The prognostic value of myocardial perfusion imaging in patients with type 2 myocardial infarction.

OBJECTIVES: The aim of this retrospective study is to evaluate the prognostic role of myocardial perfusion imaging (MPI) in patients with type 2 myocardial infarction (T2MI). BACKGROUND: T2MI is an increasingly common diagnosis in clinical practice. The management of this condition is controversial and the prognostic value of MPI has not been established in this setting. METHODS: We retrospectively studied T2MI patients who underwent vasodilator gated MPI within 90 days of T2MI at a single tertiary care institution in 2013. Abnormal myocardial perfusion was defined as the perfusion defect involving ≥ 5% of left ventricular (LV) myocardium. Abnormal LV ejection fraction (EF) was defined as < 50% by gated images. The primary outcome was a composite of death, myocardial infarction (other than index event) or coronary revascularization (CR). RESULTS: There were 234 patients (62 ± 14 years, 57% men) with T2MI (peak troponin 0.2 ng/ml, interquartile 0.1-1.4), of whom 136 (58%) had an abnormal MPI. During a median follow-up of 20 months, 155 patients (66%) had the primary outcome (39% death, 42% MI, 5% CR). An abnormal MPI was associated with an increased risk of the primary outcome with a hazard ratio of 1.56, 95%CI (1.12-2.18, P = .008) that remained statistically significant after multivariate adjustment (1.45, 95%CI (1.02-2.06, P = .04))). CONCLUSIONS: Patients with T2MI are at high risk for death or cardiac events in the intermediate term. More than one-half of patients with T2MI have an abnormal MPI and this is associated with the increased risk of cardiac events during follow-up. Risk stratification with MPI after T2MI may identify patients who would benefit from aggressive risk reduction.

Myocardial rupture after small acute myocardial infarction in the absence of coronary artery disease.

A 73-year-old woman with a past medical history of hypertension suffered a cardiac arrest. After successful resuscitation, she was hypotensive and tachycardic and the ECG showed ST elevation in the inferior and lateral precordial leads. Coronary angiography did not show evidence of obstructive coronary artery disease. A bedside echocardiogram demonstrated a large pericardial effusion with signs of cardiac tamponade. The echocardiogram and subsequent aortic root angiography did not reveal evidence of dissection. Pericardiocentesis removed 700 cc of bloody fluid with relief of tamponade. A few minutes later the patient again arrested. Fluid was again drained but she suffered recurrent hemodynamic collapse and could not be resuscitated. Autopsy revealed a small transmural myocardial infarction with external rupture and hemopericardium. There was only mild coronary artery disease without evidence of plaque rupture. This case illustrates that mild coronary artery disease and a small myocardial infarction can lead to catastrophic mechanical complications.