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Do cardiac troponins provide prognostic insight in hemodialysis patients?
Jonathan B Choy1, Paul W Armstrong, Raymond A Ulan
1Division of Cardiology, University of Alberta Hospital, Edmonton, Canada.
Insights
Cardiac troponin T (cTnT) elevations are common in chronic renal failure patients undergoing hemodialysis and may predict mortality. These findings suggest potential subclinical myocardial injury in this population.
Area of Science:
- Nephrology
- Cardiology
- Clinical Biochemistry
Background:
- Diagnosing myocardial necrosis in chronic renal failure (CRF) patients is challenging due to potential elevations in cardiac biomarkers like creatine kinase MB (CKMB) and cardiac troponin T (cTnT).
- Unexplained elevations in cardiac troponin I (cTnI) have been observed in CRF patients on hemodialysis, but their incidence and prognostic significance are unknown.
Purpose of the Study:
- To determine the incidence of asymptomatic elevations in cardiac troponin T (cTnT) and cardiac troponin I (cTnI) in patients undergoing hemodialysis for chronic renal failure.
- To assess the prognostic significance of these elevated cardiac troponin levels in the hemodialysis population.
Main Methods:
- A prospective cohort study was conducted at a university tertiary care teaching hospital.
- 113 patients over 21 years old undergoing hemodialysis were enrolled.
- Outcomes assessed included all-cause and cardiovascular mortality, hospitalizations for acute coronary syndromes or heart failure, arrhythmias, and unscheduled hemodialysis over 30 days and six months.
Main Results:
- The incidence of abnormal results was 42% for cTnT, 15% for cTnI, and 4% for CKMB.
- Independent predictors of six-month mortality included age > 63 years and positive cTnT.
- Diabetic patients showed a higher likelihood of positive cTnI and cTnT results compared to non-diabetics.
Conclusions:
- Cardiac troponin T (cTnT) is frequently elevated in chronic renal failure patients on hemodialysis, even without acute coronary syndromes, and may serve as an independent prognostic marker.
- Elevations in cardiac troponin I (cTnI) are less common than cTnT but more frequent than CKMB.
- The underlying cause of these troponin elevations remains unclear, potentially indicating subclinical myocardial injury, inflammation, or fluid overload.
Background:
The diagnosis of myocardial necrosis in patients with chronic renal failure is often difficult because biochemical markers of cardiac damage such as creatine kinase MB (CKMB) and cardiac troponin T (cTnT) may be spuriously elevated. Recent small studies also report unexplained elevations in cardiac troponin I (cTnI) in chronic renal failure patients undergoing hemodialysis. The relative incidence of elevated cardiac troponins in this population and their relationship to clinical events remain unknown.
Objective:
To determine the incidence and prognostic significance of asymptomatic elevations of cTnT and cTnI in patients undergoing hemodialysis for chronic renal failure.
Design:
Prospective cohort study.
Setting:
University tertiary care teaching hospital.
Patients:
One hundred thirteen patients over 21 years of age undergoing onsite hemodialysis were enrolled between December 1997 and February 1998.
Measurements:
All-cause and cardiovascular mortality, hospitalization for acute myocardial infarction, unstable angina or congestive heart failure, new onset sustained arrhythmia or need for unscheduled emergency hemodialysis due to volume overload at 30 days and six months.
Results:
The incidence of abnormal results for cTnT, cTnI and CKMB were 42%, 15% and 4%, respectively. Independent predictors of mortality at six months were median age greater than 63 years (odds ratio 14.3, 95% CI 1.5 to 130.3, P=0.019) and positive cTnT (odds ratio 13.6, 95% CI 2.5 to 73.2, P=0.002). Diabetics were more likely to have positive cTnI and cTnT results than nondiabetics (P<0.001 and P=0.023, respectively).
Conclusions:
cTnT is commonly elevated in patients with chronic renal failure even in the absence of acute coronary syndromes. cTnT may be an important independent prognostic marker in patients on hemodialysis for chronic renal failure. While less common, elevations of cTnI are more frequent than CKMB elevations. The basis of these cardiac troponin elevations is unclear. These findings may represent, in part, a subclinical myocardial injury, an inflammatory response to chronic renal failure or a chronically volume overloaded state.
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