- Email: [email protected]
Atrial natriuretic peptide polymorphisms, hydrochlorothiazide and urinary potassium excretion
72
Letters to the Editor [3] Takenaka K, Ai T, Shimizu W, et al. Exercise stress test amplifies genotype–phenotype correlation in the LOT1 and LQT2 forms of the long-QT syndrome. Circulation 2003;107:838–44. [4] Kirchhof P, Eckardt L, Franz MR, et al. Prolonged atrial action potential durations and polymorphic atrial tachyarrhythmias in patients with long QT syndrome. J Cardiovasc Electrophysiol 2003;14:1027–33. [5] Gong Q, Zhang L, Vincent GM, Horne BD, Zhou Z. Nonsense mutations in hERG cause a decrease in mutant mRNA transcripts by nonsense-mediated mRNA decay in human long-QT syndrome. Circulation 2007;116:17–24. [6] Coats AJ. Ethical authorship and publishing. Int J Cardiol 2009;131: 149–50.
Fig. 2. Mutation analysis of family members. Chromatograms showed a common single nucleotide mutation of c.C2212T, causing amino acid sequence of p.Q738X.
0167-5273/$ - see front matter © 2008 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2008.12.053
Atrial natriuretic peptide polymorphisms, hydrochlorothiazide and urinary potassium excretion Stefan Viktor Vormfelde b
a,⁎
, Mohammad Reza Toliat b , Peter Nürnberg b , Jürgen Brockmöller
a
a Department of Clinical Pharmacology, University Medical Center, Robert-Koch-Str. 40, 37075 Göttingen, Germany Cologne Center for Genomics (CCG) and Institute for Genetics, University of Cologne, Zuelpicher Straße 47, 50674 Köln, Germany
Received 6 August 2008; accepted 6 December 2008 Available online 11 January 2009
Keywords: Atrial natriuretic peptide; Genetic polymorphism; Thiazide diuretic; Hydrochlorothiazide; Antihypertensive therapy; Potassium
NPPA disruption goes with salt-sensitive hypertension in mice [1]. In humans, the methionine32 allele of Val32Met (G664A, rs5063) has been associated with low circulating proANP levels [2]. Both methionine32 and the arginine152 allele of the Ter152Arg polymorphism (T2238C, rs5065) have been associated with hypertension or hypertensionrelated disease (overview in [3]). In conclusion, both variant alleles are supposed to be low functional alleles compared
⁎ Corresponding author. Tel.: +49 551 399651; fax: +49 551 12767. E-mail address: [email protected] (S.V. Vormfelde).
to the respective wild-type alleles. Now, in the ALLHAT study, coronary heart disease outcome tended better or was significantly better in carriers of the variant alleles [3]. In contrast, the overall survival tended lower in these subjects. We explored a potential association of the NPPA polymorphisms with diuretic effects of another thiazide diuretic, hydrochlorothiazide, in a single-dose cross-over study with 25 and 100 mg hydrochlorothiazide in 103 healthy, normotensive volunteers. The study was approved by the Ethics committee of the University of Göttingen; all participants provided written informed consent. The participants were 103 normotensive, healthy, male Caucasian volunteers aged between 18 and
Letters to the Editor Table 1 Urinary excretion by ANP genotype. Na
K+ g/24 h b
Na+ g/24 h b
25 mg hydrochlorothiazide Val/Val Ter/Ter 67 Val/Val Ter/Arg 24 Val/Val Arg/Arg 3 5 Val/Met c
3.6 (1.1) 4.1 (1.4) 4.8 (0.9) 4.8 (0.9)
4.6 (1.8) 5.0 (2.4) 4.9 (1.4) 4.5 (1.9)
100 mg hydrochlorothiazide Val/Val Ter/Ter Val/Val Ter/Arg Val/Val Arg/Arg Val/Met c
3.9 (1.2) 4.3 (1.2) 6.0 (1.6) 5.0 (0.9)
6.1 (2.1) 6.9 (2.6) 5.6 (1.5) 6.4 (1.6)
64 25 3 7
a
Number of subject sums do not equal 103 as not all subjects could be included in all analyses. b Data are given as mean (SD). c Ter/Ter homozygotes and one Ter/Arg subject.
49 years (mean ± SD: 28 ± 7.5), mostly students at Göttingen university, with body mass index values ranging from 18.7 to 29.6 kg/m2 (24.4 ± 2.4). The volunteers ingested single oral doses of 25 and 100 mg of the thiazide diuretic drug hydrochlorothiazide on two separate occasions as described earlier [4]. Each occasion consisted of 3 days, a diet run-in day, a placebo day and a verum day. Low-sodium diet was mandatory throughout all 3 days. Placebo and verum days were performed identically except for the content of the drug capsule: blood and urine were collected at 0, 1, 3, 6, 10 and 24 h after drug intake and during the respective intervals. Val32Met and Ter152Arg were observed with variant allele frequencies of 0.07 and 0.16; all subjects could be analysed, both polymorphisms were in Hardy–Weinberg equilibrium. There was no linkage between the variant alleles in accordance with earlier findings (e.g. compare www.hapmap.org) and no methionine32 homozygous subject was observed. This resulted in the four genotypic groups given in Table 1. Covariance analysis was performed with SPSS 12.0. One model term was the two study days and two model terms were the interaction of each one polymorphism with the two study days. The given p-values refer to these interaction terms. Potassium excretion was significantly associated with the ANP genotype. It was higher in carriers of a variant allele of any of the two polymorphisms compared to carriers of only wild-type alleles (Table 1). Covariance analysis revealed that the 24 h urinary potassium excretion was 3.6 ± 0.1 and 3.9 ± 0.1 g in only wild-type allele carriers with 25 and 100 mg hydrochlorothiazide (mean ± SEM) and was 0.5 ± 0.2 and 0.6 ± 0.2 g higher per arginine152 allele (p = 0.004) and 1.1 ± 0.5 and 1.0 ± 0.5 g higher per methionine32 allele (p = 0.016). As this was an exploratory study we did not formally control for multiple testing. Bonferronicorrection would leave the potassium–arginine152 associa-
73
tion significant assuming up to twelve tests of unrelated parameters. On the placebo days, only minor and statistically not significant trends to higher potassium excretion in the variant allele carriers were observed (p = 0.113 and 0.416). Compared to the placebo days, hydrochlorothiazide intake increased the urinary potassium excretion by 0.7 ± 0.1 and 1.1 ± 0.1 g in carriers of only wild-type alleles on the 25 mg and the 100 mg study days. Potassium excretion was additionally increased by 0.3 ± 0.2 and 0.2 ± 0.2 g per arginine152 allele (p = 0.086) and by 0.4 ± 0.4 and 1.0 ± 0.4 g per metionine32 allele (p = 0.012) by 25 mg and 100 mg hydrochlorothiazide, respectively. These associations were stable, controlling for the three polymorphisms reported earlier to affect diuresis in this study population [4]. Sodium excretion (Table 1), chloride and volume excretion also tended somewhat higher on the verum days in the variant allele carriers but these associations were weak and statistically not significant. The serum potassium concentration fell by 0.08 ± 0.03 and 0.12 ± 0.03 mM within 24 h after 25 and 100 mg hydrochlorothiazide, respectively, and also the sodium and the chloride concentration fell. However, neither potassium, nor any other electrolyte concentration was associated with the ANP genotype, neither before, nor after hydrochlorothiazide (most p-values N 0.3). However, this doesn't rule out an effect on the long term. Carriers of ANP precursor gene alleles that are supposed to be low functional alleles excreted more potassium on hydrochlorothiazide intake than did carriers of the higher functional alleles. ANP acts diuretically by indirect inhibition of the epithelial sodium channel ENaC in renal collecting ducts. Thus it is pathophysiologically plausible that carriers of low functional alleles are prone to hypertension. ENaC reabsorbs sodium substitutional for potassium. Thus, carriers of lower functional ANP alleles may reabsorb more sodium and excrete more potassium. Thereby such subjects could be endangered by the additional urinary potassium loss that we observed. Hypokalemia can be devastating and thus it may be speculated that higher urinary potassium loss may have contributed to mortality in the ALLHAT study that caused the absent association with overall survival despite the better coronary heart disease outcome. Treatment outcome with thiazide diuretics in general may be corrupted in subjects with pre-existing low ANP activity. Adding a potassium-sparing agent might be speculated to overcome such disadvantage. In the future it may be wise to include potassium in the research on ANP and potentially salt-sensitivity and diuresis biomarkers in general. The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology [5]. References [1] John SW, Krege JH, Oliver PM, et al. Genetic decreases in atrial natriuretic peptide and salt-sensitive hypertension. Science 1995;267:679–81.
74
Letters to the Editor
[2] Rubattu S, Bigatti G, Evangelista A, et al. Association of atrial natriuretic peptide and type a natriuretic peptide receptor gene polymorphisms with left ventricular mass in human essential hypertension. J Am Coll Cardiol 2006;48:499–505. [3] Lynch AI, Boerwinkle E, Davis BR, et al. Pharmacogenetic association of the NPPA T2238C genetic variant with cardiovascular disease outcomes in patients with hypertension. JAMA 2008;299:296–307.
[4] Vormfelde SV, Sehrt D, Bolte D, Pahl S, Tzvetkov M, Brockmöller J. Hydrochlorothiazide efficacy and polymorphisms in ACE, ADD1 and GNB3 in healthy, male volunteers. Eur J Clin Pharmacol 2006;62: 195–201. [5] Coats AJ. Ethical authorship and publishing. Int J Cardiol 2009;131: 149–50.
0167-5273/$ - see front matter © 2008 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2008.12.028
Neopterin — Marker of coronary artery disease activity or extension in patients with chronic stable angina? Pablo Avanzas b , Ramón Arroyo-Espliguero c , Juan Carlos Kaski a,⁎ a
Coronary Artery Disease Research Unit, Cardiological Sciences, St. George's Hospital Medical School, London, UK b Area del Corazón, Hospital Universitario Central de Asturias, Oviedo, Spain c Division of Cardiology, Hospital General Universitario, Guadalajara, Spain Received 8 August 2008; accepted 6 December 2008 Available online 20 January 2009
Keywords: Neopterin; Inflammation; Coronary artery disease; Chronic stable angina
We read with great interest the recent article by Alber et al. [1], who assessed the relationship between the extent of coronary artery disease (CAD) and neopterin/CD4+CD28− lymphocytes in patients with chronic stable angina pectoris. They report that neopterin and CD4+CD28− lymphocytes are associated with the extent of CAD and indicate that neopterin might be useful in identifying stable angina patients who may be eligible for revascularization procedures. The results of Alber et al. [1] – in a small group of patients – contradict previous findings by our group in larger and well characterized groups of patients [2–5]. Unfortunately, however, Alber et al. seem not to have been aware of our studies, as they are not cited or discussed in the context of their recent findings reported in the Journal [1]. We have previously shown that increased neopterin levels, a marker of macrophage activation, predict adverse cardiovascular events during one year follow-up in patients with chronic stable angina [2]. Our data indicate that patients in the highest tertile of neopterin concentration had a three fold increase in ⁎ Corresponding author. Cardiovascular Biology Research Centre, Division of Cardiac and Vascular Sciences, St. George's Hospital, University of London, Cranmer Terrace, London SW17 0RE, UK. Tel.: +44 208 725 5901/3963; fax: +44 208 725 3328. E-mail address: [email protected] (J.C. Kaski).
the risk of developing adverse cardiovascular events compared to those in the lowest tertile, a finding that was independent of the severity of CAD in these patients. In addition, other studies from our group have shown a correlation between neopterin levels and the presence of multiple complex (vulnerable) plaques in patients with unstable angina [3,6]. We also showed that increased neopterin is a predictor of both worse outcome in hypertensive patients with non obstructive CAD [4] and rapid CAD progression in patients with CAD undergoing revascularization [5]. It is established that inflammation plays an important role in plaque vulnerability and disruption. In fact, previous work by Buffon et al. [7] and Rioufol et al. [8] suggests that the acute coronary syndrome represents a pancoronary condition associated with multiple plaque vulnerability. We have documented the association between neopterin and the presence of vulnerable-complex plaques thus endorsing the concept of inflammation as a pathogenic mechanism of pancoronary plaque vulnerability. Our work [2–5,9,10] and recent data from Ray et al. [11] indicate that neopterin levels identify a vulnerable phenotype among patients with both stable CAD and non-ST segment elevation ACS. These data in large groups of patients suggest – contrary to the Alber's results – that neopterin is more likely to be a marker of CAD activity rather than a measure of the anatomical extent of CAD.
Letters to the Editor [3] Takenaka K, Ai T, Shimizu W, et al. Exercise stress test amplifies genotype–phenotype correlation in the LOT1 and LQT2 forms of the long-QT syndrome. Circulation 2003;107:838–44. [4] Kirchhof P, Eckardt L, Franz MR, et al. Prolonged atrial action potential durations and polymorphic atrial tachyarrhythmias in patients with long QT syndrome. J Cardiovasc Electrophysiol 2003;14:1027–33. [5] Gong Q, Zhang L, Vincent GM, Horne BD, Zhou Z. Nonsense mutations in hERG cause a decrease in mutant mRNA transcripts by nonsense-mediated mRNA decay in human long-QT syndrome. Circulation 2007;116:17–24. [6] Coats AJ. Ethical authorship and publishing. Int J Cardiol 2009;131: 149–50.
Fig. 2. Mutation analysis of family members. Chromatograms showed a common single nucleotide mutation of c.C2212T, causing amino acid sequence of p.Q738X.
0167-5273/$ - see front matter © 2008 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2008.12.053
Atrial natriuretic peptide polymorphisms, hydrochlorothiazide and urinary potassium excretion Stefan Viktor Vormfelde b
a,⁎
, Mohammad Reza Toliat b , Peter Nürnberg b , Jürgen Brockmöller
a
a Department of Clinical Pharmacology, University Medical Center, Robert-Koch-Str. 40, 37075 Göttingen, Germany Cologne Center for Genomics (CCG) and Institute for Genetics, University of Cologne, Zuelpicher Straße 47, 50674 Köln, Germany
Received 6 August 2008; accepted 6 December 2008 Available online 11 January 2009
Keywords: Atrial natriuretic peptide; Genetic polymorphism; Thiazide diuretic; Hydrochlorothiazide; Antihypertensive therapy; Potassium
NPPA disruption goes with salt-sensitive hypertension in mice [1]. In humans, the methionine32 allele of Val32Met (G664A, rs5063) has been associated with low circulating proANP levels [2]. Both methionine32 and the arginine152 allele of the Ter152Arg polymorphism (T2238C, rs5065) have been associated with hypertension or hypertensionrelated disease (overview in [3]). In conclusion, both variant alleles are supposed to be low functional alleles compared
⁎ Corresponding author. Tel.: +49 551 399651; fax: +49 551 12767. E-mail address: [email protected] (S.V. Vormfelde).
to the respective wild-type alleles. Now, in the ALLHAT study, coronary heart disease outcome tended better or was significantly better in carriers of the variant alleles [3]. In contrast, the overall survival tended lower in these subjects. We explored a potential association of the NPPA polymorphisms with diuretic effects of another thiazide diuretic, hydrochlorothiazide, in a single-dose cross-over study with 25 and 100 mg hydrochlorothiazide in 103 healthy, normotensive volunteers. The study was approved by the Ethics committee of the University of Göttingen; all participants provided written informed consent. The participants were 103 normotensive, healthy, male Caucasian volunteers aged between 18 and
Letters to the Editor Table 1 Urinary excretion by ANP genotype. Na
K+ g/24 h b
Na+ g/24 h b
25 mg hydrochlorothiazide Val/Val Ter/Ter 67 Val/Val Ter/Arg 24 Val/Val Arg/Arg 3 5 Val/Met c
3.6 (1.1) 4.1 (1.4) 4.8 (0.9) 4.8 (0.9)
4.6 (1.8) 5.0 (2.4) 4.9 (1.4) 4.5 (1.9)
100 mg hydrochlorothiazide Val/Val Ter/Ter Val/Val Ter/Arg Val/Val Arg/Arg Val/Met c
3.9 (1.2) 4.3 (1.2) 6.0 (1.6) 5.0 (0.9)
6.1 (2.1) 6.9 (2.6) 5.6 (1.5) 6.4 (1.6)
64 25 3 7
a
Number of subject sums do not equal 103 as not all subjects could be included in all analyses. b Data are given as mean (SD). c Ter/Ter homozygotes and one Ter/Arg subject.
49 years (mean ± SD: 28 ± 7.5), mostly students at Göttingen university, with body mass index values ranging from 18.7 to 29.6 kg/m2 (24.4 ± 2.4). The volunteers ingested single oral doses of 25 and 100 mg of the thiazide diuretic drug hydrochlorothiazide on two separate occasions as described earlier [4]. Each occasion consisted of 3 days, a diet run-in day, a placebo day and a verum day. Low-sodium diet was mandatory throughout all 3 days. Placebo and verum days were performed identically except for the content of the drug capsule: blood and urine were collected at 0, 1, 3, 6, 10 and 24 h after drug intake and during the respective intervals. Val32Met and Ter152Arg were observed with variant allele frequencies of 0.07 and 0.16; all subjects could be analysed, both polymorphisms were in Hardy–Weinberg equilibrium. There was no linkage between the variant alleles in accordance with earlier findings (e.g. compare www.hapmap.org) and no methionine32 homozygous subject was observed. This resulted in the four genotypic groups given in Table 1. Covariance analysis was performed with SPSS 12.0. One model term was the two study days and two model terms were the interaction of each one polymorphism with the two study days. The given p-values refer to these interaction terms. Potassium excretion was significantly associated with the ANP genotype. It was higher in carriers of a variant allele of any of the two polymorphisms compared to carriers of only wild-type alleles (Table 1). Covariance analysis revealed that the 24 h urinary potassium excretion was 3.6 ± 0.1 and 3.9 ± 0.1 g in only wild-type allele carriers with 25 and 100 mg hydrochlorothiazide (mean ± SEM) and was 0.5 ± 0.2 and 0.6 ± 0.2 g higher per arginine152 allele (p = 0.004) and 1.1 ± 0.5 and 1.0 ± 0.5 g higher per methionine32 allele (p = 0.016). As this was an exploratory study we did not formally control for multiple testing. Bonferronicorrection would leave the potassium–arginine152 associa-
73
tion significant assuming up to twelve tests of unrelated parameters. On the placebo days, only minor and statistically not significant trends to higher potassium excretion in the variant allele carriers were observed (p = 0.113 and 0.416). Compared to the placebo days, hydrochlorothiazide intake increased the urinary potassium excretion by 0.7 ± 0.1 and 1.1 ± 0.1 g in carriers of only wild-type alleles on the 25 mg and the 100 mg study days. Potassium excretion was additionally increased by 0.3 ± 0.2 and 0.2 ± 0.2 g per arginine152 allele (p = 0.086) and by 0.4 ± 0.4 and 1.0 ± 0.4 g per metionine32 allele (p = 0.012) by 25 mg and 100 mg hydrochlorothiazide, respectively. These associations were stable, controlling for the three polymorphisms reported earlier to affect diuresis in this study population [4]. Sodium excretion (Table 1), chloride and volume excretion also tended somewhat higher on the verum days in the variant allele carriers but these associations were weak and statistically not significant. The serum potassium concentration fell by 0.08 ± 0.03 and 0.12 ± 0.03 mM within 24 h after 25 and 100 mg hydrochlorothiazide, respectively, and also the sodium and the chloride concentration fell. However, neither potassium, nor any other electrolyte concentration was associated with the ANP genotype, neither before, nor after hydrochlorothiazide (most p-values N 0.3). However, this doesn't rule out an effect on the long term. Carriers of ANP precursor gene alleles that are supposed to be low functional alleles excreted more potassium on hydrochlorothiazide intake than did carriers of the higher functional alleles. ANP acts diuretically by indirect inhibition of the epithelial sodium channel ENaC in renal collecting ducts. Thus it is pathophysiologically plausible that carriers of low functional alleles are prone to hypertension. ENaC reabsorbs sodium substitutional for potassium. Thus, carriers of lower functional ANP alleles may reabsorb more sodium and excrete more potassium. Thereby such subjects could be endangered by the additional urinary potassium loss that we observed. Hypokalemia can be devastating and thus it may be speculated that higher urinary potassium loss may have contributed to mortality in the ALLHAT study that caused the absent association with overall survival despite the better coronary heart disease outcome. Treatment outcome with thiazide diuretics in general may be corrupted in subjects with pre-existing low ANP activity. Adding a potassium-sparing agent might be speculated to overcome such disadvantage. In the future it may be wise to include potassium in the research on ANP and potentially salt-sensitivity and diuresis biomarkers in general. The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology [5]. References [1] John SW, Krege JH, Oliver PM, et al. Genetic decreases in atrial natriuretic peptide and salt-sensitive hypertension. Science 1995;267:679–81.
74
Letters to the Editor
[2] Rubattu S, Bigatti G, Evangelista A, et al. Association of atrial natriuretic peptide and type a natriuretic peptide receptor gene polymorphisms with left ventricular mass in human essential hypertension. J Am Coll Cardiol 2006;48:499–505. [3] Lynch AI, Boerwinkle E, Davis BR, et al. Pharmacogenetic association of the NPPA T2238C genetic variant with cardiovascular disease outcomes in patients with hypertension. JAMA 2008;299:296–307.
[4] Vormfelde SV, Sehrt D, Bolte D, Pahl S, Tzvetkov M, Brockmöller J. Hydrochlorothiazide efficacy and polymorphisms in ACE, ADD1 and GNB3 in healthy, male volunteers. Eur J Clin Pharmacol 2006;62: 195–201. [5] Coats AJ. Ethical authorship and publishing. Int J Cardiol 2009;131: 149–50.
0167-5273/$ - see front matter © 2008 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2008.12.028
Neopterin — Marker of coronary artery disease activity or extension in patients with chronic stable angina? Pablo Avanzas b , Ramón Arroyo-Espliguero c , Juan Carlos Kaski a,⁎ a
Coronary Artery Disease Research Unit, Cardiological Sciences, St. George's Hospital Medical School, London, UK b Area del Corazón, Hospital Universitario Central de Asturias, Oviedo, Spain c Division of Cardiology, Hospital General Universitario, Guadalajara, Spain Received 8 August 2008; accepted 6 December 2008 Available online 20 January 2009
Keywords: Neopterin; Inflammation; Coronary artery disease; Chronic stable angina
We read with great interest the recent article by Alber et al. [1], who assessed the relationship between the extent of coronary artery disease (CAD) and neopterin/CD4+CD28− lymphocytes in patients with chronic stable angina pectoris. They report that neopterin and CD4+CD28− lymphocytes are associated with the extent of CAD and indicate that neopterin might be useful in identifying stable angina patients who may be eligible for revascularization procedures. The results of Alber et al. [1] – in a small group of patients – contradict previous findings by our group in larger and well characterized groups of patients [2–5]. Unfortunately, however, Alber et al. seem not to have been aware of our studies, as they are not cited or discussed in the context of their recent findings reported in the Journal [1]. We have previously shown that increased neopterin levels, a marker of macrophage activation, predict adverse cardiovascular events during one year follow-up in patients with chronic stable angina [2]. Our data indicate that patients in the highest tertile of neopterin concentration had a three fold increase in ⁎ Corresponding author. Cardiovascular Biology Research Centre, Division of Cardiac and Vascular Sciences, St. George's Hospital, University of London, Cranmer Terrace, London SW17 0RE, UK. Tel.: +44 208 725 5901/3963; fax: +44 208 725 3328. E-mail address: [email protected] (J.C. Kaski).
the risk of developing adverse cardiovascular events compared to those in the lowest tertile, a finding that was independent of the severity of CAD in these patients. In addition, other studies from our group have shown a correlation between neopterin levels and the presence of multiple complex (vulnerable) plaques in patients with unstable angina [3,6]. We also showed that increased neopterin is a predictor of both worse outcome in hypertensive patients with non obstructive CAD [4] and rapid CAD progression in patients with CAD undergoing revascularization [5]. It is established that inflammation plays an important role in plaque vulnerability and disruption. In fact, previous work by Buffon et al. [7] and Rioufol et al. [8] suggests that the acute coronary syndrome represents a pancoronary condition associated with multiple plaque vulnerability. We have documented the association between neopterin and the presence of vulnerable-complex plaques thus endorsing the concept of inflammation as a pathogenic mechanism of pancoronary plaque vulnerability. Our work [2–5,9,10] and recent data from Ray et al. [11] indicate that neopterin levels identify a vulnerable phenotype among patients with both stable CAD and non-ST segment elevation ACS. These data in large groups of patients suggest – contrary to the Alber's results – that neopterin is more likely to be a marker of CAD activity rather than a measure of the anatomical extent of CAD.