Safety and Efficacy of Cutting Balloon Angioplasty: The Mayo Clinic Experience

There have been rapid improvements in percutaneous coronary intervention since its introduction. However, complex lesions unsuitable for routine angioplasty continue to pose a significant problem. A number of alternative devices have been developed in an attempt to facilitate treatment of resistant stenoses, including laser, rotational and directional atherectomy catheters. Unfortunately, all have their limitations, not the least of which are cost and technical complexity. Cutting balloon angioplasty combines conventional balloon angioplasty with microsurgical technology in an attempt to minimize vessel stretch and injury during balloon dilation of coronary stenoses. A number of evolving clinical indications have been described in the clinical literature, including angioplasty-resistant stenoses, in-stent restenosis, ostial lesions and small vessel disease.1 This technology was adopted at the Mayo Clinic in 2000 and has been utilized in a number of disparate interventional scenarios. We sought to describe the Mayo Clinic experience with cutting balloon angioplasty and compare this experience with published data addressing such indications and outcomes. Methods Patient population. We analyzed the records of all patients undergoing percutaneous coronary intervention utilizing the Mayo Clinic PTCA registry and according to a protocol approved by the Mayo Clinic and Foundation Institutional Review Board. The PTCA registry is a prospective interventional database that has been maintained at the Mayo Clinic since 1979. It includes demographic, clinical, angiographic and procedural data on all patients. Angiographic characteristics are coded at the time of the interventional procedure; immediate and in-hospital events are identified and recorded by a team of independent research nurses and technicians, and all patients are subsequently contacted by telephone at 6 and 12 months and each year thereafter.2 All patients in whom cutting balloon angioplasty was attempted at the Mayo Clinic were included (September 2000–August 2001). All patients gave written informed authorization for the release of all such information. Angioplasty technique. All study patients received pre-procedural aspirin (325 mg) and intravenous bolus heparin (70–100 U/kg) was administered prior to the procedure. Conventional balloon predilation was performed at the discretion of the operator based on a subjective assessment of the feasibility of device (cutting balloon) deliverability. The cutting balloon was available in an over-the-wire configuration in diameters ranging from 2.0 to 4.0 mm, in quarter millimeter increments, and 10–15 mm lengths. The cutting balloon diameter was selected to approximate a ratio of 0.8:1.0 (balloon to reference vessel diameter) and was typically inflated to 10 atmospheres (nominal pressure = 6 atmospheres, rated burst pressure = 10 atmospheres) with the goal of achieving a less than 30% residual diameter stenosis by visual estimate. When this desired result was not achieved, additional conventional balloon angioplasty and/or coronary stenting was performed at operator discretion. Conventional balloon angioplasty and coronary stent implantation were performed using standard percutaneous techniques.3 Intravascular ultrasound was performed at the discretion of the operator. Post-procedural medications included aspirin (75–325 mg daily, indefinitely) and clopidogrel (300 mg loading dose, followed by 75 mg daily for 2–4 weeks). Definitions. Diabetes mellitus was defined as a documented history of diabetes treated with medication or diet. Hypertension was defined as a documented history of hypertension, which was treated with medication. Hypercholesterolemia was defined as a documented history of a total cholesterol value greater than 240 mg/dl. PTCA-resistant lesions were defined as calcified or fibrotic lesions which resisted conventional PTCA at inflation pressures equal to or exceeding the manufacturer’s quoted rated burst pressure, and in which the operator elected to perform CBA in an attempt to dilate the vessel. Small-vessel lesions were defined by reference vessel diameter 45° (mild), 45–90° (moderate) and > 90° (severe). Eccentricity was defined as asymmetric narrowing in the form of a convex intraluminal obstruction with smooth borders and a wide neck or any asymmetric narrowing with smooth borders. The angiographic success of revascularization was defined as a reduction of at least 20 percentage points in the stenosis of at least 1 lesion, resulting in a residual stenosis of less than 50% of the luminal diameter and Thrombolysis in Myocardial Infarction (TIMI) 3 flow. This was determined by visual estimate. Clinical success was defined as angiographic success without in-hospital complications of death, reinfarction, repeated percutaneous procedure or referral for coronary artery bypass graft (CABG) surgery. Severe dissection was defined as an intimal tear resulting in at least 50% luminal obstruction. Percent diameter stenosis was defined by visual estimate. Post-procedural myocardial infarction was defined as re-elevation of serum creatine kinase concentrations that were at least 3 times higher than the reference range or positive test results for MB isoenzymes, new electrocardiographic changes consistent with transmural injury, an episode of prolonged angina, or new regional wall motion abnormalities, during hospital admission. Creatine kinase MB isoenzyme samples were collected on all patients at 8 and 16 hours after the procedure. Creatine kinase MB values and clinical follow-up to hospital discharge were available on all patients. Results Baseline clinical characteristics. One thousand seven hundred and sixty-one patients underwent percutaneous coronary intervention at the Mayo Clinic in Rochester, Minnesota, between September 2000 and August 2001. One hundred patients (5.7%) underwent cutting balloon angioplasty. One hundred and three procedures and 114 lesions were attempted. Baseline characteristics of all patients undergoing CBA are shown in Table 1. There was a male preponderance (71%) and a mean study population age of 65.7 ± 10.3 (standard deviation) years. Thirty-four patients (34%) had diabetes mellitus and 36 patients (36%) had a history of prior coronary artery bypass graft surgery. Seventy-five patients (75%) presented with unstable angina and 3 patients (3%) presented with acute myocardial infarction. Angiographic characteristics. In-stent restenosis was the most common indication for the use of the cutting balloon (Table 2). The right coronary artery was the most common location of the target lesion. Saphenous vein and internal mammary artery bypass grafts were also represented, but were infrequent. The majority of lesions were prospectively classified as at least B2 complexity (ACC/AHA lesion classification). Tortuosity was classified as moderate or severe in 34 lesions (30%), and 25 lesions (22%) were felt to have angiographic evidence of calcification. Procedural outcomes. Cutting balloon angioplasty was successfully completed in 109 lesions (96%). Five lesions could not be crossed with the cutting balloon, but were successfully dilated with a lower profile conventional PTCA balloon. Mean percent diameter stenosis prior to CBA (all lesions) was 85 ± 10% (Table 3). The post-CBA minimum lumen percent diameter stenosis was deemed unacceptable by the treating physician in 83 lesions (73%); additional conventional PTCA was performed on 45 lesions (39%) and additional stent implantation on 38 lesions (34%). Severe intimal dissection resulting in at least 50% luminal obstruction occurred in 13 lesions (11%) following CBA, and all were treated with stent implantation. A single incident of branch occlusion was documented, resulting in ST elevation myocardial infarction following CBA. There were no incidents of vessel perforation, urgent percutaneous or surgical target vessel revascularization, or in-hospital death. Discussion Cutting balloon angioplasty is both feasible and safe, with a low incidence of procedural complications and in-hospital adverse cardiac events when used primarily for in-stent restenosis, although complications, including severe dissection and branch vessel occlusion, occurred in 12% of the patients in this cohort. De novo and ostial native coronary artery lesions are also considered reasonable targets for this device. The cutting balloon consists of three (2.0 and 2.5 mm balloon) or four (>= 3.0 mm balloon) atherotomes, which are microsurgical blades, 0.010´´ in height and bonded longitudinally to the balloon surface. The balloon is folded to shield the blades and protect the vessel wall as the catheter is passed to and from the lesion. As the cutting balloon is inflated, the atherotomes expand radially and incise the plaque, facilitating maximum dilatation of the target lesion with the least amount of force and resulting in controlled injury, in contrast to the irregular and unpredictable intimal injury associated with regular balloon angioplasty. This approach was developed in an attempt to minimize the neoproliferative response, which is thought to be directly related to the force applied at the time of balloon dilation and the extent of vascular injury.4 Various lesion characteristics have been proposed as appropriate for CBA, including in-stent restenosis, de novo, ostial, conventional PTCA-resistant and small vessel lesions.1 Trials of CBA for the treatment of in-stent restenosis have yielded promising results. The potential advantages of using CBA for restenotic lesions include avoidance of “watermelon seeding” (proximal or distal movement of the balloon on inflation). This has the practical benefit of limiting the injury length and, in the event of concomitant intracoronary brachytherapy, reducing the likelihood of “geographic miss”. More reliable balloon positioning and expansion may also reduce procedure time and radiation exposure. Adamian et al. recently reported a matched comparison of CBA, rotational atherectomy, additional stent implantation and conventional PTCA.5 This study demonstrated the relative benefits of CBA, particularly with respect to target lumen revascularization, recurrent restenosis and the morphology of the lesions of recurrent restenosis, favoring focal recurrence amenable to simple repeat dilatation. These results are consistent with earlier published data, but will require a prospective randomized trial for definitive confirmation.6,7 Our data support these findings with respect to feasibility and safety, specifically regarding a relatively low incidence of procedural complications and in-hospital major adverse cardiac events. Eighty-seven lesions were treated with intracoronary brachytherapy at the time of balloon dilatation and additional stent implantation was avoided in an attempt to reduce the neointimal proliferative response and minimize the risk of stent thrombosis. CBA may facilitate this goal, achieving an adequate luminal diameter with less applied force and controlled dissection, minimizing vessel injury and possibly the neointimal response, as well as decreasing the potential for arterial damage beyond the stent which may not be covered by subsequent intracoronary brachytherapy. “Suboptimal” angiographic results (residual percent diameter stenosis >= 30%) are commonly accepted in an effort to avoid stent implantation and these aforementioned attendant risks (Table 4). CBA has also been successfully employed for the initial treatment of de novo lesions prior to stenting. A small study comparing CBA prior to stenting with direct stenting in de novo lesions demonstrated a lower restenosis rate with CBA.8 Similarly, a randomized trial of CBA in de novo lesions with reference vessel diameters Study limitations. This is a retrospective study and the limitations of this methodology are acknowledged. Specifically, we cannot draw definitive conclusions regarding the comparative efficacy and safety of CBA and alternative treatment strategies. The indications for the use of CBA are not well-defined and the decision to attempt CBA was made on an ad hoc basis; the generalizability of these results to all patients is therefore questionable. It should be noted that 5 patients failed attempted CBA due to failure to cross the target lesion with the device. Conclusion CBA is both feasible and safe, with a low incidence of procedural complications and in-hospital adverse cardiac events when used primarily for in-stent restenosis.

1. Ajani AE, Kim HS, Castagna M, et al. Clinical utility of the cutting balloon. J Invas Cardiol 2001;13:554–557. 2. Holmes DR Jr., Berger PB, Garratt KN, et al. Application of the New York State PTCA mortality model in patients undergoing stent implantation. Circulation 2000;102:517–522. 3. Holmes DR. Technical aspects. In: Vliestra RE, Holmes DR (eds). Percutaneous Transluminal Coronary Angioplasty, Volume 35. Philadelphia: F.A. Davis, 1987. 4. Inoue T, Sakai Y, Hoshi K, et al. Lower expression of neutrophil adhesion molecule indicates less vessel wall injury and might explain lower restenosis rate after cutting balloon angioplasty. Circulation 1998;97:2511–2518. 5. Adamian M, Colombo A, Briguori C, et al. Cutting balloon angioplasty for the treatment of in-stent restenosis: A matched comparison with rotational atherectomy, additional stent implantation and balloon angioplasty. J Am Coll Cardiol 2001;38:672–679. 6. Chevalier B, Guyon P, Glatt B. Treatment of in-stent restenosis: