Serum Cardiac Troponin T, But Not Troponin I, Is Elevated in Idiopathic Inflammatory Myopathies: Figure 1

Objective.

To study the association of serum cardiac troponin T (cTnT) and cardiac troponin I (cTnI) with creatine kinase (CK) in patients with idiopathic inflammatory myopathies (IIM).

Methods.

We performed a retrospective study on patients with IIM followed by the rheumatology service of a county hospital from 2004 to 2008. Patients with myocardial ischemia and/or with renal failure were excluded. Clinical data including electromyogram, muscle biopsy, and CK, cTnT and cTnI were recorded. Patients who had simultaneous analysis of CK and cardiac troponin (cTnT or cTnI) levels were studied. CK levels were correlated with cTnT and cTnI by chi-square test and Spearman correlation.

Results.

We identified 49 patients with IIM (69 observations) who satisfied our inclusion criteria. The primary diagnosis was polymyositis in 23, dermatomyositis in 16, and myositis associated with connective tissue disease in 10 patients. There were 33/49 women with average age 45.8 years. Twenty-eight patients with IIM had simultaneous CK and cTnT values assayed. Of those patients, 18/23 with elevated CK also had elevated cTnT, and 5/5 patients with normal CK levels had normal cTnT levels (p = 0.005). In 41 patients with IIM who had simultaneous CK and cTnI levels assayed, only 1/29 with elevated CK had elevated cTnI, and 12/12 patients with normal CK had normal cTnI (p = 0.5). CK correlated strongly with the cTnT (r = 0.62, p = 0.001) but did not correlate with cTnI.

Conclusion.

Elevated cTnT, but not cTnI, was highly associated with CK in patients with IIM despite the absence of myocardial ischemia.

Continuous positive airway pressure versus bilevel noninvasive ventilation in acute cardiogenic pulmonary edema: a randomized multicenter trial

STUDY OBJECTIVE

Patients with acute cardiogenic pulmonary edema may develop respiratory failure. Noninvasive respiratory support should be initiated rapidly to avoid tracheal intubation. The aim of this study is to compare the efficacy of continuous positive airway pressure (CPAP) delivered by the Boussignac CPAP device and bilevel positive airway pressure (bilevel PAP) in patients with acute respiratory failure caused by acute cardiogenic pulmonary edema.

METHODS

This prospective multicenter randomized study was conducted in 3 emergency departments. Patients were assigned to Boussignac CPAP through a facemask or to bilevel PAP, in addition to standard therapy. The main outcome was a combined criterion (tracheal intubation, death, or acute myocardial infarction). Complications, durations of ventilation, and hospitalization were also assessed.

RESULTS

After 1 hour of ventilation and at the end of the ventilation period, clinical parameters of respiratory distress and blood gas exchange significantly improved in each treatment arm. No significant differences were observed between the Boussignac CPAP and bilevel PAP arms for the combined criterion (5% versus 12%, respectively; odds ratio [OR] 0.4; 95% confidence interval [CI] 0.0 to 1.9) and also for severe complications (9% versus 6%; OR 1.5; 95% CI 0.3 to 9.9), duration of ventilation (median for both groups 2 hours; interquartile range [IQR] 1.2 to 3.0 hours), duration of hospitalization (CPAP 8.5 [IQR 6 to 14] days; bilevel PAP 10 [IQR 7 to 16] days), or intrahospital mortality (8% versus 14%; OR 1.8 [IQR 0.4 to 8.8]). Similar results were obtained among hypercapnic patients (PaCO2 >45 mm Hg). Whatever the ventilation support used, the combined criterion and severe complications were more frequently observed among hypercapnic patients.

CONCLUSION

Both Boussignac CPAP and bilevel PAP appeared effective in rapidly improving respiratory distress even in hypercapnic patients, but they were not different in terms of patient outcome.

The prevalence of false-positive cardiac troponin I in ED patients with rhabdomyolysis

OBJECTIVE

Cardiac troponin I (cTnI) is considered the most specific marker of cardiac muscle injury. We encountered several patients with rhabdomyolysis and elevated cTnI, although they did not otherwise have evidence of cardiac injury. We determined the prevalence of false-positive cTnI in emergency department (ED) patients with rhabdomyolysis.

METHODS

We conducted a retrospective cohort study of ED patients admitted with a diagnosis of rhabdomyolysis. Patients were included in the study if they had a serum creatine kinase (CK) of 1000 U/L or greater and at least one serum cTnI determination. Patients with positive cTnI were considered true positives if they had either electrocardiography (EKG) or echocardiography abnormalities; false positives if both the EKG and the echocardiography were considered normal; or indeterminate if they did not have both an EKG and an echocardiogram. The primary outcome of the study was the prevalence of false-positive cTnI. Secondary outcomes included risk stratification by cocaine use, myoglobinuria, and renal failure and correlation of peak CK and troponin levels.

RESULTS

One hundred nine patients were included in the final analysis; 55 (50%) patients had a positive cTnI. Of the 55 patients with positive cTnI, 32 (58%) were true positives, 18 (33%) were false positives, and 5 (9%) were indeterminate. The prevalence of false-positive cTnI was 17% (18/109, 95% confidence interval 0.10-0.25). There was no association between false-positive cTnI and cocaine use, renal failure, or myoglobinuria. There was poor correlation between peak CK and peak cTnI levels (r = -.08, 95% confidence interval -0.34 to 0.19).

CONCLUSION

The prevalence of false-positive cTnI in ED patients with rhabdomyolysis is 17%.

Cardiac troponin I and creatine kinase isoenzyme MB in patients with intradialytic hypotension

BACKGROUND

Intradialytic hypotension (IH) has been long recognized as a common complication during hemodialysis (HD) therapy, but few studies have discussed IH-related myocardial injuries and the long-term prognosis of patients prone to IH (HP).

METHODS

We conducted a prospective study on 70 chronic HD patients who had no recent occurrences of acute coronary artery syndrome. The patients were divided into two groups: HP (n = 29) and IH resistant (n = 41). While they underwent HD therapy, we monitored and evaluated their baseline data and their patterns of cardiac troponin I (cTnI), creatine kinase, and creatine kinase isoenzyme MB.

RESULTS

The HP and IH-resistant patients had similar baseline cardiac marker levels that did not seem to be influenced by uneventful HD therapy. However, if during HD therapy the patients experienced an episode of symptomatic IH, they were found to have significant increases in the creatine kinase MB activity at the end of HD therapy and in the cTnI levels 44 h following HD. After 12 months, the HP patients with baseline cTnI levels > or =0.20 ng/ml were more likely to experience cardiovascular events or death (adjusted odds ratio 15.0, p = 0.012).

CONCLUSIONS

Our study showed that, after symptomatic IH episodes, the HP patients were more likely to suffer occult myocardial injuries. HP patients who have high cTnI levels should be closely monitored for cardiovascular diseases.

Measurement of cardiac troponins

The cardiac troponins form part of the regulatory mechanism for muscle contraction. Specific cardiac isoforms of cardiac troponin T and cardiac troponin I exist and commercially available immunoassay systems have been developed for their measurement. A large number of clinical and analytical studies have been performed and the measurement of cardiac troponins is now considered the 'gold standard' biochemical test for diagnosis of myocardial damage. There have been advances in understanding the development and structure of troponins and their degradation following myocardial cell necrosis. This has contributed to the understanding of the problems with current assays. Greater clinical use has also highlighted areas of analytical and clinical confusion. The assays are reviewed based on manufacturers' information, current published material as well as the authors' in-house experience.