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Biomedical subjects

A Tonkin

Publications and source records attributed to A Tonkin.

At least 19 recordsLinked to original sources

Effects of pravastatin on mortality in patients with and without coronary heart disease across a broad range of cholesterol levels. The Prospective Pravastatin Pooling project.

AIMS: To assess the effects of pravastatin on all-cause mortality and cause-specific mortality and to compare the effects for patients with prior coronary heart disease with those for patients without, using pooled data from the Long-Term Intervention with Pravastatin in Ischaemic Disease (LIPID) study, the Cholesterol and Recurrent Events (CARE) study, and the West of Scotland Coronary Prevention Study (WOSCOPS). METHODS AND RESULTS: 13 173 patients with coronary heart disease and 6595 men with elevated cholesterol and no prior coronary disease received pravastatin, 40 mg daily, or placebo for an average of 5 to 6 years. Data were analysed according to a pre-specified, published protocol. For all three trials combined, the mortality among patients assigned pravastatin was significantly lower, at 7.9%, than the 9.8% among those assigned placebo, a relative risk reduction of 20% (95% confidence interval (CI) 12-27%, P<0.0001). Active treatment was associated with a reduction in coronary mortality (24%, 95% CI 14-33%). Larger reductions in absolute risk were estimated in those with prior coronary heart disease than in those without. CONCLUSION: Treatment with pravastatin over 5 years reduces all-cause mortality and coronary mortality in patients with and those without a history of coronary heart disease. The size of the benefit was related principally to the baseline risk.

Aged↗

High-density lipoprotein cholesterol and treatment guidelines.

Setting consistent guidelines for the treatment of lipid abnormalities must take into consideration several factors and must balance the need for precision (favored by specialists) and practicality in the patient setting (favored by general medical practitioners). The appropriate populations for treatment should be clearly defined, and usual threshold levels, target levels, and treatment should be well established. Plasma high-density lipoprotein cholesterol (HDL-C) has not been widely incorporated in guidelines as a significant abnormality predictive of cardiovascular risk and as a therapeutic target. However, that view is changing in the light of recent improved understanding of the importance of each lipid fraction abnormality, including HDL-C, in the pathophysiology of atherosclerotic disease. In addition, clinical trials have demonstrated the apparent benefit of increasing low levels of HDL-C in reducing cardiovascular events. The use of guidelines incorporating threshold and target levels for managing HDL-C in high-risk populations is becoming seen as a practical means of improving the outcome for patients, especially for special groups, such as the elderly and those with type 2 diabetes mellitus.

Anticholesteremic Agents↗

Benefits of pravastatin on cardiovascular events and mortality in older patients with coronary heart disease are equal to or exceed those seen in younger patients: Results from the LIPID trial.

BACKGROUND: The effect of cholesterol-lowering therapy on death from coronary heart disease in older patients with previous coronary heart disease and average cholesterol levels is uncertain. OBJECTIVE: To compare the relative and absolute effects of pravastatin on cardiovascular disease outcomes in patients with coronary heart disease who are 65 years of age or older with those in patients 31 to 64 years of age. DESIGN: Subgroup analysis of a randomized, placebo-controlled trial. SETTING: 87 centers in Australia and New Zealand. PATIENTS: 3514 patients 65 to 75 years of age, chosen from among 9014 patients with previous myocardial infarction or unstable angina and a baseline plasma cholesterol level of 4.0 to 7.0 mmol/L (155 to 271 mg/dL). INTERVENTION: Pravastatin, 40 mg/d, or placebo. MEASUREMENTS: Major cardiovascular disease events over 6 years. RESULTS: Older patients were at greater risk than younger patients (31 to 64 years of age) for death (20.6% vs. 9.8%), myocardial infarction (11.4% vs. 9.5%), unstable angina (26.7% vs. 23.2%), and stroke (6.7% vs. 3.1%) (all P < 0.001). Pravastatin reduced the risk for all cardiovascular disease events, and similar relative effects were observed in older and younger patients. In patients 65 to 75 years of age, pravastatin therapy reduced mortality by 21% (CI, 7% to 32%), death from coronary heart disease by 24% (CI, 7% to 38%), coronary heart disease death or nonfatal myocardial infarction by 22% (CI, 9% to 34%), myocardial infarction by 26% (CI, 9% to 40%), and stroke by 12% (CI, -15% to 32%). For every 1000 older patients treated over 6 years, pravastatin prevented 45 deaths, 33 myocardial infarctions, 32 unstable angina events, 34 coronary revascularization procedures, 13 strokes, or 133 major cardiovascular events, compared with 22 deaths and 107 major cardiovascular events per 1000 younger patients. Among older patients, the numbers needed to treat were 22 (CI, 17 to 36) to prevent one death from any cause, 35 (CI, 24 to 67) to prevent one death from coronary heart disease, and 21 (CI, 17 to 31) to prevent one coronary heart disease death or nonfatal myocardial infarction. CONCLUSIONS: In older patients with coronary heart disease and average or moderately elevated cholesterol levels, pravastatin therapy reduced the risk for all major cardiovascular events and all-cause mortality. Since older patients are at greater risk than younger patients for these events, the absolute benefit of treatment is significantly greater in older patients.

Adult↗

Effect of pravastatin on frequency of fracture in the LIPID study: secondary analysis of a randomised controlled trial. Long-term Intervention with Pravastatin in Ischaemic Disease.

BACKGROUND: Statins inhibit the same biochemical pathway as aminobisphosphonates, therefore these cholesterol-lowering agents may have a beneficial effect on osteoporosis. This possibility has been supported by the finding that some statins also stimulate bone formation, and by observational studies suggesting that patients using statins have higher bone densities and lower fracture rates than controls. To assess whether statins have clinically significant effects on bone, we studied the frequency of fractures in a large randomised controlled trial of these agents. METHODS: 9014 patients (17% women, median age 62 years) with ischaemic heart disease were randomly assigned pravastatin 40 mg daily or placebo and followed up for a mean of 6.0 years. Fractures were ascertained from adverse-event reports. FINDINGS: 101 patients in the placebo group were admitted to hospital for fracture compared with 107 in the pravastatin group (hazard ratio 1.05 [95% CI 0.80-1.37]). When patients with fractures not necessitating hospital admission were added, the total number of patients having a fracture was 183 in the placebo group and 175 in the pravastatin group (0.94 [0.77-1.16]). Separate analyses for women alone and for individuals aged 65 years and over gave similar results. INTERPRETATION: These findings offer no support for the hypothesis that statins have a significant effect on fracture risk. However, this study was not of an osteoporotic population, and fracture rate, although clinically important, is an insensitive index of effects on bone. Statins should not be used to prevent osteoporosis until there is evidence for their efficacy based on randomised controlled trials.

Aged↗

Long-term risk stratification for survivors of acute coronary syndromes. Results from the Long-term Intervention with Pravastatin in Ischemic Disease (LIPID) Study. LIPID Study Investigators.

OBJECTIVES: We developed a prognostic strategy for quantifying the long-term risk of coronary heart disease (CHD) events in survivors of acute coronary syndromes (ACS). BACKGROUND: Strategies for quantifying long-term risk of CHD events have generally been confined to primary prevention settings. The Long-term Intervention with Pravastatin in Ischemic Disease (LIPID) study, which demonstrated that pravastatin reduces CHD events in ACS survivors with a broad range of cholesterol levels, enabled assessment of long-term prognosis in a secondary prevention setting. METHODS: Based on outcomes in 8,557 patients in the LIPID study, a multivariate risk factor model was developed for prediction of CHD death or nonfatal myocardial infarction. Prognostic indexes were developed based on the model, and low-, medium-, high- and very high-risk groups were defined by categorizing the prognostic indexes. RESULTS: In addition to pravastatin treatment, the independently significant risk factors included: total and high density lipoprotein cholesterol, age, gender, smoking status, qualifying ACS, prior coronary revascularization, diabetes mellitus, hypertension and prior stroke. Pravastatin reduced coronary event rates in each risk level, and the relative risk reduction did not vary significantly between risk levels. The predicted five-year coronary event rates ranged from 5% to 19% for those assigned pravastatin and from 6.4% to 23.6% for those assigned placebo. CONCLUSIONS: Long-term prognosis of ACS survivors varied substantially according to conventional risk factor profile. Pravastatin reduced coronary risk within all risk levels; however, absolute risk remained high in treated patients with unfavorable profiles. Our risk stratification strategy enables identification of ACS survivors who remain at very high risk despite statin therapy.

Aged↗

Angina pectoris and coronary artery disease in severe isolated valvular aortic stenosis.

BACKGROUND: Angina pectoris has long been recognised as one of the principal symptoms of severe aortic valve stenosis (AS), even in patients without significant coronary artery disease (CAD). However, controversy exists concerning the prevalence of angina pectoris and associated CAD in such patients. OBJECTIVE: To determine the prevalence of CAD detectable by angiography and its relation to angina pectoris and coronary risk factors in patients with severe AS. PATIENTS AND METHODS: All patients with symptomatic AS who had undergone aortic valve replacement and preoperative cardiac catheterisation at the Austin and Repatriation Medical Centre between 1 January 1986 and 31 May 1996 were retrospectively analysed. Those patients with multiple valve disease, aortic regurgitation of grade 2 or more in severity, or who had had prior coronary artery or valve surgery were excluded from this analysis. RESULTS: A total of 328 consecutive patients with severe AS (242 men and 86 women; mean age 72 years, range 39-84 years) were studied. Significant CAD (reduction in luminal diameter > or = 50%) was found in 162 patients (49.4%). Typical angina was present in 74.7% of these 162 patients but it was also found in 44.6% of the 166 patients without obstructive CAD. Of the patients without angina (n = 133), 30.8% had significant CAD. By multivariate logistic regression, we have identified seven significant predictors for CAD among severe AS patients. Five factors increased risk. Expressed as odds ratio with 95% confidence interval, these included: (i) age in years (1.07; 1.04-1.11, P = 0.001); (ii) male gender (2.09; 1.14-3.80, P = 0.016); (iii) angina pectoris (3.19; 1.89-5.37, P < 0.001); (iv) history of myocardial infarction (2.87; 1.38-5.97, P = 0.005); and (v) peripheral vascular disease (2.28; 1.28-4.05, P = 0.005). Factors associated with decreased likelihood of CAD were serum high density lipoprotein (HDL) cholesterol (0.58; 0.34-0.71, P = 0.002) and peak systolic gradient across the aortic valve (0.97; 0.95-0.99, P = 0.0113). CONCLUSION: Coronary arteriography can probably be omitted for a patient with severe AS if that patient has no symptoms of angina and has no risk factors known to increase its incidence.

Journal Article↗

Guar gum reduces postprandial hypotension in older people.

OBJECTIVE: To determine whether slowing of gastric emptying and glucose absorption with guar gum would reduce the fall in blood pressure after an oral glucose load in older subjects. DESIGN: A randomized, experimental, cross-over study. SETTING: Department of Nuclear Medicine, Royal Adelaide Hospital, Adelaide, SA, Australia. PARTICIPANTS: Ten healthy subjects, age 67 to 78. MEASUREMENTS: Simultaneous measurements of gastric emptying, blood pressure, blood glucose, serum insulin, and oral glucose absorption (3-O-methyl-D-glucose [3-OMG]) on two occasions after ingestion of 300 mL water containing 50 g glucose and 30 mL lemon juice, 3 g 3-OMG labeled with 99mTc-sulphur colloid; with or without 9 g guar gum. Blood pressure and gastric emptying were monitored for 180 minutes. RESULTS: The magnitude of the falls in systolic (P = .02), diastolic (P < .05), and mean arterial (P = .05) blood pressure were less, and gastric emptying slower (P < .05), after guar. Blood glucose, insulin, and 3-OMG concentrations were reduced (P < .001 for all) by guar. 3-OMG concentrations were inversely related to the intragastric retention of glucose (r = -0.72, P = .02) and blood pressure was inversely related to 3-OMG (r = -0.64, P < .05) after the drink without guar. The blood glucose concentration was related to 3-OMG (r > 0.64, P < .05). CONCLUSION: Guar gum reduces the magnitude of the fall in blood pressure after oral glucose. Slowing of gastric emptying and glucose absorption may represent a novel approach to the treatment of postprandial hypotension.

Age Factors↗

Evaluation of the dose-response relationship for intra-nasal oxymetazoline hydrochloride in normal adults.

OBJECTIVES: To evaluate the dose-response relationship of increasing doses of oxymetazoline compared with placebo in normal subjects, and to determine the sensitivities of rhinomanometry, acoustic rhinometry and symptoms in discriminating between differing doses of oxymetazoline in normal subjects. METHODS: The study had a randomized, double-blind, placebo-controlled, parallel group, dose-response design. One hundred and twenty-five healthy volunteers with no nasal obstruction were randomized to administration of a single intra-nasal dose of oxymetazoline (6.25 microg, 12.5 microg, 25 microg or 50 microg) or placebo to each nasal cavity. Nasal airway resistance (NAR) was measured by active posterior rhinomanometry. Total minimum cross-sectional area (tMCA) and volume (tVOL) were measured by acoustic rhinometry. Symptoms of congestion (CON) were assessed on a visual analogue scale. RESULTS: The two highest doses of oxymetazoline produced a significant decrease in NAR compared with placebo (P = 0.015) but not between placebo and 12.5 microg or 6.25 microg. There was a dose-response relationship for tVOL, which increased significantly after all doses compared with placebo (P < 0. 001) and showed differences between 6.25-microg and 25-microg (P < 0. 014) and 12.5-microg and 50-microg (P < 0.05) doses. tMCA increased compared with placebo after all treatments (P = 0.028), but there were no significant differences between any of the active doses. There were no significant changes in CON after any treatments compared with placebo. CONCLUSIONS: tVOL shows a clear dose-response relationship for the range of doses of oxymetazoline administered. tVOL provides a sensitive and discriminatory measure of small nasal changes after low doses of oxymetazoline. NAR is able to discriminate between doses, but is less sensitive than tVOL and tMCA, requiring a higher threshold dose before significant changes are seen in nasal patency.

Administration, Intranasal↗

Non-rheumatic atrial fibrillation and stroke.

The risk of systemic embolism and stroke in patients with non-rheumatic atrial fibrillation (NRAF) should not be underestimated. The annual embolic rate is approximately 5% and in those with left atrial enlargement and/or left ventricular (LV) dysfunction, or who have already had systemic embolism, this rate may be as high as 20%. Decisions on patient management and the prophylaxis of stroke must always be individualised. The risk of bleeding related to warfarin is almost certainly greater than that encountered in the previous randomised trials. Also, clinical and echocardiographic features can further define absolute risk in an individual patient with NRAF. Clinical markers of increased risk of embolism in patients with NRAF include older age, previous cerebral embolism, recent congestive heart failure, hypertension and diabetes mellitus. Transthoracic echocardiography improves risk stratification and should be performed in the vast majority of patients. Embolic risk is greatest in those with increasing left atrial dilation, atrial dysfunction and LV dysfunction. Transoesophageal echocardiography sharpens the risk profile in selected patients. Overall randomised trials show greater benefit with warfarin than aspirin. In general, increasing age is associated with a greater incidence of structural heart disease and probably implies greater potential benefit with warfarin. Increasing age per se may not increase the risk of warfarin-related bleeding. When the decision is made to warfarinise patients, at the present time data suggest that the target INR should be in the range of 2.0-3.0.

Anticoagulants↗

Implementation of nationally developed guidelines in cardiology: a survey of NSW cardiologists and cardiothoracic surgeons.

BACKGROUND: In July 1996, the National Health and Medical Research Council (NHMRC) published clinical practice guidelines for 'The Procedural and Surgical Management of Coronary Heart Disease'. Despite increasing interest in dissemination and implementation of guidelines, initial reactions to these specific Guidelines and factors critical to their successful implementation had not been determined until our study. AIMS: To determine views of New South Wales (NSW) clinicians towards these NHMRC Guidelines; to identify perceptions about local relevance, usefulness and likely impact and to elicit preferred implementation strategies. METHODS: A postal survey in November 1997 of all cardiologists and cardiothoracic surgeons in NSW. RESULTS: One hundred and ten of 174 clinicians returned the questionnaire (63% response rate). Forty-eight per cent indicated that they were aware of the Guidelines before receiving a copy with the questionnaire while 26% had commented on the draft version of the Guidelines when distributed in November 1995. More than half of respondents 'agreed' or 'strongly agreed' with six of nine statements about potential strengths of the Guidelines. While at least 25% 'disagreed' or 'strongly disagreed' on 11 out of the 13 statements about potential criticisms of the Guidelines, more than half agreed or 'strongly' agreed that the Guidelines did not tell them 'anything they didn't already know'. Fifty-two per cent 'agreed' or 'strongly agreed' that guidelines will be misinterpreted by lawyers. At least 30% rated nine out of 11 implementation strategies as important. Local audits of care and regular feedback, reports from colleagues at conferences and hospital workshops outranked other implementation strategies in encouraging uptake of the Guidelines. CONCLUSIONS: Clinicians in NSW have generally positive views about the Guidelines, however, medicolegal concerns are apparent. To strengthen evidence-based decision-making as exemplified by the Guidelines, audits, presentations by opinion leaders and hospital-based workshops are recommended.

Attitude of Health Personnel↗

Rate of gastric emptying is a determinant of postprandial hypotension in non-insulin-dependent diabetes mellitus.

1. Postprandial hypotension is now recognized as an important clinical problem, particularly in the elderly and in patients with autonomic dysfunction. The mechanisms responsible are poorly understood; however, impaired regulation of splanchnic blood flow and the release of gastrointestinal hormones appear to be important. The effect of gastric emptying on the magnitude of the postprandial fall in blood pressure has not been evaluated. 2. The aim of this study was to determine whether there is a relationship between changes in blood pressure and the rate of gastric emptying after ingestion of 75 g of glucose in patients with non-insulin-dependent diabetes mellitus (NIDDM) and both young and older normal subjects. Sixteen patients with recently diagnosed NIDDM, median age 57 (39-79) years, 10 'young' subjects with a median age of 23 (19-26) years and nine 'older' subjects, median age 48 (40-68) years, were measured simultaneously for gastric emptying of 75 g of glucose in 350 ml of water blood pressure and blood glucose concentrations, commencing at approximately 10.00 hours after an overnight fast. Measurements of blood pressure were made in the sitting position immediately before glucose ingestion and at 15 min intervals up to 180 min. 3. Gastric emptying of glucose was not significantly different between the three groups [50% emptying time (T50): 95 +/- 7.3 min in patients with NIDDM compared with 120 +/- 13.2 min in the 'young' group and 97 +/- 8.1 min in the 'older' group]. There was a significant fall in mean blood pressure after the glucose load in the patients with NIDDM (P < 0.0001) and the 'older' normal subjects (P < 0.05), but not the 'young' normal subjects. Postprandial hypotension (fall in systolic blood pressure > or = 20 mmHg) was evident in seven (44%) patients with NIDDM and three (33%) 'older' normal subjects. The area under the change in mean blood pressure curve was related significantly to the gastric emptying T50 (r = 0.67, P < 0.005) in the patients with NIDDM, but not in either control group. 4. In conclusion, in patients with recently diagnosed NIDDM the fall in blood pressure after an oral glucose load is (i) greater than in both young and older normal subjects and (ii) related to the rate of gastric emptying.

Adult↗

Management of isolated systolic hypertension.

Isolated systolic hypertension (ISH) [systolic blood pressure (SBP) > or = l60mm Hg with diastolic blood pressure (DBP) <90mm Hg] is the commonest form of hypertension in the elderly, and accounts for about 60% of all hypertensive conditions in the population aged over 65 years. It is associated with a significantly increased risk of cardiovascular and cerebrovascular morbidity and mortality. The landmark Systolic Hypertension in the Elderly Program (SHEP) study, published in 1991, has shown that lowering the SBP in elderly patients with ISH results in a significant reduction in cardiovascular events. These results have had a major impact on clinical practice in hypertension. On theoretical grounds, considering the pathophysiological mechanisms of ISH in the elderly, any drug which lowers total peripheral resistance and/or arterial stiffness should reduce SBP effectively in these patients. This effect has been observed in outcome studies and short term clinical trials using a variety of drugs from the 4 major antihypertensive classes: diuretics, beta(1)-blockers, calcium channel antagonists and ACE inhibitors. Other drugs, including alpha antagonists, may also be effective. In general, there is compelling evidence to support active treatment of any individual with an SBP > or = 160mm Hg. As in essential hypertension, the maximum benefit is gained by aggressive treatment of those individuals at highest risk because of coexisting cardiovascular risk factors. In these people, an SBP of 140 to 159mm Hg should be considered to be an indication for active management. Initial management should be by manipulation of lifestyle factors such as bodyweight, salt and alcohol intake and aerobic exercise. Drug therapy, generally well tolerated in low doses, should be considered if SBP remains > or = 160mm Hg, or > or = 140mm Hg in the presence of multiple risk factors. The choice of initial drug therapy should be influenced by the particular clinical situation. If there are no coexisting contraindications or co-indications for particular drugs, it is reasonable to begin treatment with a low dose of a thiazide-like diuretic, as used in the SHEP study. However, in short term treatment trials calcium channel antagonists and ACE inhibitors have been shown to lower SBP effectively and can be used in the appropriate clinical context. Beta-blockers appear to be less effective as monotherapy in ISH. Combination therapy is frequently required and can be effective and well tolerated if carefully chosen.

Antihypertensive Agents↗

Unstable angina. An approach to management.

Unstable angina is an increasingly important medical problem. Initial assessment includes whether the pain is likely to be cardiac in origin, a risk stratification based upon the nature of the chest pain, and assessment of any haemodynamic changes or electrocardiographic changes (although this may be normal). After pain relief and aspirin administration, patients with prolonged rest pain should be referred immediately to hospital. Hospital management involves anti ischaemic therapy and then a decision as to whether coronary angiography or non-invasive testing is the initial investigation. The risk of myocardial infarction and death is highest in the first 4-6 weeks. Depending on clinical progress and angiographic findings, patients may continue medical therapy or have revascularisation by bypass surgery or coronary angioplasty.

Angina, Unstable↗

Reperfusion injury, stunning and myocardial viability.

Recent experimental data suggest that current thrombolytic strategies may not yet have achieved their full potential for myocardial salvage. In fact, reperfusion may result in microvascular and myocardial cellular injuries. These may translate into transient loss of contractile function ('myocardial stunning'), and possibly contribute to the ultimate extent of myocardial necrosis. A number of imaging modalities are now available to detect the presence and amount of these dysfunctional but viable myocardial segments. Myocardial reperfusion experiments using animal models have studied possible mechanisms responsible for reperfusion injury. These may help in the search for novel pharmacological and other adjunctive approaches which may overcome potential adverse effects of reperfusion.

Animals↗

Radiofrequency catheter ablation of tachyarrhythmias--adult and paediatric experience.

BACKGROUND AND AIMS: Until recently, curative therapy for supraventricular tachycardia (SVT) was possible only with map-guided cardiac surgery. The ability to ablate permanently the reentrant circuit responsible for tachycardia using radiofrequency electrical current (RF) delivered through a catheter has now allowed cure of SVT by non-surgical means. We present our initial experience with this technique in both adult and paediatric patients. METHODS: In 53 patients of median age 32 years, 56 radiofrequency catheter ablation procedures were performed for control of tachyarrhythmias. Fourteen patients were aged 18 years or less. Indications for RF ablation were SVT due to an accessory pathway (n = 27), SVT due to atrioventricular junctional reentry (AVJRT) (n = 22), incessant SVT (n = 2), ventricular tachycardia (n = 2), and uncontrolled atrial fibrillation (n = 3). General anaesthesia was used in 88% of procedures. Ablation was preceded by electrophysiological testing to confirm tachycardia mechanism in all cases. RESULTS: The ablation procedure was completely successful in 49/56 cases (87.5%) and partially successful in another two cases. Only five procedures (9%) failed. Median procedure time was two hours, median fluoroscopy time was 24 min, and the median number of RF applications was four. There were no major differences in results comparing adult and paediatric patients. A transient ulnar nerve palsy was the only major complication observed. After a follow-up of one to 15 months, tachycardia has recurred in two patients (4%). Of the total 53 patients, 90.5% are currently asymptomatic and off all cardiac drug therapy. RF catheter ablation appears to be an effective, curative, and relatively safe alternative to long term drug therapy in the management of troublesome SVT.

Adolescent↗

The use of calcium channel blockers in general practice.

Over the past decade the calcium antagonist drugs, also known as calcium channel blockers, have become established for use in a variety of cardiovascular diseases. A bewildering (and ever-growing) number of drugs in this class now becoming available. This article summarises the important characteristics of the calcium antagonists and discusses their practical use in hypertension, angina and other conditions in general practice.

Calcium Channel Blockers↗