ABCA1 impacts athero-thrombotic risk and 10-year survival in a contemporary secondary prevention setting.

OBJECTIVES: We prospectively investigated the effects of ATP-binding cassette protein-1 (ABCA1) variants on long-term clinical outcome in patients with coronary artery disease (CAD). BACKGROUND: ABCA1 is implicated in the etiology of atherothrombosis and may offer a target to reduce cardiovascular risk. However, the impact of ABCA1 on recurrent cardiovascular disease in a secondary prevention setting is as of yet unknown. METHODS: We studied cause-specific 10-year mortality and quantitative coronary angiography data from the Regression GRowth Evaluation Statin Study (REGRESS), comprising 884 male CAD patients genotyped for promoter variants encompassing a proximal regulatory region (rs2422493, rs1800976, rs2740483 and rs1800977). Kaplan-Meier, proportional hazards and haplotype analyses were used to ascertain single-variant and multi-marker effects on absolute risk and extent of CAD. RESULTS: Protection from 10-year vascular death could be attributed to the rs2422493 genotype (available in 639 patients) T allele with absolute risk decreasing stepwise from 12.2% to 8.6% to 4.7% per each added allele copy, HR 0.64, p=0.03 and HR 0.53, p=0.04 in the TGCC haplotype context. The TGCC (p=0.04) and TCCT (p=0.003) haplotypes exhibited less extensive CAD. CONCLUSIONS: On a background of contemporary secondary prevention, variation in the ABCA1 promoter influences 10-year risk of vascular death and angiographic extent of CAD in men. These insights contribute to identification of patients sharing a specific prognosis, understanding of its etiological basis and development of strategies of risk reduction in CAD.

Paraoxonase variants relate to 10-year risk in coronary artery disease: impact of a high-density lipoprotein-bound antioxidant in secondary prevention.

OBJECTIVES: We investigated the effects of paraoxonase (PON)-1 variants on long-term clinical outcome in patients with coronary artery disease (CAD). BACKGROUND: PON-1 is a potential therapeutic target to further reduce cardiovascular risk because it is a detoxifying esterase with antioxidant properties. The PON-1 knockout models result in higher susceptibility to atherosclerosis, and PON activity contributes to cardiovascular risk in humans. Human gene variants determine PON activity; however, the impact of these variants on recurrent cardiovascular events in vascular disease is as of yet unknown. METHODS: We conducted a 10-year follow-up study of 793 CAD patients in the REGRESS (REgression GRowth Evaluation Statin Study) trial cohort, using nationwide registries. Genotypes were obtained of 2 PON-1 isotypes (L55M, rs854560, and Q192R, rs662), which were previously associated with PON activity. Absolute and relative risks by genotype were estimated using Kaplan-Meier and proportional hazards analyses. RESULTS: Carriership of the PON-1 glutamine isotype at codon 192 and methionine at codon 55 was associated with a higher risk of death due to ischemic heart disease. Hazard ratios per allele copy were 1.71 (95% confidence interval: 1.0 to 2.8, p=0.03) for the glutamine isotype at codon 192 and 1.56 (95% confidence interval: 1.1 to 2.3, p=0.03) for methionine at codon 55. Both isotypes had previously been related to lower PON activity. No effect was observed on all-cause mortality. CONCLUSIONS: PON-1 gene variants influence the 10-year risk of fatal complications from CAD in male patients, despite no effect on all-cause mortality. These long-term findings confirm functional data on PON-1 activity, emphasize the relevance of this pathway in vascular disease, and enforce its putative role as a target to modify and estimate cardiovascular risk.

PPAR gamma variant influences angiographic outcome and 10-year cardiovascular risk in male symptomatic coronary artery disease patients.

OBJECTIVE: Activation of peroxisome proliferator-activated receptor (PPAR)-gamma signaling influences metabolic profiles and the propensity toward inflammation. Small-molecule stimulation of PPARgamma is investigated for secondary prevention of cardiovascular disease. The common PPARgamma Pro12Ala variant has functional and prognostic consequences. A protective effect of the 12Ala-allele carriership on diabetes and myocardial infarction in healthy populations has been suggested. The relevance of this pathway also needs exploration in patients with manifest vascular disease. We investigated the effects of carriership of the Pro12Ala variant on angiographic and cardiovascular event outcomes in male patients with symptomatic coronary artery disease (CAD). RESEARCH DESIGN AND METHODS: The Regression Growth Evaluation Statin Study (REGRESS) cohort was genotyped for the Pro12Ala variant (rs1801282). Ten-year follow-up was derived from nation-wide registries, and risks were estimated using proportional hazards. Quantitative coronary angiography measurements were obtained and relations with genotype estimated using a generalized linear model. RESULTS: Genotypes ascertained (n = 679) comprised 540 (80%) Pro/Pro, 126 (19%) Pro/Ala, and 13 (2%) Ala/Ala subjects. The 12Ala allele was associated with less extensive focal (P = 0.001) and diffuse (P = 0.002) atherosclerosis and lower 10-year cardiovascular risk. Hazard ratios were 0.10 (95% CI 0.01-0.70, P = 0.02) for ischemic heart disease and 0.24 (0.08-0.74, P = 0.013) for vascular death, per each added copy of 12Ala, respectively. CONCLUSIONS: Carriers of the 12Ala allele of PPARgamma have less widespread CAD and are considerably protected against 10-year (cardio)vascular morbidity and mortality. These long-term findings in patients with manifest CAD support an important role of PPARgamma in determining vascular risk.

Coronary collaterals improve prognosis in patients with ischemic heart disease.

BACKGROUND: The recruitment of coronary collateral vessels results from an endogenous adaptation to ischemic heart disease (IHD). Presence of collaterals may exert protection at the time of acute or chronic obstructive coronary disease. The protective role of collaterals in patients with extensive coronary artery disease however, has been disputed. We examined the effects of coronary collateral circulation on cardiovascular outcomes, with an emphasis on clinical prognostic value and on a putative role of IHD burden. METHODS: Data analyzed were obtained in the REGRESS study, involving 879 male participants undergoing coronary angiography and being followed for 24 months. Presence of coronary collaterals spontaneously visible on angiography was assessed. Events included: myocardial infarction (MI), coronary heart disease death and percutaneous or surgical coronary intervention. Estimates of relative risks of outcome events were calculated using proportional hazard analysis, with adjustments for confounding factors and stratification for initial revascularization strategy and factors reflecting extent of IHD burden. RESULTS: Event-free survival after two years was 84% in patients without collaterals, and 92% in patients with collaterals (p=0.0020). The crude HR was 0.48 (95% CI: 0.30-0.77), and 0.38 (0.23-0.65) after adjustment for confounders and cardiovascular risk factors. The protective effect of coronary collaterals was not modified by the extent of IHD burden (interaction p=0.99). CONCLUSION: The angiographical presence of coronary collaterals is a clinical predictor of cardiovascular prognosis. Collaterals exert a protective effect on outcome in a broad spectrum of patients. Our data suggest that this protective effect is independent of disease burden, and remains present in patients with extensive IHD.

CETP genotype predicts increased mortality in statin-treated men with proven cardiovascular disease: an adverse pharmacogenetic interaction.

AIMS: Inhibition of cholesteryl ester transfer protein (CETP) increases HDL-cholesterol. However, its combination with statins may increase mortality by factors incompletely understood. We previously observed that patients with intrinsically low CETP levels (carriers of the TaqIB-B2 allele) may have less benefit from statin therapy, and here tested this pharmacogenetic hypothesis on long-term outcomes. METHODS AND RESULTS: We performed a 10-year follow-up analysis in 812 coronary artery disease (CAD) patients (REGRESS cohort), treated with statins after an initial 2-year study period. Carriers of TaqIB-B2 showed reduced CETP levels and higher HDL-cholesterol (P < 0.001 for both). Despite these lower CETP and higher HDL-cholesterol levels, hazard ratios per B2 copy were 1.59 (P = 0.01) for atherosclerotic disease death, 1.53 (P = 0.03) for ischaemic heart disease death, and 1.30 (P = 0.04) for all-cause mortality. Haplotype-effects analysis provided even stronger basis for the genetics involved: one risk-haplotype was identified that was highly significantly associated with these endpoints. CONCLUSION: In statin-treated male CAD patients, genetic variation conferring low CETP levels is associated with increased 10-year mortality. This suggests that efficacy of statin therapy to reduce cardiovascular risk depends on CETP genotype and associated CETP plasma levels. This effect may need consideration when administering CETP inhibition to CAD patients.

Inflammatory gene haplotype-interaction networks involved in coronary collateral formation.

OBJECTIVES: Formation of collateral circulation is an endogenous response to atherosclerosis, and is a natural escape mechanism by re-routing blood. Inflammatory response- related genes underlie the formation of coronary collaterals. We explored the genetic basis of collateral formation in man postulating interaction networks between functional Single Nucleotide Polymorphisms (SNPs) in these inflammatory gene candidates. METHODS: The contribution of 41 genes as well as the interactions among them was examined in a cohort of 226 coronary artery disease patients, genotyped for 54 candidate SNPs. Patients were classified to the extent of collateral circulation. Stepwise logistic regression analysis and a haplotype entropy procedure were applied to search for haplotype interactions among all 54 polymorphisms. Multiple testing was addressed by using the false discovery rate (FDR) method. RESULTS: The population comprised 84 patients with and 142 without visible collaterals. Among the 41 genes, 16 pairs of SNPs were implicated in the development of collaterals with the FDR of 0.19. Nine SNPs were found to potentially have main effects on collateral formation. Two sets of coupling haplotypes that predispose to collateral formation were suggested. CONCLUSIONS: These findings suggest that collateral formation may arise from the interactions between several SNPs in inflammatory response related genes, which may represent targets in future studies of collateral formation. This may enhance developing strategies for risk stratification and therapeutic stimulation of arteriogenesis.

Sustained suppression of peripheral blood immune functions by treatment with mycophenolate mofetil correlates with reduced severity of cardiac allograft rejection.

BACKGROUND: We tested the hypothesis that sustained suppression of immune functions by mycophenolate mofetil (MMF) throughout the dosing interval reduces the severity of rejection. METHODS: Four groups of rat heart allograft recipients were treated orally daily through Day 5 with either: "low-dose" MMF, 10 mg/kg once daily (QD) or 5 mg/kg twice daily (BID); or "high-dose" MMF, 20 mg/kg QD or 10 mg/kg BID. The following were determined for all animals on Day 6: pharmacokinetics (PK, using high-performance liquid chromatography) of mycophenolic acid (MPA); pharmacodynamics (PD, by flow cytometry quantitation of whole blood mitogen-stimulated lymphocyte proliferation and expression of diverse T-cell surface activation molecules); and histologic graft rejection scores (RS). RESULTS: RS correlated with PD for suppression of both lymphocyte proliferation and transferrin receptor expression (r2 = 0.85 and 0.81, respectively) more highly than with MPA plasma levels (r2 = 0.45), which shows the validity of PD as surrogate markers of MMF efficacy. MMF 5 mg/kg BID produced greater (p < 0.001) suppression of lymphocyte proliferation (area under the PD effect-time curve, AUE = 2,010% inhibition. hour) and sustained trough (E0) PD effect (86% suppression) than MMF 10 mg/kg QD (AUE = 1,436% inhibition. hour, E0 = 55%). RS did not differ between the 20 mg/kg QD and 10 mg/kg BID "high-dose" groups, because PD was maximally suppressed. CONCLUSIONS: PD were surrogate markers for MMF immunosuppressive efficacy. MMF 5 mg/kg BID produced more sustained suppression of both PD and rejection than MMF 10 mg/kg QD.