Carnitine and acylcarnitine profiles in dried blood spots of patients with acute myocardial infarction
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Earlier studies have suggested an important role of carnitine pathway in cardiovascular pathology. However, the redistribution of carnitine and acylcarnitine pools, as a result of altered carnitine metabolism, is not clearly known in patients with acute myocardial infarction (AMI). We compared the carnitine and acylcarnitine profiles of 65 AMI patients, including 26 ST-elevated myocardial infarction (STEMI) and 39 non-ST-elevated myocardial infarction (NSTEMI), 28 patients with chest pain and 154 normal controls. The levels of carnitine and acylcarnitines in the blood spots were determined using LC-MS/MS. Total and free carnitine levels were significantly higher in all the patient groups in the following order: STEMI > NSTEMI > chest pain. The levels of short- and medium-chain acylcarnitines were significantly higher in patient groups. Among the long-chain acylcarnitines, C14:2 and C16:1 levels were significantly increased in STEMI and NSTEMI. The ratio of free carnitine to short-chain or medium-chain acylcarnitines was significantly decreased in STEMI, NSTEMI and chest pain patients however a significant increase was observed in the ratio of carnitine to long-chain acylcarnitines in all the patient groups as compared to normal controls. In conclusion, alterations in carnitine and acylcarnitine levels in the blood of AMI patients indicate the possibility of impaired carnitine homeostasis in ischemic myocardium. The clinical implications of these findings for the risk screening or diagnosis and prognosis of AMI require additional follow-up studies on large number of patients. We also suggest that a dual-marker strategy using carnitine (longer plasma half-life) in combination with troponin (shorter plasma half-life) could be a more promising biomarker strategy in risk stratification of patients.