Plasma myeloperoxidase predicts incident cardiovascular risks in stable patients undergoing medical management for coronary artery disease

BACKGROUND

Myeloperoxidase (MPO) concentrations predict adverse clinical outcomes in the setting of acute coronary syndromes and heart failure, but the prognostic role of MPO in stable patients with known atherosclerotic burden is unclear.

METHODS

We examined plasma MPO concentrations and their relationship with prevalent significant coronary artery disease (defined as >50% stenosis in any coronary vessel) and incident major adverse cardiovascular events (MACEs), including death, myocardial infarction, and stroke, in a 3-year prospective follow-up study of 1895 patients undergoing elective coronary angiography.

RESULTS

The median plasma MPO concentration was 101 pmol/L (interquartile range 68-187 pmol/L). Patients with plasma MPO concentrations >322 pmol/L (14.6% of population) had increased risk of developing future MACEs [hazard ratio (HR) 1.78, 95% CI 1.33-2.37, P < 0.001], and MPO as a single variable predictor of MACE showed an area under the ROC curve of 0.67. After adjusting for traditional cardiac risk factors, creatinine clearance, B-type natriuretic peptide, and high-sensitivity C-reactive protein (hsCRP), increased MPO concentrations remained significantly associated with incident MACEs over the ensuing 3-year period (HR 1.71; 95% CI 1.27-2.30, P < 0.001). In patients with increased hsCRP, MPO ≤322 pmol/L was associated with lower event rates than observed with MPO >322 pmol/L.

CONCLUSIONS

Plasma MPO concentrations provide independent prognostic value for the prediction of long-term incident MACEs in a stable, medically managed patient population with coronary artery disease. In individuals with increased hsCRP concentrations, we observed lower risk of incident MACEs when concomitant MPO concentrations were low vs when MPO concentrations were high.

Biomarkers of inflammation and oxidative stress in atherosclerosis

Increasing evidence has highlighted the roles of oxidative stress and inflammation in the promotion of atherosclerotic cardiovascular disease. Recent pathological studies have elucidated specific mediators that appear to link these pathways to the progression and rupture of atherosclerotic plaque in the artery wall. The ability to measure levels of these mediators in the systemic circulation has provoked interest in their development as biomarkers for potential use in risk assessment and in evaluation of the response to the use of preventive therapies. The discovery of these pathological mediators and their potential translation to the clinical arena will be reviewed.

Strategies for the development of new PPAR agonists in diabetes

Diabetes is associated with a range of metabolic abnormalities including insulin resistance, atherogenic dyslipidemia, hypertension, and inflammation. These factors are likely to underlie the adverse cardiovascular outcome typically observed in diabetic cohorts. The family of peroxisome proliferator-activated receptors (PPARs) have been implicated in the regulation of a number of physiologic and metabolic pathways. Pharmacologic agonists directed against various PPARs have been shown to have a beneficial impact on these metabolic risk factors. The potential impact on cardiovascular risk with the use of PPAR agonists will be reviewed.

Lipoprotein(a) levels and long-term cardiovascular risk in the contemporary era of statin therapy

Lipoprotein(a) [Lp(a)] has enhanced atherothrombotic properties. The ability of Lp(a) levels to predict adverse cardiovascular outcomes in patients undergoing coronary angiography has not been examined. The relationship between serum Lp(a) levels and both the extent of angiographic disease and 3-year incidence of major adverse cardiovascular events (MACE: death, myocardial infarction, stroke, and coronary revascularization) was investigated in 2,769 patients who underwent coronary angiography [median Lp(a) 16.4 mg/dl, elevated levels (≥30 mg/dl) in 38%]. An elevated Lp(a) was associated with a 2.3-fold [95% confidence interval (CI), 1.7-3.2, P < 0.001] greater likelihood of having a significant angiographic stenosis and 1.5-fold (95 CI, 1.3-1.7, P < 0.001) greater chance of three-vessel disease. Lp(a)≥30 mg/dl was associated with a greater rate of MACE (41.8 vs. 35.8%, P = 0.005), primarily due to a greater need for coronary revascularization (30.9 vs. 26.0%, P = 0.02). A relationship between Lp(a) levels and cardiovascular outcome was observed in patients with an LDL cholesterol (LDL-C) ≥70-100 mg/dl (P = 0.049) and >100 mg/dl (P = 0.02), but not <70 mg/dl (P = 0.77). Polymorphisms of Lp(a) were also associated with both plasma Lp(a) levels and coronary stenosis, but not a greater rate of MACE. Lp(a) levels correlate with the extent of obstructive disease and predict the need for coronary revascularization in subjects with suboptimal LDL-C control. This supports the need to intensify lipid management in patients with elevated Lp(a) levels.

Intravascular ultrasound-derived measures of coronary atherosclerotic plaque burden and clinical outcome

OBJECTIVES

The aim of this study was to investigate the relationship between intravascular ultrasound (IVUS)-derived measures of atherosclerosis and cardiovascular outcomes.

BACKGROUND

IVUS has been used in clinical trials to evaluate the effect of medical therapies on coronary atheroma progression.

METHODS

Coronary plaque progression was evaluated in 4,137 patients in 6 clinical trials that used serial IVUS. The relationship between baseline and change in percent atheroma volume (PAV) and total atheroma volume with incident major adverse cardiovascular events (MACE) was investigated.

RESULTS

PAV increased by 0.3% (p < 0.001), and 19.9% of subjects experienced MACE (0.9% death, 1.8% myocardial infarction, 18.9% coronary revascularization). Greater baseline PAVs were observed in patients who experienced myocardial infarctions (42.2 +/- 9.6% vs. 38.6 +/- 9.1%, p = 0.001), coronary revascularization (41.2 +/- 9.3% vs. 38.1 +/- 9.0%, p < 0.001), or MACE (41.3 +/- 9.2% vs. 38.0 +/- 9.0%, p < 0.001). Each standard deviation increase in PAV was associated with a 1.32-fold (95% confidence interval: 1.22 to 1.42; p < 0.001) greater likelihood of experiencing a MACE. During follow-up (21.1 +/- 3.7 months), greater increases in PAV, but not total atheroma volume, were observed in subjects who experienced MACE compared with those who did not (0.95 +/- 0.19% vs. 0.46 +/- 0.16%, p < 0.001). Each standard deviation increase in PAV was associated with a 1.20-fold (95% confidence interval: 1.10 to 1.31; p < 0.001) greater risk for MACE. Multivariate analysis revealed that factors associated with MACE included baseline PAV (p < 0.0001), change in PAV (p = 0.002), smoking (p = 0.0002) and hypertension (p = 0.01).

CONCLUSIONS

A direct relationship was observed between the burden of coronary atherosclerosis, its progression, and adverse cardiovascular events. The relationship between disease progression and outcomes largely reflected the need for coronary revascularization. These data support the use of atherosclerosis imaging with IVUS in the evaluation of novel antiatherosclerotic therapies.

Plaque progression in coronary arteries with minimal luminal obstruction in intravascular ultrasound atherosclerosis trials

The relation among the burden of disease, progression of atherosclerosis, and remodeling in angiographically minimally diseased coronary arteries has not been defined. The present analysis included 1,906 patients who participated in 5 prospective clinical trials examining atheroma progression using intravascular ultrasonography. For the present analysis, the patients were stratified according to baseline quantitative coronary angiographic stenosis: <20%, 20% to 35%, and >35%. Patients with a lesser degree of luminal stenosis had less atherosclerosis. However, in the arteries with minimal angiographic stenosis, a large percentage of images contained atheroma, demonstrating the diffuse nature of coronary atherosclerosis. All 3 groups showed evidence of disease progression. The serial changes in vessel dimensions revealed that both the external elastic membrane and lumen volumes decreased in all 3 subgroups, in keeping with vessel and luminal constriction. In conclusion, these findings have demonstrated that patients with at least one luminal stenosis have diffuse atherosclerosis that progressed during 18 to 24 months, making them a target for therapeutic intervention. These minimally diseased arteries demonstrated evidence of vessel and luminal constriction, regardless of the angiographic appearance.

Comparison of rates of progression of coronary atherosclerosis in patients with diabetes mellitus versus those with the metabolic syndrome

Diabetes mellitus (DM) and metabolic syndrome (MS) are associated with adverse cardiovascular outcomes. However, the extent and progression of coronary atherosclerosis for these conditions have not been directly compared. Three thousand four hundred fifty-nine patients with coronary artery disease underwent serial evaluation of atheroma burden by intravascular ultrasound. Patients with DM, MS, or neither diagnosis were compared with regard to plaque burden, progression, and arterial remodeling. Among the 3 groups, patients with MS had the largest number of individual cardiovascular risk factors. Patients with DM demonstrated more extensive atherosclerosis burden with a greater percent atheroma volume compared to patients with MS or those with neither diagnosis (40.3 +/- 9.0%, 37.6 +/- 8.9%, and 38.1 +/- 9.1%, p <0.001) and total atheroma volume (198.3 +/- 85.9, 190.7 +/- 85.0, and 186.3 +/- 79.1 mm(3), p = 0.05). MS compared to neither diagnosis was accompanied by expansion of the external elastic membrane (501.3 +/- 174.3 vs 484.4 +/- 160.7 mm(3), p = 0.02), whereas DM was associated with lumen constriction (290.6 +/- 111.7 vs 298.1 +/- 105.5 mm(3), p <0.0001). On serial evaluation, DM, but not MS, was associated with greater progression of percent atheroma volume compared to neither diagnosis (+0.8 +/- 0.3, +0.3 +/- 0.2, and +0.1 +/- 0.2%, p <0.0001) and total atheroma volume (-1.0 +/- 1.8, -3.3 +/- 1.8, and -4.0 +/- 1.8 mm(3), p = 0.001). Meeting criteria for MS was not associated with greater disease progression in patients with DM. In conclusion, despite having fewer individual risk factors, DM is associated with greater plaque progression and more constrictive remodeling than MS. This finding highlights the deleterious effects of DM on the arterial wall independent of its associated metabolic abnormalities.

Effects of fibrates on cardiovascular outcomes: a systematic review and meta-analysis

BACKGROUND

Several clinical trials have reported inconsistent findings for the effect of fibrates on cardiovascular risk. We undertook a systematic review and meta-analysis to investigate the effects of fibrates on major clinical outcomes.

METHODS

We systematically searched Medline, Embase, and the Cochrane Library for trials published between 1950 and March, 2010. We included prospective randomised controlled trials assessing the effects of fibrates on cardiovascular outcomes compared with placebo. Summary estimates of relative risk (RR) reductions were calculated with a random effects model. Outcomes analysed were major cardiovascular events, coronary events, stroke, heart failure, coronary revascularisation, all-cause mortality, cardiovascular death, non-vascular death, sudden death, new onset albuminuria, and drug-related adverse events.

FINDINGS

We identified 18 trials providing data for 45 058 participants, including 2870 major cardiovascular events, 4552 coronary events, and 3880 deaths. Fibrate therapy produced a 10% RR reduction (95% CI 0-18) for major cardiovascular events (p=0.048) and a 13% RR reduction (7-19) for coronary events (p<0.0001), but had no benefit on stroke (-3%, -16 to 9; p=0.69). We noted no effect of fibrate therapy on the risk of all-cause mortality (0%, -8 to 7; p=0.92), cardiovascular mortality (3%, -7 to 12; p=0.59), sudden death (11%, -6 to 26; p=0.19), or non-vascular mortality (-10%, -21 to 0.5; p=0.063). Fibrates reduced the risk of albuminuria progression by 14% (2-25; p=0.028). Serious drug-related adverse events were not significantly increased by fibrates (17 413 participants, 225 events; RR 1.21, 0.91-1.61; p=0.19), although increases in serum creatinine concentrations were common (1.99, 1.46-2.70; p<0.0001).

INTERPRETATION

Fibrates can reduce the risk of major cardiovascular events predominantly by prevention of coronary events, and might have a role in individuals at high risk of cardiovascular events and in those with combined dyslipidaemia.

FUNDING

National Health and Medical Research Council of Australia.

Critical appraisal of laropiprant and extended-release niacin combination in the management of mixed dyslipidemias and primary hypercholesterolemia

Niacin is a B-complex vitamin which has been used for decades for the management of mixed dyslipidemias and primary hypercholesterolemia. It decreases the risk of cardiovascular events either when used as a monotherapy or in combination with other lipid lowering medications. However, a major limitation to its use is niacin-induced flushing occurring even with the extended-release formulations. Laropiprant, a selective prostaglandin-2 receptor inhibitor, specifically targets the cascade of events causing the flushing. It has been recently used in combination with extended-release niacin. This article will review the early experience with this combination with focus on efficacy, safety, tolerability and current place in therapy. Early data are promising and suggest that more patients in clinical practice will benefit from niacin combined with laropiprant. Ongoing clinical trials will provide a better insight on the long-term safety of the drug and its efficacy for reducing cardiovascular events.

The metabolic syndrome, its component risk factors, and progression of coronary atherosclerosis

BACKGROUND

The mechanism that confers adverse cardiovascular prognosis in patients with the metabolic syndrome (MetS) remains unclear. We sought to investigate the association of MetS and its component risk factors with progression of coronary atherosclerosis.

METHODS

We performed a systematic review of 3459 patients who participated in 7 clinical trials that monitored coronary atheroma progression with intravascular ultrasonography. Patients with or without MetS were compared with regard to clinical characteristics, coronary atheroma burden at baseline, and change on serial evaluation. Relationships between plaque progression (> or =5% increase in percent atheroma volume [PAV]), MetS, and its component risk factors were investigated.

RESULTS

The metabolic syndrome was highly prevalent and was associated with greater progression of PAV (+0.51% +/- 0.23% vs +0.23% +/- 0.24%; P = .003). Multivariable analysis showed that MetS was associated with a greater likelihood of undergoing progression of PAV (adjusted odds ratio [OR], 1.25; 95% confidence interval [CI], 1.05-1.48; P = .01). When the individual components were used in the model instead of MetS, hypertriglyceridemia (OR, 1.26; 95% CI, 1.06-1.49; P = .008) and a body mass index of 30 or higher (1.18, 1.00-1.40; P = .05) predicted progression of PAV. However, after adjusting for its individual components, MetS was no longer an independent predictor (OR, 1.04; 95% CI, 0.79-1.37; P = .79).

CONCLUSION

Although accelerated disease progression is observed in the setting of MetS, this is owing to the presence of individual component risk factors rather than to the presence of the syndrome itself.

Rationale and approach to evaluation of the impact of medical therapies on progression of atherosclerosis with arterial wall imaging

BACKGROUND

Despite the benefit of medical therapies, there remains a substantial residual risk of cardiovascular events. Atherosclerosis imaging has been used to assess new therapies.

SCOPE

A selective review of current imaging techniques used to evaluate novel anti-atherosclerotic therapies.

FINDINGS

Noninvasive and invasive arterial wall imaging permits characterization of the quantity and composition of atherosclerotic plaque. Serial imaging enables assessment of the impact of therapies on the natural history of disease progression.

CONCLUSION

Both noninvasive and invasive imaging modalities can be used in development programs to provide an early assessment of the impact of novel anti-atherosclerotic agents.

Findings of clinical trials that evaluate the impact of medical therapies on progression of atherosclerosis

BACKGROUND

Arterial wall imaging has been increasingly employed in clinical trials to evaluate the impact of medical therapies on progression of atherosclerosis.

SCOPE

A selective overview of major findings from clinical trials that assessed the impact of medical therapies on atherosclerosis progression.

FINDINGS

Targeting established risk factors including LDL cholesterol, HDL cholesterol and blood pressure has a beneficial impact on disease progression.

CONCLUSION

As a result, vascular imaging has been employed in the early evaluation of experimental therapies.

Future requirement for arterial wall imaging modalities in the evaluation of novel anti-atherosclerotic therapies

BACKGROUND

While arterial wall imaging has been used to characterize progression of atherosclerosis, there remain limitations to this approach.

SCOPE

A selective overview of emerging modalities to image the artery wall and highlight how they may be used to evaluate emerging anti-atherosclerotic agents.

FINDINGS

Ongoing developments appear to enable assessment of composition and molecular properties of plaque in addition to quantitation of burden. Non-invasiveness and correlation with clinical outcome remains a challenge.

CONCLUSION

New developments in imaging should enhance the ability to provide early characterization of the potential therapeutic efficacy of experimental agents.

Meta-analysis of comparative efficacy of increasing dose of Atorvastatin versus Rosuvastatin versus Simvastatin on lowering levels of atherogenic lipids (from VOYAGER)

Statins are the most commonly prescribed agents for lowering levels of low-density lipoprotein (LDL) cholesterol. Although dose-dependent reductions in levels of atherogenic lipids are observed with all statins, the impact of increasing dose has not been fully elucidated. An individual patient data pooled analysis was performed of 32,258 patients in studies comparing the efficacy of rosuvastatin with that of atorvastatin or simvastatin. The impact of increasing dose on lowering LDL cholesterol, triglycerides, non-high-density lipoprotein (HDL) cholesterol, and apolipoprotein B was investigated. Doubling the dose of each statin was accompanied by a 4% to 7% greater degree of lowering of all atherogenic lipids. A stronger correlation was observed between changes in LDL cholesterol and non-HDL cholesterol (r = 0.92, p <0.001) or apolipoprotein B (r = 0.76, p <0.001) than triglycerides (r = 0.14, p <0.001). On multivariate analysis, baseline lipid level (p <0.0001) and increasing statin dose (p <0.0001) were strong predictors of achieving treatment goals in high-risk patients. Increasing age was a strong independent predictor of achieving goal for all atherogenic lipids (p <0.0001). Achieving LDL cholesterol goals was also more likely in women (p <0.0001), patients with diabetes (p <0.0001), and patients without atherosclerotic disease (p = 0.0002). In contrast, normal triglyceride levels were more often observed in men (p <0.0001) and patients without diabetes mellitus (p = 0.03). In conclusion, doubling statin dose was associated with greater lowering of LDL cholesterol by 4% to 6% and non-HDL cholesterol by 3% to 6%. Greater lipid goal achievement with increasing dose supports the use of high-dose statin therapy for more effective cardiovascular prevention.

Subclinical myocardial necrosis and cardiovascular risk in stable patients undergoing elective cardiac evaluation

OBJECTIVE

The presence of subclinical myocardial necrosis as a prodrome to longer-term adverse cardiac event risk has been debated. The debate has focused predominantly within patients with acute coronary syndrome, and on issues of troponin assay variability and accuracy of detection, rather than on the clinical significance of the presence of subclinical myocardial necrosis (ie, "troponin leak") within stable cardiac patients. Herein, we examine the relationship between different degrees of subclinical myocardial necrosis and long-term adverse clinical outcomes within a stable cardiac patient population with essentially normal renal function.

METHODS AND RESULTS

Sequential consenting patients (N=3828; median creatinine clearance, 100 mL/min/1.73m(2)) undergoing elective diagnostic coronary angiography with cardiac troponin I (cTnI) levels below the diagnostic cut-off for defining myocardial infarction (<0.03 ng/mL) were evaluated. The relationship of subclinical myocardial necrosis with incident major adverse cardiovascular events (defined as any death, myocardial infarction, or stroke) over 3-year follow-up was examined. "Probable" (cTnI 0.001-0.008 ng/mL) and "definite" (cTnI 0.009-0.029 ng/mL) subclinical myocardial necrosis were observed frequently within the cohort (34% and 18%, respectively). A linear relationship was observed between the magnitude of subclinical myocardial necrosis and risk of 3-year incident major adverse cardiovascular events, particularly in those with cTnI 0.009 ng/mL or higher (hazard ratio, 3.00; 95% confidence interval, 2.4-3.8), even after adjustment for traditional risk factors, C-reactive protein, and creatinine clearance. The presence of subclinical myocardial necrosis was associated with elevations in acute phase proteins (C-reactive protein, ceruloplasmin; P<0.01 each) and reduction in systemic antioxidant enzyme activities (arylesterase; P<0.01) but showed no significant associations with multiple specific measures of oxidant stress, and showed borderline associations with myeloperoxidase, a marker of leukocyte activation.

CONCLUSIONS

In stable cardiology patients, prodromal subclinical myocardial necrosis is associated with substantially higher long-term risk for major adverse cardiovascular events. The underlying mechanisms contributing to this minimal troponin leak phenomenon warrants further investigation.