Cardiac allograft endothelial dysfunction

Prognostic value of myocardial flow reserve obtained by 82-rubidium positron emission tomography in long-term follow-up after heart transplantation

BACKGROUND

Cardiac allograft vasculopathy (CAV) is a leading cause of death following heart transplantation (HTx) and non-invasive prognostic methods in long-term CAV surveillance are needed. We evaluated the prognostic value of myocardial flow reserve (MFR) obtained by 82-rubidium (82Rb) positron emission tomography (PET).

METHODS

Recipients undergoing dynamic rest-stress 82Rb PET between April 2013 and June 2017 were retrospectively evaluated in a single-center study. Evaluation by PET included quantitative myocardial blood flow and semiquantitative myocardial perfusion imaging. Patients were grouped by MFR (MFR ≤ 2.0 vs MFR > 2.0) and the primary outcome was all-cause mortality.

RESULTS

A total of 50 patients (68% men, median age 57 [IQR: 43 to 68]) were included. Median time from HTx to PET was 10.0 (6.7 to 16.0) years. In 58% of patients CAV was documented prior to PET. During a median follow-up of 3.6 (2.3 to 4.3) years 12 events occurred. Survival probability by Kaplan-Meier method was significantly higher in the high-MFR group (log-rank P = .02). Revascularization (n = 1), new CAV diagnosis (n = 1), and graft failure (n = 4) were more frequent in low-MFR patients. No retransplantation occurred.

CONCLUSIONS

Myocardial flow reserve appears to offer prognostic value in selected long-term HTx recipients and holds promise as a non-invasive method for CAV surveillance possibly guiding management strategy.

Sudden death due to coronary tree hypoplasia

A 20-year-old woman complained for several weeks before her death of unspecific epigastric pains. Such episodes were labeled as "dyspeptic episode." A month later, once again she started to complain about stomach pains, then she collapsed unconscious. She was rushed to a hospital, where she was admitted in cardiorespiratory arrest. An electrocardiogram revealed a ventricular fibrillation. All resuscitation efforts were unsuccessful. The autopsy revealed nonspecific general changes (subpleural petechiae and blood pooling). Dissection of the coronary arteries revealed a normal topography of coronary arteries but a marked hypoplasia of all the subepicardial coronary arteries (maximum diameter of left anterior descending coronary artery = 1.9 mm, maximum diameter of right coronary artery = 1.43 mm). Furthermore, the left anterior descending coronary artery was slightly compressed by a fibrous bridge at about 1.5 cm of its origin; a fibrinoleukocytic thrombus has formed immediately above this bottleneck, obstructing the entire lumen of the artery. Microscopic examination revealed an area of recent myocardial necrosis; diffuse subendocardial fibrosis, with extension into the subjacent myocardium, disorganizing the myocardial fibers; and variable thickening of the vascular walls with periarteriolar fibrosis. Weigert stain has shown marked intimal hyperplasia, either focal or diffuse, in different segments of vascular wall, accompanied by disruption of the internal elastic lamina due to subintimal cellular proliferation, in the medium branches of coronary arteries. The micrometric measurements showed that intimal thickening was at least the size of the media (∼358 vs 356.8 μm) and sometimes double.