Myocardial perfusion studies in abnormal ventricular activation

Abstract

Imaging of perfusion of the myocardium with nuclear cardiac imaging is an uncontested technique for diagnostic as well as prognostic purposes in patients with chest pain and a normal activation pattern of the heart. However, when the activation pattern of the heart is abnormal as happens with intraventricular conduction disorders or artificial cardiac pacing, the value of this technique becomes disputable. This shortcoming is predominantly caused by the presence of perfusion defects not caused by coronary artery disease. These false positive perfusion defects diminish the diagnostic and prognostic value of nuclear imaging in patients with chest pain and abnormal activation who are studied in this thesis. We showed that these false positive defects meet specific diagnostic criteria. In addition it was demonstrated that wall motion abnormalities due to abnormal activation are strongly related to perfusion defects. The limited resolution of the nuclear camera for a movi ng organ is presumably the cause of these false positive defects. We strengthened this assumption by showing a normal myocardial blood-flow in the walls where false positive perfusion are found. The abnormal activation related defects (AARD) follow a typical pattern. We defined a triad to recognize these AARD and demonstrated that the prognosis of patients with AARD compares well those patients with a completely normal perfusion with abnormal activation of the heart. By recognizing these AARD in patients with chest pain it is possible to distinguish patients with perfusion defects that are at a low risk for future cardiac events from those with perfusion defects at high risk for future cardiac events. The results of this thesis allow to identify patients with chest pain and abnormal left ventricular activation pattern but are nevertheless at a low cardiac risk. This category has a prognosis that merits a watchful waiting strategy, and invasive, expensive diagnostic procedures can be av oided. This strategy prevents patient burden and complication risk. However patients with chest pain and abnormal activation of the heart with a high risk estimated by nuclear imaging, require further diagnostic work up often followed by surgical coronary revascularization or Dotter procedures. The results of these cardiac nuclear studies are of relevance for patient care in terms of improved management and saving of costs.