INOCA – Ischemia and No Obstructive Coronary Artery Disease

INOCA – Ischemia and No Obstructive Coronary Artery Disease

INOCA is the acronym for Ischemia and No Obstructive Coronary Artery Disease [1]. They have elevated risk for cardiovascular events like acute coronary syndrome and hospitalization for heart failure. Risk of development of heart failure with preserved ejection fraction (HFpEF) is also higher in these subjects. Some of them have coronary microvascular dysfunction and evidence of inflammation.

In spite of the absence of obstructive coronary arteries, they have a risk of repeated hospitalizations and repeated coronary angiographies, involving significant health care costs. In general, INOCA is more common in females. They tend to have coronary microvascular dysfunction, plaque erosion and thrombus formation [2]. They may have more extensive non obstructive coronary artery disease and have associated hypertension and diabetes mellitus. Major adverse events are similar to those with obstructive coronary artery disease.

The CORE320 Study was an observational study of INOCA defined with computed tomography (CT) angiography and perfusion imaging [3]. Invasive coronary angiography and single photon emission computed tomography (SPECT) were also performed. 381 symptomatic persons referred for invasive coronary angiography underwent CT angiography, rest-adenosine stress CT perfusion and rest-stress SPECT prior to invasive coronary angiography. They were divided into three groups depending on CT angiography/CT perfusion or invasive coronary angiography/SPECT data. Group a had 50% or more coronary stenosis. Group b had no obstructive stenosis, but ischemia (INOCA).  Group c had no obstructive stenosis and normal perfusion imaging results. 31 of the 115 participants without obstructive coronary artery disease at CT angiography had abnormal CT perfusion studies. In those who had a combination of invasive coronary angiography and SPECT, 45 of the 151 without obstructive coronary artery disease had INOCA. Those with INOCA had greater atherosclerotic burden and more adverse plaque features on CT compared with those who had no obstructive stenosis and no ischemia. This would imply that treatment aimed at prevention of progression of atherosclerosis is needed in those with INOCA.

An accompanying editorial mentioned that CT perfusion provides data on the presence of microvascular dysfunction in INOCA [4].

References

1. Bairey Merz CN, Pepine CJ, Walsh MN, Fleg JL. Ischemia and No Obstructive Coronary Artery Disease (INOCA): Developing Evidence-Based Therapies and Research Agenda for the Next Decade. Circulation. 2017 Mar 14;135(11):1075-1092.
2. Pepine CJ, Ferdinand KC, Shaw LJ, Light-McGroary KA, Shah RU, Gulati M, Duvernoy C, Walsh MN, Bairey Merz CN; ACC CVD in Women Committee. Emergence of Nonobstructive Coronary Artery Disease: A Woman’s Problem and Need for Change in Definition on Angiography. J Am Coll Cardiol. 2015 Oct 27;66(17):1918-33.
3. Schuijf JD, Matheson MB, Ostovaneh MR, Arbab-Zadeh A, Kofoed KF, Scholte AJHA, Dewey M, Steveson C, Rochitte CE, Yoshioka K, Cox C, Di Carli MF, Lima JAC. Ischemia and No Obstructive Stenosis (INOCA) at CT Angiography, CT Myocardial Perfusion, Invasive Coronary Angiography, and SPECT: The CORE320 Study. Radiology. 2020 Jan;294(1):61-73.
4. François CJ. “One-Stop Shop” For Evaluating Epicardial and Microvascular Coronary Artery Disease with Coronary CT Angiography and CT Myocardial Perfusion. Radiology. 2020 Jan;294(1):74-75.