Coronary heart disease mortality in treated familial hypercholesterolaemia: Update of the UK Simon Broome FH register.

BACKGROUND AND AIMS: Patients with familial hypercholesterolaemia (FH) have an elevated risk of coronary heart disease (CHD). Here we compare changes in CHD mortality in patients with heterozygous (FH) pre 1992, before lipid-lowering therapy with statins was used routinely, and in the periods 1992-2008 and 2008-2016. METHODS: 1903 Definite (DFH) and 1650 Possible (PFH) patients (51% women) aged 20-79 years, recruited from 21 lipid clinics in the United Kingdom and followed prospectively between 1980 and 2016 for 67,060 person-years. The CHD standardised mortality ratio (SMR) compared to the population in England and Wales was calculated (with 95% Confidence intervals). RESULTS: There were 585 deaths, including 252 from CHD. Overall, the observed 2.4-fold excess coronary mortality for treated DFH post-1991 was significantly higher than the 1.78 excess for PFH (35% 95% CI 3%-76%). In patients with DFH and established coronary disease, there was a significant excess coronary mortality in all time periods, but in men it was reduced from a 4.83-fold excess (2.32-8.89) pre-1992 to 4.66 (3.46-6.14) in 1992-2008 and 2.51 (1.01-5.17) post-2008, while in women the corresponding values were 7.23 (2.65-15.73), 4.42 (2.70-6.82) and 6.34 (2.06-14.81). Primary prevention in men with DFH resulted in a progressive reduction in coronary mortality over the three time-periods, with no excess mortality evident post-2008 (0.89 (0.29-2.08)), although in women the excess persisted (post-2008 3.65 (1.75-6.72)). CONCLUSIONS: The results confirm the benefit of statin treatment in reducing CHD mortality, but suggest that FH patients with pre-existing CHD and women with FH may not be treated adequately.

Clinical experience of scoring criteria for Familial Hypercholesterolaemia (FH) genetic testing in Wales.

BACKGROUND/OBJECTIVE: Familial Hypercholesterolaemia (FH) is caused by mutations in genes of the Low Density Lipoprotein (LDL) receptor pathway. A definitive diagnosis of FH can be made by the demonstration of a pathogenic mutation. The Wales FH service has developed scoring criteria to guide selection of patients for DNA testing, for those referred to clinics with hypercholesterolaemia. The criteria are based on a modification of the Dutch Lipid Clinic scoring criteria and utilise a combination of lipid values, physical signs, personal and family history of premature cardiovascular disease. They are intended to provide clinical guidance and enable resources to be targeted in a cost effective manner. METHODS: 623 patients who presented to lipid clinics across Wales had DNA testing following application of these criteria. RESULTS: The proportion of patients with a pathogenic mutation ranged from 4% in those scoring 5 or less up to 85% in those scoring 15 or more. LDL-cholesterol was the strongest discriminatory factor. Scores gained from physical signs, family history, coronary heart disease, and triglycerides also showed a gradient in mutation pick-up rate according to the score. CONCLUSION: These criteria provide a useful tool to guide selection of patients for DNA testing when applied by health professionals who have clinical experience of FH.

All-cause and cardiovascular mortality in treated patients with severe hypertriglyceridaemia: A long-term prospective registry study.

OBJECTIVE: To examine all-cause and cardiovascular mortality in patients with severe hypertriglyceridaemia. METHODS: 337 patients aged less than 80 years (47 with diabetes, 75 women) with a fasting triglyceride concentration on at least two occasions of >5.0mmol/l were registered by 21 lipid clinics in the United Kingdom and followed prospectively between 1980 and 2008 for 4353 person-years. The standardised mortality ratio (SMR) was calculated by comparison with the general population. RESULTS: The mean untreated total cholesterol concentration was 9.8 (SD 3.6)mmol/l for men and 11.9 (7.2)mmol/l for women and the corresponding geometric mean triglyceride concentration was 12.6 (inter-quartile range 7.3, 21.6) and 15.7 (8.2, 29.2)mmol/l. There were 70 deaths, including 35 from CHD and 7 from stroke. The SMR for CHD was raised at 327 (95% confidence intervals 228, 455; p<0.0001) and remained elevated after excluding patients with diabetes at registration (SMR=287, 95% CI 190, 419; p<0.0001), and after excluding patients with CHD at registration (SMR=259, 95% CI 158, 400; p=0.0003). The increased SMR was most marked in younger men aged 40-59 years (SMR=544, 95% CI 304, 897; p<0.0001). The SMR for stroke for patients aged 20-79 years was raised at 262 (95% CI 105, 540; p=0.04), as was all-cause mortality at 164 (95% CI 129, 208; p<0.001). CONCLUSION: Severe hypertriglyceridaemia is associated with a substantially increased mortality from cardiovascular disease, even in the absence of diabetes. In addition to lowering triglyceride concentrations to reduce the risk of pancreatitis, treatment should aim to reduce the overall cardiovascular risk.

The contribution of ApoB and ApoA1 measurements to cardiovascular risk assessment.

LDL has been widely recognized as the major atherogenic lipoprotein and designated as the primary target for prevention of coronary heart disease (CHD); however, there is growing evidence that other triglyceride-rich lipoproteins, such as very low-density lipoprotein (VLDL) and intermediate density lipoprotein (IDL) carry atherogenic potential as well. This led to the designation of non-HDL cholesterol (HDL-C) (LDL + IDL + VLDL) as a secondary target of treatment for hyperlipidaemia. As each one of LDL, IDL and VLDL particles carries only one apolipoprotein B-100 (ApoB-100) molecule, the total ApoB value represents the total number of potentially atherogenic lipoproteins, whereas non-HDL-C provides the cholesterol content of these same lipoproteins. Recent data from epidemiological, observational and interventional studies suggest that non-HDL-C, apolipoproteins ApoA1 and ApoB may improve CHD risk assessment by identifying more high-risk individuals than the usual lipid profile alone. However, the targets for the optimal treatment of dyslipidaemia remain a subject of considerable debate. Further studies are needed to determine whether ApoB and ApoA1 are superior to conventional lipid parameters as predictors of cardiovascular disease or therapeutic targets of hyperlipidaemias. In this review, we summarize the current opinions on the use of ApoA1 and ApoB values as estimates of cardiovascular risk or as treatment goals in patients undergoing treatment for hyperlipidaemia.

High- but not low-dose folic acid improves endothelial function in coronary artery disease.

BACKGROUND: While folic acid (FA) reduces plasma homocysteine (Hcy), whether the simultaneous improvement in endothelial function is dependent on Hcy lowering per se is questionable. In the present study the relationship between FA dose, Hcy lowering and endothelial function in patients with coronary artery disease (CAD) was investigated. MATERIALS AND METHODS: Eighty-four patients with CAD received either 400 microg FA or 5 mg placebo daily for a 6-week treatment period. A further 44 patients with CAD received either 100 mg kg(-1) day(-1) of betaine or placebo for a 6-week treatment period. Flow-mediated dilatation (FMD), a measure of endothelial function, was assessed before and after the 6-week periods. Isometric tension and Western blotting were used to investigate the effect of FA on endothelial function and endothelial nitric oxide synthase (eNOS) dimerization in isolated rabbit aortic rings and cultured porcine aortic endothelial cells (PAEC), respectively. RESULTS: Both 400 micro g day(-1) and 5 mg day(-1) FA significantly increased plasma folate and decreased plasma Hcy. The FMD improved significantly after 6 weeks' treatment of 5 mg day(-1) FA but did not correlate with the reduction in Hcy. There was no change in FMD in either the 400 micro g FA or placebo group. In a subgroup analysis of 11 patients in the betaine group, despite a reduced Hcy, a significant impairment in FMD was observed. In the in vitro studies FA, but not betaine, reversed methionine-induced endothelial dysfunction. Moreover, the FA promoted eNOS dimerization in cultured PAEC. CONCLUSIONS: These data suggest that FA dose-dependently improves endothelial function in CAD via a mechanism independently of Hcy lowering. It may involve promotion of eNOS dimerization.

Recommended standards for biochemical markers of myocardial damage: All Wales Clinical Biochemistry Audit Group.

The effective use of cardiac-specific troponin estimations in the diagnosis of acute myocardial infarction (AMI) is clouded by the imprecise definition surrounding the decision limits. This has led to a wide variation of criteria for the diagnosis of myocardial infarction. A survey of troponin measurements in Welsh laboratories, undertaken in 2003 under the auspices of the All Wales Clinical Biochemistry Audit Group, revealed significant variations in laboratory and clinical practice. Extensive discussion and consultation led by a working group of clinical biochemists and cardiologists in Wales culminated in recommendations concerning the use of troponin assays to establish myocardial damage. The key recommendations are: Cardiac troponin (T or I) should be the first-line test for myocardial damage; Two samples should be collected, at admission and 12-24 h later. The first sample is used for 'rule in' purposes, but not to 'rule out' myocardial damage; Only one threshold (cut-off) value for troponin should be quoted on laboratory reports, values above which are indicative of myocardial damage. A study by the Wales External Quality Assurance Scheme (WEQAS) enabled the derivation of the recommended cut-off concentrations of troponin for defining myocardial damage, defined for each assay as the concentration that can be reliably distinguished, with a confidence interval of 99%, from the 99th percentile reference limit. These recommended standards provide a rationale for a uniform approach for troponin assays for patients with chest pain, working towards a standardized approach to the diagnosis and management of patients presenting with acute coronary syndromes.

A review of troponin assay performance in Wales: can the same (method-dependent) decision limits be used in different sites?

An audit of troponin measurement protocols in use in Wales showed significant variations in practice with no consensus on analytical methods, or in the selection of a decision limit for the diagnosis of myocardial damage. Peer review data on assay imprecision at concentrations approaching the analytical limit of detection are lacking. The objective of the study was to establish clinically relevant precision profiles for the troponin methods used throughout Wales, which could be used to develop a standardized approach to the selection of a decision limit. A series of five pools of human serum spiked with troponin I-T complex were prepared and stored at -70 degrees C until dispatch. Five sets of each pool were dispatched to all Welsh laboratories and stored at -20 degrees C until analysis. The analysis protocol consisted of two replicates of each pool per batch, and two batches per day for five days (n=20). All the laboratories performed all the measurements in the same week. The lowest concentration providing a 10% coefficient of variation (CV) was 0.02 microg/L for the Roche method and 0.11 microg/L for the Beckman AccuTnI. The lowest concentrations that could be distinguishable from the 99th percentile reference limit were 0.02 microg/L for the Roche method and 0.07 microg/L for the Beckman AccuTnI. Current methods do not achieve the 10% CV at the 99th percentile reference limit proposed by the European Society of Cardiology. Use of the lowest concentration that can be reliably distinguished from the 99th percentile reference limit offers a novel alternative decision limit, which provides a slightly lower concentration than at the 10% CV but maintaining confidence in the assay that false-positive rates will be minimized.

Urinary catecholamines and metabolites in the immediate postoperative period following major surgery.

BACKGROUND: Induction of anaesthesia can precipitate catecholamine release from an undiscovered pheochromocytoma and induce a hypertensive crisis. However, it is assumed that catecholamine and metabolite values resulting from the effects of surgery per se in the early postoperative period would overlap with the values generated by a tumour, and it is not known how soon after biochemical investigations can be carried out. AIM: To study patterns of urinary catecholamine excretion and the feasibility of biochemical screening for phaeochromocytomas in the immediate postoperative period in otherwise healthy subjects undergoing a single type of major surgical procedure. METHODS: Catecholamines and metabolites were measured for each mole of creatinine in single voided urine on one preoperative and four postoperative days in five subjects who underwent elective coronary artery bypass graft surgery with an uncomplicated postoperative course. Reference ranges were established from 33 healthy normotensive volunteers. RESULTS: Excretion of adrenaline, noradrenaline, dopamine, vanillylmandelic acid, and metadrenaline was within normal limits. Normetadrenaline excretion was mildly raised in four patients, but did not exceed 1.5 times the upper reference limit, and returned to normality by the fourth postoperative day. CONCLUSION: It is feasible to perform simple urinary screening for possible phaeochromocytoma in the immediate postoperative period.

Reduction in plasma total homocysteine through increasing folate intake in healthy individuals is not associated with changes in measures of antioxidant activity or oxidant damage.

BACKGROUND: Various mechanisms have been proposed to explain the association between plasma total homocysteine (tHcy) and risk of cardiovascular disease, including oxidative activity of homocysteine. OBJECTIVE: To explore the putative role of reactive oxygen species in the association between plasma tHcy and risk of cardiovascular disease in healthy individuals. DESIGN: A double-blind, placebo-controlled crossover intervention to increase folate intake through diet (increased consumption of folate-rich foods) and supplement (400 micro g folic acid) was carried out in 126 healthy men and women. Measurements were made of antioxidant activity in red blood cells and plasma, and products of oxidant damage in plasma. RESULTS: Diet and supplement-based interventions led to an increase in measures of folate status and a reduction in plasma tHcy. This was not associated with any significant change in measures of antioxidant activity (plasma and red blood cell glutathione peroxidase activity and red blood cell superoxide dismutase activity) or oxidant damage (plasma malondialdehyde), although an improvement in plasma total antioxidant capacity just failed to reach significance. CONCLUSIONS: In healthy individuals lowering plasma tHcy does not have any functional implications regarding oxidative damage.

A comparison of the effect of advice to eat either '5-a-day' fruit and vegetables or folic acid-fortified foods on plasma folate and homocysteine.

OBJECTIVE: To assess and compare the effects of natural folate (100 micro g) with those of folic acid from fortified sources (100 micro g/day) on plasma folate and homocysteine. DESIGN: Randomized controlled trial (parallel groups). SETTING: Men and women living in South Wales, UK. SUBJECTS: A total of 135 healthy individuals recruited from the local workforce and blood donor sessions. All subjects possessed the 'wild-type' CC genotype for C677T polymorphism in methylenetetrahydrofolate reductase (MTHFR). INTERVENTIONS: Subjects underwent one of the following dietary interventions for 4 months: (1) fortified diet-usual diet plus 100 microg/day folic acid from fortified foods; (2) natural folate diet-usual diet plus 100 microg/day folate from natural sources; (3) control-usual diet. RESULTS: The fortified group increased reported intake of folic acid from fortified foods compared to other groups (P<0.001) achieving an extra 98 microg/day (95% CI 88-108). The natural folate group increased reported intake of natural source folates compared with the other two groups (P<0.001), but achieved a mean increase of only 50 microg/day (95% CI 34-66). Plasma folate increased (P<0.01) by a similar amount in both intervention groups compared to controls (fortified group 2.97, 95% CI 0.8-5.1; natural group 2.76, 95% CI 0.6-4.9. Plasma homocysteine, vitamins B(6) and B(12) were not significantly changed. CONCLUSIONS: Subjects achieved increases in folate intake using fortified foods more easily than by folate-rich foods, however both sources increased plasma folate by a similar amount. These levels of intake were insufficient to reduce homocysteine concentrations in MTHFR CC homozygotes, but may be more effective in other genotypes.

Vitamin C therapy ameliorates vascular endothelial dysfunction in treated patients with homocystinuria.

OBJECTIVES: We sought to investigate the effects of short- and long-term vitamin C therapy on endothelial dysfunction in patients with homocystinuria. BACKGROUND: Untreated homocystinuria due to cystathionine beta-synthase deficiency is associated with premature atherothrombotic disease; 25% of untreated patients suffer a vascular event by the age of 16 years and 50% by 29 years. Treatment directed at reducing homocysteine accumulation significantly reduces this risk. However, despite 'optimal' treatment and compliance, hyperhomocysteinaemia usually persists and individuals exhibit endothelial dysfunction indicative of an adverse cardiovascular prognosis. Additional intervention is therefore required to further reduce cardiovascular risk. METHODS: We investigated the endothelial effects of acute (2 g single dose) and chronic (1 g/day for 6 months) administration of oral vitamin C in 5 patients with homocystinuria (mean age 26 years, 1 male) and 5 age- and sex-matched controls. Brachial artery endothelium-dependent flow-mediated dilatation (FMD) and endothelium-independent responses to nitroglycerin (NTG) were measured using high-resolution ultrasonic vessel wall-tracking. RESULTS: Baseline: Plasma total homocysteine was 100.8 +/- 61.6 and 9.2 +/- 1.9 micromol/L in the patient and control groups, respectively (p < 0.001). FMD responses were impaired in the patient group (20 +/- 40 microm) compared with the controls (116 +/- 30 microm) (p < 0.001). Vitamin C administration: FMD responses in the patient group improved both acutely, 160 +/- 65 microm at 4 h (p < 0.001), and chronically, 170 +/- 70 microm at 2 weeks (p < 0.001) and 170 +/- 40 microm at 6 months (p < 0.001). FMD responses in the control group were unaltered (p = 0.526). Within both groups, neither the vascular response to NTG nor plasma homocysteine was altered (p > 0.4). CONCLUSIONS: Vitamin C ameliorates endothelial dysfunction in patients with homocystinuria, independent of changes in homocysteine concentration and should therefore be considered as an additional adjunct to therapy to reduce the potential long-term risk of atherothrombotic disease.

Optimization of dietary folate or low-dose folic acid supplements lower homocysteine but do not enhance endothelial function in healthy adults, irrespective of the methylenetetrahydrofolate reductase (C677T) genotype.

OBJECTIVES: We sought to study the effect of low-dose folic acid supplementation or optimization of dietary folate intake on plasma homocysteine and endothelial function in healthy adults. BACKGROUND: Elevated homocysteine is associated with cardiovascular disease, but it is not known whether this relationship is causal. Individuals homozygous (TT) for the C677T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene ( approximately 12% of the population) have increased homocysteine levels, particularly in association with suboptimal folate intake. METHODS: Healthy subjects (n = 126; 42 of each MTHFR genotype) were included in this cross-over study of three interventions of four months each: 1) placebo plus natural diet; 2) daily 400-microg folic acid supplement plus natural diet; and 3) increased dietary folate intake to 400 microg/day. RESULTS: At baseline, homocysteine was inversely related to plasma folate and was higher in TT homozygotes. For the whole group, plasma folate increased by 46% after dietary folate and by 79% after supplementation, with reductions of homocysteine of 14% and 16%, respectively. Within the genotype, TT homozygotes exhibited the most marked changes in these variables. Brachial artery endothelial function, as determined by a change in end-diastolic diameter in response to increased flow, was not changed by increased folate intake (98 +/- 73 microm at baseline, 110 +/- 69 microm after a high-folate diet, 114 +/- 59 microm after supplementation and 118 +/- 68 microm after placebo). Plasma von Willebrand factor antigen was unaltered. CONCLUSIONS: Optimization of dietary folate or low-dose folic acid supplementation reduces plasma homocysteine but does not enhance endothelial function, irrespective of the MTHFR (C667T) genotype.

Folate, homocysteine, endothelial function and cardiovascular disease. What is the link?

Elevated plasma homocysteine concentrations are associated with an increased risk of cardiovascular disease, but the relationship has not been proven to be causal. Folate is the strongest nutritional and pharmacological determinant of plasma homocysteine concentrations, which also interact with the genetic variation in methylenetetrahydrofolate reductase (MTHFR). Endothelial dysfunction due to reduced nitric oxide bioavailability is an early feature of vascular pathology. This can be assessed noninvasively by measurement of flow-mediated dilatation. Human studies on folic acid, homocysteine and endothelial function are reported. It is proposed that folic acid in high doses may have beneficial effects on endothelial function, which are independent of homocysteine lowering.

Folate improves endothelial function in coronary artery disease: an effect mediated by reduction of intracellular superoxide?

Homocysteine is a risk factor for coronary artery disease (CAD). Folic acid lowers homocysteine and may improve endothelial function in CAD, although the mechanism is unclear. We investigated the effect of folic acid on endothelial function, homocysteine, and oxidative stress in patients with CAD. We also examined the acute effect of 5-methyltetrahydrofolate (5-MTHF), the principal circulating folate, on endothelial function in vivo and on intracellular superoxide in cultured endothelial cells. A randomized crossover study of folic acid (5 mg daily) for 6 weeks was undertaken in 52 patients with CAD. Ten further patients were given intra-arterial 5-MTHF. Endothelial function was assessed by flow-mediated dilatation (FMD). Folic acid increased plasma folate (P<0.001), lowered homocysteine by 19% (P<0.001), and improved FMD (P<0.001). FMD improvement did not correlate with homocysteine reduction. Malondialdehyde and total plasma antioxidant capacity, markers of oxidative stress, were unchanged. 5-MTHF acutely improved FMD (P<0.001) without altering homocysteine (P=0.47). In vitro, 5-MTHF abolished homocysteine-induced intracellular superoxide increase (P<0.001); this effect was also observed with folic acid and tetrahydrobiopterin. Our data support the beneficial effect of folic acid on endothelial function in CAD but suggest that the mechanism is independent of homocysteine. Reduction of intracellular endothelial superoxide may have contributed to the effect.

Neutrophil superoxide anion--generating capacity, endothelial function and oxidative stress in chronic heart failure: effects of short- and long-term vitamin C therapy.

OBJECTIVES: First, we sought to study the effects of short- and long-term vitamin C therapy on oxidative stress and endothelial dysfunction in chronic heart failure (CHF), and second, we sought to investigate the role of neutrophils as a cause of oxidative stress in CHF. BACKGROUND: Oxidative stress may contribute to endothelial dysfunction in CHF. Vitamin C ameliorates endothelial dysfunction in CHF, presumably by reducing oxidative stress, but this is unproven. METHODS: We studied 55 patients with CHF (ischemic and nonischemic etiologies) and 15 control subjects. Flow-mediated dilation (FMD) in the brachial artery was measured by ultrasound wall-tracking, neutrophil superoxide anion (O2-) generation by lucigenin-enhanced chemiluminescence and oxidative stress by measurement of free radicals (FRs) in venous blood using electron paramagnetic resonance (EPR) spectroscopy and plasma thiobarbituric acid reactive substances (TBARS). Measurements were performed at baseline in all subjects. The effects of short-term (intravenous) and long-term (oral) vitamin C therapy versus placebo were tested in patients with nonischemic CHF. RESULTS: At baseline, FRs were higher in patients with CHF than in control subjects (p < 0.01), TBARS were greater (p < 0.005), neutrophil O2- -generating capacity was enhanced (p < 0.005) and FMD was lower (p < 0.0001). Compared with placebo, short-term vitamin C therapy reduced FR levels (p < 0.05), tended to reduce TBARS and increased FMD (p < 0.05), but did not affect neutrophil O2- -generating capacity. Long-term vitamin C therapy reduced FR levels (p < 0.05), reduced TBARS (p < 0.05) and improved FMD (p < 0.05), but also reduced neutrophil O2- -generating capacity (p < 0.05). Endothelial dysfunction was not related to oxidative stress, and improvements in FMD with vitamin C therapy did not relate to reductions in oxidative stress. CONCLUSIONS: Oxidative stress is increased in ischemic and nonischemic CHF, and neutrophils may be an important cause. Vitamin C reduces oxidative stress, increases FMD and, when given long term, decreases neutrophil O2- generation, but the lack of a correlation between changes in endothelial function and oxidative stress with vitamin C implies possible additional non-antioxidant benefits of vitamin C.

Homocysteine and endothelial dysfunction: a link with cardiovascular disease.

The nature of the link between homocysteine and cardiovascular disease has not yet been clearly established. Impaired endothelium-independent vasodilatation is an early feature of vascular disease. In human studies, methionine loading, which acutely elevates plasma homocysteine, induces endothelial dysfunction. Folate therapy, which lowers homocysteine, enhances endothelial function. This is consistent with, but not proof of, homocysteine toxicity to endothelium in vivo. Homocysteine, in high concentration, can induce endothelial dysfunction in vitro. This is accompanied by increased superoxide production, which when inhibited, restores normal endothelial function. These observations suggest that homocysteine may induce vascular endothelial dysfunction by a mechanism involving reactive oxygen species.