Effect of coronary artery bypass graft surgery on survival: overview of 10-year results from randomised trials by the Coronary Artery Bypass Graft Surgery Trialists Collaboration

Outcome of acute myocardial infarction according to the specialty of the admitting physician

BACKGROUND

In order to limit costs, health care organizations in the United States are shifting medical care from specialists to primary care physicians. Although primary care physicians provide less resource-intensive care, there is little information concerning the effects of this strategy on outcomes.

METHODS

We examined mortality according to the specialty of the admitting physician among 8241 Medicare patients who were hospitalized for acute myocardial infarction in four states during a seven-month period in 1992. Proportional-hazards regression models were used to examine survival up to one year after the myocardial infarction. To determine the generalizability of our findings, we also examined insurance claims and survival data for all 220,535 patients for whom there were Medicare claims for hospital care for acute myocardial infarction in 1992.

RESULTS

After adjustment for characteristics of the patients and hospitals, patients who were admitted to the hospital by a cardiologist were 12 percent less likely to die within one year than those admitted by a primary care physician (P<0.001). Cardiologists also had the highest rate of use of cardiac procedures and medications, including medications (such as thrombolytic agents and beta-blockers) that are associated with improved survival.

CONCLUSIONS

Health care strategies that shift the care of elderly patients with myocardial infarction from cardiologists to primary care physicians lower rates of use of resources (and potentially lower costs), but they may also cause decreased survival. Additional information is needed to elucidate how primary care physicians and specialists should interact in the care of severely ill patients.

Are the marginal returns of coronary artery surgery smaller in high-rate areas? The Steering Committee of the Provincial Adult Cardiac Care Network of Ontario

BACKGROUND

Population-based rates of surgery vary within and between health-care systems, causing concern that case selection is less appropriate in high-rate areas. This inverse relationship has not been shown with appropriateness criteria generated by expert panels. We applied a trials-based measure of the potential survival benefit of coronary artery bypass graft surgery (CABG) to patients in a provincial registry, to determine the relationship between survival gains and rates of CABG.

METHODS

We did a population-based retrospective review of linked registry and administrative datasets. 5058 patients in the linked datasets underwent isolated CABG in Ontario between April 1, 1992, and March 31, 1993. Potential survival benefit of surgery was scored with an algorithm derived from a published overview of trials comparing CABG to medical treatment, analysed by county and by referral regions.

FINDINGS

Overall, case selection was appropriate whether assessed clinically (96.3% had either severe disease as judged on the coronary arteries affected or moderate to severe angina) or on the basis of survival benefit scores (94.0% predicted to obtain moderate or high benefit). There was significant variation in benefit scores across referral regions (p < 0.001). Benefit scores correlated inversely with county surgical rate (r = -0.49, p < 0.005) and the proportion of low-benefit cases increased with rates (r = 0.50, p < 0.005). Referral regions served by high-rate surgical centres had lower mean benefit scores.

INTERPRETATION

Most patients undergoing CABG in Ontario are in the high-survival benefit category. Surgery is defensible for patients with low survival benefit on the grounds of symptom relief, but the proportion of cases with low benefit rises with higher local rates of surgery. The inverse relationship between surgery rates and appropriateness of case selection may be better understood as diminishing marginal returns for specific outcomes with rising local use of procedures.

Assessing quality of care: what are the implications of the potential lack of sensitivity of outcome measures to differences in quality?

Measuring outcome can be an insensitive way to detect differences in the quality of health care. This paper captures the implications of this poor sensitivity for the interpretation of studies of outcome that compare provider performance, and considers in what circumstances monitoring outcome might be useful. When interpreting studies, it is important to consider the size of the effect that a difference in the quality of care might be expected to have on outcome and whether it is likely that important differences in quality might not have been detected. It is argued that outcome measures may be of value when how you do something is as important as what you do, when process measures are invalid or impractical, and when the overall effectiveness of an intervention is critically dependent upon its complication rate.

Meta-analysis of clinical trials: a consumer's guide

Meta-analysis is a popular statistical tool allowing the synthesis of related research studies in a quantitative manner. Components of a good meta-analysis are first discussed, with a view toward critical reading of reports of meta-analyses. Examples include lipid-lowering drugs and coronary artery bypass graft surgery. A role for meta-analysis in the design and monitoring of clinical trials was examined at a workshop held at the National Institutes of Health and aspects of these uses of meta-analyses are considered. Basic analytical and graphical methods of meta-analysis are briefly reviewed. The goal is to encourage more thoughtful evaluation of the many meta-analyses that are published or are presented.

Determinants of the use of coronary angiography and revascularization after thrombolysis for acute myocardial infarction

BACKGROUND

Clinical trials and practice guidelines have identified clinical criteria for the use of coronary angiography and revascularization procedures after thrombolysis for acute myocardial infarction. The effect of these criteria on clinical practice has not been extensively evaluated.

METHODS

We used classification-and-regression-tree (CART) and logistic-regression models to study the patients in the first Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries trial, to identify the variables that best predicted the use of angiography and revascularization procedures after thrombolysis.

RESULTS

Among the 21,772 U.S. patients in the trial, 71 percent underwent coronary angiography before discharge from the hospital. Of these, 58 percent underwent revascularization (73 percent receiving angioplasty). The CART model for the use of angiography showed that age was the variable most predictive of angiography; only 53 percent of patients at least 73 years of age underwent angiography, as compared with 76 percent of those under 73. Among the older patients, age was again the most predictive factor; among the younger patients, the availability of angioplasty was a more important predictor (67 percent of patients in hospitals without angioplasty facilities underwent angiography, as compared with 83 percent in hospitals with such facilities). The next most important variable was recurrent ischemia, which was more predictive at hospitals without angioplasty facilities than at those with them. Both statistical models identified coronary anatomy as the most important predictor of the use and type of revascularization.

CONCLUSIONS

More patients treated with thrombolysis underwent angiography and revascularization before discharge than might be expected. Younger age and the availability of the procedures appeared to be the major determinants of the use of coronary angiography, whereas coronary anatomy largely determined the use and type of revascularization. This process appeared to select low-risk patients for intervention rather than those at higher risk, who would be the most likely to benefit.

Risk stratification in coronary artery disease and special populations

In patients with coronary artery disease (CAD), left ventricular (LV) function, the number of diseased vessels, and the severity of myocardial ischemia are important determinants of survival. These factors can be used to identify subsets of high-risk patients who are candidates for aggressive intervention. Among patients with LV dysfunction, those with left main CAD, three-vessel disease, and one- or two-vessel disease with inducible ischemia are at highest risk. High-risk subsets among those with preserved LV function include patients with left main CAD and those with inducible ischemia and either three-vessel disease or two-vessel disease with involvement of the proximal left anterior descending coronary artery. Thus, exercise testing, assessment of ventricular function and, in selected patients, coronary angiography to determine coronary anatomy are valuable tools in risk stratification. In the primary-care setting, patient characteristics such as gender, race, age, and concomitant medical conditions may also be most useful in identifying high-risk patients. Although women in general have some primary protection against premature CAD, especially prior to the menopause, coronary risk in women who have experienced a cardiovascular event is similar to that in men. Coronary mortality is increased in minority populations, and the presence of other risk factors, such as diabetes and hyperlipidemia, can further increase this risk. Up to 80% of diabetic patients die of cardiovascular disease, 75% of which is CAD. The risk in this population is exacerbated by the abnormalities in lipid metabolism associated with the diabetic state. CAD mortality increases with aging, but it is recommended that elderly patients with CAD also receive risk factor intervention, such as cholesterol-lowering therapy. Consideration of the impact of such therapy on quality of life is especially important in initiating such interventions in the older population.

Long-term outcome and quality of life of patients requiring multidisciplinary intensive care unit admission after cardiac operations

Patients with organ failure or severe infection after cardiac operations may require prolonged stays in the intensive care unit. This study examined long-term mortality and determined quality of life for surviving patients in this group. This observational cohort study was conducted at Bichat Hospital, Paris, an academic tertiary care center. The study group consisted of 116 consecutive patients who underwent cardiac operations and were transferred to the multidisciplinary intensive care unit between January 1986 and December 1987. Patients referred for mediastinitis were automatically excluded. Respiratory failure (88.8%) and hemodynamic instability (81.9%) were the main causes of transfer; an infection was present in 23.3% of patients at entry into the intensive care unit. Twenty-seven patients (23.3%) died in the intensive care unit. Presurgical New York Heart Association functional class, postoperative bacteremia before admission to the intensive care unit, and severity of illness on admission to the intensive care unit were independent predictors of death in the intensive care unit. After an average follow-up of 81 months (range 70 to 93 months), 69% of the patients alive at transfer from the intensive care unit were still alive. Preoperative New York Heart Association functional class was the only long-term independent prognostic factor. Quality of life, as evaluated by the Nottingham Health Profile, was good for more than 70% of the survivors and was not influenced by any recorded variables, with the exception of age.

Prognostic value of noninvasive risk stratification in younger and older patients referred for evaluation of suspected coronary artery disease

OBJECTIVES

The purpose of this investigation is to explore the relationship of patient gender and age on coronary artery disease diagnostic evaluation and to assess the impact of noninvasive testing results on coronary revascularization rates and cardiac event-free survival.

STUDY DESIGN

Retrospective observational cohort.

PARTICIPANTS

From a series of 5322 consecutively tested patients from a Midwestern university tertiary medical center, a hospital cohort of 1345 patients with clinically suspected coronary artery disease was enrolled from 1988 through 1989.

MEASUREMENTS AND RESULTS

Cardiac risk factor and symptom profiles were worse in women, whereas rates of positive test results were similar in both sexes. Multivariable-adjusted risk for follow-up diagnostic testing was 1.8 and 1.9 times greater, respectively, for men < or = and > 65 years of age than for women (P < .01). Younger women were 4.9 times (P = .001) more likely to experience a cardiac event than younger men, with no differences between younger and older women (relative risk = 1.1; P > .20). Overall cardiac event rates were 2.3, 7.4, 16.7, and 20.2% for young men, young women, older women, and older men, respectively. Initial screening was delayed 2 to 7 times longer for older and younger women compared with men (P < .001); the greatest delays were observed for younger women. Diagnostic follow-up and subsequent cost of total care from initial evaluation through 2 years of follow-up were higher for men than for women (P < .0001), with older women having the lowest rate of subsequent diagnostic and interventional follow-up. In the highest risk patients, subsequent utilization rates were 40 and 20% higher for younger and older men than for similarly aged women. In particular, diabetics were less likely to undergo follow-up diagnostic testing and revascularization (67% younger women).

CONCLUSIONS

Age appears to significantly and differently influence decisions regarding noninvasive and invasive medical service utilization in men and women and may partially account for variable outcomes in this and previous gender-based comparisons.

The relation between treatment benefit and underlying risk in meta-analysis

In meta-analyses of clinical trials comparing a treated group with a control group it has been common to ask whether the treatment benefit varies according to the underlying risk of the patients in the different trials, with the hope of defining which patients would benefit most and which least from medical interventions. The usual analysis used to investigate this issue, however, which uses the observed proportions of events in the control groups of the trials as a measure of the underlying risk, is flawed and produces seriously misleading results. This arises through a bias due to regression to the mean and will be particularly acute in meta-analyses which include some small trials or in which the variability in the true underlying risks across trials is small. Approaches which previously have been thought to be more appropriate are to substitute the average proportion of events in the control and treated groups as the measure of underlying risk or to plot the proportion of events in the treated group against that in the control group (L'Abbé plot). However, these are still subject to bias in most circumstances. Because of the potentially seriously flawed conclusions that can result from such analyses, they should be replaced either by statistically appropriate (but more complex) approaches or, preferably, by analyses which investigate the dependence of the treatment effect on measured baseline characteristics of the patients in each trial.

Collagen subtypes III and IV expression in human vein graft atherosclerosis

This study examined the expression of collagen subtypes III and IV in a series of freshly excised human venous coronary artery bypass grafts. The results of this study demonstrate that these collagen subtypes are differentially expressed in vein graft atherosclerosis.

Cost-effectiveness of routine coronary angiography after acute myocardial infarction

BACKGROUND

Coronary angiography is indicated for many patients after acute myocardial infarction (AMI). There are a number of subgroups of AMI patients, however, for whom the indication for coronary angiography is not well established.

METHODS AND RESULTS

We developed a decision-analytic model for AMI in representative patient subgroups based on relevant clinical characteristics. The model estimates quality-adjusted life expectancy and direct lifetime costs for two strategies: coronary angiography and treatment guided by its results versus initial medical therapy without angiography. Decision tree chance node probabilities were estimated with the use of pooled data from randomized clinical trials and other relevant literature, costs were estimated with the use of the Medicare Part A database, and quality of life adjustments were derived from a survey of 1051 patients who had had a recent AMI. In our analysis, incremental cost-effectiveness ratios for coronary angiography and treatment guided by its result, compared with initial medical therapy without angiography, ranged between $17,000 and > $1 million per quality-adjusted year of life gained. Patient subgroups with severe postinfarction angina or a strongly positive exercise tolerance test (ETT) typically had cost-effectiveness ratios of < $50,000 per quality-adjusted year of life gained. In addition, most patient subgroups with a prior AMI had cost-effectiveness ratios of < $50,000 per quality-adjusted year of life gained, even with a negative ETT result.

CONCLUSIONS

In many patient subgroups after AMI, the cost-effectiveness of routine coronary angiography and treatment guided by its results compares favorably with other treatment strategies for coronary heart disease.

Current views on neurostimulation in the treatment of cardiac ischemic syndromes

Most clinicians are still unacquainted with the beneficial effects of neurostimulation as an additional therapeutic strategy for severe angina pectoris. Patients with therapeutically refractory angina pectoris suffer from chest discomfort during minimal exercise, despite maximal tolerated antianginal drug therapy (at least 2 out of a beta-blocker, calcium-antagonist or long-acting nitrate). In these patients, revascularization procedures, such as a percutaneous transluminal coronary angioplasty or coronary artery bypass surgery, are often technically impossible because of diffuse coronary artery disease or should be withheld as a consequence of absolute contraindications such as severe left ventricular dysfunction. All patients have inoperable multivessel disease, experienced one or more myocardial infarctions, and were treated by earlier invasive interventions. This group of patients are severely physically and psychologically disabled by their intractable angina pectoris. Available published data and the neurostimulation experience of the authors are reviewed in relation to the treatment of cardiac ischemic syndromes. We conclude that neurostimulation is an effective therapeutic adjuvant for patients with severe angina pectoris unresponsive to standard treatment. This treatment modality appears to be safe, and a promising tool for other ischemic cardiac syndromes.

Angina pectoris refractory for conventional therapy--is neurostimulation a possible alternative treatment?

The treatment of angina pectoris as a symptom of coronary artery disease usually is focused on restoring the balance between oxygen demand and supply of the myocardium by administration of drugs interfering in heart rate, cardiac pre- and afterload, and coronary vascular tone. For nonresponders to drug therapy or for those with jeopardized myocardium, revascularization procedures such as coronary bypass surgery and percutaneous transluminal coronary angioplasty are at hand. However, the atherosclerotic process is not stopped by these therapies and, at longer terms, angina may recur. It is not always possible to revascularize all the patients who do not positively react to medical treatment. Those with angina, not responding to adequate medication and who are not suitable anymore for revascularization, are considered to suffer from refractory angina pectoris. This group of patients has a poor quality of life, for their exercise tolerance is severely afflicted. For these patients, neurostimulation has been described repeatedly as an effective and safe therapy. The mechanism of action of neurostimulation is not completely known, but recent studies suggest an anti-ischemic effect, exerted through changes in myocardial blood flow. As soon as its safety is sufficiently established, it may become a useful alternative in the treatment of refractory angina pectoris.

Prognosis of patients with stable angina pectoris on antianginal drug therapy

Antianginal drug treatment reduces symptoms and ischemia but may also influence the prognosis of patients with stable angina pectoris. The Atenolol Silent Ischemia Study (ASIST) compared atenolol and placebo treatment (about 140 patient-years on each) in patients with mainly silent ischemia and found less aggravation of angina and a tendency toward fewer cardiac complications with atenolol treatment. The Total Ischaemic Burden European Trial (TIBET) compared slow release nifedipine, atenolol, or the combination (about 450 patient-years on each) and found no significant differences with regard to cardiac complications, a nonsignificant trend toward better prognosis on combined treatment, and more side effects on nifedipine alone compared with the other treatments. The Angina Prognosis Study in Stockholm (APSIS) compared metoprolol and verapamil (about 1,400 patient-years on each) and found similar effects on cardiovascular endpoints, tolerability, and psychosocial variables with the 2 treatments. Hypothesis-generating subgroup analyses in APSIS suggest that treatment effects may differ in hypertensive and diabetic subgroups. Beneficial effects in primary and secondary prevention, together with data from ASIST, suggest that beta 1 blockade influences prognosis favorably. The safety of short-acting nifedipine in ischemic heart disease is questioned, but TIBET data suggest that slow release nifedipine may be safe. Verapamil has beneficial effects after myocardial infarction (Danish Verapamil Infarction Trial II) and shows similar efficacy as metoprolol in the APSIS study. The paucity of placebo data (antianginal treatment cannot be withheld during long periods of time in symptomatic patients) precludes firm conclusions regarding effects of drug treatment on prognosis. It is argued that patients with stable angina pectoris do well on medical treatment, and that beta 1 blockers, verapamil, and, possibly, slow-release nifedipine may influence their prognosis favorably.

Effectiveness of revascularization in the Emory angioplasty versus surgery trial. A randomized comparison of coronary angioplasty with bypass surgery

BACKGROUND

The Emory Angioplasty Versus Surgery Trial (EAST) was designed to determine whether percutaneous transluminal coronary angioplasty (PTCA) is as effective as coronary artery bypass graft surgery (CABG) in restoring arterial perfusion capacity in eligible patients with multivessel disease.

METHODS AND RESULTS

Of 392 patients in EAST, 198 were randomized to PTCA and 194 to CABG. Index lesions (2.7 +/- 1.0 per patient) were those with > or = 50% stenosis judged treatable by both angioplasty and surgery. Coronary segments jeopardized by these index lesions were designated as index segments (4.4 +/- 1.4 per patient). Percent stenosis was measured by quantitative angiography at the point of greatest obstruction in the main perfusion path of each index segment. The EAST primary arteriographic end point was the percent of a patient's index segments with < 50% stenosis in the main perfusion pathways at 1 and 3 years. At baseline, the percent of index segments for which revascularization was attempted was 85% for PTCA and 98% for CABG (P < .0001). At 1 year, PTCA patients had a smaller percentage of successfully revascularized index segments than CABG patients (59% versus 88%, P < .001). At 3 years, the findings were similar but less striking (70% versus 87%, P < .001). When only "high-priority" index segments (2.1 +/- 1.6 per patient) were considered, baseline attempts were comparable (96% versus 99%, P = NS); despite this, CABG remained more successful at 1 (64% versus 93%, P < .001) and 3 (76% versus 89%, P < .01) years. However, the mean percent of index segments free of severe stenosis (> or = 70%) did not differ between PTCA and CABG patients at 3 years (93% versus 95%, P = NS). Furthermore, the frequency of patients with all index segments free of severe stenosis did not differ between the two groups at 1 (76% versus 83%, P = NS) or 3 (82% for both PTCA and CABG) years.

CONCLUSIONS

In patients with multivessel disease, index segment revascularization was more complete with CABG than PTCA at both 1 and 3 years. However, when the physiological priority of the target lesion and the measured severity of the residual stenosis are taken into account, the advantage of CABG becomes less significant or nonsignificant. This may, in part, explain why these two strategies did not differ in terms of the EAST primary clinical end points over 3 years.

Cost-effective management of chronic stable angina

In certain patients with stable angina who are at moderate to high risk, coronary bypass surgery or coronary angioplasty are the therapeutic options of choice. However, in selected other patients the use of anti-ischemic drug therapy and secondary prevention reduce episodes of myocardial ischemia and result in a good long-term prognosis. Factors affecting management include the extent of coronary disease, the magnitude of cardiac symptoms, the severity of myocardial ischemia and of left ventricular function. Based upon these and other clinical characteristics, patients can be divided into low-, moderate-, or high-risk categories for morbidity and mortality. Patients at high risk are more likely to be selected for myocardial revascularization and patients at low risk are often treated with medical therapy, at least initially. Based on the available cost-effectiveness data, medical therapy or coronary angioplasty are the preferred initial strategies for low-risk coronary disease, whereas coronary bypass surgery (CABG) is recommended for many high-risk patients, particularly for those with triple-vessel disease and impaired left ventricular function or ischemia at a low workload. CABG is cost-effective for patients with severe angina and left main coronary artery disease and also for patients with mild angina and triple-vessel disease. Coronary angioplasty is cost-effective for patients with severe angina, and single- or multivessel disease. In patients with lesser symptoms and mild coronary disease, the cost effectiveness of myocardial revascularization therapy is less likely to be as good as it is in patients with more extensive disease and severe symptoms.

Cigarette smoking in British men and selection for coronary artery bypass surgery

OBJECTIVE

To examine the relation between smoking status, clinical need, and likelihood of coronary artery bypass grafting in middle aged men.

DESIGN

A prospective study of cardiovascular disease in British men aged 40 to 59 years, screened in 1978-80 and followed until December 1991.

SUBJECTS AND SETTING

7735 men drawn from one general practice in each of 24 British towns.

MAIN OUTCOME MEASURE

Coronary artery bypass graft surgery.

RESULTS

Of the 3185 current smokers, 38 (1.03/1000/year) underwent coronary artery bypass surgery compared with 47 of 2715 (1.45/1000/year) ex-smokers, and 19 of 1817 (0.85/1000/year) never-smokers. Ex-smokers had a lower incidence of major ischaemic heart disease during follow up than current smokers. After adjustment for incidence of ischaemic heart disease during follow up, the hazard ratio of coronary artery bypass surgery for ex-smokers compared with smokers was 1.52 (95% confidence interval 0.99 to 2.34). Ex-smokers were more likely at screening to recall a doctor diagnosis of ischaemic heart disease than smokers (7.1% v 5.3%), but among those who recalled a doctor diagnosis, smokers were less likely to undergo coronary artery bypass surgery than ex-smokers (9.4% v 3.5%, P = 0.026). By 1992, men defined as smokers at screening were no less likely than ex-smokers to have been referred to a cardiologist (18.5% v 18.8%), nor to report having undergone coronary angiography less frequently than ex-smokers (12.7% v 11.4%).

CONCLUSION

Even allowing for the strong relation between coronary artery bypass surgery and clinical need, continuing smokers were less likely to undergo coronary artery bypass surgery than ex-smokers. A complex interplay exists between the men's experience of heart disease, the decision to stop smoking, and the willingness of doctors to consider coronary artery bypass surgery.

Assessment of patients after coronary artery bypass grafting by dobutamine stress echocardiography

Dobutamine stress echocardiography is an accurate method for the diagnosis and localization of vascular compromise in patients evaluated after coronary artery bypass graft surgery. The test provides useful data for selection of patients for whom coronary angiography may be indicated.

Long-term survival benefits of coronary artery bypass grafting and percutaneous transluminal angioplasty in patients with coronary artery disease

The purpose of this study was to evaluate long-term survival benefits of bypass surgery and angioplasty versus medical therapy in 9263 patients at Duke University Medical Center between 1984 and 1990 with coronary artery disease confirmed by cardiac catheterization to involve one, two, or three vessels. Clinical data were prospectively entered into an established cardiovascular database, and annual follow-up was 97% complete for a mean interval of 5.3 years and a maximal interval of 10 years. Outcomes were analyzed with the Coronary Artery Surgery Study "method A" to define patient groups treated by medicine (n = 2449), angioplasty (n = 2924), or bypass surgery (n = 3890). Differences among treatment groups in baseline characteristics were adjusted by Cox proportional hazard models. The anatomic severity of coronary artery stenosis best defined survival benefit from bypass surgery and angioplasty versus medical treatment. One or both interventional treatments provided better long-term survival than did medical treatment for all levels of disease severity. All patients with single-vessel disease, except those with at least 95% proximal left anterior descending stenosis, benefited from angioplasty versus bypass. All patients with three-vessel disease and those two-vessel patients with > or = 95% proximal left anterior descending stenosis benefited from bypass surgery versus angioplasty. All other patients with two-vessel disease and those with > or = 95% proximal left anterior descending stenosis only had similar survival with either interventional treatment. The absolute survival benefit was greatest for patients with severe three-vessel disease treated with bypass surgery.

The number needed to treat: a clinically useful nomogram in its proper context

The number needed to treat is a meaningful way of expressing the benefit of an active treatment over a control. It can be used either for summarising the results of a therapeutic trial or for medical decision making about an individual patient, but its use at the bedside has been impeded by the need for time consuming calculations. A nomogram has therefore been devised that will greatly simplify the calculations. Since calculations are now easy, the number needed to treat can be used to access the value of several interventions, although it does have its limitations. In particular it should not be used when it is not known whether the relative risk reduction associated with an intervention is constant for all levels of risk, or for periods of time longer than that studied in the original trials.

Care of acute myocardial infarction by noninvasive and invasive cardiologists: procedure use, cost and outcome

OBJECTIVES

This study sought to determine how noninvasive and invasive cardiologists may differ in the hospital care of patients with acute myocardial infarction.

BACKGROUND

Scant information exists regarding the effect of noninvasive and invasive cardiology subspecialization on invasive cardiac procedural use, cost and outcome in the care of patients with acute myocardial infarction.

METHODS

This study analyzed a prospective cohort of 292 patients admitted to an urban tertiary care hospital from the emergency room under the care of noninvasive or invasive cardiologists. Clinical characteristics; hospital course, including management, utilization of diagnostic coronary angiography and percutaneous transluminal coronary angioplasty; direct hospital costs; length of hospital stay; and post-hospital discharge follow-up data were collected by a prospective data base instrument.

RESULTS

Despite similar clinical characteristics, extent and severity of coronary artery disease and utilization of diagnostic coronary angiography in the two groups of patients, those under the care of an invasive cardiologist were significantly more likely to undergo coronary angioplasty than those under the care of a noninvasive cardiologist. The direct hospital costs and length of stay of the noninvasive and invasive group patients who underwent coronary angioplasty were similar, although overall the direct hospital costs and length of stay were higher for the invasive than for the noninvasive group patients.

CONCLUSIONS

Noninvasive and invasive cardiologists differ in their rate of utilization of coronary angioplasty in similar patients with acute myocardial infarction.

Cost-effectiveness of coronary angioplasty versus medical treatment: the impact of cost-shifting

BACKGROUND

Coronary angioplasty (PTCA) offers improved symptom control over medical treatment in patients with stable angina and single-vessel disease. However, it is uncertain if PTCA is more cost-effective. Cost-shifting could also influence the provision of PTCA.

METHODS

Data from the only randomised trial comparing PTCA to medical therapy (ACME study) were used with costs from an Australian teaching hospital to estimate the costs and freedom from angina in 100 patients over three years. The incremental cost-effectiveness of PTCA, and the potential for cost-shifting were also examined.

RESULTS

Although the total cost of treating 100 patients over three years with PTCA ($678,978) was higher than a medical strategy ($631,078), PTCA was more cost-effective ($10,930 versus $12,682 per patient free of angina). The incremental cost-effectiveness of PTCA ($3875 per extra patient free of angina) was also substantially less than the cost of the medical strategy. These should be considered crude estimates as they were based on limited data on resource use. The hospital could reduce costs by pursuing a medical strategy, but 54% of the savings would result from shifting the cost of treating patients to the Federal Government and patients. By performing PTCA on privately insured rather than Medicare patients, the hospital could shift $29,876 per 100 patients to the Federal government and private insurance funds.

CONCLUSIONS

From society's perspective, PTCA may be more cost-effective than a medical strategy. However, the financial interests of the hospital are best served by limiting PTCA or restricting PTCA to privately insured patients. Cost-shifting may have a major impact on the provision of PTCA. The costs of providing medical services need to be weighed against the cost of not providing them.

Waiting for coronary artery bypass surgery: population-based study of 8517 consecutive patients in Ontario, Canada. The Steering Committee of the Adult Cardiac Care Network of Ontario

Deaths and delays in queues for coronary surgery in Canada have been highlighted by American interest groups opposed to "socialized medicine". Since 1991 all nine cardiac surgery centres in Ontario register and follow patients after acceptance for surgery. We examined the experience of 8517 consecutive patients leaving the registry from October 1991 to July 1993. Individual acuity scores were determined based on symptoms, angiographic findings, left ventricular function, and, where available, non-invasive tests of ischaemic jeopardy. Planned surgery was declined or deferred for 3.2% of registrants. While in the queue, 31 (0.4%) patients died and three had surgery indefinitely deferred after a non-fatal myocardial infarction. Among 8213 patients receiving surgery, the median wait was 17 days (inter-quartile range [IQR]: 4, 51), ranging from one day (IQR 0:4) for patients needing very urgent surgery (acuity score 2-3) to 42 days (IQR: 18, 77) for those rated low priority (acuity score 6-7). In a multivariate analysis, the most important determinant of waiting time was symptom status (p < 0.001), followed by anatomy (p < 0.001). Age did not alter waiting time; depending on statistical methods, female sex was either not significant or independently associated with approximately 11% relative delay (p = 0.001). Whether controlling for significant clinical factors or the multifactorial acuity scores, waiting times clearly varied (p < 0.001) among hospitals. We conclude that, during 1991-93, patients queuing for coronary surgery in Ontario rarely suffered critical events or extreme delays, and individual variation in waiting times primarily reflected clinical acuity. Nonetheless, symptoms provoked by very modest exertion were commonplace in the queue, and waiting times did vary inequitably among hospitals.

A meta-analysis of randomized trials comparing coronary artery bypass grafting with percutaneous transluminal coronary angioplasty in multivessel coronary artery disease

We performed a meta-analysis of randomized trials that compared percutaneous transluminal coronary angioplasty (PTCA) with coronary artery bypass graft (CABG) surgery in patients with multivessel coronary artery disease. The outcomes of death, combined death, and nonfatal myocardial infarction (MI), repeat revascularization, and freedom from angina were analyzed. The overall risk of death and nonfatal MI was not different over a follow-up of 1 to 3 years (CABG:PTCA odds ratio [OR] 1.03, 95% confidence interval 0.81 to 1.32, p = 0.81). Patients randomized to CABG tended to have a higher risk of death or MI in the early, periprocedural period (OR 1.33, p = 0.091), but a lower risk in subsequent follow-up (OR 0.74, p = 0.093). CABG patients were much less likely to undergo another revascularization procedure (p < 0.00001), and were more likely to be angina free (OR 1.57, p < 0.00001). Thus, CABG and PTCA patients have similar overall risks of death and nonfatal MI at 1 to 3 years of follow-up, but relative risk differences in mortality of up to 25% cannot be excluded. CABG patients have significantly less angina and less repeat revascularization than PTCA patients.

Meta-analysis of randomised trials comparing coronary angioplasty with bypass surgery

A patient with severe angina will often be eligible for either angioplasty (PTCA) or bypass surgery (CABG). Results from eight published randomised trials have been combined in a collaborative meta-analysis of 3371 patients (1661 CABG, 1710 PTCA) with a mean follow-up of 2.7 years. The total deaths in the CABG and PTCA groups were 73 and 79, respectively, with a relative risk (RR) of 1.08 (95% CI 0.79-1.50). The combined endpoint of cardiac death and non-fatal myocardial infarction occurred in 169 PTCA patients and 154 CABG patients (RR 1.10 [0.89-1.37]). Amongst patients randomised to PTCA 17.8% required additional CABG within a year, while in subsequent years the need for additional CABG was around 2% per annum. The rate of additional non-randomised interventions (PTCA and/or CABG) in the first year of follow-up was 33.7% and 3.3% in patients randomised to PTCA and CABG, respectively. The prevalence of angina after one year was considerably higher in the PTCA group (RR 1.56 [1.30-1.88]) but at 3 years this difference had attenuated (RR 1.22 [0.99-1.54]). Overall there was substantial similarity in outcome across the trials. Separate analyses for the 732 single-vessel and 2639 multivessel disease patients were largely compatible, though the rates of mortality, additional intervention, and prevalent angina were slightly lower in single vessel disease. The combined evidence comparing PTCA with CABG shows no difference in prognosis between these two initial revascularisation strategies. However, the treatments differ markedly in the subsequent requirement for additional revascularisation procedures and in the relief of angina. These results will influence the choice of revascularisation procedure in future patients with angina.

Late outcome after coronary artery bypass graft surgery in patients < 40 years old

BACKGROUND

Randomized trials confirm the long-term efficacy of coronary artery bypass graft surgery (CABG), although there are no randomized data in patients < 40 years old. Because these patients have been reported to have an early recurrence of symptoms, the long-term postoperative outcome was examined.

METHODS AND RESULTS

The long-term outcome of patients (n = 221) < 40 years old undergoing CABG at Green Lane Hospital, New Zealand, from 1970 to 1992 was determined. The 30-day mortality rate was 1.8% for initial and 9.5% for redo CABG. The median times to angina or myocardial infarction (recurrent ischemic event), further intervention, and death were 6.0, 9.6, and 14.2 years, respectively. Factors associated with increased late mortality on univariate analysis included end-systolic volume (ESV) > or = 80 mL (P = .004; 10-year mortality 19% versus 39% ESV > or = 80 mL), no internal mammary conduit (P = .01), no lipid-modifying therapy (P = .005), and no postoperative aspirin use (P = .0002); the latter was also associated with increased recurrent ischemic events (P = .04) or increased reintervention (P = .02). On stepwise logistic regression analysis, factors associated with increased late mortality were increasing ESV (P = .004), no internal mammary artery conduit (P = .009), diabetes (P = .04), and no postoperative aspirin (P = .02); the latter was also associated with increased recurrent ischemic events (P = .02). Hypercholesterolemia (> or = 6.5 mmol/L) was present in 65% of patients at presentation and 45% at follow-up.

CONCLUSIONS

To attempt to prevent recurrent ischemia or late death, patients < 40 years old who require CABG should receive internal mammary conduits, aspirin, lipid-modifying therapy, therapy to inhibit ventricular dilatation, and strict diabetes management.

Asymptomatic Cardiac Ischemia Pilot (ACIP) Study. Improvement of cardiac ischemia at 1 year after PTCA and CABG

BACKGROUND

Cardiac ischemia on the ambulatory ECG (AECG) and/or on the exercise treadmill test (ETT) is associated with an increased risk of adverse outcome. Myocardial revascularization more often suppresses cardiac ischemia than does medical management alone. However, few studies have compared the effects of percutaneous transluminal coronary angioplasty (PTCA) with those of coronary artery bypass grafting (CABG) on cardiac ischemia and clinical outcome.

METHODS AND RESULTS

A total of 558 patients were randomly assigned to one of three treatment strategies in the Asymptomatic Cardiac Ischemia Pilot (ACIP) study: angina-guided medical strategy (n = 184), ischemia-guided medical strategy (n = 182), or revascularization (n = 192). In patients assigned to revascularization, the choice of the procedure, PTCA or CABG, was made by the clinical unit staff and patient based on a coronary angiogram usually performed within 2 months of enrollment. CABG was selected in 78 patients and PTCA in 92 patients. At 12 weeks, ischemia on the AECG was suppressed in 70% of CABG patients versus 46% of PTCA patients (P = .002). Ischemia on the ETT was no longer present in 46% versus 23% of the patients, respectively (P = .005). Angina, within 4 weeks of the follow-up visit, was absent in 90% versus 68%, respectively (P = .001). These clinical variables remained improved in both groups at 1 year. Clinical events (myocardial infarction or repeat revascularization) occurred in 1 CABG patient versus 7 PTCA patients at 12 weeks, and in 1 versus 16 patients, respectively, at 12 months (P < .001).

CONCLUSIONS

Ischemia on the AECG and ETT and angina were relieved in many patients after both procedures; however, CABG was superior to PTCA, and it was associated with a lower incidence of clinical events at 1 year. These results suggest that more complete revascularization relates to better clinical outcome. However, a large trial is needed to confirm these results.

Evidence based purchasing: understanding results of clinical trials and systematic reviews

OBJECTIVE

To assess whether the way in which the results of a randomised controlled trial and a systematic review are presented influences health policy decisions.

DESIGN

A postal questionnaire to all members of a health authority within one regional health authority.

SETTING

Anglia and Oxford regional health authorities.

SUBJECTS

182 executive and non-executive members of 13 health authorities, family health services authorities, or health commissions.

MAIN OUTCOME MEASURES

The average score from all health authority members in terms of their willingness to fund a mammography programme or cardiac rehabilitation programme according to four different ways of presenting the same results of research evidence--namely, as a relative risk reduction, absolute risk reduction, proportion of event free patients, or as the number of patients needed to be treated to prevent an adverse event.

RESULTS

The willingness to fund either programme was significantly influenced by the way in which data were presented. Results of both programmes when expressed as relative risk reductions produced significantly higher scores when compared with other methods (P < 0.05). The difference was more extreme for mammography, for which the outcome condition is rarer.

CONCLUSIONS

The method of reporting trial results has a considerable influence on the health policy decisions made by health authority members.

Relationship between quality of life and exercise test findings after coronary artery bypass surgery

We studied the correlation between quality of life and exercise testing in 554 patients 2 years after coronary artery bypass surgery. Quality of life constitutes a person's perceptions of physical and mental functional capacity, health and symptoms. Traditionally, evaluations after coronary bypass surgery have focused on physical performance, medication and anginal symptoms, which cannot be said to represent quality of life. We used the Physical Activity Score, the Nottingham Health Profile and the Psychological General Well-being Index for evaluation of quality of life. Significant correlations were found between quality of life and exercise capacity (P < 0.0001), and quality of life and chest pain at exercise for all questionnaires (P < 0.0001). Significant correlations, although of small or moderate magnitude, were found between exercise capacity, chest pain and most subscales of quality of life, with the highest correlation coefficients for dimensions reflecting physical abilities and pain. We conclude that quality of life correlates significantly with exercise capacity and chest pain during exercise 2 years after coronary bypass surgery. However, only dimensions of pain and physical performance are reasonably well correlated with exercise test results. Several aspects of quality of life are only weakly related to exercise test results and may escape identification in an exercise test.