Early Initiation of Sacubitril/Valsartan in Patients With Acute Heart Failure and Renal Dysfunction: An Analysis of the TRANSITION Study

BACKGROUND

Treatment of patients with heart failure with reduced ejection fraction (HFrEF) and renal dysfunction (RD) is challenging owing to the risk of further deterioration in renal function, especially after acute decompensated HF (ADHF).

METHODS AND RESULTS

We assessed the effect of RD (estimated glomerular filtration rate of ≥30 to <60 mL/min/1.73 m2) on initiation, up-titration, and tolerability of sacubitril/valsartan in hemodynamically stabilized patients with HFrEF admitted for ADHF (RD, n = 476; non-RD, n = 483). At week 10, the target dose of sacubitril/valsartan (97/103 mg twice daily) was achieved by 42% patients in RD subgroup vs 54% in non-RD patients (P < .001). Sacubitril/valsartan was associated with greater estimated glomerular filtration rate improvements in RD subgroup than non-RD (change from baseline least squares mean 4.1 mL/min/1.73 m2, 95% confidence interval 2.2-6.1, P < .001). Cardiac biomarkers improved significantly in both subgroups; however, compared with the RD subgroup, the improvement was greater in those without RD (N-terminal pro-brain natriuretic peptide, -28.6% vs -44.8%, high-sensitivity troponin T -20.3% vs -33.9%) (P < .001). Patients in the RD subgroup compared with those without RD experienced higher rates of hyperkalemia (16.3% vs 6.5%, P < .001), investigator-reported cardiac failure (9.7% vs 5.6%, P = .029), and renal impairment (6.4% vs 2.1%, P = .002).

CONCLUSIONS

Most patients with HFrEF and concomitant RD hospitalized for ADHF tolerated early initiation of sacubitril/valsartan and showed significant improvements in estimated glomerular filtration rate and cardiac biomarkers.

CLINICAL TRIAL REGISTRATION

NCT02661217.

P773Initiation of sacubitril/valsartan and optimisation of evidence-based heart failure therapies after hospitalisation for acute decompensated heart failure: An analysis of the TRANSITION study

Background

Optimisation of chronic heart failure (HF) therapy remains the key strategy to improve outcomes after hospitalisation for acute decompensated HF (ADHF) with reduced ejection fraction (HFrEF). Initiation and uptitration of disease-modifying therapies is challenging in this vulnerable patient population. We aimed to describe the patterns of treatment optimisation including sacubitril/valsartan (S/V) in the TRANSITION study.

Methods

TRANSITION (NCT02661217) was a randomised, open-label study comparing S/V initiation pre- vs. post-discharge (1–14 days) in patients admitted for ADHF after haemodynamic stabilisation. The primary endpoint was the proportion of patients achieving 97/103 mg S/V twice daily (bid) at 10 weeks post-randomisation. Up-titration of S/V was as per label. Information on dose of S/V and on the use of concomitant HF medication was collected at each study visit up to week 26.

Results

A total of 493 patients received at least one dose of S/V in the pre-discharge arm and 489 patients in the post-discharge arm. One month after randomisation, 45% of patients in the pre-d/c arm vs. 44% in the post-discharge arm used 24/26 mg bid starting dose and 42% vs. 40% were on 49/51 mg S/V bid, respectively. At week 10, 47% of patients had achieved the target dose in the pre-discharge arm vs. 51% in the post-discharge arm. At the end of the follow-up at 26 weeks, the proportion of patients on S/V target dose further increased to 53% in the pre-discharge and 61% in the post-discharge arm (Figure 1). At week 10, the mean dose of S/V was 132 mg in the pre-discharge arm and 136 mg in the post-discharge arm, and at week 26, it was 140 mg and 147 mg, respectively.

Before hospital admission, 52% and 54% of the patients received a beta-blocker (BB) in the pre-discharge and post-discharge group, respectively, and 42% in both arms received a mineralcorticoid receptor antagonist (MRA). At time of discharge, 68% and 71%% of the patients received a BB and 68% and 65% an MRA, in the pre-discharge and post-discharge groups, respectively. These proportions remained stable to week 10 and week 26.

Uptitration of sacubitril/valsartan

Conclusions

In the vulnerable post-ADHF population, initiation of S/V and up-titration to target dose was feasible within 10 weeks in half of the patients alongside with a 20% increase in the use of other disease-modifying medications that remained stable through the end of the 6-month follow-up.

Acknowledgement/Funding

The TRANSITION study was funded by Novartis

P1637Rehospitalisations during 26 weeks of follow up from initiation of sacubitril/valsartan after acute decompensated heart failure: An analysis of the TRANSITION study

Background

Patients with acute decompensated heart failure (ADHF) are at high risk of recurrent hospitalisations and death. In-hospital initiation of sacubitril/valsartan (S/V) reduced the risk for HF re-hospitalisation by 44% compared to enalapril in the PIONEER-HF study during the 8-week follow-up period. We aimed to describe the pattern of readmissions and their causes in the TRANSITION study, which randomised participants to pre-discharge or post-discharge initation of S/V.

Methods

TRANSITION (NCT02661217) was a randomised, open-label study comparing S/V initiation pre- vs. post-discharge (1–14 days) in haemodynamically stabilised patients with HF with reduced ejection fraction, admitted for ADHF. The primary endpoint was the proportion of patients achieving 97/103 mg S/V twice daily at 10 weeks post-randomisation. Information on rehospitalisation was collected throughout the study up to 26 weeks.

Results

A total of 493 patients received S/V in the pre-discharge arm and 489 patients in the post-discharge arm. Readmissions due to any cause were reported in 9.7% and 18.1% in the pre-discharge arm vs. 10.6% and 21.3% in the post-discharge arm within 30 days, and 10 weeks respectively. During the 26-weeks follow-up, all-cause readmission was reported in 34.5% of patients in the pre-discharge arm vs. 34.6% in the post-discharge arm. Median time to first rehospitalisation was 67 days in the pre-discharge arm (IQR: 26–110 days) and 50 days (IQR: 23–108 days) in the post-discharge arm. At least one HF hospitalisation was reported in 7.5% of patients in the pre-discharge arm and 7.4% in the post-discharge arm during 10 weeks and in 11.8% and 12.3% of patients, respectively, during 26 weeks of follow-up. Median duration of HF readmission was 7 days (IQR: 4–11 days) in the pre-discharge group and 6.5 days (IQR: 6.5–10 days) in the post-discharge arm. In total 2.6% and 5.5% patients in pre-discharge arm and 3.9% and 7% in the post-discharge arm visited an emergency room during 10 weeks and 26 weeks, respectively.

Conclusions

Initiation of S/V in patients hospitalised for ADHF either before or shortly after discharge, results in comparable rates of all cause and HF rehospitalisations, as well as emergency room visits without hospital admission over the 26 week follow-up period. HF re-hospitalisations rates at 10 weeks in TRANSITION are in line with the 8% in S/V arm reported in PIONEER-HF during the 8-weeks follow-up.

Acknowledgement/Funding

The TRANSITION study was funded by Novartis

Vitamin D and progression of carotid intima-media thickness in HIV-positive Canadians

OBJECTIVES

Based on a growing body of evidence implicating low vitamin D status in the development of cardiovascular disease (CVD), we hypothesized that in Canadian HIV-positive adults, low 25-hydroxyvitamin D (25(OH)D) concentration would be associated with increased subclinical vascular disease progression.

METHODS

We prospectively studied the relationship between baseline 25(OH)D and subsequent progression of carotid intima-media thickness (CIMT) between 2002 and 2011, in the Canadian HIV Vascular Study using stored blood specimens.

RESULTS

Of the 128 participants, 89.1% were men, the mean age (standard deviation [SD]) was 46.5 (8.2) years, 93.8% were white, and 36.7% were current smokers. Mean (SD) annual CIMT follow-up was 5.9 (1.8) years (maximum 8.5 years), providing approximately 750 patient-years of follow-up. Mean (SD) CIMT progression was 0.027 (0.030) mm/year. Mean (SD) 25(OH)D was 95.0 (46.9) nmol/L. Only 13.3% of participants were vitamin D deficient (25(OH)D < 50 nmol/L), whereas 61.7% had a 25(OH)D exceeding the sufficiency threshold (75 nmol/L). Vitamin D quartiles were inversely associated with body mass index (BMI) (P = 0.034), total cholesterol to high-density lipoprotein (HDL) cholesterol ratio (P = 0.001) and parathyroid hormone concentration (P = 0.003), but not efavirenz exposure (P = 0.141). In linear regression analyses, baseline 25(OH)D as a continuous variable was inversely associated with CIMT progression in univariable (P < 0.001) and multivariable (P < 0.001) models.

CONCLUSIONS

Baseline 25(OH)D was associated with CIMT progression in this relatively vitamin D replete, predominately white and male, Canadian HIV-positive population. Future research needs to establish causality as this may warrant more targeted screening or supplementation.

Low resting heart rates are associated with new-onset atrial fibrillation in patients with vascular disease: results of the ONTARGET/TRANSCEND studies

BACKGROUND

Elevated systolic blood pressure (SBP) and high resting heart rate (HR) are associated with cardiovascular end-points. Although the association between atrial fibrillation (AF) and SBP is well established, the relation between AF and HR remains unclear.

METHODS

In patients from the ONTARGET and TRANSCEND studies with high cardiovascular disease risk (n = 27 064), new-onset AF was evaluated in relation to mean SBP, visit-to-visit variation in SBP (SBP-CV; i.e. SD/mean × 100%), mean HR and visit-to-visit variation in HR (HR-CV).

RESULTS

Low mean HR (P < 0.0001) and high SBP (P = 0.0021) were associated with incident AF. High SBP-CV (P = 0.031) and HR-CV (P < 0.0001) were also associated with incident AF. After adjustment for confounders, SBP and SBP-CV were no longer significantly associated with AF. The detrimental effect of low HR was particularly evident in subjects who were not receiving treatment with beta-blockers (P = 0.014 for interaction between beta-blocker use and mean HR). In addition to low HR, high HR-CV and high SBP had additive effects on incident AF.

CONCLUSIONS

Low mean HR (<60 beats min(-1) ) is independently associated with incident AF, and low HR-CV and high SBP further increase the incidence of new-onset AF in patients at high risk of cardiovascular disease.

Resting heart rate is associated with renal disease outcomes in patients with vascular disease: results of the ONTARGET and TRANSCEND studies

BACKGROUND

Resting heart rate (RHR) is associated with cardiovascular disease outcomes in high-risk patients. It is not known whether RHR is predictive of renal outcomes such as albuminuria, end-stage renal disease (ESRD) or doubling of creatinine. We evaluated whether RHR could predict renal endpoints in patients at a high risk of cardiovascular disease. We also tested the effects of RHR at different levels of systolic blood pressure (SBP).

METHODS

We analysed data from 28 757 patients in the ONTARGET and TRANSCEND trials. RHR and SBP were available for a mean of 4.9 ± 0.4 visits (range 3-5) within the first 2 years of the studies. Albuminuria was determined at baseline, at 2 years and at study end.

RESULTS

Mean RHR was predictive of incident micro-albuminuria [hazard ratio (HR) for RHR ≥80 vs. <60 beats min(-1) 1.49, 95% confidence interval (CI) 1.29-1.71, P < 0.0001], incident macro-albuminuria (HR 1.84, 95% CI 1.39-2.42, P < 0.0001), doubling of creatinine (HR 1.47, 95% CI 1.00-2.17, P = 0.050) and ESRD (HR 1.78, 95% CI 1.00-3.16, P = 0.050), and the combined renal end-point (HR 1.51, 95% CI 1.32-1.74, P < 0.0001). Associations were robust at SBPs from <120 to ≥150 mmHg, with the lowest risk at a SBP of 130-140 mmHg.

CONCLUSION

Resting heart rate is a potent predictor of these renal outcomes, as well as their combination, in patients with cardiovascular disease. RHR at all SBP levels should be considered as a possible renal disease risk predictor and should be investigated as a treatment target with RHR-reducing agents.

Increased cardiovascular risk after pre-eclampsia in women with dysglycaemia

AIMS

Compared with women with uncomplicated pregnancies, women with a history of pre-eclampsia have two to five times the risk of cardiovascular disease. It is not known whether this risk is related to albuminuria, a known cardiovascular risk factor that is part of the definition of pre-eclampsia and that often persists after delivery. Our objective was to determine if the high risk of cardiovascular disease in women with pre-eclampsia is accounted for by known cardiovascular risk factors including albuminuria.

METHODS

We performed a cross-sectional analysis of 4080 dysglycaemic women enrolled in a large randomized controlled trial who provided an obstetric history and had at least one delivery. Blood pressure, height, weight, waist circumference and hip circumference were measured. An oral glucose tolerance test, lipids, an electrocardiogram and an albumin/creatinine ratio from a first morning urine sample were obtained.

RESULTS

There were 3613 women with no history of pre-eclampsia during their pregnancies, 108 with severe pre-eclampsia and 359 with non-severe pre-eclampsia. Women with a history of severe pre-eclampsia had higher rates of previous cardiovascular disease than women with non-severe pre-eclampsia or women without pre-eclampsia (87, 72 and 72%, P = 0.0019). The high risk of previous cardiovascular disease in women with a history of severe pre-eclampsia (odds ratio 2.67, 95% CI 1.52-4.70) persisted after adjustment for albuminuria (odds ratio 2.74, 95% CI 1.55-4.83) and also after adjusting for other covariates including albuminuria (odds ratio 3.03, 95% CI 1.69-5.44).

CONCLUSION

Even after accounting for cardiovascular risk factors including albuminuria, a history of severe pre-eclampsia is independently associated with a threefold higher risk of cardiovascular disease.

Myocardial infarction associated with recency of immigration to Ontario

BACKGROUND

New immigrants to North America exhibit lower rates of obesity and hypertension than their native-born counterparts. Whether this is reflected by a lower relative risk of acute myocardial infarction (AMI) is not known.

OBJECTIVE

To determine the risk of AMI among new immigrants compared to long-term residents, and, among those who develop AMI, their short- and long-term mortality rate.

DESIGN

Population-based, matched, retrospective cohort study.

SETTING

Entire province of Ontario, the most populated province in Canada, from 1 April 1995 to 31 March 2007.

PARTICIPANTS

A total of 965,829 new immigrants were matched to 3,272,393 long-term residents by year of birth, sex and geographic location.

MEASUREMENTS

The main study outcome was hospitalization with a most responsible diagnosis of AMI. Secondary study outcomes among those who sustained an AMI were in-hospital, 30-day and 1-year mortality.

RESULTS

The mean age of the participants at study entry was approximately 34 years. The incidence rate of AMI was 4.14 per 10,000 person-years among new immigrants and 6.61 per 10,000 person-years among long-term residents. After adjusting for age, income quintile, urban vs. rural residence, history of hypertension, diabetes mellitus and smoking and number of health insurance claims, the hazard ratio for AMI was 0.66 [95% confidence interval (CI): 0.63-0.69].

CONCLUSION

New immigrants appear to be at lower risk of AMI than long-term residents. This finding does not appear to be explained by the availability of health-care services or income level.

Risk of premature stroke in recent immigrants (PRESARIO): population-based matched cohort study

BACKGROUND

New immigrants to North America, most of whom are under age 50 years, exhibit fewer risk factors for cardiovascular disease than their native-born counterparts, yet the stress of resettlement may conceivably place them at higher risk of stroke. We determined the risk of acute stroke associated with recency of immigration.

METHODS

We completed a population-based matched cohort study in Ontario, the largest province in Canada, from April 1, 1995, to March 31, 2007. Overall, 965,829 new immigrants were matched to 3,272,393 long-term residents by year of birth, sex, and location. New immigrants were identified as new recipients of universally available public health insurance, and long-term residents were those insured for 5 years or longer.

RESULTS

The mean age of the participants at study entry was about 34 years and the total number of observed strokes was 6,216 after a median duration of follow-up of about 6 years. The incidence rate of acute stroke was 1.69 per 10,000 person-years among new immigrants and 2.56 per 10,000 person-years among long-term residents (crude hazard ratio [HR] 0.66, 95% confidence interval [CI] 0.62-0.71). After adjusting for age, income quintile, urban vs rural residence, history of hypertension, diabetes mellitus and smoking, and number of health insurance claims, the HR for stroke was 0.69 (95% CI 0.64-0.74). Similar risk estimates were seen for both ischemic and hemorrhagic stroke subtypes.

CONCLUSION

New immigrants appear to be at lower risk of premature acute stroke than long-term residents. This finding does not appear to be explained by the availability of health care services or income level.

Effects of ramipril and rosiglitazone on cardiovascular and renal outcomes in people with impaired glucose tolerance or impaired fasting glucose: results of the Diabetes REduction Assessment with ramipril and rosiglitazone Medication (DREAM) trial

OBJECTIVE

Impaired glucose tolerance (IGT) and/or impaired fasting glucose (IFG) are risk factors for diabetes, cardiovascular disease (CVD), and kidney disease. We determined the effects of ramipril and rosiglitazone on combined and individual CVD and renal outcomes in people with IGT and/or IFG in the Diabetes REduction Assessment With ramipril and rosiglitazone Medication (DREAM) trial.

RESEARCH DESIGN AND METHODS

A total of 5,269 people aged >or=30 years, with IGT and/or IFG without known CVD or renal insufficiency, were randomized to 15 mg/day ramipril versus placebo and 8 mg/day rosiglitazone versus placebo. A composite cardiorenal outcome and its CVD and renal components were assessed during the 3-year follow-up.

RESULTS

Compared with placebo, neither ramipril (15.7% [412 of 2,623] vs. 16.0% [424 of 2,646]; hazard ratio [HR] 0.98 [95% CI 0.84-1.13]; P = 0.75) nor rosiglitazone (15.0% [394 of 2,635] vs. 16.8% [442 of 2,634]; 0.87 [0.75-1.01]; P = 0.07) reduced the risk of the cardiorenal composite outcome. Ramipril had no impact on the CVD and renal components. Rosiglitazone increased heart failure (0.53 vs. 0.08%; HR 7.04 [95% CI 1.60-31.0]; P = 0.01) but reduced the risk of the renal component (0.80 [0.68-0.93]; P = 0.005); prevention of diabetes was independently associated with prevention of the renal component (P < 0.001).

CONCLUSIONS

Ramipril did not alter the cardiorenal outcome or its components. Rosiglitazone, which reduced diabetes, also reduced the development of renal disease but not the cardiorenal outcome and increased the risk of heart failure.

Venous thromboembolism in association with features of the metabolic syndrome

BACKGROUND

Central obesity, diabetes mellitus, dyslipidaemia and chronic hypertension--features of the metabolic syndrome--have been individually associated with venous thromboembolism (VTE). However, whether each of these factors additively increases the risk of VTE is uncertain.

AIM

To determine whether features of the metabolic syndrome independently increase the risk of VTE.

DESIGN

Prospective cohort study derived from the Heart Outcomes Prevention Evaluation 2 (HOPE-2) randomized clinical trial.

SETTING

One hundred and forty-five clinical centres in 13 countries.

METHODS

We studied 5522 adults aged > or =55 years with cardiovascular disease or diabetes mellitus. At enrollment, 35% had 0-1 features of the metabolic syndrome, 30% had two, 24% had three and 11% had four. We defined symptomatic VTE as an objectively confirmed new episode of deep-vein thrombosis or pulmonary embolism.

RESULTS

VTE occurred in 88 individuals during a median 5.0 years of follow-up. The incidence rate of VTE (per 100 person-years) was 0.30 with 0-1 features, 0.36 with two features, 0.38 with three features and 0.40 with four features of the metabolic syndrome (trend p = 0.43). Relative to the presence of 0-1 features of the metabolic syndrome, the adjusted hazard ratio (95%CI) for VTE was 1.22 (0.71-2.08) with two features, 1.25 (0.70-2.24) with three features, and 1.26 (0.59-2.69) with four features.

DISCUSSION

The number of features of the metabolic syndrome present was not a clinically important risk factor for VTE in older adults with vascular arterial disease.

Rationale, design and baseline characteristics of a large, simple, randomized trial of combined folic acid and vitamins B6 and B12 in high-risk patients: the Heart Outcomes Prevention Evaluation (HOPE)-2 trial

BACKGROUND

Epidemiological studies suggest that mild to moderate elevation in plasma homocysteine concentration is associated with increased risk of atherothrombotic cardiovascular (CV) disease. Simple, inexpensive and nontoxic therapy with folic acid and vitamins B6 and B12 reduces plasma homocysteine levels by approximately 25% to 30% and may reduce CV events. Therefore, a large, randomized clinical trial--the Heart Outcomes Prevention Evaluation (HOPE)-2 study--is being conducted to evaluate this therapy in patients at high risk for CV events.

OBJECTIVES

To evaluate whether long-term therapy with folic acid and vitamins B6 and B12 reduces the risk of major CV events in a high-risk population. The primary study outcome is the composite of death from CV causes, myocardial infarction and stroke.

METHODS

A total of 5522 patients aged 55 years or older with pre-existing CV disease or with diabetes and additional risk factor(s) at 145 centres in 13 countries were randomly assigned to daily therapy with combined folic acid 2.5 mg, vitamin B6 50 mg and vitamin B12 1 mg, or to placebo. Follow-up will average five years, to be completed by the end of 2005.

RESULTS

The patients' baseline characteristics confirmed their high-risk status. Baseline homocysteine levels varied between countries and regions. HOPE-2 is one of the largest trials of folate and vitamins B6 and B12 and is expected to significantly contribute to the evaluation of the role of homocysteine lowering in CV prevention.

The HOPE (Heart Outcomes Prevention Evaluation) Study and its consequences

The HOPE study was a 19 country, prospective randomized trial in which the ACE-inhibitor Ramipril but not Vitamin E significantly reduced the risk of future cardiovascular events in a high-risk population of men and women, including many with diabetes. The benefits were present in all sub-groups, independent of the presence or absence of diabetes, hypertension, evidence of cardiovascular disease, microalbuminuria, blood pressure lowering, the use of aspirin, lipid-lowering or antihypertensive medication. It provided clear evidence that Ramipril should safely and cost-effectively be used in individuals not known to have low ventricular ejection fraction or heart failure but at high-risk of cardiovascular events. It was also beneficial in patients with renal insufficiency, reducing progression of proteinuria and development of new microalbuminuria. It provided micro- and macrovascular benefits in people with diabetes, reduced the development of new cases of diabetes and showed a positive and graded association between the waist-to-hip ratio and the risk of developing diabetes. Sub-studies completed and on-going into the predictive role of natriuretic peptides, infectious and inflammatory markers, provide insight into possible mechanisms of action of Ramipril.

The relationship between dysglycaemia and cardiovascular and renal risk in diabetic and non-diabetic participants in the HOPE study: a prospective epidemiological analysis

AIMS/HYPOTHESIS

Emerging data suggest that different indices of glycaemia are risk factors for clinical events. The aim of this analysis was to investigate the relationship between fasting plasma glucose or glycated haemoglobin (GHb) levels and incident cardiovascular (CV) outcomes, death, heart failure and overt nephropathy in diabetic and non-diabetic individuals enrolled in the Heart Outcomes Prevention Evaluation (HOPE) study.

MATERIALS AND METHODS

The adjusted 4.5-year risk of CV events (myocardial infarction or stroke or CV death), heart failure, death and overt nephropathy was analysed in relation to baseline and updated GHb levels (in 3,529 diabetic HOPE study participants) and baseline fasting plasma glucose levels (in 1,937 non-diabetic and 1,013 diabetic participants).

RESULTS

In diabetic participants, a 1% absolute rise in the updated GHb predicted future CV events (relative risk [RR]=1.07, 95% CI 1.01-1.13; p=0.014), death (RR=1.12, 95% CI 1.05-1.19; p=0.0004), heart failure (RR=1.20, 95% CI 1.08-1.33; p=0.0008) and overt nephropathy (RR=1.26, 95% CI 1.17-1.36; p<0.0001) after adjusting for age, sex, diabetes duration, blood pressure, WHR, hyperlipidaemia and ramipril. Similarly, a 1 mmol/l rise in fasting plasma glucose was related to an increased risk of CV outcomes (RR=1.09, 95% CI 1.05-1.13; p<0.0001), death (RR=1.06, 95% CI 1.01-1.12; p=0.017), heart failure (RR=1.16, 95% CI 1.06-1.13; p=0.0007) and overt nephropathy (RR=1.34, 95% CI 1.23-1.45; p<0.0001) in the group composed of diabetic and non-diabetic individuals. The significant relationship between fasting plasma glucose and CV outcomes persisted after adjustment for diabetes status (RR=1.06, 95% CI 1.00-1.12; p=0.043).

CONCLUSIONS/INTERPRETATION

There is an independent progressive relationship between indices of glycaemia and incident CV events, renal disease and death. Clinical trials of glucose lowering to prevent these outcomes in diabetic and non-diabetic individuals are indicated.

The relevance of tissue angiotensin-converting enzyme: manifestations in mechanistic and endpoint data

Angiotensin-converting enzyme (ACE) is primarily localized (>90%) in various tissues and organs, most notably on the endothelium but also within parenchyma and inflammatory cells. Tissue ACE is now recognized as a key factor in cardiovascular and renal diseases. Endothelial dysfunction, in response to a number of risk factors or injury such as hypertension, diabetes mellitus, hypercholesteremia, and cigarette smoking, disrupts the balance of vasodilation and vasoconstriction, vascular smooth muscle cell growth, the inflammatory and oxidative state of the vessel wall, and is associated with activation of tissue ACE. Pathologic activation of local ACE can have deleterious effects on the heart, vasculature, and the kidneys. The imbalance resulting from increased local formation of angiotensin II and increased bradykinin degradation favors cardiovascular disease. Indeed, ACE inhibitors effectively reduce high blood pressure and exert cardio- and renoprotective actions. Recent evidence suggests that a principal target of ACE inhibitor action is at the tissue sites. Pharmacokinetic properties of various ACE inhibitors indicate that there are differences in their binding characteristics for tissue ACE. Clinical studies comparing the effects of antihypertensives (especially ACE inhibitors) on endothelial function suggest differences. More comparative experimental and clinical studies should address the significance of these drug differences and their impact on clinical events.

Risk factors, atherosclerosis, and cardiovascular disease among Aboriginal people in Canada: the Study of Health Assessment and Risk Evaluation in Aboriginal Peoples (SHARE-AP)

BACKGROUND

Little is known about the rates of cardiovascular disease (CVD), atherosclerosis, and their risk factors among Canada's Aboriginal people. To establish the relative prevalence of risk factors, atherosclerosis, and CVD, we undertook a population-based study among people of Aboriginal and European ancestry in Canada.

METHODS

We randomly recruited 301 Aboriginal people from the Six Nations Reservation, and 326 people of European origin from Hamilton, Toronto, and Edmonton, Canada. Clinical CVD was defined by history or electrocardiographic findings, atherosclerosis was measured by B-mode carotid ultrasonography, and conventional and new CVD risk factors were measured using standardised methods.

FINDINGS

Aboriginal people had significantly more carotid atherosclerosis (mean of the maximum intimal-medial thickness 0.82 (SD 0.20) mm vs 0.78 (0.20) mm, p=0.027), and had a higher frequency of CVD (18.5% vs 7.6%, p=0.00002) compared with Europeans. Aboriginal people had significantly higher rates of smoking, glucose intolerance, obesity, abdominal obesity, and substantially higher concentrations of fibrinogen, and plasminogen activator inhibitor-1. Aboriginal people had significantly higher rates of unemployment and a lower annual household income. For any given income level, Aboriginal people had higher rates of risk factors and CVD compared with the Europeans.

INTERPRETATION

A significant proportion of Aboriginal people live in poverty which is associated with high rates of CVD and CVD risk factors. Improvement of the socioeconomic status of Aboriginal people might be a key to reduce CVD in this group.

Reduction of cardiovascular risk by regression of electrocardiographic markers of left ventricular hypertrophy by the angiotensin-converting enzyme inhibitor ramipril

BACKGROUND

Electrocardiographic markers of left ventricular hypertrophy (LVH) predict poor prognosis. We determined whether the ACE inhibitor ramipril prevents the development and causes regression of ECG-LVH and whether these changes are associated with improved prognosis independent of blood pressure reduction.

METHODS AND RESULTS

In the Heart Outcomes Prevention Evaluation (HOPE) study, patients at high risk were randomly assigned to ramipril or placebo and followed for 4.5years. ECGs were recorded at baseline and at study end. We compared prevention/regression and development/persistence of ECG-LVH in the two groups and related these changes to outcomes. At baseline, 676 patients had LVH (321 in the ramipril group and 355 in the placebo group) and 7605 patients did not have LVH (3814 in the ramipril group and 3791 in the placebo group). By study end, 336 patients in the ramipril group (8.1%) compared with 406 in the placebo group (9.8%) had development/persistence of LVH; in contrast, 3799 patients in the ramipril group (91.9%) compared with 3740 in the placebo group (90.2%) had regression/prevention of LVH (P=0.007). The effect of ramipril on LVH was independent of blood pressure changes. Patients who had regression/prevention of LVH had a lower risk of the predefined primary outcome (cardiovascular death, myocardial infarction, or stroke) compared with those who had development/persistence of LVH (12.3% versus 15.8%, P=0.006) and of congestive heart failure (9.3% versus 15.4%, P<0.0001).

CONCLUSIONS

The ACE inhibitor ramipril decreases the development and causes regression of ECG-LVH independent of blood pressure reduction, and these changes are associated with reduced risk of death, myocardial infarction, stroke, and congestive heart failure.

The use of surrogate endpoints in clinical trials: focus on clinical trials in cardiovascular diseases

Surrogate endpoints include a wide range of laboratory or physical measurements used in clinical trials as a substitute for meaningful clinical endpoints that directly assess effects of the intervention(s) tested on mortality and/or morbidity. These surrogate endpoints are frequently employed in clinical trials and when used judiciously, can accelerate and focus the study of new therapies and can greatly enhance our understanding of their mechanisms of action. The current review provides a definition of surrogate endpoints, proposes practical criteria for establishing their validity, outlines some of the advantages, disadvantages and specific statistical considerations associated with their use in clinical trials and attempts also to highlight drug approval issues associated with the use of these endpoints. A number of examples are also provided related to the use of surrogate endpoints in clinical trials with special emphasis on their use in cardiovascular medicine.

Use of carotid ultrasound to stratify risk

B-mode carotid ultrasound is a well validated imaging technique for evaluating the anatomical extent of subclinical atherosclerosis. It is used to measure arterial carotid intima-media thickness (IMT), and there is clear evidence that carotid IMT measurements can be used to identify individuals at increased risk for coronary events and stroke. The validity and the usefulness of the technique - primarily as a research tool but also in the assessment of clinical cardiovascular risk - have been shown in a number of studies.

Effects of ramipril and vitamin E on atherosclerosis: the study to evaluate carotid ultrasound changes in patients treated with ramipril and vitamin E (SECURE)

BACKGROUND

Activation of the renin-angiotensin-aldosterone system and oxidative modification of LDL cholesterol play important roles in atherosclerosis. The Study to Evaluate Carotid Ultrasound changes in patients treated with Ramipril and vitamin E (SECURE), a substudy of the Heart Outcomes Prevention Evaluation (HOPE) trial, was a prospective, double-blind, 3x2 factorial design trial that evaluated the effects of long-term treatment with the angiotensin-converting enzyme inhibitor ramipril and vitamin E on atherosclerosis progression in high-risk patients.

METHODS AND RESULTS

A total of 732 patients >/=55 years of age who had vascular disease or diabetes and at least one other risk factor and who did not have heart failure or a low left ventricular ejection fraction were randomly assigned to receive ramipril 2.5 mg/d or 10 mg/d and vitamin E (RRR-alpha-tocopheryl acetate) 400 IU/d or their matching placebos. Average follow-up was 4.5 years. Atherosclerosis progression was evaluated by B-mode carotid ultrasound. The progression slope of the mean maximum carotid intimal medial thickness was 0.0217 mm/year in the placebo group, 0.0180 mm/year in the ramipril 2.5 mg/d group, and 0.0137 mm/year in the ramipril 10 mg/d group (P=0.033). There were no differences in atherosclerosis progression rates between patients on vitamin E and those on placebo.

CONCLUSIONS

Long-term treatment with ramipril had a beneficial effect on atherosclerosis progression. Vitamin E had a neutral effect on atherosclerosis progression.

Modifying the natural history of atherosclerosis: the SECURE trial

Experimental and epidemiological evidence suggests that activation of the reninangiotensin-aldosterone system and oxidative modification of low density lipoprotein cholesterol both play important roles in atherosclerosis. A substudy of the HOPE (Heart Outcomes Prevention Evaluation) trial, the SECURE trial (Study to Evaluate Carotid Ultrasound changes in patients treated with Ramipril and vitamin E), evaluated the effects of long-term treatment with the angiotensin-converting enzyme (ACE) inhibitor, ramipril, and with vitamin E on atherosclerosis progression in high risk patients. A total of 732 patients were enrolled into the study. These patients were 55 years or older, had vascular disease or diabetes with at least one other cardiovascular risk factor, but did not have heart failure or low ejection fraction. Patients were randomly assigned according to a three-by-two factorial design to receive placebo, ramipril 2.5 mg/day or ramipril 10 mg/day and placebo or vitamin E 400 IU/day. Progression of atherosclerosis was evaluated by B-mode carotid ultrasonography. The primary outcome evaluated was the annualised progression slope of the mean maximum carotid intimal-medial thickness (IMT) across 12 pre-selected carotid arterial segments. The average follow-up was 4.5 years. The progression slope of the mean maximum IMT was 0.0217 +/- 0.04 mm/year in the placebo group, 0.018 +/- 0.44 mm/year in the ramipril 2.5 mg/day group and 0.0137 +/- 0.04 in the ramipril 10 mg/day group (P = 0.33 for the overall effect of ramipril and P = 0.028 for the comparison between patients receiving ramipril placebo and ramipril 10 mg/day). The reduction in atherosclerotic progression observed with ramipril remained significant after adjusting for systolic and diastolic blood pressure changes (P = 0.043) and after multivariate adjustment (P = 0.046). Administration of vitamin E 400 IU/day had no impact on atherosclerosis progression. The SECURE study is the first demonstration, in human subjects, of an effect of ACE inhibition on atherosclerotic progression. This benefit cannot be explained by the lowering of blood pressure alone. Vitamin E 400 IU/day had a neutral effect on the ultrasound measurements of atherosclerosis progression in the SECURE trial.

Antiatherosclerotic effects of ACE inhibitors: where are we now?

ACE inhibitors have been used extensively in the management of patients with hypertension and heart failure. Over the past decade, a large body of evidence has emerged indicating that ACE inhibition also favorably affects the vasculature, and that these effects are associated with improved patient outcomes. Such evidence is provided by several sources: (i) experimental studies, which demonstrate that in addition to blood pressure lowering, ACE inhibitors improve endothelial function and have a host of other beneficial effects on the arterial wall; (ii) epidemiologic studies, which link the renin-angiotensin-aldosterone system to increased risk for myocardial infarction, and (iii) clinical trials, which demonstrate that treatment with these agents reduces the risk for acute ischemic events, improves the function of the arterial endothelium and can retard the progression of the anatomic extent of atherosclerosis.

Differences in risk factors, atherosclerosis and cardiovascular disease between ethnic groups in Canada: the study of health assessment and risk in ethnic groups (SHARE)

Cardiovascular disease rates vary greatly between ethnic groups in Canada. To establish whether this variation can be explained by differences in disease risk factors and subclinical atherosclerosis, we undertook a population-based study of three ethnic groups in Canada: South Asians, Chinese and Europeans. A total of 985 participants were recruited from three cities (Hamilton, Toronto and Edmonton) by stratified random sampling. Clinical cardiovascular disease was defined by history or electrocardiographic findings. Carotid atherosclerosis was measured with B-mode ultrasonography. Conventional (smoking, hypertension, diabetes, raised cholesterol) and novel risk factors (markers of a prothrombotic state) were measured. Within each ethnic group and overall, the degree of carotid atherosclerosis was associated with a higher prevalence of cardiovascular disease. South Asians had the highest prevalence of this condition compared with Europeans and Chinese (11%, 5% and 2%, respectively; p=0.0004). Despite this finding, Europeans had more atherosclerosis (mean of the maximum intimal medial thickness 0.75 [0.16] mm) than South Asians (0.72 [0.15] mm) and Chinese (0.69 [0.16] mm). South Asians had an increased prevalence of glucose intolerance, higher total and low-density lipoprotein cholesterol, higher triglycerides and lower high-density lipoprotein cholesterol, and much greater abnormalities in novel risk factors including higher concentrations of fibrinogen, homocysteine, lipoprotein(a), and plasminogen activator inhibitor-1. Although there are differences in conventional and novel risk factors between ethnic groups, this variation and the degree of atherosclerosis only partly explains the higher rates of cardiovascular disease among South Asians compared with Europeans and Chinese. The increased risk of cardiovascular events could be due to factors affecting plaque rupture, the interaction between prothrombotic factors and atherosclerosis, or as yet undiscovered risk factors.

Differences in risk factors, atherosclerosis, and cardiovascular disease between ethnic groups in Canada: the Study of Health Assessment and Risk in Ethnic groups (SHARE)

BACKGROUND

Cardiovascular disease rates vary greatly between ethnic groups in Canada. To establish whether this variation can be explained by differences in disease risk factors and subclinical atherosclerosis, we undertook a population-based study of three ethnic groups in Canada: South Asians, Chinese, and Europeans.

METHODS

985 participants were recruited from three cities (Hamilton, Toronto, and Edmonton) by stratified random sampling. Clinical cardiovascular disease was defined by history or electrocardiographic findings. Carotid atherosclerosis was measured with B-mode ultrasonography. Conventional (smoking, hypertension, diabetes, raised cholesterol) and novel risk factors (markers of a prothrombotic state) were measured.

FINDINGS

Within each ethnic group and overall, the degree of carotid atherosclerosis was associated with a higher prevalence of cardiovascular disease. South Asians had the highest prevalence of this condition compared with Europeans and Chinese (11%, 5%, and 2%, respectively, p=0.0004). Despite this finding, Europeans had more atherosclerosis (mean of the maximum intimal medial thickness 0.75 [0.16] mm) than South Asians (0.72 [0.15] mm), and Chinese (0.69 [0.16] mm). South Asians had an increased prevalence of glucose intolerance, higher total and LDL cholesterol, higher triglycerides, and lower HDL cholesterol, and much greater abnormalities in novel risk factors including higher concentrations of fibrinogen, homocysteine, lipoprotein (a), and plasminogen activator inhibitor-1.

INTERPRETATION

Although there are differences in conventional and novel risk factors between ethnic groups, this variation and the degree of atherosclerosis only partly explains the higher rates of cardiovascular disease among South Asians compared with Europeans and Chinese. The increased risk of cardiovascular events could be due to factors affecting plaque rupture, the interaction between prothrombotic factors and atherosclerosis, or as yet undiscovered risk factors.

Echocardiographically guided pericardiocentesis - the gold standard for the management of pericardial effusion and cardiac tamponade

BACKGROUND

The conventional surgical pericardiotomy and blind needle-puncture pericardiocentesis using a subxiphoid approach have been reported to have only moderate success rates and to be associated with unacceptably high rates of morbidity and mortality. More recently, echocardiographically guided pericardiocentesis was reported to improve considerably the likelihood of success and the safety of this procedure.

OBJECTIVE

To evaluate the efficacy and safety of echocardiographically guided pericardiocentesis in the authors' institution.

PATIENTS AND METHODS

A series of consecutive patients who underwent percutaneous pericardiocentesis at the Hamilton General Hospital, Hamilton, Ontario, from June 1994 to December 1998.

RESULTS

Forty-one patients underwent a total of 46 echocardiographically guided pericardiocentesis procedures. The procedure was successful in 100% of attempts. Clinical complications occurred in two (5%) patients: one patient with known coagulopathy developed hemothorax and one patient developed purulent pericarditis several days after the procedure. There were no deaths, and no patient required urgent referral for surgical management.

CONCLUSIONS

Echocardiographically guided pericardiocentesis is safe and effective, and is the method of choice for therapeutic and diagnostic drainage of pericardial effusions. While echocardiographically guided pericardiocentesis was described originally at centres with large volumes of patients with clinically significant pericardial effusions and with extensive experience in using this technique, similar high success and low complication rates were attained at an institution with relatively low numbers of patients requiring pericardial drainage.

Homocyst(e)ine and cardiovascular disease: a critical review of the epidemiologic evidence

PURPOSE

To review epidemiologic studies on the association between homocyst(e)ine level and risk for cardiovascular disease and the potential benefits of homocysteine-decreasing therapies.

DATA SOURCES

Computerized and manual searches of the literature on total homocysteine levels and cardiovascular disease.

STUDY SELECTION

Prospective studies and major retrospective epidemiologic studies evaluating the association between homocyst(e)ine levels and cardiovascular disease and the association between blood levels or dietary intake of folate, vitamin B6, and vitamin B12 and cardiovascular disease.

DATA EXTRACTION

Relevant data on patient population, plasma homocyst(e)ine levels, duration of follow-up, and main results were extracted from studies that met the inclusion criteria.

DATA SYNTHESIS

The designs and results of studies included in this review are summarized. A formal meta-analysis was not performed because the studies were heterogeneous in method and design.

CONCLUSIONS

Results of epidemiologic studies suggest that moderately elevated plasma or serum homocyst(e)ine levels are prevalent in the general population and are associated with an increased risk for cardiovascular disease, independent of classic cardiovascular risk factors. Simple, inexpensive, nontoxic therapy with folic acid, vitamin B6, and vitamin B12 reduces plasma homocyst(e)ine levels. Although the association between homocyst(e)ine levels and cardiovascular disease is generally strong and biologically plausible, the data from the prospective studies are less consistent. In addition, epidemiologic observations of an association between hyperhomocyst(e)inemia and cardiovascular risk do not prove the existence of a causal relation. Therefore, the effectiveness of folate, vitamin B6, and vitamin B12 in reducing cardiovascular morbidity and mortality requires rigorous testing in randomized clinical trials. Several such trials are under way; their results may greatly affect cardiovascular morbidity and mortality, given the simplicity and low cost of vitamin therapy.

Summary of randomized trials of angiotensin converting enzyme inhibitors

Angiotensin converting enzyme (ACE) inhibitors have been shown to reduce the risk of death, worsening heart failure and recurrent infarction in patients with left ventricular dysfunction and heart failure. They have also been shown to reduce mortality in the acute phase of myocardial infarction. They have been demonstrated to reduce major vascular events and progression of renal disease in diabetes with hypertension, compared to placebo and to calcium channel blockers. Current trials are evaluating their role in preventing major vascular events in patients with coronary artery disease, strokes and Type II diabetes who are normotensive.

The Study of Health Assessment and Risk in Ethnic groups (SHARE): rationale and design. The SHARE Investigators

The Study of Health Assessment and Risk in Ethnic groups (SHARE) is a study to determine the risk factors for atherosclerosis among three ethnic populations in Canada. Three hundred and thirty South Asian Canadian, 320 Chinese Canadian and 320 European Canadian men and women between 35 and 75 years of age are being randomly sampled from communities in Hamilton and Toronto, Ontario and Edmonton, Alberta for assessment of conventional (i.e., smoking, dyslipidemia, diabetes and hypertension) and emerging (i.e., candidate genes for atherosclerosis, homocysteine, fibrinolytic parameters, neurohormones, glucose intolerance, markers of infection, socioeconomic status, psychosocial status and diet) cardiovascular disease risk factors. Subclinical atherosclerosis is measured by quantitative B-mode ultrasonography of the carotid arteries, and other objective measures of vascular disease are a 12-lead electrocardiogram, a two-dimensional echocardiogram, ankle to arm blood pressure ratio and urine microalbumin concentration. The relationship between the conventional and emerging risk factors, and atherosclerosis, vascular disease and markers of end-organ damage will be evaluated between and within ethnic groups.

Anti-ischaemic effects of ACE inhibitors: review of current clinical evidence and ongoing clinical trials

Important ongoing experimental and clinical research is evaluating the potential use of ACE inhibitors in a wider range of patients, in addition to their well accepted use in heart failure, left ventricular dysfunction and hypertension. We review briefly the clinical data supporting a potential role for ACE inhibitors in the prevention of myocardial infarction and stroke and the wider use of these agents in hypertension, renal disease and diabetes. We also briefly review the major ongoing trials evaluating these hypotheses.

The antioxidant vitamins and cardiovascular disease. A critical review of epidemiologic and clinical trial data

PURPOSE

To review prospective epidemiologic studies and randomized trials regarding the role of antioxidant vitamins (vitamins E and C and beta-carotene) in the prevention of cardiovascular disease, with emphasis on differences in results obtained by these two types of studies.

DATA SOURCES

Computerized and manual searches of the literature on antioxidant vitamins and cardiovascular disease.

STUDY SELECTION

Prospective epidemiologic studies and randomized trials that included 100 or more participants and provided quantified estimates of antioxidant vitamin intake.

DATA SYNTHESIS

Comparisons of relative risk reductions (RRR) across observational studies and randomized trials, including assessment of dose-response relations.

RESULTS

All three large epidemiologic cohort studies of vitamin E noted that high-level vitamin E intake or supplementation was associated with a significant reduction in cardiovascular disease (RRR range, 31% to 65%), as measured by various fatal and nonfatal cardiovascular end points. To obtain these reductions, vitamin E supplementation must last at least 2 years. Less consistent reductions were seen in studies of beta-carotene (RRR range, -2% to 46%) and vitamin C (RRR range, -25% to 51%). Considerable biases in observational studies, such as different health behaviors of persons using antioxidants, may account for the observed benefit. By contrast, none of the completed randomized trials showed any clear reduction in cardiovascular disease with vitamin E, vitamin C, or beta-carotene supplementation. The trials were not specifically designed to assess cardiovascular disease, did not provide data on nonfatal cardiovascular end points, may have had insufficient treatment durations, and used suboptimal vitamin E doses. The completed trials were of adequate size to indicate that the true therapeutic benefit of vitamin E and other antioxidants in reducing fatal cardiovascular disease (a survival benefit as long as 5 years) is probably more modest than the epidemiologic data suggest.

CONCLUSION

The epidemiologic data suggest that antioxidant vitamins reduce cardiovascular disease, with the clearest effect for vitamin E; however, completed randomized trials do not support this finding. Much of this controversy should be resolved by the ongoing large-scale and long-term randomized trials designed specifically to evaluate effects on cardiovascular disease.

Abnormalities in intramyocardial arteries detected in cardiac transplant biopsy specimens and lack of correlation with abnormal intracoronary ultrasound or endothelial dysfunction in large epicardial coronary arteries

OBJECTIVES

We sought to determine whether abnormalities in small intramyocardial vessels could be detected on routine cardiac transplant biopsy specimens and whether these features correlate with intimal thickening by intracoronary ultrasound and endothelial dysfunction in large epicardial vessels.

BACKGROUND

Variability in clinical presentation of allograft vasculopathy suggests differential involvement of large and small vessels. Intracoronary ultrasound and endothelial function studies detect large-vessel abnormalities but may not reflect changes in small intramyocardial arteries. The latter could be detected in routine cardiac biopsy specimens by histologic and immunohistochemical studies.

METHODS

Thirty-nine cardiac transplant recipients underwent intracoronary ultrasound and acetylcholine studies 5 to 7 days after endomyocardial biopsy. Biopsy tissue was evaluated for coronary artery endothelial plumping and intimal thickening and increased immunostaining for fibronectin, tumor necrosis factor-alpha and receptor for hyaluronan-mediated motility. Large-vessel disease was assessed by calculating an average intimal index from intracoronary ultrasound of the left anterior descending coronary artery. Endothelial function was determined by quantitative coronary analysis after acetylcholine challenge.

RESULTS

Coronary arteries were found in the biopsy tissue of 30 (76%) of the 39 patients who formed the study group. Fourteen of 30 patients had abnormal histologic findings. Immunohistochemical analysis for fibronectin, possible in 20 of 30 patients, was positive in 14 (70%) of 20 and correlated with abnormal histologic findings (p = 0.01). Immunostaining was positive for tumor necrosis factor-alpha and receptor for hyaluronan-mediated motility in 12 (40%) and 13 (43%) of 30 patients, respectively. All patients had intimal thickening by intracoronary ultrasound, but intimal index did not correlate significantly with small-artery disease by histologic or immunohistochemical analysis. Large-vessel endothelial dysfunction in 13 patients (43%) did not correlate with either abnormal ultrasound findings or small-vessel disease.

CONCLUSIONS

Intramyocardial arteries are readily observed in biopsy specimens from cardiac transplant recipients and provide useful information about allograft vasculopathy. Lack of correlation between intramyocardial and epicardial vessel disease suggests discordant progression of allograft vasculopathy.

Effects of oxygen free radicals and scavengers on the cardiac extracellular collagen matrix during ischemia-reperfusion

OBJECTIVE

Collagen is lysed early during ischemia-reperfusion, but whether this is due to ischemia or reperfusion injury is not known. The effect of oxygen free radicals and free radical scavengers on left ventricular hemodynamics, myocardial morphology and collagen content were studied in an isolated, Langendorff-perfused rat heart model of regional ischemia-reperfusion.

METHODS

All hearts received left anterior descending coronary artery ischemia for 20 mins. Group 1 had ischemia only; group 2 had ischemia followed by reperfusion with oxygenated Krebs-Henseleit buffer for 20 mins; group 3 had oxygen free radicals generated by hypoxanthine and xanthine oxidase during reperfusion; group 4 had free radical scavengers with superoxide dismutase plus catalase; group 5 had both oxygen free radicals and free radical scavengers during reperfusion.

RESULTS

Left ventricular developed pressure decreased significantly in group 3 during ischemia followed by reperfusion (58 +/- 3.1 mmHg versus 42 +/- 2.4 mmHg, P = 0.004), but did not change significantly in any of the other groups. Necrosis score on pathology was highest in group 3; this score also was higher than that in group 5 with free radical scavengers added (3.0 +/- 0.3 versus 2.0 +/- 0.4, P = 0.07) and higher than that of group 2 with reperfusion with buffer only (3.0 +/- 0.3 versus 1.4 +/- 0.5, P < 0.05). Collagen content decreased significantly compared with control in group 3 only with ischemia followed by reperfusion with the addition of oxygen free radicals (18.4 +/- 1.5 versus 11.9 +/- 1.7 g/mg protein, P < 0.05). The addition of free radical scavengers in group 5 mainly attenuated the collagen loss. Scanning electron microscopy revealed profound structural changes of the extracellular collagen matrix in numerous regions of 'stunning' independent of tissue necrosis.

CONCLUSIONS

We conclude that: first, oxygen free radicals trigger significant collagen damage and left ventricular dysfunction during reperfusion; second, these changes extend beyond the ischemic damage alone; and third, free radical scavengers can effectively limit oxygen free radical-induced collagen loss and left ventricular dysfunction.

Primary and secondary prevention of myocardial infarction and strokes: an update of randomly allocated, controlled trials

AIM

To summarize the risk factors associated with coronary heart disease and strokes and to evaluate measures used in the prevention and treatment of these diseases.

METHOD

A review of the results of randomly allocated clinical trials of treatment for both primary and secondary prevention of coronary heart disease and strokes.

RESULTS

Reductions in elevated blood pressure and cholesterol and cessation of cigarette smoking have clearly been shown to reduce the incidence of coronary heart disease. A reduction in blood pressure has also been shown to reduce the risk of strokes. In addition to other classical risk factors, such as abnormal serum lipids, diabetes and a genetic predisposition, recent studies have shown that elevated levels of fibrinogen and other clotting factors, elevated levels of renin and decreased levels of anti-oxidant vitamins such as E, C and beta-carotene can predict coronary heart disease and strokes. Thrombolytic therapy, aspirin and beta-blockers have been shown to reduce mortality in patients with myocardial infarction, and the latter two agents reduce mortality, re-infarction and strokes with long-term use. Treatment with intravenous magnesium and nitrates has shown promise but larger trials are required to confirm the results. Both aspirin and heparin have proven value in reducing the incidence of myocardial infarction and death in unstable angina. Following an acute myocardial infarction, long-term therapy with aspirin, beta-blockers, lipid-lowering agents and oral anticoagulants has been shown to reduce mortality and re-infarction. In patients with large infarcts associated with a low ejection fraction or heart failure, the use of angiotensin converting enzyme (ACE) inhibitors reduces mortality, hospitalization for heart failure and re-infarction. The use of diuretics to lower blood pressure reduces strokes. In contrast, calcium antagonists do not appear to consistently reduce mortality or prevent vascular events when used for primary or secondary prevention of either myocardial infarction or strokes.

CONCLUSIONS

Myocardial infarction and strokes can be prevented by refraining from smoking and maintaining appropriate blood pressure levels and a favourable balance of lipids. Following a myocardial infarction, further drug treatment should include aspirin, thrombolytic therapy (in acute myocardial infarction), beta-blockers, ACE inhibitors (in patients with a low ejection fraction) and perhaps anticoagulants.

In vitro high resolution intravascular imaging in muscular and elastic arteries

High resolution (125-microns lateral, 55-microns axial) images of 16 muscular (femoral) and 15 elastic (common carotid) human arteries were made in vitro with use of a prototype 45-MHz intravascular imaging system. Four distinct regions of scattering, excluding plaque, were identified in the ultrasound images corresponding histologically to the adventitia, media, thickened intima and elastic laminae, both internal and external. Arterial samples imaged under pressure and in a collapsed state underwent dimensional changes but exhibited similar levels of backscatter amplitude. All the elastic arteries displayed a prominent echogenic media, whereas all the muscular arteries displayed an echolucent media. Scattering from the internal elastic lamina in muscular arteries provided an excellent landmark for defining the location and extent of intimal thickening or plaque. In elastic arteries the internal elastic lamina could not be distinguished from the echogenic media; consequently, the boundary between the media and intimal layer was indistinct. Differences in the relative concentration and organization of collagen and elastin were found to provide a consistent explanation for the differences in scattering that were observed between individual layers within an artery as well as between muscular and elastic arteries.

Reciprocal electrocardiographic changes in acute myocardial infarction

If reciprocal electrocardiographic changes during acute myocardial infarction (AMI) are a result of ischemia of the wall opposite the AMI, a stress test is expected to induce similar changes in the corresponding electrocardiographic leads. Right atrial pacing was used as a myocardial stress method in 137 consecutive patients recovering from a transmural AMI, and the appearance of pacing-provoked ischemia before hospital discharge was correlated to the presence of absence of ST depression in the opposite wall during the initial 48 hours. Of the 137 patients, 83 (61%) had reciprocal changes; they were more common in inferior (87%) than in anterior (37%) AMI (p less than 0.01). Of 54 patients without reciprocal changes, only 5 (9%) had ST depression during predischarge pacing; however, of the 83 patients with reciprocal changes, 41 had pacing-induced ischemia (p less than 0.01) and 42 did not, indicating that in half of this group the reciprocal changes represent ischemia of the opposite wall. In the other half of the group, without ST depression during pacing, these changes may be a "mirror image" phenomenon. Follow-up showed that angina pectoris, positive treadmill test response 6 months later, or recurrent AMI all consequences of impaired myocardial blood supply, were significantly more frequent in patients with reciprocal changes. This group could be further separated according to the results of right atrial pacing, because angina pectoris or recurrent AMI were infrequent among those with reciprocal changes and negative pacing responses, but was frequent among those with reciprocal changes and positive pacing responses.(ABSTRACT TRUNCATED AT 250 WORDS)