Examine Thy Heart With All Diligence

Abstract

Cardiovascular disease is a major cause of mortality in Western society but at its early phase may manifest as subtle alterations in coronary epicardial or microvascular function, including endothelial dysfunction, abnormal perfusion or permeability, and remodeling, which may precede clinical manifestation of vascular disease. These modifications might be associated with subclinical decline in diastolic and/or systolic function and left ventricular (LV) remodeling. Evaluation of myocardial perfusion and microvascular function to identify areas of persistent ischemia or hibernating myocardium, endothelial, or LV dysfunction is, therefore, important for clinical decision-making and fuels the search for noninvasive techniques assessing different stages of cardiac disease. Several noninvasive or minimally invasive techniques currently used to explore cardiac function, such as echocardiography, scintigraphy, and single-photon emission computed tomography, show diagnostic reliability but low spatial resolution and poor anatomic details. Therefore, higher-resolution techniques, like positron emission tomography, MRI, and computed tomography (CT), have been steadily gaining popularity.1 MRI can assess cardiac function, mass, volume, and myocardial viability, with limited application in patients with metal fragments, and positron emission tomography provides reliable estimates of myocardial perfusion and metabolism, albeit at low spatial resolution. Furthermore, since its inception in the 1970s, CT quickly incorporated into clinical practice, and recent technical advances have placed it in the forefront for comprehensive evaluation of cardiac function at several levels, from the function of the heart as a pump, to the behavior of the microvessels that feed its walls (Figure 1). For example, CT overcomes some of the limitations of MRI, because it can study patients with defibrillators or pacemakers, has a shorter acquisition time, and is more available and affordable than positron emission tomography, thus allowing access to cardiac imaging to a greater number of patients. Figure 1. A, schematic of the different levels for cardiac functional evaluation, including global heart, …