Determinants of Myocardial Lactate Production During Acetylcholine Provocation Test in Patients With Coronary Spasm

Isa WYH. An Evaluation of the Role of Oxidative Stress in Non-Obstructive Coronary Artery Disease

Approximately half of all women presenting to the emergency department with angina chest pain do not have obstructive coronary artery disease (CAD) on coronary angiography. This condition is termed non-obstructive coronary artery disease (NOCAD), and includes ischemia with no obstructive coronary artery disease (INOCA) and myocardial infarction with non-obstructive coronary arteries (MINOCA). Oxidative stress has been reported to be involved in the development and progression of CAD. However, a scarcity of studies has assessed a correlation between oxidative stress and NOCAD. Thus, a literature review was performed of available reports on the role of oxidative stress in NOCAD. Possible mechanisms involved in oxidative stress that may contribute to NOCAD were identified and evaluated. A key finding of this literature review was that oxidative stress caused vasoconstriction and endothelial damage, and this results in coronary microvascular dysfunction and vasospasm, which, in turn, lead to the pathogenesis of NOCAD.

Role of acetylcholine spasm provocation test as a pathophysiological assessment in nonobstructive coronary artery disease

Coronary angiography (CAG) sometimes shows nonobstructive coronary arteries in patients with suspected angina or acute coronary syndrome (ACS). The high prevalence of nonobstructive coronary artery disease (CAD) in those patients has recently been reported not only in Japan but also in Western countries, and is clinically attracting attention. Coronary spasm is considered to be one of the leading causes of both suspected stable angina and ACS with nonobstructive coronary arteries. Coronary spasm could also be associated with left ventricular dysfunction leading to heart failure, which could be improved following the administration of calcium channel blockers. Because we rarely capture spontaneous attacks of coronary spasm with electrocardiograms or Holter recordings, an invasive diagnostic modality, acetylcholine (ACh) provocation test, can be useful in detecting coronary spasm during CAG. Furthermore, we can use the ACh-provocation test to identify high-risk patients with coronary spasm complicated with organic coronary stenosis, and then treat with intensive care. Nonobstructive CAD includes not only epicardial coronary spasm but also microvascular spasm or dysfunction that can be associated with recurrent anginal attacks and poor quality of life. ACh-provocation test could also be helpful for the assessment of microvascular spasm or dysfunction. We hope that cardiologists will increasingly perform ACh-provocation test to assess the pathophysiology of nonobstructive CAD.

CYP2C19 variants and epoxyeicosatrienoic acids in patients with microvascular angina

BACKGROUND

Categorization as a cytochrome P450 (CYP) 2C19 poor metabolizer (PM) is reported to be an independent risk factor for cardiovascular disease. Epoxyeicosatrienoic acids (EETs) are metabolites of arachidonic acid by CYP2C19 epoxygenases and anti-inflammatory properties, especially in microvascular tissues. We examined the impact of CYP2C19 polymorphisms and EETs on the patients with microvascular angina (MVA) caused by coronary microvascular dysfunction.

METHODS AND RESULTS

We examined CYP2C19 genotypes in patients with MVA (n = 81). MVA was defined as absence of coronary artery stenosis and epicardial spasms, and the presence of inversion of lactic acid levels between intracoronary and coronary sinuses in acetylcholine-provocation test or the adenosine-triphosphate-induced coronary flow reserve ratio was below 2.5. CYP2C19 PM have two loss-of-functon alleles (*2, *3). We measured serum dihydroxyeicosatrienoic acid (DHET) as representative EET metabolite. In MVA, the patients with CYP2C19 PM were 34.6% and high sense C-reactive protein (hs-CRP) levels in CYP2C19 PM were significantly higher than that of non-PM group (0.165 ± 0.116 vs. 0.097 ± 0.113 mg/dL, P = 0.026). Moreover, DHET levels in CYP2C19 PM were significantly lower than that of non-PM (10.4 ± 4.58 vs. 15.6 ± 11.1 ng/mL, P = 0.003 (11,12-DHET); 12.1 ± 3.79 vs. 17.3 ± 6.49 ng/mL, P = 0.019 (14,15-DHET)).

CONCLUSIONS

The decline of EET owing to CYP2C19 variants may affects coronary microvascular dysfunction via chronic inflammation.

Association of CYP2C19 variants and epoxyeicosatrienoic acids on patients with microvascular angina

Categorization as a cytochrome P450 (CYP) 2C19 poor metabolizer (PM) is reported to be an independent risk factor for cardiovascular disease. Epoxyeicosatrienoic acids (EETs) are metabolites of arachidonic acid by CYP2C19 epoxygenases and anti-inflammatory properties, especially in microvascular tissues. We examined the association of CYP2C19 polymorphisms and EETs on microvascular angina (MVA) caused by coronary microvascular dysfunction. We examined CYP2C19 genotypes in patients with MVA ( n = 71) and healthy subjects as control ( n = 71). MVA was defined as the absence of coronary artery stenosis and epicardial spasms and the presence of inversion of lactic acid levels between intracoronary and coronary sinuses in acetylcholine-provocation test or the adenosine-triphosphate-induced coronary flow reserve ratio was below 2.5. CYP2C19 PM have two loss-of-functon alleles (*2, *3). We measured serum dihydroxyeicosatrienoic acid (DHET) as representative EET metabolite. MVA group showed significantly higher CYP2C19 PM incidence (35% vs. 16%; P = 0.007) and high sense C-reactive protein (hs-CRP) levels (0.127 ± 0.142 vs. 0.086 ± 0.097 mg/dl; P = 0.043) than those of controls. Moreover, in MVA group, hs-CRP levels in CYP2C19 PM were significantly higher than that of non-PM (0.180 ± 0.107 vs. 0.106 ± 0.149 mg/dl, P = 0.045). Multivariate analysis indicated that smoking, hypertension, high hs-CRP, and CYP2C19 PM are predictive factors for MVA. In MVA group, DHET levels for CYP2C19 PM were significantly lower than that of non-PM [10.9 ± 1.64 vs. 14.2 ± 5.39 ng/ml, P = 0.019 (11,12-DHET); 15.2 ± 4.39 vs. 17.9 ± 4.73 ng/ml, P = 0.025 (14,15-DHET)]. CYP2C19 variants are associated with MVA. The decline of EET-based defensive mechanisms owing to CYP2C19 variants may affect coronary microvascular dysfunction.

Impact of aspirin on the prognosis in patients with coronary spasm without significant atherosclerotic stenosis

BACKGROUND

Coronary spasm is one of the mechanisms of myocardial infarction with nonobstructive coronary arteries (MINOCA). The aim of this study was to investigate the effects of aspirin on future cardiovascular events in patients with coronary vasospastic angina (VSA) with non-significant atherosclerotic stenosis.

METHODS

This was the retrospective analysis of the 640 VSA patients with non-significant atherosclerotic stenosis (≤50% stenosis) among 1,877 consecutive patients who underwent acetylcholine (ACh)-provocation testing between January 1991 and December 2010. The patients were divided into 2 groups treated with (n=137) or without (n=503) low-dose aspirin (81-100mg/day). We evaluated major adverse cardiac events (MACE), defined as cardiac death, nonfatal myocardial infarction, and unstable angina.

RESULTS

In the study population, 24 patients (3.8%) experienced MACE; there were 6 cases in VSA patients with aspirin and 6 in those without aspirin. Multivariate Cox hazards analysis for correlated factors of MACE indicated that use of statin (HR: 0.11; 95% CI: 0.02 to 0.84; P=0.033), ST-segment elevation during attack (HR: 5.28; 95% CI: 2.19-12.7; P<0.001), but not the use of aspirin as a significant predictor of MACE. After propensity score matching (n=112, each), Kaplan-Meier survival analysis indicated almost identical rate of 5-year survival free from MACE in those with aspirin, compared to those without aspirin in the entire and matched cohort (P=0.640 and P=0.541, respectively).

CONCLUSIONS

Low-dose aspirin might not reduce future cardiovascular events in VSA patients with non-significant stenosis.

Sex differences in the impact of CYP2C19 polymorphisms and low-grade inflammation on coronary microvascular disorder

Categorization as a cytochrome P-450 (CYP) 2C19 poor metabolizer (PM) is reported to be an independent risk factor for cardiovascular disease. It is correlated with an increase in the circulating levels of high-sense C-reactive protein (hs-CRP) in women only, although its role in coronary microcirculation is unclear. We examined sex differences in the impact of the CYP2C19 genotype and low-grade inflammation on coronary microvascular disorder (CMVD). We examined CYP2C19 genotypes in patients with CMVD (n = 81) and in healthy subjects as control (n = 81). CMVD was defined as the absence of coronary artery stenosis and epicardial spasms, the presence of inverted lactic acid levels between the intracoronary and coronary sinuses, or an adenosine triphosphate-induced coronary flow reserve ratio < 2.5. CYP2C19 PMs have two loss-of-function (LOF) alleles (*2, *3). Extensive metabolizers have no LOF alleles, and intermediate metabolizers have one LOF allele. The ratio of CYP2C19 PM and hs-CRP levels in CMVD was significantly higher than that of controls, especially in women (40.9 vs. 13.8%, P = 0.013; 0.11 ± 0.06 vs. 0.07 ± 0.04 mg/dl, P = 0.001). Moreover, in each CYP2C19 genotype, hs-CRP levels in CMVD in CYP2C19 PMs were significantly higher than those of the controls, especially in women (0.15 ± 0.06 vs. 0.07 ± 0.03, P = 0.004). Multivariate analysis for CMVD indicated that the female sex, current smoking, and hypertension were predictive factors, and that high levels of hs-CRP and CYP2C19 PM were predictive factors in women only (odds ratio 3.5, 95% confidence interval 1.26-9.93, P = 0.033; odds ratio 4.1, 95% confidence interval 1.15-14.1, P = 0.038). CYP2C19 PM genotype may be a new candidate risk factor for CMVD via inflammation exclusively in the female population.