Richard E. Kuntz

Evaluating the potential cost-effectiveness of stenting as a treatment for symptomatic single-vessel coronary disease. Use of a decision-analytic model.

BACKGROUND Coronary stenting appears to provide more predictable immediate results and lower rates of restenosis than conventional balloon angioplasty for selected lesion types, but its hospital costs are significantly higher. This study was designed to evaluate the potential cost-effectiveness of Palmaz-Schatz coronary stenting relative to conventional balloon angioplasty for the treatment of patients with symptomatic, single-vessel coronary disease. METHODS AND RESULTS We developed a decision-analytic model to predict quality-adjusted life expectancy and lifetime treatment costs for patients with symptomatic, single-vessel coronary disease treated by either Palmaz-Schatz stenting (PSS) or conventional angioplasty (PTCA). Estimates of the probabilities of overall procedural success (PTCA, 97%; PSS, 98%), abrupt closure requiring emergency bypass surgery (PTCA, 1.0%; PSS, 0.6%), and angiographic restenosis (PTCA, 37%; PSS, 20%) were derived from review of the literature published as of September 1993. Procedural costs were based on the true economic (ie, variable) costs of each procedure at Bostons Beth Israel Hospital. On the basis of these data, coronary stenting was estimated to result in a higher quality-adjusted life expectancy than conventional angioplasty but to incur additional costs as well. Compared with conventional angioplasty, stenting had an estimated incremental cost-effectiveness ratio of

Frequency and consequences of intimal hyperplasia in specimens retrieved by directional atherectomy of native primary coronary artery stenoses and subsequent restenoses

23,600 per quality-adjusted life year gained. Although the cost-effectiveness ratio for stenting changed with variations in assumptions about the relative costs and restenosis rates, it remained less than

A predictive method for estimating the late angiographic results of coronary intervention despite incomplete ascertainment.

40,000 per quality-adjusted year of life gained--and thus was similar to many other accepted medical treatments--unless the stent angiographic restenosis rate was > 23%, the angioplasty restenosis rate was < 34%, or the cost of stenting (including vascular complications) exceeded that of conventional angioplasty by more than

Evaluation of Restenosis Following New Coronary Interventions

3000. The alternative strategy of secondary stenting (initial angioplasty followed by stenting only for symptomatic restenosis) was estimated to be both less effective and less cost-effective than primary stenting over a wide range of plausible assumptions and thus does not appear to be cost-effective when primary stenting is also an option. CONCLUSIONS Decision-analytic modeling can be used to evaluate the potential cost-effectiveness of new coronary interventions. Our analysis suggests that despite its higher cost, elective coronary stenting may be a reasonably cost-effective treatment for selected patients with single-vessel coronary disease. Primary stenting is unlikely to be cost-effective for lesions with a low probability of restenosis (eg, < 30%) or for patients for whom the cost of stenting is expected to be much higher than usual (eg, because of a high risk of vascular complications). Given the sensitivity of the cost-effectiveness ratios to even modest variations in the relative restenosis rates and cost estimates, future studies will be necessary to determine more precisely the cost-effectiveness of coronary stenting for specific patient and lesion subsets.

Incidence and treatment of 'no-reflow' after percutaneous coronary intervention.

Although intimal hyperplasia is a frequent occurrence after arterial interventional procedures, the overall frequency and significance of intimal hyperplasia in primary coronary lesions has not been previously addressed. The incidence of intimal hyperplasia was therefore examined using standard light microscopy in specimens obtained from native coronary arteries of patients undergoing directional coronary atherectomy. The associated clinical history, angiographic results and clinical outcomes were also tabulated. Intimal hyperplasia was identified in 51 of 55 patients (93%) treated with directional coronary atherectomy for restenosis after a prior intervention. These restenosis lesions had less acute gain in lumen diameter after directional coronary atherectomy, a smaller late lumen diameter, more severe late stenosis (p < 0.04), and tended to have more restenosis defined as late stenosis > or = 50% (restenosis rate 40% for prior restenosis vs 26% for primary lesions). Surprisingly, however, intimal hyperplasia was also identified in 45 of 102 (44%) primary stenoses. Primary lesions (n = 45) with intimal hyperplasia were more likely to occur in younger patients and in the left anterior descending artery than were either primary lesions without intimal hyperplasia (n = 57) or prior restenosis lesions. There were otherwise no differences in the baseline characteristics, angiographic findings or clinical outcome of primary lesions with or without intimal hyperplasia (restenosis rate 28 and 24%, respectively). The event-free survival (72% at 12 months) was similar in all 3 groups. Thus, even though intimal hyperplasia is an almost universal finding in restenosis lesions, intimal hyperplasia is not specific for restenosis since histologically identical hyperplasia may be found in nearly half of primary coronary artery stenoses.(ABSTRACT TRUNCATED AT 250 WORDS)

Rheolytic thrombectomy with the Possis AngioJet: technical considerations and initial clinical experience.

BackgroundInvestigations of coronary restenosis typically use late (4-6-month) angiographic end points. Since only 50-80%o of patients generally undergo repeat angiography, however, restenosis for the population as a whole is usually estimated by assuming that nonrestudied and restudied patients are similar. If restudied and nonrestudied patients differ, incomplete angiographic follow-up can yield an erroneous estimate of restenosis. No suitable method has yet been devised to detect and correct these errors. Methods and ResultsWe studied the clinical indications for angiographic restudy in an actual series of 301 treated lesions in 267 consecutive patients who underwent either Palmaz-Schatz stenting (126 patients) or directional coronary atherectomy (141 patients) at our institution. While only 249 (83%) treated segments underwent 4-6-month angiographic follow-up, all had clinical follow-up that described whether specific indications for restudy were present. Patients who had no clinical indications for such restudy were designated as having elective follow-up. In contrast, patients who had recurrent symptoms or positive exercise studies and were scheduled for repeat angiography at the independent recommendation of their referring cardiologist were designated as having nonelective follow-up. Mean late percent stenosis or binary restenosis rate (>50%o diameter stenosis) was determined for elective versus nonelective lesions that underwent follow-up angiography. These values were then used to impute the behavior of the nonrestudied lesions according to their clinical status. From these imputations, a “predictive” model was developed to estimate the mean restenosis values that would have been found had the entire population actually undergone angiographic follow-up. Comparisons between the estimates of this predictive method and the traditional method that uses only the actual angiographic data demonstrate how alterations in various parameters influence the selection bias caused by incomplete angiographic follow-up. Of the 301 lesions available for follow-up, 100 of the 103 (97%) nonelective versus 149 of the 198 (75%, p<0.001) elective lesions actually underwent angiographic follow-up. Mean follow-up percent stenosis (50%o versus 27%) and the binary restenosis rate (53% versus 13%) differed significantly for the nonelective versus the elective lesions, respectively (both p<0.001). Even at the fairiy high (83%) angiographic follow-up rate, elective versus nonelective status was thus a confounder that caused differences between the restenosis rate estimated by the traditional (29.1%; 95% CI: 23.4, 34.7) and the predictive methods (263%; 95% CI: 21.4, 31.1). Larger (and even statistically significant) differences may be present under the conditions that exist in many current studies. ConclusionsRestenosis trials with <90%o angiographic follow-up suffer from selection bias. Traditional methods that analyze only the restudied patients fail to correct for the important confounding influence of the clinical status of the nonrestudied patients. By using this readily available clinical information about the nonrestudied patients, a predictive method may be developed that provides a closer estimate of the true restenosis behavior for the population as a whole.

Comprehensive Approach Post-Market Approval Surveillance: A Call for a More Integrated and

Restenosis following conventional balloon coronary angioplasty is a well established phenomenon that has persisted despite growing operator experience and technical advancement [1, 2]. If significant restenosis is defined as late luminal narrowing greater than 50%, approximately 30–35% of patients will manifest such restenosis by 3 to 6 months following conventional balloon angioplasty [3–5]. Nearly two dozen “second generation” coronary interventional devices have been developed in an effort to improve immediate and long-term results, and widen the application of percutaneous techniques to include coronary lesions which are currently not optimal for conventional angioplasty [6–8]. Preliminary reports have suggested that some new devices may reduce restenosis [9], although the mechanism of that reduction remains unclear. Evaluation of restenosis by newer non-traditional approaches may allow insight into some of the geometric considerations responsible for this reduction, and for differences in restenosis based on multiple variables (e.g., vessel treated, patient demographics, etc.).