Prognostic value of myocardial perfusion entropy in patients with normal thallium-201 myocardial perfusion with a CZT camera : PROMHETE study

Objectives We assessed the prognostic value of myocardial perfusion heterogeneity (entropy) in patients with normal myocardial perfusion as estimated from a dual isotope high-speed protocol (Thallium-201 stress and technetium- 99m-sestamibi rest) performed on a semiconductor camera. Background The prognostic value of normal myocardial perfusion scintigraphic imaging has been widely established for over twenty years but the clinical value of perfusion heterogeneity quantification beyond perfusion imaging as routinely performed is unknown. Methods From May 2011 to September 2012, 1159 patients with a normal scan or a non-significant perfusion abnormality (SSS   45%) were retrospectively identified. This study reports an interim analysis of 443 patients. A dual isotope high-speed protocol was performed on a semiconductor camera following exercise testing (37%) or pharmacological stress (63%). Myocardial perfusion images were then used to quantify myocardial perfusion heterogeneity as estimated by stress and rest image entropy. The primary endpoint was the occurrence of a cardiovascular event (cardiovascular death, non-fatal myocardial infarction, coronary angiography with or without revascularization, and stroke). Results The primary endpoint occurred in 73 patients during follow-up (3.3 ± 0.4 years). In a multivariate analysis, age (HR 1.04 [1.01; 1.06] P   4.06) underwent more events than those with a lower entropy ( Conclusions Myocardial perfusion heterogeneity (entropy) determined from thallium-201 stress perfusion images acquired on a semiconductor camera represent an independent prognostic factor of cardiovascular events with additive value over the classical interpretation of images from patients with normal myocardial perfusion scintigraphy. Myocardial perfusion heterogeneity (entropy) might represent a surrogate of coronary microvascular dysfunction.