Catheterization and Cardiovascular Diagnosis 25:l-3 (1992)

Editorial

ABC’s of Coronary Ang ioplasty : Too Much?

Have We Simplified It

lnterventional Cardiology Committee, Society for Cardiac Angiography and Interventions

In 1987 the American College of Cardiology and the American Heart Association established a task force to assess diagnostic and therapeutic cardiovascular proce- dures [ 11. A subcommittee was appointed to specifically examine guidelines for indications for the performance of percutaneous transluminal coronary angioplasty . The goal of the task force was to make recommendations regarding the appropriate utilization of coronary angio- plasty in patients with cardiovascular disease in 1987- 1988. The committee formulated its final report after numerous meetings, a review of the world’s literature on this topic, and a discussion with a large number of ex- ternal consultants. The final report was published jointly in Circulation and the Journal of American College of Cardiology. It has proven to be an extremely useful guide to those involved in the procedure itself as well physicians and allied health professionals concerned with angioplasty .

It is also used with increasing frequency by agencies and organizations involved with the allocation and fund- ing of health care resources. Finally it is being used as a reference standard to compare the results of new tech- nology such as coronary laser angioplasty. The guide- lines have been widely quoted with regard to lesion- specific characteristics relative to expected success and risk of coronary angioplasty. These criteria arose from a desire to indicate that all lesions are not the same and therefore certain expected outcomes should influence the selection for angioplasty. The designations of A, B, and C lesions were chosen to reflect the various levels of difficulty of performance and risk of complications from the most benign to the most problematic. It was felt that an operator faced with a greater than 90% chance of success and a low risk as judged from his own experience should use that data in selecting patients; conversely the interventionist should consider lesions in which he would expect less than 60% success in a much different light. Characteristics of lesions which might make them more difficult were added to the text. The most common fea-

ture resulting in a success rate as low as the 60% range for most operators was a chronic total occlusion. The committee’s formulated recommendations clearly were not based upon firm prospective data but rather repre- sented the collective wisdom of experienced angioplasty operators. The criteria were meant to be a guide when considering patients for angioplasty based on one’s esti- mate of the likelihood of a successful procedure or an associated complication. In addition, the introduction to the guidelines clearly stated that “Because the technique of angioplasty is an evolution and the intermediate-term results are not yet fully elucidated, these recommenda- tions are likely to change over the years. This report is not intended to provide strict indications or contraindi- cations for the procedure because multiple variables must be weighed in selecting the individual for balloon angio- plasty treatment.” While this was the intent of these guidelines, this initial intent has not been fully recog- nized since the guidelines have been treated as factual benchmarks. Remarkably the lesion specific criteria have been universally adopted without conclusive proof of their validity. Only one report by Ellis and colleagues has examined the value of lesion classification in pre- dicting success and complications [2]. Using a modifi- cation of the criteria to include two levels of type B lesions, the criteria predicted a success ranging from 92% to 61% and associated complications from 2% to 21%. This study indicated that while these lesion criteria were correlated with outcome they were not highly pre- dictive. The authors also demonstrated that certain lesion criteria carry more weight than others. For instance le- sions on bends >60 degrees or high grade stenosis were important independent predictors of outcome. In addi- tion, type C lesions felt by the initial committee to rep-

Received and accepted August 27. 1991.

Address reprint requests to David P. Faxon, 88 East Newton Street, Boston, MA 021 18-2393.

0 1992 Wiley-Liss, Inc.

2 Editorial

resent lesions with a success of <60% in fact had a success rate of slightly more. Furthermore this analysis failed to consider that most type C lesions never undergo angioplasty .

Unfortunately, ACC/AHA lesion criteria have been misused in a number of ways. It has been suggested by some that low volume operators should be restricted to performing angioplasty in patients with Type A lesions while more experienced operators might be able to do Type B and even Type C. However, the risk associated with angioplasty was clearly more complicated than merely the lesion classification and clinical variables such as the severity of coronary disease, left ventricular dysfunction, congestive heart failure, diabetes, age, gen- der etc. are also important [3-81. In addition, experience can lead to improved technical skills such that a Type A lesion for one operator is not a Type A lesion for another. Operator experience has been felt by many to be the single most important predictor of success [9]. A theo- retical concern was that lesion criteria might be used by third party payers to determine reimbursement to physi- cians. For instance, since success is low and risk is high in Type C lesions, payers might decide not to reimburse for an angioplasty in this setting. Determination of what was or was not appropriate for a specific patient can often not be made solely from a chart review and is highly individual for the patient and physician.

These lesion criteria cannot be used as the gold stan- dard against which other new interventional techniques will be compared. It has not been uncommon for new interventional devices such as laser angioplasty or atherectomy to be compared to balloon angioplasty [9- 131. This very problem was recently addressed by the investigators in the NHLBI PTCA Registry [13]. In many cases, these studies involved a retrospective com- parison of their results to that of balloon angioplasty, particularly from large multicenter studies such as the NHLBI PTCA Registry. Studies often compared their success rates to those of angioplasty in Type A, B, and C lesions. Since the lesion criteria were derived solely for angioplasty and are relative to that procedure alone, it makes little sense to compare a new interventional device with criteria derived for balloon angioplasty. A Type B lesion due to vessel tortuosity (a type B charac- teristic) may have very different implications than a Type B lesion due eccentricity. The former stenosis may be inadequately treated by directional atherectomy while the latter may be optimally treated by it. Since the success and complication rates for all types of lesions have greatly changed since the criteria were first developed, the only meaningful way to compare new technology to balloon angioplasty would be to perform a randomized trial. While the concept of examining lesion morphology as a predictor of outcome may be reasonable they may

need to be prospectively more accurately defined and individualized to the device.

The overall success of coronary angioplasty continues to rise. A recent report by O’Keefe supports a high suc- cess rate and low complications in patients with multi- vessel angioplasty [ 141. Improved operator experience as well as technologic improvements enables certain Type C lesions to be as successfully dilated as some Type B or even Type A lesions. Thus as we enter 1992 the use of these criteria, based upon data collected prior to 1988, is unreliable, particularly in view of the widespread recog- nition that as technology improves and experience in- creases, success and complications change favorably. In addition, as the bailout devices become more widely used, complications are likely to be reduced further. The concept that lesion morphology has been an important determinant of angioplasty outcome has not been dis- puted by the cardiovascular interventionist. We would urge continued study of lesion factors that influence out- come but would argue that due to the aforementioned changes that the usage be kept within the context out- lined in the subcommittee’s statement. Perhaps further data obtained from more detailed analysis of coronary morphology, particularly quantitative analysis, may help further define how best to select patients for coronary angioplasty as well as new interventional techniques.

David P. Faron, MD David Holmes, MD Geoffrey Hartzler, MD Spencer B . King, MD Gerald Dorros, MD

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