ISCHEMIA Trial: Are We Still Fighting the Last War?

[Clinical use of Cardiac Nuclear Medicine in Germany]

Cardiac nuclear medicine comprises various diagnostic techniques using radiopharmaceuticals for functional imaging in vivo. This article provides an overview of current clinical use of cardiac imaging in nuclear medicine in Germany: Myocardial perfusion imaging using SPECT is a well-established noninvasive tool to semi-quantitatively measure left ventricular myocardial perfusion. Ischemia and chronic myocardial scars can be idenified with a high diagnostic accuracy. Gated SPECT enables measuring left ventricular function. With new dedicated solid-state camera systems examinations have become faster and better while radiation exposure has been minimized. These new camera systems allow quantitative calculations of myocardial blood flow, which will further improve diagnostic accuracy.For patients with severe chronic coronary artery disease and myocardial dysfunction analyzing myocardial viability is crucial for guiding therpeutic decisions. For detection of hibernating myocardium and its differentiation from scar tissue, two nuclear cardiac methods are combined: Rest myocardial perfusion imaging detects perfusion defects and cardiac 18F-FDG-PET/CT detects glucose metabolism in the hypoperfused area. As long as glucose metabolism is intact therapeutic interventions can be beneficial.In general 18F-FDG-PET/CT allows visualization and quantification of celluar glucose metabolism in oncologic and inflammatory processes. For analysis of cardiac inflammation (e. g. endocarditis or sarcoidosis) a no-carb and high-protein diet is needed at leat 24 hours prior to imaging in order to suppress the physiologic myocardial glucose metabolism. Then, specific inflammatory tracer uptake can be assessed.Cardiac amyloidosis is a rare but dangerous condition. With a specific amyloidosis scintigraphy (bone scintigraphy), cardiac ATTR-amyloidosis can be diagnosed with high accuracy. A potenitally harmful myocardial biopsy often is not needed any more and specific therapy can be initiated.In summary, diagnostic methods in cardiac nuclear medicine non-invasively allow visualization and function analysis of biological processes and are essential for diagnosis finding and therapy guidance. The continuous advancement of diagnostic tools makes nuclear cardiology a highly relevant and interesting field.

Myocardial viability testing: all STICHed up, or about to be REVIVED?

Patients with ischaemic left ventricular dysfunction frequently undergo myocardial viability testing. The historical model presumes that those who have extensive areas of dysfunctional-yet-viable myocardium derive particular benefit from revascularization, whilst those without extensive viability do not. These suppositions rely on the theory of hibernation and are based on data of low quality: taking a dogmatic approach may therefore lead to patients being refused appropriate, prognostically important treatment. Recent data from a sub-study of the randomized STICH trial challenges these historical concepts, as the volume of viable myocardium failed to predict the effectiveness of coronary artery bypass grafting. Should the Heart Team now abandon viability testing, or are new paradigms needed in the way we interpret viability? This state-of-the-art review critically examines the evidence base for viability testing, focusing in particular on the presumed interactions between viability, functional recovery, revascularization and prognosis which underly the traditional model. We consider whether viability should relate solely to dysfunctional myocardium or be considered more broadly and explore wider uses of viability testingoutside of revascularization decision-making. Finally, we look forward to ongoing and future randomized trials, which will shape evidence-based clinical practice in the future.