Quantification of Absolute Myocardial Flow and Resistance by Continuous Thermodilution in Patients with Ischemia and Nonobstructive Coronary Artery Disease (INOCA)

In approximately half of the patients undergoing coronary angiography for angina pectoris or for signs or symptoms suggestive of ischemic heart disease, no obstructive coronary artery disease is angiographically visible. The majority of these patients with angina or ischemia and no obstructive coronary artery disease (INOCA) have an underlying coronary vasomotor dysfunction, and current consensus documents recommend diagnostic invasive coronary vasomotor function testing (CFT).

During CFT, a variety of vasomotor dysfunction endotypes can be assessed, including vasospastic coronary dysfunction (epicardial or microvascular vasospasm), and/or microvascular vasodilatory dysfunction, including impaired vasodilatory capacity and increased microvascular resistance. The quantification of the continuous thermodilution derived absolute coronary blood flow and resistance might be a better measure compared to the currently used standard physiologic measures. This article provides an overview of this continuous thermodilution method.