New insights in the pathophysiology of acute myocardial infarction detectable by a contemporary troponin assay

Objectives: ST-elevation and non-ST-elevation myocardial infarction (STEMI, NSTEMI) are considered two distinct pathophysiologic entities. We evaluated cardiac troponin I (cTnI) release in STEMI and NSTEMI using a “contemporary” (CV > 10 to 20% at the 99th percentile concentration) cTnI assay for patients undergoing early percutaneous coronary intervention (PCI). Design andmethods: 856 patients with suspected acute coronary syndrome consecutively admitted to the Emergency Department of the Maggiore Hospital of Novara (225 STEMI and 135 NSTEMI) were selected according to: 1) early (≤4 h from admission) and successful PCI; and 2) cTnI measurements at ED presentation and within 24 h. The influence of the MI type on cTnI concentrations at baseline and after PCI as well as the velocity of cTnI [cTnI V = absolute increase (after log conversion of cTnI measurements) / delay between the two measurements] was studied by multiple regression analysis, adjusting for patient parameters. Results: A statistically significant interaction between MI type and time from symptoms was reported on cTnI concentrations (p b 0.0001): STEMI and NSTEMI differed for cTnI releases at admission and after revascularization. Higher cTnI V in STEMI was detectable in patients admitted within 6 h from symptoms. Baseline cTnI concentrations were lower in patients with a history of coronary artery disease (CAD) and increased with aging (p b 0.0001). In the elderly (>75 years), the cTnI V was significantly increased. Conclusion: STEMI and NSTEMI patients have different patterns and dynamics of cTnI release influenced by the interaction with time from symptoms, by aging and history of CAD.