Implications of Elevated Cardiac Troponin T in Ambulatory
Implications of Elevated Cardiac Troponin T in Ambulatory
Background: Elevated concentrations of cardiac troponin T (TnT) have been reported in patients hospitalized for decompensated heart failure (HF). We assessed whether elevated TnT levels are associated with the severity, etiology, and prognosis of HF in stable, ambulatory patients.
Methods: From 19981999, we prospectively collected data from 136 ambulatory patients with HF, New York Heart Association functional class II to IV, ejection fraction ≤35%, and no recent unstable angina, myocardial infarction, surgery, or coronary revascularization. Blood was obtained and analyzed by immunoassay for TnT, and patients were followed for 14.0 ± 4.3 months for death or HF hospitalization (primary end point) and other adverse cardiovascular outcomes.
Results: Thirty-three patients (24%) had an elevated TnT level (≥0.02 ng/mL). Mean TnT concentration did not differ by etiology of HF (0.002 ± 0.03 ng/mL vs 0.02 ± 0.04 ng/mL for ischemic and nonischemic etiologies, P = .25). Compared with patients with normal (undetectable) levels of TnT, patients with elevated TnT were significantly older, had worse functional class, and had poorer renal function. Elevated TnT concentrations were associated with increased relative risks (RR) of death or HF hospitalization (RR 2.7, 95% CI 1.74.3, P = .001) and death alone (RR 4.2, 95% CI 1.89.5, P = .001) during follow-up. Elevated TnT and New York Heart Association class were significant, independent predictors of death or HF hospitalization. Increased age and serum creatinine concentrations were significant independent predictors of death alone.
Conclusions: Nearly one fourth of ambulatory patients with chronic HF have ongoing myocardial necrosis as shown by abnormal TnT values, which are associated with increased mortality and morbidity.
In patients with acute coronary syndromes, the sequence of atherosclerotic plaque rupture, thrombosis, and myocardial necrosis causes release of cardiac markers into the bloodstream. Cardiac troponin T (TnT) and troponin I (TnI) are highly sensitive and specific markers of myocardial necrosis that can confirm the diagnosis of myocardial infarction (MI) and predict a 3-fold higher risk of death or MI immediately after an episode of unstable coronary artery disease. More recently, the FRagmin during Instability in Coronary Artery Disease (FRISC-II) trial investigators have shown significant associations between lower threshold TnT values (≥0.01 and ≥0.03 ng/mL) and long-term mortality.
Detectable concentrations of TnT (below the diagnostic threshold values for acute coronary syndromes) have been reported in patients without coronary ischemia, in the clinical settings of noncardiac surgery, stroke, cardiotoxic chemotherapy, renal insufficiency, and decompensated heart failure (HF). Among hospitalized patients with HF, in particular, elevated concentrations of TnT have been associated with lower ejection fractions, poorer functional status, and adverse outcomes such as death and repeat hospitalization for HF. In this study, we investigated whether a current TnT immunoassay could detect low levels of ongoing myocardial cell injury in patients with chronic, stable HF and whether TnT levels could identify patients at increased risk of death or hospitalization for HF.
Background: Elevated concentrations of cardiac troponin T (TnT) have been reported in patients hospitalized for decompensated heart failure (HF). We assessed whether elevated TnT levels are associated with the severity, etiology, and prognosis of HF in stable, ambulatory patients.
Methods: From 19981999, we prospectively collected data from 136 ambulatory patients with HF, New York Heart Association functional class II to IV, ejection fraction ≤35%, and no recent unstable angina, myocardial infarction, surgery, or coronary revascularization. Blood was obtained and analyzed by immunoassay for TnT, and patients were followed for 14.0 ± 4.3 months for death or HF hospitalization (primary end point) and other adverse cardiovascular outcomes.
Results: Thirty-three patients (24%) had an elevated TnT level (≥0.02 ng/mL). Mean TnT concentration did not differ by etiology of HF (0.002 ± 0.03 ng/mL vs 0.02 ± 0.04 ng/mL for ischemic and nonischemic etiologies, P = .25). Compared with patients with normal (undetectable) levels of TnT, patients with elevated TnT were significantly older, had worse functional class, and had poorer renal function. Elevated TnT concentrations were associated with increased relative risks (RR) of death or HF hospitalization (RR 2.7, 95% CI 1.74.3, P = .001) and death alone (RR 4.2, 95% CI 1.89.5, P = .001) during follow-up. Elevated TnT and New York Heart Association class were significant, independent predictors of death or HF hospitalization. Increased age and serum creatinine concentrations were significant independent predictors of death alone.
Conclusions: Nearly one fourth of ambulatory patients with chronic HF have ongoing myocardial necrosis as shown by abnormal TnT values, which are associated with increased mortality and morbidity.
In patients with acute coronary syndromes, the sequence of atherosclerotic plaque rupture, thrombosis, and myocardial necrosis causes release of cardiac markers into the bloodstream. Cardiac troponin T (TnT) and troponin I (TnI) are highly sensitive and specific markers of myocardial necrosis that can confirm the diagnosis of myocardial infarction (MI) and predict a 3-fold higher risk of death or MI immediately after an episode of unstable coronary artery disease. More recently, the FRagmin during Instability in Coronary Artery Disease (FRISC-II) trial investigators have shown significant associations between lower threshold TnT values (≥0.01 and ≥0.03 ng/mL) and long-term mortality.
Detectable concentrations of TnT (below the diagnostic threshold values for acute coronary syndromes) have been reported in patients without coronary ischemia, in the clinical settings of noncardiac surgery, stroke, cardiotoxic chemotherapy, renal insufficiency, and decompensated heart failure (HF). Among hospitalized patients with HF, in particular, elevated concentrations of TnT have been associated with lower ejection fractions, poorer functional status, and adverse outcomes such as death and repeat hospitalization for HF. In this study, we investigated whether a current TnT immunoassay could detect low levels of ongoing myocardial cell injury in patients with chronic, stable HF and whether TnT levels could identify patients at increased risk of death or hospitalization for HF.
Source...