Elevated troponins in the absence of angiographically visible coronary lesions are seen in upto 10-15% of those undergoing angiography for suspected coronary artery disease. It is important to identify the cause of myonecrosis in such patients to devise appropriate treatment plans. This retrospective study aims to elucidate the etiology and pathophysiology of elevated cardiac Troponin I (cTnI) in patients with normal coronary arteries on angiography.
We retrospectively identified 1551(8.6%) patients with normal coronary arteries from our catheterization database from Jan 2000-Jun 2004. Elevated Troponin levels were found in 217 (14%) patients. Surgical patients were excluded to form group I (n=144). Group II comprised of age and gender matched patients with myocardial infarction and coronary artery disease.
The etiology of elevated cTnI in group I is shown in table 1. The commonest cause of elevated cTnI was tachycardia followed by myocarditis. Significantly higher prevalence of atherosclerotic risk factors, with the exception of smoking, is seen in group II (Figure 1). Patients in group I have significantly higher left ventricular ejection fractions.
This is the largest series on retrospective study of patients with elevated troponin levels. Acute myocardial infarction is a clinical diagnosis. Elevated Troponin reflects myonecrosis as a result of direct myocardial injury and an imbalance between oxygen supply and demand. It does not equate to myocardial infarction. The laboratory is an aide to, not a replacement for,informed decision making.
Elevated troponin levels do not necessarily imply myocardial infarction. Elevated troponin levels should be interpreted in the underlying clinical context.
Nitin Mahajan, None.Table 1—
The Causes of Elevated Troponin in Group I.EventNumber of events Proportion of patients, % (N)Congestive Heart Failure (Ef<25)8 (12)AICD/Resuscitation/ Defibrillator3 (4)Myocarditis16 (23)Pericarditis5 (7)Cerebrovascular Accident1 (2)Sepsis3 (4)Collagen Vascular Disease1 (2)Severe Aortic Stenosis (Aortic Area < 0.1)6 (8)Left Anterior Descending artery bridging4 (5)Documented Coronary Spasm1 (2)Tachycardia (±hemodynamic compromise)24 (35)Hypertensive Emergency1 (1)Microvascular Ischemia2 (3)Gastro intestinal Bleeding6 (8)Myocardial Concussion1 (1)Hypercoagulable State2 (3)Pulmonary Embolism1 (2)Diabetic Ketoacidosis1 (2)Chronic Obstructive Pulmonary Disease exacerbation1 (1)Left Ventricular Hypertrophy1 (2)Septic Shock4 (5)Renal Failure1 (2)Unknown7 (10)