Practice still makes perfect James G. Jollis, MD, FACC Durham, NC
See related article on page 437. One of the most contentious issues among the cardiology community involves procedural volume standards for coronary angioplasty. The origin of the controversy dates back to 1988, when an American College of Cardiology expert panel first recommended that physicians perform at least 50 procedures annually and hospitals perform 200 cases annually.1 On the basis of literature demonstrating an inverse relation between volume and outcome for other surgical procedures, the panel believed that at least one procedure per week should be required to maintain adequate skill. The number 50 was also chosen on the basis of experience in other manual endeavors, namely “one has to golf once a week to maintain skill.” This number was increased to 75 in 1993, based on continued expert opinion and a single study from California showing an inverse relation between hospital angioplasty volume and bypass surgery or death.2,3 When the college prepared to reissue proficiency guidelines in 1998, some members requested that the need for volume standards be reconsidered according to existing evidence rather than expert opinion. The requests were partly spurred by the refusal of an insurance provider to reimburse low volume operators. This issue was particularly important to the estimated one half of physicians performing angioplasty who did not meet the minimum volume criteria. With growing enthusiasm for direct angioplasty, the issue was also important to hospitals and physicians who wished to open additional facilities to rapidly treat patients with acute myocardial infarction. When the panel reconvened, additional data were presented from Medicare, New York, Northern New England, the Society for Cardiac Angiography and Intervention, and an academic medical center consortium, all supporting volume standards.4-9 Improving outcomes were seen in up to 400 to 600 annual cases for hospitals and in up to 150 annual cases for physicians. After reviewing the evidence, the panel continued to recommend hospital and physician volume standards of 400 and 75 cases, respectively.10 Based on data indicating low-volume physicians had better outcomes in high-vol-
From Duke Clinical Research Institute. Reprint requests: James G. Jollis, MD, Duke Clinical Research Institute, Room 0311, Terrace Level, 2400 Pratt St, Durham, NC 27705. Am Heart J 1999;138:394-5. 0002-8703/99/$8.00 + 0 4/4/96335
ume institutions, the panel also suggested that physicians with an “intermediate” experience of 50 to 75 cases per year perform angioplasty under the guidance of an experienced mentor. It is important to note that these recommendations are simply guidelines, as all physician and hospital practice standards are specified at the local and state level. Despite the growing body of literature on which to base recommendations, the clinical evidence left some important questions unanswered. For example, what experience is necessary to proficiently operate other interventional technologies such as directional and rotational atherectomy devices? Given the additional complexity of these devices compared with balloon catheters, proficiency would be expected to improve beyond volumes of 75 cases per year. With less frequent use of such devices by even the most experienced operators, higher-volume standards would obviate most physicians from performing atherectomy procedures. Other unresolved issues include whether volume standards encourage the performance of procedures on patients who may otherwise have not been selected for angioplasty, whether cumulative experience over a number of years can substitute for annual volume as a marker of proficiency, how to uniformly implement proficiency standards at the local level, and whether it is statistically possible to confidently identify high-quality, low-volume operators. The most pressing question left unanswered is whether newly introduced technologies—stents and direct platelet inhibitors—will reduce angioplasty complications to the point that the volume experience relation is no longer apparent. Two scenarios involving the dissemination of these technologies can be considered. In the first, successful use of stents and platelet inhibitors requires a certain level of proficiency, resulting in a persistence of worse outcomes for low-volume operators. For example, deploying a stent in the setting of abrupt closure requires skill not readily attainable by low-volume operators such that their patients continue to have higher surgery rates. In the second scenario, complications become so rare for all operators such that volume standards are no longer necessary. Because these technologies were already widely used at the time the third set of guidelines were published, more contemporary data are urgently needed. Work by Kastrati et al11 concerning single-center experience in Munich showed improving outcomes according to operator stent volume. The article by Ritchie et al12 in this issue of the Journal adds a second piece of important
American Heart Journal Volume 138, Number 3, Part 1
evidence regarding angioplasty outcomes in the era of stents. In 1996, Medicare began to identify coronary stent procedures by a separate ICD-9-CM code. Ritchie et al used these claims to identify 75,000 patients who received coronary stents in 1996, approximately 37% of all Medicare patients undergoing angioplasty. The inverse relation between hospital volume and outcome was observed in both 1994 and 1996, including among patients who received coronary stents in 1996. In interpreting this study, the bias introduced in selection of patients for coronary stents must be taken into account. Patients with abrupt closure in whom stents could not be deployed would have been relegated to the “no stent” cohort, significantly confounding the comparison of surgery and death between the stent and no-stent cohorts. This bias would make the relation between outcome and volume less apparent among stent patients. Taking into account the selection bias, the volume-outcome relation is likely to be stronger than that suggested by this observational study. The work by Ritchie et al also further addresses concerns regarding direct angioplasty. In this study and other work, the volume-outcome relation is most apparent among the acute myocardial infarction cohorts, accounting for approximately 1 of every 8 deaths among Medicare patients receiving angioplasty at lowvolume hospitals. In the absence of randomized trials demonstrating a benefit for direct angioplasty over thrombolytic therapy, the higher complication rates at low-volume hospitals cannot be reconciled among patients with acute myocardial infarction who are eligible for thrombolytic therapy. Although this study provides important contemporary data in addressing the concerns of patients and physicians for quality standards, the issues of angioplasty proficiency are far from settled. Relative to the half million angioplasty procedures performed annually, adequate data that address issues of proficiency and optimal practice are sparse. The energy generated by the “volume outcome” debate should be directed toward clinical tri-
als and population-based registries, such that practice can be based on a procedure performed once each minute rather than a sport played once per week.
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