Introduction: The differential diagnosis of chest pain associated with elevation of myocardial necrosis biomarkers encompasses, among others, acute myocardial infarction (AMI), acute myocarditis (AM) and stress cardiomyopathy (SCM), which may be distinguished by some clinical particularities, not always obvious.
Objective: To identify the main clinical differences between AMI, AM and SCM.
Methods and results: Retrospective observational cohort study including patients admitted in a Coronary Unit for the period of 4 years, until June 2013, with the diagnosis of AMI (n=1836, 47% without ST elevation and 53% with ST elevation), AM (n=66) and SCM (n=39). The minimum follow-up realized was 6 months. In the next sentences we describe the results with statistic significance (p<0.05). Comparatively with AMI and SCM, AM was more frequent in male (92.4%) and younger patients (mean age 37 years), with lower prevalence of cardiovascular risk factors, which presented without heart failure (97.0%), absence of T wave inversion in ECG (91.7%) and were less medicated with beta-blockers (33.3%), ACE-I (39.4%) and diuretics (0%). These patients had better prognosis at short and long term (none died). Analytically, they expressed higher values of C-reactive protein (mean 49.2 mg/L). On the other hand, SCM was more frequent in women (74.4%) and was associated with higher heart rate (mean 93/min) and heart failure at admission (35.9%), large QRS in ECG (32.4%), left ventricle dysfunction (75.7% with ejection fraction ≤40%), high NT-proBNP (mean 8113 pg/mL), low peak troponin I (mean 4.5 ng/mL) and lower hemoglobin (mean 11.7 g/dL) during hospital stay. The patients with AMI had higher prevalence of diabetes (27.6%) and slow progression of r wave in ECG (64.0%). Peak troponin I value was the highest (mean 52.6 ng/mL). Intermediate values of heart failure at admission (21.7%), left ventricular dysfunction (32.4% with ejection fraction ≤40%) and NT-proBNP (mean 2936 pg/mL) were observed. The NT-proBNP/peak troponin I quotient was statistically different among the 3 groups, being higher in SCM (mean 4563), intermediate in AMI (mean 866) and lower in AM (mean 146). The same happened with QTc interval, which was superior in SCM (mean 466 ms), intermediate in AMI (mean 446 ms) and inferior in AM (416 ms).
Conclusion: Regarding the patient with chest pain and elevation of myocardial necrosis biomarkers, there are some clinical, analytical and echocardiographic parameters that may suggest the most probable diagnosis. These include gender, age, C-reactive protein level, NT-proBNP/peak troponin I quotient and QTc interval.