Cardiac troponin I in patients with acute upper and lower limb ischemia
M Koutouzis1, G Sfyroeras, K G Moulakakis
1Red Cross Hospital, Athens, Greece.
Insights
Elevated troponin I levels are common in acute lower limb ischemia but not upper limb ischemia, indicating a non-cardiac source. Focus on treating limb ischemia rather than troponin elevation alone.
Area of Science:
- Cardiology
- Vascular Surgery
Background:
- Troponin I is a biomarker for myocardial damage, but elevated levels can occur in non-cardiac conditions.
- Acute limb ischemia (ALI) presents diagnostic challenges regarding cardiac involvement.
Purpose of the Study:
- To investigate the presence, etiology, and clinical significance of elevated troponin I in patients with ALI.
- To differentiate troponin I elevation causes in upper versus lower limb ischemia.
Main Methods:
- 71 patients with ALI (60 lower, 11 upper limb) were studied.
- Serial measurements of troponin I, creatine kinase (CK), and CK-isoenzyme MB (CK-MB) were performed.
- Patients were analyzed based on limb affected and troponin I levels.
Main Results:
- 46% of patients had elevated troponin I (> 0.2 ng/ml), exclusively in the lower limb ischemia group (p=0.04).
- Lower limb ischemia patients showed significantly higher peak troponin I, CK, and CK-MB levels compared to upper limb ischemia patients (p<0.05).
- Peak troponin I levels correlated with peak CK and CK-MB values.
Conclusions:
- Elevated troponin I in ALI often originates from a non-cardiac source, particularly in lower limb ischemia.
- Physicians should prioritize immediate treatment for ALI, even with elevated troponin I, if acute cardiac involvement is unlikely.
- Focusing on the primary limb ischemia is crucial for patient management.
Background:
The aim of this study was to investigate the presence, etiology and clinical significance of elevated troponin I in patients with acute upper or lower limb ischemia. The high sensitivity and specificity of cardiac troponin for the diagnosis of myocardial cell damage suggested a significant role for troponin in the patients investigated for this condition. The initial enthusiasm for the diagnostic potential of troponin was limited by the discovery that elevated cardiac troponin levels are also observed in conditions other than acute myocardial infarction, even conditions without obvious cardiac involvement.
Patients And Methods:
71 consecutive patients participated in this study. 31 (44%) of them were men and mean age was 75.4 +/- 10.3 years (range 44-92 years). 60 (85%) patients had acute lower limb ischemia and the remaining (11; 15%) had acute upper limb ischemia. Serial creatine kinase (CK), isoenzyme MB (CK-MB) and troponin I measurements were performed in all patients.
Results:
33 (46%) patients had elevated peak troponin I (> 0.2 ng/ml) levels, all from the lower limb ischemia group (33/60 vs. 0/11 from the acute upper limb ischemia group; p = 0.04). Patients with lower limb ischemia had higher peak troponin I values than patients with upper limb ischemia (0.97 +/- 2.3 [range 0.01-12.1] ng/ml vs. 0.04 +/- 0.04 [0.01-0.14] ng/ml respectively; p = 0.003), higher peak CK values (2504 +/- 7409 [range 42-45 940] U/ml vs. 340 +/- 775 [range 34-2403] U/ml, p = 0.002, respectively, in the two groups) and peak CK-MB values (59.4 +/- 84.5 [range 12-480] U/ml vs. 21.2 +/- 9.1 [range 12-39] U/ml, respectively, in the two groups; p = 0.04). Peak cardiac troponin I levels were correlated with peak CK and CK-MB values.
Conclusions:
Patients with lower limb ischemia often have elevated troponin I without a primary cardiac source; this was not observed in patients presenting with acute upper limb ischemia. It is very important for these critically ill patients to focus on the main problem of acute limb ischemia and to attempt to treat the patient rather than the troponin elevation per se. Cardiac troponin elevation should not prevent physicians from providing immediate treatment for limb ischaemia to these patients, espescially when signs, symptoms and electrocardiographic findings preclude acute cardiac involvement.
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