Directional coronary atherectomy: An update

CA INTERVENTIONAL Los~n~e., EXECUTIVE EDITORS David P. Faxon, MD

CARDlO~O~Y

~~@~!?~~; New York.‘NY

NEWSLETTER VOLUME 4, NUMBER 6

’

NOVEMBER 1996

Directional Coronary Atherectomy: An Update David R. Holmes, Jr., MD Cardiovascular Diseases and Internal Medicine Mayo Clinic 200 First Street SW Rochester, MN 55905

D

irectional coronary atherectomy was the fmt alternative device approved by the FDA after the introduction of conventional percutaneous transluminal coronary angioplasty (PKA). It was developed as a method to make percutaneous procedures safer and more reliable than PTCA by excising atherosclerotic plaque in a controlled fashion. Interest in the device was great and the number of cases increased rapidly after FDA approval. This increase was the result of published individual experiences and multicenter registries which documented safety and improved initial and longer term outcome. In the initial Interventional Cardiology Newsletter addressing directional coronary atherectomy (Match 1993), it was reported that the device has been used in 50,000 patients with favorable results. Following the initial high enthusiasm, three multicenter randomized trials were designed and carried out-CCAT and CAVEAT I, which involved de novo native coronary arterial lesions, and CAVEAT II, which was restricted to de novo saphenous vein gmft lesions. These trials have been extensively reviewed and critiqued with the KANEB 4(6)1996,43-50

major findings that directional coronary atherectomy did result in 1) improved initial success rates compared to conventional PTCA with improved initial angiographic results 2) a small decrease in angiographic restenosis in CAVEAT I 3) an increase in preprocedural complications with increased in non Q wave myocardial infarction and increased distal embolization 4) increased procedural costs, e.g., contrast and procedural time 5) no clinically meaningful reduction in restenosis rates at the time of follow-up angiogmphy. During this same time period which was characterized by unfullilled expectations, stents became more widely available. The combination of these two events led to an overall decrease in use of directional coronary atherectomy. Although the randomized trials did not yield positive results, a substantial body of information about device performance was accumulated. The need for “optimal atherectomy” with adjunctive PTCA frequently needed to achieve a residual stenosis 20% was emphasized in contrast to CAVEAT and CCST in which the mean residual stenosis was approximately 30%. In addition, the safety of deeper wall excision was confirmed and the importance of more complete plaque excision was emphasized either with or without IWS guidance. A new trial was

designed to test a more contemporary directional coronary atherectomy practice the Balloon Optimal Atherectomy Trial of approximately 1,000 patients again with angiographic restenosis as the primary endpoint. The preliminary results of this trial were presented at the European Society of Cardiology in August 1996 and again at the American Heart Association meeting in November 1996. An earlier issue of this newsletter (Interventional Cardiology Newsletter, Volume 1, Number 2, March/April 1993) focused on directional coronary atherectomy use. The survey includes 53 physicians who had experience with a total of 2,527 atherectomy procedures, averaging

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INTERVEt’0lONAl CARDIOLOGYNEWSLETTER

486 procedures per physician, In this survey, 33.3% of respondents reported that they used atherectomy in 3 to 5 % of cases. 23.5% reported that they used the device in 10 to 15%. The physicians were not optimistic that restenosis rates with DCA in randomized trials would be found to be lower than with conventional PTCA (65%). Despite this feeling, 40% of respondents felt that the frequency of DCA would increase. The current survey reflects contemporary thought about the practice of directional coronary atherectomy and has changed substantially. Questions 1 and 2: While the majority of respondents (82%) thought that directional coronary atherectomy will remain an established technique, it was clear that the majority also though that it was a niche device; 50% felt that it would be limited to less than 10% of patients undergoing treatment. Question 3: There are several reasons for the reduction in directional coronary atherectomy given by the respondents; the dominant reason is the widespread availability of stems. Although only two stems have been approved for use in the United States, they are used frequently particularly in large proximal vessels that are also well suited for directional coronary atherectomy. 91% of respondents found that was the most important reason for the reduction in directional coronary atherectomy use. The two most important other reasons were the results of CCAT and CAVEAT I and inherent problems with device flexibility and performance.

Questions 4 and 5: The actual frequency of device utilization varied among different respondents. Of the five devices evaluated, PTCA alone or stenting was used most often, while laser therapy was the most infrequently used device. Directional atherectomy use was uncommon: with most respondents using it in ~4% of cases, Future use patterns indicated continual growth in stent use while directional coronary atherectomy remained stable. Questions 7 and 8: Given the fact that the current directional coronary atherectomy device remains relatively large and inflexible, the device is apt to continue to be most suited for large proximal vessels, similar to those which are ideal for stent implantation. As might be expected, for single discrete lesions in native coronary stenosis or for vein graft disease, stems are overwhelmingly preferred compared to directional coronary atherectomy. 96% of respondents favored stent implantation for one of three reasons-a predictable result, ease of use and documented decreased restenosis. Given the continued improvements in stent technology with smaller more flexible stems, coated stems, and continued documentation of dramatic reduction in restenosis with stents, this relative pattern of directional coronary athemctomy versus stems for lesions suitable for either is apt to remain unchanged. In addition to changing frequency of use patterns for DCA, the technique has also changed (Question 6). A 7 French device is used in the majority of cases

VOLUME 4, NUMBER 6,1996

(63%) and most respondents used routine post dilatation on I WS guidance to optimire tissue removal, it was used infrequently. A major recent addition to atherectomy has been the BOAT trial. Interest in this trial has been significant as it offers the potential for growth in athenectomy based upon the degree of restenosis improvement detected. Most of the respondents in the survey felt that for interest in DCA to be rekindled, that a 40% reduction in restenosis would have to be identified In the BOAT trial, the central questions to address were 1) can multiple operators apply an optimal DCA technique to optimize the initial angiographic result 2) can that goal be accomplished without increasing initial complications? and 3) will an improved initial angiographic result translate into clinical outcome with reduced angiographic and clinical outcome? In the preliminary analysis, 497 patients were randomized to DCA and 492 to PTCA. Provisional success was achieved in 93.0% of DCA compound to 86.7% of PTCA patients. The incidence of death (o is 0.4%) Q MI ( 1.2%) and emergency CAB6 (1% is 2%) was low in both groups. DCA was associated with improved angiographic outcome with a final diameter stenosis of 15% versus 20% for PTCA. Large or moderate non Q wave infarctions were more common in DCA patients as was previously found with earlier randomized trials at 6 months, angiographic restenosis was sig-

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VOLUME 4, NUMBER 6,1996

nificantly improved in DCA patients (32% in 40%) (pE.02). Interventional technology continues to evolve. At the present time, stems reign supreme based upon the translation of improved rester&s documented in randomized trials to the wider group of pa-

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tients being treated. Them are compounds in the stent based technology as well as in directional atherectomy. The latter continues to be a valuable niche device and has now been added to the lit of interventions which has been definitely proven to decrease restenosis. Continued improve-

NEWSLET”l-l3? 45

merits in directional atherectomy with smaller more flexible devices and combined imaging/cutting devices will impart on the field of interventional cardiology.

Directional Coronarv Atherectomv - - - - - - ---- - - -- - _- --Survey Summary ’ _ SekctedQuestions

Does directional athaectomy have a future? 81.8% YeS 18.2% No If so, what role will it have: a) Limited to
a aandb no answer a,b,andc aandc

Percentage of Responses 50.0% 19.7% 19.7% 9.1% 1.5%

30.3%

16.7Y.

What reduction in restenosis rates will be required in the BOAT trial to rekindle interest in DCA?

NA 20% reduction 30% reduction 40% reduction No snswer

16.7% 30.3% 48.5% 4.5%

(4.5%)

What have been the major reascms fa the reduction in use of directional atherectcxny? (h4ae thanone answer accepted) Availability of stenting Device performance (flexibility) and delivery Results of CAVEAl and CCAT trials Device performance (flexibility) and delivery Tie required for optimal atherectomy

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90.9% 53.0% 54.5% 53.0% 28.8%

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