Plasma hydroxyanthranilic acid as a predictor of stress induced myocardial ischemia in non-obstructive coronary artery disease

Background

The tryptophan catabolite hydroxyanthranilic acid (HAA) has potent immunomodulatory and vasoactive effects. HAA is also a precursor in the synthesis of nicotinamide adenine dinucleotide (NAD), a crucial cofactor in energy-metabolism. We have previously demonstrated that elevated plasma HAA predicted risk of myocardial infarction.

Purpose

To explore if plasma HAA is associated with stress induced myocardial ischemia in non-obstructive coronary artery disease (CAD).

Methods

In 132 patients with chest pain and non-obstructive CAD by coronary computed tomography angiography (CCTA), plasma HAA was analyzed by gas chromatography tandem mass spectrometry. All participants underwent myocardial contrast stress echocardiography. Myocardial ischemia was assessed as delayed contrast replenishment at peak dobutamine stress during real-time low mechanical index imaging and destruction replenishment. The extent of ischemia was defined as the number of segments with delayed contrast enhancement using a 17-segment left ventricular model. Associations of plasma HAA with myocardial ischemia was evaluated in a multivariate adjusted linear regression model.

Results

Mean (SD) age at inclusion was 63 (8) years and 56% were women. At CCTA, the median (25th, 75th percentile) coronary artery calcium (CAC) score was 42 (13–107) Agatston units, whereas the mean (SD) segment involvement score (SIS) was 2.6 (1.6). Myocardial ischemia was found in 52% of patients with on average 5 (3) ischemic segments per patient. Serum HAA did not correlate with the CAC score or SIS (p>0.29). After multivariate adjustment including age, sex, body mass index, systolic blood pressure, diabetes, current smoking, and LDL cholesterol, the odds ratio and 95% confidence interval for myocardial ischemia was 1.55 (1.04–2.32), P=0.03, per SD increment of plasma HAA levels (log transformed). Plasma HAA was also associated with the extent of myocardial ischemia with a multivariate adjusted β of 0.26, P=0.004.

Conclusion

Plasma HAA is associated with the extent of myocardial ischemia in non-obstructive CAD. Potential roles of this metabolite in atherogenesis, vascular dysfunction and as a predictor of myocardial ischemia should be further elucidated.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): Western Norway Regional Health Authority

Associations of circulating polyunsaturated fatty acids with coronary artery calcium score in hospitalized patients with suspected coronary artery disease

Background

Inadequate intake of polyunsaturated fatty acids (PUFAs) is recognized as a modifiable risk factor for atherosclerotic cardiovascular disease (CVD) (1,2). The n-6 PUFA linoleic acid (LA) constitutes the predominant portion of total dietary PUFAs (3). However, whereas cardiometabolic effects of PUFAs belonging to the n-3 series have been studied for decades, less attention has been payed to potential health effects from n-6 PUFAs (4). Further, there has been concern regarding possible proinflammatory properties of several n-6 PUFA related metabolites.

Purpose

We explored correlations of serum total PUFAs, LA and the n-3 PUFA docosahexaenoic acid (DHA) with the inflammation marker GlycA. Further, we evaluated associations of total PUFAs, LA and DHA with the extension of atherosclerosis, as determined by the Agatston coronary artery calcium (CAC) score (5).

Methods

The study includes 250 patients who were hospitalized due to acute chest pain and referred to coronary CT angiography (CCTA) during in hospital stay. Exclusion criteria included diagnosis of acute myocardial infarction and/or revascularization within 24 hours after admittance. Serum levels of total PUFAs, LA, DHA and GlycA were analyzed by NMR technology in samples that had been frozen and stored at −80°C. After logarithmic transformation, relations of total PUFA, LA, and DHA with GlycA were evaluated by Pearson correlation analyses. The associations with CAC score were visualized in generalized additive regression plots and further evaluated in linear regression models including age, gender, body mass index, diabetes, hypertension and smoking status as independent covariables.

Results

Mean (SD) age was 57.6 (12.0) years, and 91 (36.4%) of the patients were women. Median (25th-75th percentiles) serum levels (in mmol/L) were for total PUFA 6.36 (5.76–7.06), LA 5.00 (4.51–5.55), DHA 0.36 (0.31–0.43) and GlycA 1.04 (0.94–1.13). Interestingly, GlycA was strongly, positively correlated with total PUFA (r=0.54). LA (r=0.53) and DHA (r=0.27), all P<0.001. In contrast, total PUFA and LA were inversely associated with CAC score both providing standardized betas of −0.17, P=0.03 after multivariable adjustments. No significant associations were found between CAC score and DHA or GlycA (P≥0.22). Further, the addition of GlycA to the multivariable model did not materially affect the relationship between CAC score and total PUFA or LA, which remained statistically significant (P=0.04).

Conclusion

In patients undergoing CCTA due to acute chest pain, serum levels of total PUFA and LA were strongly positively correlated with the pro-inflammatory marker GlycA. Still, total PUFA and LA were both inversely associated with the CAC score and the associations remained statistically significant after adjustments for CVD risk factors and GlycA levels. Future studies should further address the diverse effects of n-6 PUFAs on inflammatory pathways, atherogenesis and coronary calcification.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): Western Norway Regional Health Authority

HDL, apo a1 and long-term cardio-metabolic prognosis in statin-treated patients with suspected stable angina pectoris: a prospective cohort study

Background

Reduced serum levels of high density lipoprotein cholesterol (HDL-C) is a hallmark of the metabolic syndrome. Epidemiologic studies have reported an inverse correlation between HDL- C and cardiovascular disease (CVD) risk. However, recent works suggest that the association is strongest in healthy individuals. Changes in particle number and functional properties of HDL may more closely reflect CVD prognosis in patients with pre-existent disease. The majority of such patients receive statin treatment, which affects both HDL-C levels, and particle composition. Hence, serum apoA1 and the HDL-C:apoA1 ratio have been proposed as more sensitive indicators of cardio-metabolic prognosis.

Purpose

We studied the associations of serum HDL-C, apoA1 and the HDL-C: apoA1 ratio to long term risk of CVD mortality and incident type 2 diabetes (T2D) patients with suspected stable angina pectoris (SAP).

Methods

A total of 41064 patients underwent elective coronary angiography in 2000–2004 and were followed-up for CVD mortality throughout 2016. In a subgroup of 2519 participants without verified or possible diabetes at baseline, the associations to incident type 2 diabetes (T2D) were evaluated throughout 2014. Information on clinical endpoints was obtained through national health registries. Risk estimates are reported per 1 SD increment of (log transformed) biomarkers and were calculated by cox or logistic regression. We explored risk classification by calculating the continuous net reclassification improvement (NRI).

Results

At inclusion, median (25th-75th percentiles) age was 62 (55–70) years, 28% were women 76% had obstructive coronary artery disease and 80% received statins. During median (25th-75th percentiles) 13.9 (12.0–15.3) years of follow-up, 14.1% of the participants died from CVD. After multivariate adjustment (age, gender, body mass index, HbA1c, triglycerides, statin treatment, fasting status) HDL and apoA1, but not the HDL: apoA1 ratio, significantly predicted CVD mortality. The hazard ratio (HR) and 95% confidence interval (CI) was: 0.86 (0.78–0.94), 0.88 (0.80–0.98) and 0.96 (0.86–1.03) for HDL-C, apoA1 and the HDL-C:apoA1 ratio, respectively. HDL-C was the only of the evaluated biomarkers providing a significant NRI (95% CI) of 0.14 (0.04–0.19). In the subset evaluated for incdent T2D, HDL-C provided multivariate adjusted odds ratios (OR; 95% CI) and NRI (95% CI) of 0.69 (0.58–0.82) and 0.34 (0.21–0.47) for new onset TSD. The corresponding OR (95% CI) and NRI (95% CI) for apoA1 were: 0.85 (0.73–0.99) and 0.20 (0.06–0.33), respectively. The HDL:apo A1 ratio provided an OR (95% CI) of 0.66 (0.55–0.80) and NRI (95% CI) of 0.24 (0.11–0.37) for T2D. No significant effect modifications according to statin treatment were found (P≥0.22).

Conclusion

Among patients with suspected SAP, of which the majority received statins, HDL-C was non-inferior to apoA1 and the HDL:apoA1 ratio in predicting long term risk of CVD mortality and T2D.

Funding Acknowledgement

Type of funding source: Public hospital(s). Main funding source(s): Department of Heart Disease, Haukeland University Hospital; Department of Clinical Science, University of Bergen

P1531The association between plasma choline and acute myocardial infarction is modified by potential markers of endogenous PPAR activation

Background

Choline is related to lipid handling and higher plasma concentrations have been associated with an adverse cardiovascular risk profile. However, previous studies have suggested that the relationship between plasma free choline and later cardiovascular events may differ according to patient phenotypes.

Purpose

To explore the risk association between plasma choline and later acute myocardial infarction (AMI) according to plasma methylmalonic acid (MMA) or dimethylglycine (DMG). The latter two metabolites are suggested markers of endogenous activation of perixosome proliferator-activated receptors (PPARs), which are nuclear receptor proteins involved in lipid metabolism.

Methods

Risk relationships were explored by Cox regression among 2232 patients evaluated for suspected stable angina pectoris in the overall population and according to median plasma MMA and DMG.

Results

Baseline plasma choline was related to several cardiovascular risk factors (Table 1). After median follow-up of 7.3 years, 338 patients were reported with at least one incident AMI. In the overall population, the age and gender adjusted HR (95% CI) for each increment of 1 SD log-transformed plasma choline and AMI was 1.21 (1.08–1.35), P=0.001, and the association persisted in multivariate analyses.

In patients with plasma MMA or DMG≥median, the HRs (95% CIs) were 1.33 (1.16–1.54) and 1.38 (1.20–1.58), respectively, both P<0.0001; however no significant relationships were observed between plasma choline and later AMI among patients with either plasma MMA or DMG < median (P interaction <0.008) (Figure 1).

<MEDIAN (P>

Table 1. Baseline characteristics according to plasma choline quartiles Quartile 1 Quartile 4 P for trend Age, years 58 (52–66) 66 (58–73) <0.0001 Smoking, n (%) 212 (37.9) 153 (27.9) <0.0001 Diabetes, n (%) 61 (10.9) 85 (15.5) 0.12 Previous acute myocardial infarction, n (%) 200 (35.7) 238 (43.4) <0.0001 Estimated glomerular filtration rate, mL/min/1.73m2 96 (87–104) 79 (63–92) <0.0001 Serum hs-troponin T, ng/L 4 (3–8) 9 (4–17) 0.0002 Serum triglycerides, mmol/L 1.35 (1.00–2.03) 1.60 (1.16–2.25) <0.0001 Serum apolipoprotein A1, mg/L 1.29 (1.12–1.51) 1.32 (1.17–1.53) 0.01 Statin therapy, n (%) 384 (68.6) 435 (79.4) 0.01

Figure 1

Conclusion

Among patients with stable angina, plasma choline was related to increased long-term AMI risk among patients with higher plasma MMA or DMG only. This finding potentially reflects increased risk conferred by choline during concomitant endogenous PPAR activation.

Acknowledgement/Funding

None