrations and echocardiographic findings were investigated in heart failure patients without acute coronary syndrome. cTnT was also compared with other cardiac markers and plasma levels of brain natriuretic peptide (BNP).

METHODS

Twenty-six patients hospitalized with heart failure were included in the study. Echocardiographic measurements and blood sampling were carried out 12-36 h after admission. Serum cTnT (3rd generation assay), cardiac troponin I (cTnI), creatine kinase MB (CKMB) and CK were measured. Plasma BNP was analysed using the Shionoria assay. LVH was defined as left ventricular mass index (LVMI) > 125 g/m for males and > 110 g/m for females. Left ventricular systolic function was estimated from the mitral annulus motion (AV-mean LV).

RESULTS

Median cTnT was 0.012 (< 0.010-0.032) microg/L. Sixty-two percent of the patients (16 of 26) had elevated serum cTnT >or= 0.010 micro/L. cTnT was positively correlated with CKMB (rho = 0.40, p = 0.04) and BNP (rho = 0.43, p = 0.03), but not with cTnI and CK. A negative correlation was found between cTnT and AV-mean LV (rho = -0.58, p = 0.007), and there was a positive correlation between cTnT and LVMI (rho = 0.44, p = 0.03). No other analyte was correlated to LVMI.

CONCLUSIONS

Serum cTnT but not cTnI was associated with left ventricular dysfunction and LVH in patients hospitalized with heart failure. This explains why cTnT tends to be slightly elevated in patients with heart failure without symptoms of acute myocardial ischaemia.

Frequency of elevated troponin I and diagnosis of acute myocardial infarction

This study evaluated the incidence and type of acute myocardial infarction (AMI) in a consecutive population with increased troponin I (TnI). AMI has recently been redefined and subclassified. Incidence, demographic data, angiographic findings, and hospital mortality of patients with various AMI subtypes or an increased TnI in the absence of AMI have not been previously reported in a prospective study. Over a 3-month period, all patients admitted from an emergency room or from in-patient services with >1 TnI level >0.04 ng/ml were evaluated and subclassified in AMI subgroups. In-hospital or recent coronary angiograms were reviewed. In-hospital mortality was noted. Of 2,944 patients with serial TnI measurements, 728 had an increased TnI and 701 (23.8%) were evaluated. Two hundred sixteen (30.8% with increased TnI and 42.7% with "rule-out MI" on admission) met criteria for AMI. One hundred forty-three (20.4%) had type 1, 64 (9.1%) had type 2, whereas 461 (65.8%) did not meet criteria for AMI. On multivariate analysis, use of angiography, peak TnI level, hyperlipidemia, and illicit drug use were independently associated with the diagnosis of AMI. TnI of 0.28 ng/ml had a 70% sensitivity and specificity for AMI diagnosis. In conclusion, a minority admitted with increased TnI have AMI by the universal definition. Type 1 is the most common AMI and is associated with higher TnI values and these patients are more likely to undergo angiography. Type 2 AMI is often associated with illicit drug use.

Effect of transvenous cardiac resynchronization therapy device implantation on cardiac troponin I release

BACKGROUND

Pacemaker and implantable cardioverter defibrillator (ICD) implantation increases cardiac troponin I (cTnI) levels which indicates myocardial injury. During implantation of a cardiac resynchronization therapy (CRT) device, balloon inflation for coronary sinus (CS) venogram, cannulation of CS side branch, and electrode advancement may interfere with CS drainage and, hence, may decrease the washout of toxic metabolites from the heart. Thus, CRT implantation may further increase cTnI levels. In this study, we investigated the effects of CRT implantation on cTnI release.

METHODS

We included 10 patients (mean age = 57 +/- 15 years) in whom a successful transvenous CRT system was implanted (CRT group). Twenty patients (mean age = 65 +/- 10 years) who underwent a transvenous pacemaker or ICD implantation were included as the control group. Blood samples for cTnI were drawn at baseline and at six, 12, 18, and 24 hours thereafter.

RESULTS

Baseline median cTnI levels were similar in CRT and control groups (0.03 ng/mL vs 0.02 ng/mL, respectively; P = 0.1). Postoperative cTnI levels during 24 hours were significantly higher in the CRT group (P < 0.05) by two-way repeated measures of analysis of variance. Post hoc analysis revealed that cTnI levels were higher at the 6th, 12th, 18th, and 24th hours compared to baseline levels (P < 0.001, P < 0.001, P < 0.01, and P < 0.01, respectively). There was a significant difference in the area under the curves (AUCs) of cTnI measurements (1.79 hr.ng/mL in the CRT group and 0.78 hr.ng/mL in the control group, P < 0.05).

CONCLUSION

Postoperative cTnI levels were higher after CRT implantation than simple pacemaker/ICD implantation. This may be due to CS manipulation during CRT implantation.

Cardiac troponin I as prognostic marker in heart failure patients discharged from emergency department

Despite evidence that cardiac troponin I (cTnI) identifies patients with advanced heart failure (HF) at risk of death, data on heterogeneous HF populations are scarce. Our purpose was to verify and analyze the prognostic role of cTnI in acute HF patients admitted to the emergency department. This was an observational longitudinal prospective study carried out in an urban hospital. We studied 99 patients discharged from the department between March and December 2002 with a HF diagnosis and samples of cTnI. Patients with acute coronary syndromes, myocarditis or renal failure were excluded. The main outcome was death from any cause. The detection level of the cTnI assay was 0.05 ng/ml. cTnI was detected in 45.5% of HF patients. These patients had a higher NYHA class (P<0.001) at initial presentation and longer hospitalization (P=0.004) than cTnI-negative patients. Nineteen deaths occurred during the study: 17 for HF and 2 for acute coronary syndrome. Finally, detectable cTnI was associated with increased mortality risk (RR 4.7; 95% CI 1.3-17.1; P=0.021) also after adjustment for other adverse prognosis factors (age, NYHA class and presence of relapses). Our HF cTnI-positive patients had a worse clinical presentation and longer hospitalization. cTnI is a significant independent predictor of death and of longer hospitalization. It could be used for the early identification of HF patients at an increased risk of death in the long term, and of longer hospitalization. Thus, cTnI can aid decision-making and clinical management in the emergency department.

Release of cardiac troponin I from viable cardiomyocytes is mediated by integrin stimulation

Elevated cardiac troponin-I (cTnI) levels have been demonstrated in serum of patients without acute coronary syndromes, potentially via a stretch-related process. We hypothesize that this cTnI release from viable cardiomyocytes is mediated by stimulation of stretch-responsive integrins. Cultured cardiomyocytes were treated with (1) Gly-Arg-Gly-Asp-Ser (GRGDS, n = 22) to stimulate integrins, (2) Ser-Asp-Gly-Arg-Gly (SDGRG, n = 8) that does not stimulate integrins, or (3) phosphate-buffered saline (control, n = 38). Cells and media were analyzed for intact cTnI, cTnI degradation products, and matrix metalloproteinase (MMP)-2. Cell viability was examined by assay of lactate dehydrogenase (LDH) activity and by nuclear staining with propidium iodide. GRGDS-induced integrin stimulation caused increased release of intact cTnI (9.6 +/- 3.0%) as compared to SDGRG-treated cardiomyocytes (4.5 +/- 0.8%, p < 0.001) and control (3.0 +/- 3.4%, p < 0.001). LDH release from GRGDS-treated cardiomyocytes (15.9 +/- 3.8%) equalled that from controls (15.2 +/- 2.3%, p = n.s.), indicating that the GRGDS-induced release of cTnI is not due to cell necrosis. This result was confirmed by nuclear staining with propidium iodide. Integrin stimulation increased the intracellular and extracellular MMP2 activity as compared to controls (both p < 0.05). However, despite the ability of active MMP2 to degrade cTnI in vitro, integrin stimulation in cardiomyocytes was not associated with cTnI degradation. The present study demonstrates that intact cTnI can be released from viable cardiomyocytes by stimulation of stretch-responsive integrins.

Detectable troponin levels predict poor prognosis in patients with left ventricular dysfunction undergoing internal defibrillator implantation

INTRODUCTION

Troponin levels have been demonstrated to predict mortality in patients with cardiomyopathy. Implantable cardiac defibrillator (ICD) devices have been demonstrated to improve survival. It is not clear if ICDs would mitigate the negative outcome predicted by elevated troponin levels.

METHODS

We collected baseline blood samples for troponin T (TnT) and creatinine kinase-MB fraction in consecutive patients immediately before successful pectoral transvenous ICD implant. Patients were followed for total mortality. For analysis, patients were grouped by TnT detectability (>or=0.01 ng/mL).

RESULTS

Fifty-two men, aged 68 +/- 10 years, were studied. Mean ejection fraction was 29 +/- 12% and 65% had ischemic cardiomyopathy. Follow-up duration was 17 +/- 8 months. None of the patients had abnormal creatinine kinase-MB fraction levels (1.7 +/- 1.1 ng/mL). There were 37 patients with no detectable TnT (Group I) and 15 with detectable TnT (Group II). There was no difference between the two groups in terms of age (68 vs 69, P = NS), ejection fraction (30 vs 29%, P = NS), or proportion of patients with ischemic cardiomyopathy (68 vs 60%, P = NS). During follow-up 16 (31%) patients died. Patients in group I had mortality of 16% (6/37) compared to 67% mortality (10/15, P < 0.001) in group II. On multivariate analysis, detectable TnT remained an independent predictor of mortality (HR 4.5, CI 1.4-14.25, P = 0.01).

CONCLUSION

In a cohort of patients with cardiomyopathy undergoing ICD implantation for standard clinical indications, presence of detectable TnT was associated with high mortality despite ICD implantation. TnT obtained before ICD implantation may be useful for risk stratification.

Relation between cardiac troponin I and mortality in acute decompensated heart failure

BACKGROUND

Troponin level elevations are common in patients with acute decompensated heart failure (ADHF), yet their prognostic value above and beyond traditional predictors of outcomes in heart failure is uncertain.

METHODS

In the EFFECT study, we determined the association between cardiac troponin I and all-cause mortality in 2025 patients hospitalized for heart failure in Ontario, Canada, between April 1, 1999, and March 31, 2001.

RESULTS

Cardiac troponin I levels >0.5 microg/L (median 1.7 microg/L, interquartile range 0.9-4.8 microg/L) occurred in 699 (34.5%) patients and was an independent predictor of mortality (adjusted hazard ratio 1.49, 95% CI 1.25-1.77, P < .001). Furthermore, we observed a dose-response relationship between cardiac troponin I and mortality that persisted after adjustment for potential confounding factors (adjusted hazard ratio 1.10 per 1 microg/L increase, 95% CI 1.05-1.15, P < .001). The association between cardiac troponin I and mortality was similar for patients with and without other features of acute ischemia on presentation (P > .05 for interaction).

CONCLUSIONS

In patients hospitalized for ADHF who had cardiac troponin levels measured during the course of clinical practice, cardiac troponin I was an independent predictor of all-cause mortality. Cardiac troponin testing is easily accessible, has predictive value above and beyond traditional clinical predictors of mortality, and may help guide medical decision making in patients with ADHF.

Diversity of the Elevation of Serum Cardiac Troponin I Levels in Patients During Their First Visit to the Emergency Room

BACKGROUND

Although measurement of serum creatine kinase levels, as well as myoglobin levels, has been used for screening patients with acute coronary syndrome (ACS), the specificity of both is low. Measurement of cardiac troponin levels is now extensively used for the diagnosis of ACS because of their superior cardiac specificity. However, troponin levels are reportedly elevated not only in patients with ACS but also in those with other diseases.

METHODS AND RESULTS

The clinical characteristics of 1,023 patients (mean age: 63.5+/-16.3 years; males: 665, females: 358) whose serum cardiac troponin I (cTnI) levels had been measured at the initial visit to the emergency room of Toyota Memorial Hospital between April 2004 and March 2005 were retrospectively analyzed. A positive elevation of cTnI was defined as cTnI > or =0.03 ng/ml. There were 432 patients (42.2%) with positive cTnI levels. The cTnI levels (8.48+/-2.64 ng/ml) in patients with acute myocardial infarction (AMI) were greater than those (0.25+/-0.07 ng/ml) in patients with unstable angina pectoris (AP), as well as those (0.04+/-0.01 ng/ml) in patients with stable AP. In terms of the diagnosis of AMI, the sensitivity was high enough (94.6%), but its specificity was relatively low (61.9%). Furthermore, the differentiation between AMI and unstable AP by the cTnI value alone was impossible. The cTnI levels were elevated in patients with a variety of diseases other than ACS, including heart failure, cardiomyopathies, myocarditis, renal failure, tachyarrhythmias, and pulmonary embolism.

CONCLUSIONS

Elevation of the cTnI level is frequently observed in patients in the emergency room with common diseases other than ACS.

Biomarker-based strategy for screening right ventricular dysfunction in patients with non-massive pulmonary embolism

OBJECTIVE

To evaluate the usefulness of B-type natriuretic peptide and troponin I measurements in predicting right ventricular dysfunction (RVD) in non-massive pulmonary embolism.

DESIGN

Prospective observational study.

SETTING

University-affiliated emergency unit, cardiology and pneumology departments.

PATIENTS

Sixty-seven patients admitted because of acute pulmonary embolism, without shock on admission, completed the study.

INTERVENTIONS

Blood samples and echocardiography were obtained on admission for subsequent and independent assessment of B-type natriuretic peptide (BNP) and troponin I levels as well as RVD.

MEASUREMENTS AND RESULTS

Echocardiographic RVD was diagnosed in 36 patients and was severe in 13 on admission. BNP and troponin I levels were higher in patients with RVD than in those with no RVD [62 (27-105) vs. 431 (289-556) pg/ml for BNP, p<0.001; 0.01 (0-0.09) vs. 0.16 (0.03-0.32) microg/l for troponin I, p=0.005]. The area under the receiving operating characteristic curve (AUC) for diagnosing RVD was 0.93 for BNP and 0.72 for troponin I. The troponin I level increased further when RVD was severe, compared with moderate, and the AUC was 0.91 for identifying severe RVD. Diagnoses of RVD and severe RVD were ruled out by BNP<or=100 pg/ml (30% of patients) and troponin I 0.10 microg/l (58% of patients), respectively. In-hospital death or circulatory failure occurred in nine patients; all had echographic RVD and level of BNP >100 pg/ml and troponin I >0.10 microg/l.

CONCLUSION

In hemodynamically stable pulmonary embolism, BNP/troponin I measurement is helpful on admission, especially for ruling out RVD, i.e. patients with in-hospital high-risk.

Troponin T, left ventricular mass, and function are excellent predictors of cardiovascular congestion in peritoneal dialysis

Patients on maintenance peritoneal dialysis (PD) are frequently complicated with volume overload. In this study, we sought to evaluate troponin T testing alone or in combination with echocardiographic measures in predicting cardiovascular congestion in PD patients. This was a prospective study of 222 chronic PD patients with echocardiography and measurement of serum troponin T carried out at baseline. Patients were followed for 3 years or until death. The end point was first episode of cardiovascular congestion. Troponin T emerged as an independent predictor of cardiovascular congestion (hazard ratio, 2.98, 95% confidence intervals (CI), 1.19-7.42) in a multivariable Cox regression model, including also left ventricular mass index (LVMi) and ejection fraction (EF). Patients with troponin T>median (0.06 microg/l) and EF<or=50% and patients with troponin T>median but EF>50% had a 3.10-fold (95% CI, 1.71-5.63) and 1.88-fold (95% CI, 1.05-3.38) adjusted risk of cardiovascular congestion, respectively, than those with troponin T<or=median and EF>50%. Patients with troponin T>median and LVMi>or=median (96.23 g/m2.7) had a 2.68-fold (95% CI, 1.39-5.19) adjusted risk of cardiovascular congestion than those with troponin T<or=median and LVMi <median. In conclusion, troponin T predicts cardiovascular congestion in chronic PD patients without acute myocardial ischemia and provides incremental prognostic value for cardiovascular congestion when used in combination with LVM and EF. This easily available parameter adds significant value to echocardiography in identifying PD patients at risk of cardiovascular congestion.

Elevated troponin level is not synonymous with myocardial infarction

BACKGROUND

Elevated troponin I in the absence of angiographically visible coronary lesions is seen in up to 10-15% of those undergoing angiography for suspected coronary artery disease. This study aims to elucidate the etiology of elevated cardiac troponin I in patients with normal coronary arteries on angiography.

METHODS

We identified 1551 (8.6%) patients with normal coronary arteries from our catheterization database of 17,950 patients from Jan 2000 to Jun 2004. Elevated troponin I levels were found in 217 (14%) of 1551 patients with normal coronary arteries. Of these 217 patients, 73 surgical patients were excluded, and the remaining 144 patients formed the study population. The study population was compared with age and gender matched patients with myocardial infarction and coronary artery disease (Group II).

RESULTS

The patients with elevated cardiac troponin I (cTnI) with normal coronary arteries had significantly lower prevalence of atherosclerotic risk factors and significantly higher left ventricular ejection fractions. The cTnI in patients with normal coronary arteries was elevated due to a number of causes including tachycardia, myocarditis, pericarditis, severe aortic stenosis, gastrointestinal bleeding, sepsis, left ventricular hypertrophy, severe congestive heart failure, cerebrovascular accident, electrical trauma, myocardial contusion, hypertensive emergency, myocardial bridging, pulmonary embolism, diabetic ketoacidosis, chronic obstructive pulmonary disease exacerbation and coronary spasm.

CONCLUSIONS

Cardiac troponin I could be elevated in a number of conditions, apart from acute myocardial infarction, and could reflect myonecrosis. Acute myocardial infarction is a clinical diagnosis as the laboratory is an aide to, not a replacement for, informed decision making.

Cardiac troponin I and ventricular arrhythmia in patients with chronic heart failure

BACKGROUND

Both detectable serum cardiac troponin I (cTnI) and ventricular dysrhythmias are common in patients with chronic heart failure (CHF) and are paralleled with the severity of the CHF. However, the relationship between serum cTnI and ventricular arrhythmia severity in patients with CHF remains unknown; the mechanism of the ventricular arrhythmia in the CHF patients also remains unclear.

MATERIALS AND METHODS

The study group included 218 patients with CHF who had cTnI assay drawn at the time of initial presentation. Patients with acute myocardial infarction or myocarditis were excluded from the analysis. The patients were divided into two groups: cTnI-positive with serum cTnI > 0.5 ng mL(-1) (n = 98) and cTnI-negative with serum cTnI < or = 0.5 ng mL(-1) (n = 120). The severity of ventricular dysrhythmias was assessed by 24-h Holter monitoring, using prospectively defined measures of ventricular arrhythmic burden.

RESULTS

Prevalence of risk factors for ventricular dysrhythmias was equal in both groups. All measures of ventricular ectopy were much higher in patients of the cTnI-positive groups. Mean hourly ventricular pairs (13.59 +/- 10.3 vs. 11.1 +/- 6.01, P = 0.027), mean hourly repetitive ventricular beats (26.01 +/- 13.67 vs. 22.01 +/- 13.56, P = 0.032), and the frequency of ventricular tachycardia episodes per 24 h (12.54 +/- 16.68 vs. 7.68 +/- 11.54, P = 0.012) were higher in patients with detectable cTnI levels. After inclusion of clinical variables and drug therapies in a multivariate analysis, the positive relationship between cTnI and the frequency of ventricular pairs (P = 0.03), repetitive ventricular beats (P = 0.037), and ventricular tachycardia (P = 0.03) remained independent. In multivariate logistic regression, the risk of developing ventricular tachycardia was higher in patients with detectable cTnI levels with an adjusted odds ratio (OR) of 2.31 (95% CI, 1.22-2.65, P = 0.003).

CONCLUSIONS

In patients with CHF, serum cTnI is closely related to increased occurrence of ventricular dysrhythmias and could identify a subgroup of patients with ventricular tachycardia. The minimal myocardial injury detected by serum cTnI might be the abnormal substrate for ventricular dysrhythmias.

Myocardial injury in critically ill patients: relation to increased cardiac troponin I and hospital mortality

OBJECTIVE

To examine the relationship between myocardial injury, assessed by cardiac troponin I (cTnI) levels, and outcome in selected critically ill patients without acute coronary syndromes or cardiac dysfunction.

DESIGN AND SETTING

Prospective, observational study in the emergency ICU of a university teaching hospital.

POPULATION

Over a 6-month period, 217 consecutive patients admitted to the ICU were studied.

METHODS AND RESULTS

cTnI assays were performed in all patients on admission to the ICU. The incidence of myocardial injury, defined by cTnI level > 0.1 ng/mL, was 32% (69 of 217 patients). Overall mortality was 27% (58 of 217 patients). Patients with myocardial injury had a mortality rate of 51%, compared with only 16% mortality for those without myocardial injury (p < 0.001). The hospital mortality rate was highest among older patients (71 +/- 14% vs 58.5 +/- 20%, p < 0.0001) and patients with higher simplified acute physiology scale (SAPS) II score (62 +/- 25% vs 37 +/- 17%, p < 0.0001). Mechanical ventilation was associated with higher in-hospital death (50% vs 31%, for patients who died in the hospital vs those who were discharged alive; p = 0.03). Elevated blood levels of cTnI were found to be independently associated with hospital mortality, regardless of the presence of SAPS II score and mechanical ventilation, in the logistic regression analysis (odds ratio, 2.09; 95% confidence interval, 1.06 to 4.11; p = 0.01).

CONCLUSIONS

This study demonstrates the high frequency of myocardial injury (32%) in critically ill patients without acute coronary syndromes or cardiac dysfunction on admission to ICU. Myocardial injury is an independent determinant of hospital mortality. Assessment of myocardial injury on admission to ICU would make it possible to identify patients at increased risk of death.

The Pilot Randomized Study of Nesiritide Versus Dobutamine in Heart Failure (PRESERVD-HF)

Acute heart failure syndromes (AHFS) are related to several diseases affecting not only the heart but also the kidneys and blood vessels. Emerging evidence indicates that myocardial injury may also play a role in the pathophysiology of AHFS, as suggested by increased levels of markers of injury, such as cardiac troponin (cTn). Although cTn is a known prognostic marker, the release of cTn during hospitalization has not been evaluated prospectively with serial measures. We prospectively evaluated patterns of cTn release by conducting serial measures of cTnI and cTnT in patients hospitalized for AHFS. This study enrolled 51 patients with AHFS who were admitted with worsening heart failure (HF) and a history of coronary artery disease (CAD) in whom an acute coronary event was not suspected. Levels of cTnI and cTnT were measured at 8, 32, 56, and 80 hours after study entry. At baseline, 73.9% of patients had detectable cTnI, and 43.5% had detectable cTnT levels. The median concentrations of cTnI and cTnT were unchanged from 0 to 32 hours, increased from 32 to 56 hours, then either plateaued (cTnT) or decreased to baseline (cTnI). Of the 26 patients who had no detectable cTn levels at baseline, 2 (7.7%) developed detectable cTnT and 5 (41.7%) developed detectable cTnI release during hospitalization. Detectable levels of cTn at baseline were related to short-term clinical events. In this study of patients with CAD in whom an acute coronary event was not suspected, most had detectable levels of cTn present at admission, and some patients developed cTn release during hospitalization. Because cTn release may be a marker for myocardial injury, this study raises the possibility that injury occurred in most patients admitted with AHFS. Therefore, the goal of therapy for AHFS should be not only to improve symptoms and hemodynamics but also to salvage myocardium. Accordingly, therapies for AHFS that are aimed at improving hemodynamics may affect long-term prognosis by either injuring or salvaging myocardium.

Minor myocardial damage detected by troponin T is a powerful predictor of long-term prognosis in patients with acute decompensated heart failure

BACKGROUND

The progression of chronic heart failure (CHF) is characterized by frequent exacerbation requiring hospitalization and high mortality. Clinical deterioration is triggered by many factors that could promote ongoing myocytes injury. We sought to determine whether a specific marker of cardiac injury, troponin T (cTnT), is associated with prognosis in acute decompensated heart failure (ADHF).

METHODS

One hundred and eighty-four consecutive patients with ADHF were enrolled in the absence of an acute coronary syndrome. A cTnT value> or =0.1 ng/ml in samples drawn at 6, 12 or 24 h after hospital admission was considered abnormal.

RESULTS

Increased levels of cTnT were found in 58 patients (31.5%, group 1). There were no significant differences between group 1 and patients with cTnT<0.1 ng/ml (group 2) in terms of demographic and clinical characteristics, although ischemic etiology was more prevalent in group 1 (51.7% vs. 31.7%, p=0.009). During follow-up, the mortality in groups 1 and 2 was 31% and 17.5% (p=0.038, OR=2.13, 95% CI: 1.03-4.69), respectively. The 3-year free-CHF readmission survival in group 1 and 2 was 25% and 53% (log rank test p=0.015). In a Cox proportional hazard model, poor tissue perfusion (HR=2.46, 95% CI=1.31-4.6), previous infarction (HR=1.99, 95% CI=1.02-3.9) and cTnT> or =0.1 ng/ml (HR=1.74, 95% CI=1.05-2.9) emerged as the independent predictors of long-term outcome.

CONCLUSIONS

One third of patients with decompensated CHF had elevated levels of cTnT. Troponin T was an independent long-term prognostic marker of morbidity and mortality and it suggests a role of biochemical risk stratification in this setting.

Prognostic value of cardiac troponin T in patients with both acute and chronic stable congestive heart failure: comparison with atrial natriuretic peptide, brain natriuretic peptide and plasma norepinephrine

BACKGROUND

The prognostic value of cardiac troponin T (cTn-T) in a mixture of patients with both acute and chronic congestive heart failure (CHF), simultaneously assessed and compared with neurohormonal factors, has not yet been thoroughly evaluated. Thus, we focused on the prognostic value of cTn-T in comparison with atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and plasma norepinephrine (PNE) in this population.

METHODS

Prognostic correlates of elevation of cTn-T, ANP, BNP, PNE were analyzed in 63 acute and chronic CHF patients followed up to record worsening CHF and cardiac death.

RESULTS

cTn-T (> or =0.03 microg/L) was found in 17.4% (11 of 63) of patients. cTn-T correlated with ANP, BNP, PNE. Acute CHF patients were more positive for cTn-T and BNP. In our cohort, neither cTn-T (> or =0.03 microg/L) nor PNE were associated with increased mortality and worsening HF in CHF patients. After adjustment, BNP was the only independent predictor of cardiac events (RR, 3.23; p=0.01).

CONCLUSIONS

BNP emerged as the only independent predictor of cardiac events in a mixture of patients with both acute and chronic CHF, suggesting that it is the analyte that best reflects long-term prognosis in a diverse population enrolled to mirror the "real world" situation.

Troponin I as a specific marker of myocardial injury: from theory to clinical practice in the diagnosis of acute coronary syndrome

OBJECTIVE

To assess the diagnostic accuracy of troponin I (TnI) elevation in patients with acute coronary syndrome (ACS) in the emergency department (ED).

METHODS

We retrospectively studied 166 patients with elevated TnI and electrocardiographic (ECG) change consistent with non-ST-segment elevation myocardial infarction. They were transferred from the ED to our coronary care unit (CCU) to undergo coronary angiography.

RESULTS

Significant coronary stenosis were identified in 101 (61%) of patients. The other 65 patients were found to have different cardiac diseases (n=52) and in 13 patients diagnoses were not even related to the cardiovascular system. Wall motion abnormalities were assessed by echocardiographic wall motion score index (WMSI). Positive predictive value (PPV) of TnI varied from 53 to 65% for higher progressive values of the biomarker. The following PPVs were then calculated: PPV(TnI+CK-MB)=64%; PPV(TnI+WMSI)=72%, PPV(TnI+CK-MB+WMSI)=74%.

CONCLUSIONS

Abnormal values of TnI were detected in a variety of diseases not related to ACS. Even if troponin release indicates myocardial injury, it is not always synonymous with infarction or ischemia. A misinterpretation of TnI elevation may give rise to a diagnostic dilemma and cause unnecessary morbidity. An integration of biomarkers (TnI and CK-MB), ECG and WMSI will help identify false-positive ACS patients and avoid inappropriate admissions to CCU.

Etiology of troponin I elevation in patients with congestive heart failure and low clinical suspicion of myocardial infarction

BACKGROUND

Increased troponin I (TnI) has been detected in congestive heart failure (CHF) patients. We demonstrate that occurrence of LVH, and systolic and diastolic blood pressure values (SBP and DBP, respectively) correlate with increasing levels of serum TnI in a selected CHF population.

METHODS

Our team reviewed the medical records of 40 consecutive patients admitted with CHF symptoms, low clinical suspicion of myocardial infarction (MI), and serum TnI measured upon admission. Twenty numerical and categorical parameters were screened. Patients were divided in to seven non-exclusive groups by increasing cutoff values of serum TnI (0, 0.1, 0.2, 0.3, 0.4, 0.6, and 1.5 ng/ml). In each group the average value of numerical parameters and the occurrence of categorical ones were calculated. The correlation between these values and the seven TnI cutoffs were analyzed.

RESULTS

Occurrence of electrocardiographic left ventricular hypertrophy (ECG-LVH), and average values of SBP and DBP significantly correlated with the TnI cutoffs by means of multiple regression analysis (P = 0.001, 0.02 and 0.007, respectively).

CONCLUSION

ECG-LVH and values of SBP and DBP significantly correlate with increasing cutoff levels of serum TnI in hospitalized patients with CHF and low clinical suspicion of MI.

Ongoing Myocardial Injury in Stable Severe Heart Failure

Background— The progression of chronic heart failure (CHF) is related to ongoing myocyte loss, which can be detected by cardiac troponin T (cTnT). We examined the prevalence and prognostic value of increased cTnT concentrations in serial blood specimens from patients with severe CHF.

Methods and Results— Clinical, echocardiographic, and 6-minute walk test data were collected prospectively at baseline and at 1 year in 115 outpatients (mean age, 61±11 years; 75% men; 62% coronary heart disease) with CHF and a left ventricular ejection fraction <40%. Blood samples were collected at baseline and at 3, 6, and 12 months of follow-up. cTnT concentrations ≥0.02 ng/mL were considered abnormal, and a Tn index (highest cTnT measurement/0.02 ng/mL) was calculated. In 62 patients (54%), cTnT was consistently <0.02 ng/mL (group 1); 28 (24%) had a single abnormal cTnT result (group 2); and 25 (22%) had ≥2 abnormal cTnT results (group 3). At 18 months, CHF hospitalization-free survival was 63%, 46%, and 17%, respectively ( P =0.0001). In a Cox proportional-hazards model, hospitalization for worsening CHF in the previous year (HR=2.1; 95% CI, 1.1 to 4.1), functional class III–IV (HR=2.3; 95% CI, 1.1 to 4.6), and number of abnormal cTnT samples (HR=1.6; 95% CI, 1.1 to 2.4) were independently associated with prognosis. A cTnT rise of 0.020 ng/mL in any sample was associated with an excess of 9% (95% CI, 1% to 18%) in the incidence of combined end point.

Conclusions— Abnormal cTnT concentrations were detected in >50% of outpatients with advanced CHF. This ongoing myocardial necrosis was a strong predictor of worsening CHF, suggesting a role of cTnT-based monitoring to identify high-risk patients.

Serial measure of cardiac troponin T levels for prediction of clinical events in decompensated heart failure

BACKGROUND

This study determined whether serial determinations of cardiac troponin T (cTnT) in decompensated heart failure (HF) are predictive of clinical events (death, need for readmission for new episode of HF decompensation, or both) during 1 year of follow-up.

METHODS AND RESULTS

Sixty-two patients with decompensated HF were enrolled in this cohort. The first measurement of cTnT (cTnT1) was from a blood sample drawn within 4 days of hospital admission; the second measurement (cTnT2) was on blood obtained 7 days later. Forty-nine clinical events (16 deaths, 10 readmissions, 23 combined readmission and deaths) occurred during the follow-up. The independent predictors of clinical events were: cTnT1>.020 ng/mL (P<.050), cTnT2>.020 ng/mL (P<.050), and serum sodium<135 mEq/L (P<.050). Based on levels of cTnT1 and cTnT2>.020 ng/mL (+) or </=0.020 ng/mL(-), patients were divided into 2 groups: group 1 (cTnT1-, cTnT2- or cTnT1+, cTnT2-), group 2 (cTnT1-, cTnT2+ or cTnT1+, cTnT2+). Group 2 patients had higher rates of death (45.0% versus 71.4%, P<.050), hospital readmission (35.0% versus 61.9%, P<.050), and clinical events (55.0% versus 90.5%, P<.010) than group 1 patients.

CONCLUSIONS

Persistently increased cTnT levels (>.020 ng/mL) are predictive of higher rates of death and hospital readmission for decompensated HF.

[Cardiac troponin I and T: specific biomarkers of cardiomyocyte]

PURPOSE

Cardiac troponin I and troponin T have replaced creatine kinase MB (CK-MB) for the diagnosis of cardiomyocyte necrosis. Cardiac specificity of these new markers leads to a change in our practice.

CURRENT KNOWLEDGE AND KEY POINTS

Following necrosis, intracellular proteins are released into blood. This easy concept overlaps a biological complexity since troponins are released as complexes leading to various cut-off values depending on the assay used, as least for cardiac troponin I. The increase in both specificity and analytical sensitivity of these markers reached to propose a new definition of myocardial infarction. The diagnosis of acute coronary syndrome is a clinical based diagnosis, the use of troponin contributing to their classification. Finally, pathological processes leading to cardiac injury may induce an increase in the cardiac troponin level.

FUTURE PROSPECTS AND PROJECTS

Troponin standardization is a challenge for the near future leading to better follow-up of patients and comparison between cohorts.

Emergency department triage of patients with acute chest pain: definition of cardiac troponin I decisional value to manage patients without electrocardiographic evidence of ischemia

The aim of this study was to define the use of a new cardiac troponin I (cTnI) assay for emergency patients with chest pain and no specific electrocardiographic changes consistent with the presence of ischemia. Patients (n=106) admitted in Emergency/Cardiology Departments for chest pain and suspicion of acute coronary syndrome (ACS) were randomized into two diagnosis groups (ACS or non-ACS) by two independent cardiologists. cTnI measurements were performed at admission, and 6 hours and 12 hours later with a new generation assay (Access AccuTnI, Beckman Coulter). Using an upper reference limit of 0.04 μg/l, 27 patients had a cTnI elevation not related to the final diagnosis of ischemia; the positive predictive value (PPV) was 67% with specificity 48%. The decisional value was re-defined and set at 0.16 μg/l, a concentration corresponding to the 99th percentile of the non-ACS patient group. Precision (coefficient of variation) was 8% at this level, PPV 97% and specificity 98%. This new decisional value is now used in our institution and could be included in standard care guidelines to improve the management of patients presenting chest pain in emergency departments.

Cardiac Troponin Levels in Heart Failure

Congestive heart failure (CHF) is a major cardiovascular disorder that is increasing in incidence, prevalence, and lethality. The prognostic significance of cardiac troponin levels among symptomatic and asymptomatic CHF has attracted recent interest. We sought to assess the significance of cardiac troponins in heart failure. These cardiac markers are associated with decreased left ventricular ejection fraction and poor prognosis in patients with CHF and are related to the severity of heart failure. The mechanism for the release of these markers seems to be from ventricular remodeling, ongoing myocyte degeneration, the presence of coronary artery disease, and reduced coronary reserve. In addition to B-type (brain) natriuretic peptide (BNP), cardiac troponin levels measured in patients admitted to the hospital could help risk-stratify patients and manage them effectively. BNP and cardiac troponins are easy to measure and can be repeated many times to follow patients, without interobserver variability. Theoretically, BNP is a marker of heart failure status and cardiac troponin is a marker of myocyte injury. The first therapeutic goal could be relief of circulatory congestion and lowering of BNP. The second goal could be attenuation of myocyte injury and lowering of cardiac troponins. Measuring and monitoring the levels of both could be highly effective means to reliably stratify the patients into low-, intermediate-, and high-risk groups for cardiac events and progression of heart failure. Furthermore, large-scale trials are necessary to establish them as noninvasive monitoring markers of heart failure and effectiveness of treatment.

Troponin levels as a guide to treatment of pulmonary embolism

Right ventricular dysfunction in hemodynamically stable patients with acute pulmonary embolism may be a harbinger of adverse outcomes and may potentially result in the early use of thrombolytic therapy. Risk stratification of these patients is an area of recent and intense investigation with a focus on the assessment of right ventricular function after the embolic event. Echocardiography has been used to identify right ventricular dysfunction but is potentially hampered by a number of limitations. With the onset of right ventricular dilation and possible ischemia in acute pulmonary embolism, elevated serum troponins may be an early and reliable marker of right ventricular dysfunction. In acute pulmonary embolism, both right ventricular dysfunction by echocardiogram and elevated troponin levels have been shown to predict an adverse outcome. Therefore, serum troponin levels should help stratify patients with submassive acute pulmonary embolism into a group in which aggressive medical or surgical intervention would be considered.

[Circulating troponin I assay: uses and misuses in medical practice]

Cardiac troponin I (cTnI) contributes to the modulation of the myocardial contractile function in the troponins complex. The assay of circulating cTnI is highly specific of the cardiac isoform and allows a quantification of the myocardial injury provided that both free and combined cTnI were recognized by the antibodies. The assay is a major contribution to the diagnosis of postoperative cardiac complications through its specificity because peripheral muscle trauma is a confounding factor during this period. Circulating cTnI mirrors the magnitude of an acute circulatory failure whatever the origin (cardiac, hemorrhagic or septic). A positive cTnI assay in an "asymptomatic" patient has to be confirmed and needs some investigations to discard an occult cardiac disease; cTnI has a limited role by itself in predicting mortality and hospital admissions. Circulating cTnI confirms the severity of an acute coronary syndrome and has a level-dependent prognostic value.

Cardiac troponin I is associated with impaired hemodynamics, progressive left ventricular dysfunction, and increased mortality rates in advanced heart failure

BACKGROUND

Cardiac troponin I (cTnI), a sensitive and specific marker of myocardial cell injury, is useful in diagnosing and assessing prognosis in acute coronary syndromes. Small studies report that cTnI is elevated in severe heart failure (HF) and may predict adverse outcomes.

METHODS AND RESULTS

The present study evaluated 238 patients with advanced HF referred for cardiac transplantation evaluation who had cTnI assay drawn at the time of initial presentation. Patients with acute myocardial infarction or myocarditis were excluded from analysis. cTnI was detectable (cTnI > or =0.04 ng/mL) in serum of 117 patients (49.1%). Patients with detectable cTnI levels had significantly higher B-type natriuretic peptide (BNP) levels (P<0.001) and more impaired hemodynamic profiles, including higher pulmonary wedge pressures (P=0.002) and lower cardiac indexes (P<0.0001). A significant correlation was found between detectable cTnI and progressive decline in ejection fraction over time. Furthermore, detectable cTnI was associated with increased mortality risk (RR, 2.05; 95% CI, 1.22 to 3.43). After adjustment for other factors associated with adverse prognosis including age, sex, ejection fraction, and coronary artery disease, cTnI remained a significant predictor of death. cTnI used in conjunction with BNP further improved prognostic value.

CONCLUSIONS

cTnI is associated with impaired hemodynamics, elevated BNP levels, and progressive left ventricular dysfunction in patients with HF. cTnI may be a novel, useful tool in identifying patients with HF who are at increased risk for progressive ventricular dysfunction and death.

Cardiac troponin I in aortic valve disease

BACKGROUND

Plasma cardiac troponin I levels may be higher than normal in conditions other than ischemic heart disease. We aimed at measuring troponin I levels in aortic valve patients, in which increased values for left ventricular dimensions and pressure are frequently found.

METHODS

Plasma levels of troponin I, creatine kinase (CK) and the MB fraction of the same enzyme were measured in a group of 25 clinically stable aortic valve patients. Echocardiographic study was performed in all patients; hemodynamic and coronary angiographic study was performed in 19 patients. Troponin I was also measured in a control population (n=305).

RESULTS

The mean value for troponin I was found to be higher in aortic valve patients (0.07+/-0.02 ng/ml), when compared to controls (0.01+/-0.02 ng/ml; P<0.05). Significant correlations were found between troponin I and both creatine kinase and its MB fraction. When the 25 patients were divided into two groups, with lower (up to 0.04 ng/ml; 12 patients) and higher (0.05 ng/ml or greater; 13 patients) values for troponin I, patients with higher values were found to have greater mean left ventricular wall thickness (9.9+/-0.3 mm, n=11, vs. 12.1+/-0.3 mm, n=13) and pulmonary artery systolic pressures (36.6+/-2.5 mmHg, n=7, vs. 53.7+/-3.4 mmHg, n=9).

CONCLUSIONS

We conclude that slightly raised plasma levels of cardiac troponin I are relatively common in aortic valve patients with no evidence of ischemia. Higher left ventricular wall thickness and pulmonary artery systolic pressure may be related to slightly raised troponin I plasma levels.

Cardiac troponin T and myocardial injury during routine cardiac catheterisation in children

BACKGROUND

This study aims to investigate whether intracardiac catheterization produces myocardial damage on pediatric heart.

METHODS

Five blood samples were collected (basal, immediate post procedure, at 4, 12 and 24 h after the procedure) for troponin T and creatine kinase MB (CKMB) from 48 consecutive patients (age: 5.34+/-6.03 years). The effect of age, duration of procedure, pulmonary hypertension, cyanosis, and medication taken for congestive heart failure on the levels of troponin T and CKMB were sought.

RESULTS

The increase in CKMB (basal CKMB: 3.93+/-3.70 ng/ml; peak CKMB: 8.68+/-10.89 ng/ml; P<0.0001) and troponin levels (basal troponin: 0.002+/-0.003 ng/ml; peak troponin: 0.11+/-0.23 ng/ml; P<0.0001) over time was significant in the study group. Additionally younger patients (</=1 year), patients with pulmonary hypertension (mean pulmonary artery pressure >25 mmHg), longer procedure time (>30 min), and patients taking anti-congestive heart failure therapy had significantly higher levels of CKMB and troponin (P>0.05).

CONCLUSION

All patients undergoing cardiac catheterization are under risk of myocardial injury, and younger patients with pulmonary hypertension and especially with compensated cardiac failure have increased risk of myocardial damage, and need to be handled carefully.

Diagnosis of myocardial injury by biochemical markers: problems and promises

The role of biochemical markers in the diagnosis of acute coronary syndromes has increased considerably in the past decade. The World Health Organization previously defined acute myocardial infarction as a combination of at least 2 of 3 components: symptoms consistent with acute myocardial infarction, electrocardiogram changes diagnostic of acute myocardial infarction, and an enzyme pattern with classic rise and fall. Measurement of creatine kinase and its MB fraction by various assays was the gold standard for the diagnosis. Troponins are more specific and sensitive markers for myocardial injury, and their increasing utilization has resulted in a broadening of the definition of acute myocardial infarction to incorporate high-risk acute coronary syndromes. Previously, traditional enzyme evaluation left patients with small amounts of cellular death undiagnosed; these patients were categorized as having unstable angina or, worse, noncardiac chest pain. Newer markers now identify these patients as a subgroup at high risk for cardiac death or cardiac events. Newer therapeutic interventions and a more invasive strategy have been shown to improve outcomes in this high-risk subgroup. Increased specificity has also reduced the number of patients who undergo extensive, expensive, and invasive evaluations for noncardiac syndromes due to false elevations of traditional markers. This article comprehensively reviews the evolution of biochemical markers for the diagnosis of acute myocardial infarction, addressing their promise for improving delivery of care and outcomes and their technical and diagnostic pitfalls.

Coronary vasospasm as a possible cause of elevated cardiac troponin I in patients with acute coronary syndrome and insignificant coronary artery disease

BACKGROUND

Abnormal levels of serum cardiac troponin I (cTnI) are occasionally found in patients presenting with acute coronary syndromes but having insignificant coronary artery disease. Before one concludes that an abnormal cTnI level is a false-positive result, the possibility of coronary vasospasm should be considered. This study investigated whether coronary vasospasm could be a reason for elevated cTnI in this patient population.

METHODS AND RESULTS

This investigation enrolled 93 patients who presented to the emergency department with suspected coronary ischemia and had insignificant coronary artery disease. cTnI was elevated in 23 patients (25%) and was normal in 70 patients (75%). Coronary vasospasm, documented by an ergonovine provocation test, was found in 38 patients (41%). Patients with elevated cTnI levels, compared with those with normal cTnI, were older (63 +/- 13 y vs 56 +/- 14 y, P =.032), had a higher incidence of males (78% vs 52%, P =.049) and positive ergonovine provocation tests (74% vs 30%, P <.0001), and tended to have a lower incidence of hypercholesterolemia (26% vs 48%, P =.088) and normal electrocardiograms (48% vs 70%, P =.078). Multivariate analysis showed that the variables independently associated with an elevated cTnI level included coronary vasospasm (odds ratio 2.41, 95% CI 1.48-3.18, P <.0001) and hypercholesterolemia (odds ratio 0.64, 95% CI 0.47-0.99, P =.049). Coronary vasospasm (positive ergonovine provocation test) could explain 74% of elevated cTnI levels in patients with insignificant coronary stenosis.

CONCLUSIONS

In patients with acute coronary syndrome with elevated cTnI and insignificant coronary artery disease, the possibility of coronary vasospasm as a cause of elevated cTnI should be considered.

Cardiac troponin I: a potential marker of exercise intolerance in patients with moderate heart failure

BACKGROUND

In severe heart failure, increased values of cardiac troponins have been detected during decompensation. In this study, we investigated whether an increase of cardiac troponin I can be observed after symptom-limited exercise and after an exercise training session in patients with moderate heart failure.

METHODS

Twenty-seven patients with moderate heart failure (New York Heart Association II-III, ejection fraction 31% +/- 8%) were compared with 9 patients with mild heart failure and 10 subjects without heart failure. They underwent a symptom-limited exercise test and a bicycle exercise training session at >80% of maximal heart rate over 20 to 30 minutes. Plasma cTnI levels were measured at baseline, after symptom-limited exercise (hourly for 5 hours), and after training (4 and 10 hours).

RESULTS

Patients with moderate heart failure showed an increase of cTnI from 37 +/- 49 pg/mL to 73 +/- 59 pg/mL (P <.001) after symptom-limited exercise. Four patients with moderate and 1 with mild heart failure and normal cTnI values at rest showed an increase of cTnI above 100 pg/mL after acute exercise but not after training. Subjects without heart failure had lower cTnI levels at rest and significantly lower values after symptom-limited exercise and training (P <.05 for each).

CONCLUSION

Patients with symptomatic heart failure reveal an increase of cTnI after symptom-limited exercise at levels that indicate minor myocardial damage. The prognostic impact of this finding should, therefore, be further investigated.