Ischemia and No Obstructive Coronary Artery Disease: Prevalence and Correlates of Coronary Vasomotion Disorders.

BACKGROUND: Determine the prevalence and correlates of microvascular and vasospastic angina in patients with symptoms and signs of ischemia but no obstructive coronary artery disease (INOCA). METHODS: Three hundred ninety-one patients with angina were enrolled at 2 regional centers over 12 months from November 2016 (NCT03193294). INOCA subjects (n=185; 47%) had more limiting dyspnea (New York Heart Association classification III/IV 54% versus 37%; odds ratio [OR], 2.0 [1.3-3.0]; P=0.001) and were more likely to be female (68% INOCA versus 38% in coronary artery disease; OR, 1.9 [1.5 to 2.5]; P<0.001) but with lower cardiovascular risk scores (ASSIGN score median 20% versus 24%; P=0.003). INOCA subjects had similar burden of angina (Seattle Angina Questionnaire) but reduced quality of life compared with coronary artery disease; subjects (EQ5D-5 L index 0.60 versus 0.65 units; P=0.041). RESULTS: An interventional diagnostic procedure with reference invasive tests including coronary flow reserve, microvascular resistance, and vasomotor responses to intracoronary acetylcholine (vasospasm provocation) was performed in 151 INOCA subjects. Overall, 78 (52%) had isolated microvascular angina, 25 (17%) had isolated vasospastic angina, 31 (20%) had both, and 17 (11%) had noncardiac chest pain. Regression analysis showed inducible ischemia on treadmill testing (OR, 7.5 [95% CI, 1.7-33.0]; P=0.008) and typical angina (OR, 2.7 [1.1-6.6]; P=0.032) were independently associated with microvascular angina. Female sex tended to associate with a diagnosis of microvascular angina although this was not significant (OR, 2.7 [0.9-7.9]; P=0.063). Vasospastic angina was associated with smoking (OR, 9.5 [2.8-32.7]; P<0.001) and age (OR, 1.1 per year, [1.0-1.2]; P=0.032]. CONCLUSIONS: Over three quarters of patients with INOCA have identifiable disorders of coronary vasomotion including microvascular and vasospastic angina. These patients have comparable angina burden but reduced quality of life compared to patients with obstructive coronary artery disease. Microvascular angina and vasospastic angina are distinct disorders that may coexist but differ in associated clinical characteristics, symptoms, and angina severity. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT03193294.

Validation of magnetic resonance myocardial perfusion imaging with fractional flow reserve for the detection of significant coronary heart disease.

BACKGROUND: Magnetic resonance myocardial perfusion imaging (MRMPI) has a number of advantages over the other noninvasive tests used to detect reversible myocardial ischemia. The majority of previous studies have generally used quantitative coronary angiography as the gold standard to assess the accuracy of MRMPI; however, only an approximate relationship exists between stenosis severity and functional significance. Pressure wire-derived fractional flow reserve (FFR) values <0.75 correlate closely with objective evidence of reversible ischemia. Accordingly, we have compared MRMPI with FFR. METHODS AND RESULTS: One hundred three patients referred for investigation of suspected angina underwent MRMPI with a 1.5-T scanner. The stress agent was intravenous adenosine (140 microg . kg(-1) . min(-1)), and the first-pass bolus contained 0.1 mmol/kg gadolinium. In the following week, coronary angiography with pressure wire studies was performed. FFR was recorded in all patent major epicardial coronary arteries, with a value <0.75 denoting significant stenosis. MRMPI scans, analyzed by 2 blinded observers, identified perfusion defects in 121 of 300 coronary artery segments (40%), of which 110 had an FFR <0.75. We also found that 168 of 179 normally perfused segments had an FFR > or = 0.75. The sensitivity and specificity of MRMPI for the detection of functionally significant coronary heart disease were 91% and 94%, respectively, with positive and negative predictive values of 91% and 94%. CONCLUSIONS: MRMPI can detect functionally significant coronary heart disease with excellent sensitivity, specificity, and positive and negative predictive values compared with FFR.

Pharmacological options for inducing maximal hyperaemia during studies of coronary physiology.

The coronary pressure wire is used for physiological assessment of the coronary vasculature increasingly frequently in clinical practice. Fractional flow reserve (FFR) can now be used to assess lesion severity in a variety of anatomical situations. Increasingly, the coronary pressure wire is being used to interrogate the coronary microvasculature. Coronary flow reserve (CFR) and Index of microcirculatory resistance (IMR) require hyperaemia to accurately assess thermodilution-derived mean transit times, and pressure derived collateral flow index (CFIp) is calculated from coronary wedge pressure and aortic pressure at hyperaemia. In addition, coronary flow velocity as assessed by a coronary Doppler flow wire needs appropriate induction of hyperaemia. However, the majority of this article will however focus on hyperaemia induction for pressure wire studies particularly FFR. Significant clinical decisions are made as a result of FFR readings, therefore it is imperative that they are carried out correctly. Maximal coronary hyperaemia is essential in producing accurate, reproducible measurements. This article focuses on the pharmacological agents that can be used for this purpose, discusses which agents can be used in specific situations, and briefly addresses the future of pharmacological stress in the catheter laboratory.