Specialized revascularization devices in the management of coronary heart disease

INTRODUCTION — The management of coronary heart disease has evolved significantly due in part to improvement in both surgical and percutaneous revascularization techniques. While the majority of patients with chronic stable angina are treated with medical therapy, revascularization on top of medical therapy is the preferred treatment strategy in many clinical subgroups. (See "Chronic coronary syndrome: Indications for revascularization".)

The majority of patients who undergo revascularization receive percutaneous coronary intervention (PCI) with stenting, as opposed to coronary artery bypass graft surgery. (See "Revascularization in patients with stable coronary artery disease: Coronary artery bypass graft surgery versus percutaneous coronary intervention".)

Most patients who undergo PCI receive stents. Specialized revascularization devices such as rotational or orbital atherectomy and intravascular lithotripsy (for severely calcified lesions) or laser angioplasty (for in-stent restenosis) have been evaluated in clinical trials.

Neither short- nor long-term benefits have been shown consistently with routine use of these revascularization devices. In particular, atherectomy devices have generally failed to improve patient survival or the durability of the revascularization [1,2]. These findings indicate that routine use of specialized device therapies (over the combination of balloon dilation and stent implantation) is not justified. However, lesion-specific benefits, such as for complex calcified stenoses, may exist.

The use and efficacy of rotational and orbital atherectomy, cutting balloon atherectomy, intravascular lithotripsy balloon angioplasty, and excimer laser angioplasty will be reviewed here. The complications associated with their use are discussed separately.

DEFINITION — For the purpose of this topic, a specialized revascularization device is a catheter-based tool designed to address unique problems associated with certain lesions, such as those that are calcified. These devices have specialized functions used at the time of percutaneous coronary intervention and typically supplement or assist balloon angioplasty and the implantation of a stent.

ROTATIONAL ATHERECTOMY — Rotational atherectomy is performed with a rapidly rotating olive-shaped burr whose leading hemisphere is coated with microscopic diamond chips. Contact of the burr with fibrocalcific plaque grinds calcified atheroma into particles small enough to pass through the distal myocardial capillary bed. It was designed to both "debulk a lesion" and to remove calcified tissue that after might interfere with the ability of a percutaneous balloon to pass.

The routine use of rotational atherectomy during percutaneous coronary intervention (PCI) was shown to not be useful in a meta-analysis of 16 device trials [1]. Using data from the four trials that evaluated rotational atherectomy, its routine use, compared to percutaneous transluminal coronary angioplasty (PTCA) alone, was associated with significant increases in restenosis (odds ratio [OR] 1.25), myocardial infarction at 30 days (OR 2.18), and major adverse cardiac events at one year (OR 1.52).

Calcified and complex lesions — Despite these shortcomings, rotational atherectomy is valuable for heavily calcified lesions that cannot be treated successfully by balloon angioplasty or that interfere with a delivery of a stent to a more distal location. It is also used commonly for calcified ostial lesions of the right coronary artery [3]. Uncontrolled results from a multicenter registry found that rotational atherectomy was successful (defined as less than 50 percent residual stenosis) in 94 percent of calcific lesions [4]. (See "Percutaneous coronary intervention of specific coronary lesions", section on 'Ostial lesions'.)

Use prior to stenting — There is no value in performing rotational atherectomy routinely before stenting. The ROTAXUS trial randomized 240 patients with complex calcified native coronary lesions to stenting using a paclitaxel-eluting stent with or without routine rotational atherectomy. At nine months, clinical outcomes of MACE, TLR, and definite stent thrombosis were not different [5]. However, rotational atherectomy does have utility prior to stenting when a proximal calcified segment prevents stent delivery or when there is a large plaque burden, which may interfere with optimal stent expansion and may be associated with an increased risk of in-stent restenosis.

Internal mammary artery graft stenosis — Although uncommon, stenosis within an internal mammary artery graft may cause recurrent ischemia after coronary artery bypass graft surgery. While such lesions are most often treated with balloon angioplasty, unsatisfactory results may occur when the lesion at the anastomotic site is rigid and fibrotic. Although data are limited to a small number of patients, rotational atherectomy may infrequently be needed for such lesions [6]. (See "Coronary artery bypass graft surgery: Graft choices", section on 'Arterial grafts'.)

Saphenous vein graft lesions — Because of the increased risk for distal embolization, we generally limit use of rotational atherectomy in saphenous vein grafts to special circumstances. (See "Coronary artery bypass graft surgery: Prevention and management of vein graft stenosis".)

Use in patients with diabetes — Patients with diabetes who undergo rotational atherectomy for diffuse coronary disease have a higher rate of angiographic restenosis at six months (72 versus 45 percent for patients without diabetes) and a higher rate of target lesion revascularization (67 versus 36 percent) [7]. (See "Coronary artery revascularization in stable patients with diabetes mellitus".)

In-stent restenosis — Rotational atherectomy has been used to treat diffuse in-stent restenosis, particularly when there is significant hyperplasia inside the stent [8,9]. It leads to acute lumen gain by removing plaque and intimal hyperplasia, while adjunctive PTCA produces additional lumen gain by further stent expansion and tissue extrusion [10]. Despite success reported from a retrospective, observational study [8], a later randomized trial of 298 patients showed higher risk for recurrent restenosis [11].

We do not generally use rotational atherectomy for treatment of in-stent restenosis.

Complications — Potential complications of rotational atherectomy include severe coronary spasm, dissection, perforation, and slow flow through the capillary bed due to excessive particle embolization. This issue is discussed separately.

Adjunctive glycoprotein IIb/IIIa inhibitor therapy — Distal particulate embolization may combine with platelet activation and aggregation to worsen coronary artery hypoperfusion and precipitate non-ST elevation myocardial infarction. This mechanism is supported by a trial in which 100 patients were randomly assigned to abciximab or placebo during atherectomy [12]. Patients treated with abciximab were less likely to have elevated levels of CK-MB (8 versus 22 percent for placebo), slow-flow, or postprocedural chest pain.

Further support for efficacy of abciximab comes from an observational study of 75 patients who underwent radionuclide myocardial perfusion imaging prior to, during, and two days after atherectomy [13]. The 30 patients who received abciximab during the procedure had a significantly lower rate of transient perfusion defects (33 versus 87 percent).

Use of glycoprotein IIb/IIIa inhibitors has declined overall, but some of our experts do use them occasionally on a case-by-case basis. Tirofiban and eptifibatide are acceptable; abciximab is no longer marketed in the United States, Canada, and most European countries.

Rotational atherectomy summary — The American College of Cardiology/American Heart Association/Society for Cardiovascular Angiography and Interventions (ACC/AHA/SCAI) guideline update for PCI concluded that there is no evidence that rotational atherectomy improves late outcomes in lesions that can be safely treated with stenting or angioplasty alone [14,15]. When rotational atherectomy is being considered, the weight of evidence or opinion was in favor of the efficacy of IVUS for establishing the presence and distribution of coronary calcium.

ORBITAL ATHERECTOMY — Orbital atherectomy, similar to rotational atherectomy, utilizes a rotating burr to ablate plaque into particles small enough to be cleared by the reticuloendothelial system. The device differs from rotational atherectomy in that the burr is flexible and the depth of plaque ablation can be changed by altering the speed of rotation. The device also performs ablation in both the forward and reverse directions. In the ORBIT II trial, 443 patients were treated with orbital atherectomy in an open-label registry. After atherectomy, successful stent delivery occurred in 98 percent of cases [16]. At 30 days, the incidence of primary efficacy end point (residual stenosis <50 percent post-stent without in-hospital major adverse events) was 88.9 percent. Components of the combined end point included a cardiac mortality rate of 0.2 percent, myocardial infarction (defined as creatine kinase MB fraction >three times the upper limit of normal) rate of 9.7 percent, and a target vessel revascularization rate of 1.4 percent. Some operators prefer orbital atherectomy over rotational atherectomy in some cases.

SHOCKWAVE INTRAVASCULAR LITHOTRIPSY — This technique uses catheter-mounted pulsed sonic waves to modify intravascular calcium. The technique likely causes intraplaque calcium fracture. Shockwave lithotripsy was first used for disruption of pancreatic, bile duct, and renal stones and was later approved by the U S Food and Drug Administration for coronary calcium disruption. (See "Kidney stones in adults: Surgical management of kidney and ureteral stones", section on 'Shock wave lithotripsy' and "Laser lithotripsy for the treatment of bile duct stones".)

The safety and efficacy of shockwave intravascular lithotripsy for treatment of severe coronary artery plaque were established with the DISRUPT CAD II study [17]. In this study, 120 patients were enrolled with severe coronary artery calcium present in 94 percent of lesions. Catheter delivery was successful in all patients. Postprocedure, coronary artery residual stenosis was on average 33 percent, which decreased to 8 percent following drug-eluting stent implantation. There were no acute procedural complications of major dissections, perforations, abrupt closure, or slow flow/no reflow. Adverse events occurred in 6 percent in hospital (non-ST-elevation myocardial infarction) and 8 percent at 30 days (cardiac death, myocardial infarction, or target vessel revascularization). A potential limitation of the study was that only 6 percent of participants were female, somewhat limiting generalizability of the results.

CUTTING BALLOON ANGIOPLASTY — The cutting balloon is a device with three to four longitudinal atherotome blades mounted on the outer surface of the balloon. It produces sharp, clean, longitudinal incisions, leaving the interincisional segments of the untreated segment intact [18]. It was proposed that this type of controlled dilatation might reduce the force needed to dilate an obstructive lesion.

An initial nonrandomized matched comparison suggested that the incidence of restenosis and target vessel revascularization was lower with cutting balloon angioplasty than with other methods of treatment [19]. This was not confirmed in the RESCUT trial that compared the cutting balloon to conventional angioplasty in 428 patients with in-stent restenosis [20] or in a meta-analysis [1]. (See "Intracoronary stent restenosis".)

Some operators favor the cutting balloon, which is less likely than a traditional balloon to slip out of the lesion, for use in ostial lesions, to reduce elastic vessel recoil, and for in-stent restenosis. Many operators also use cutting balloon angioplasty as adjunctive treatment for modification of fibrotic or calcified lesions. Such modification may provide improved expansion or assist difficult stent delivery.

The 2005 European Society of Cardiology (ESC) Task Force for percutaneous coronary intervention (PCI) concluded that the weight of evidence or opinion is in favor of efficacy of cutting balloon angioplasty for avoiding slipping-induced vessel trauma during PCI of in-stent restenosis [21].

EXCIMER LASER ANGIOPLASTY — The excimer laser produces monochromatic light energy to cause ablation of plaque and, via the generation of heat and shock waves, plaque disruption. The lumen produced by the laser is 0.9 to 2.0 mm in diameter; as a result, laser angioplasty must be followed by the use of another device to achieve a satisfactory final result. The excimer laser has not found acceptance for general use based on lack of success and higher risk for coronary dissection and perforation in earlier trials [22].

In the meta-analysis of 16 device trials cited above, three trials evaluated laser angioplasty [1]. Laser therapy was associated with a significant increase in restenosis compared to percutaneous transluminal coronary angioplasty (PTCA) (odds ratio [OR] 1.55), a trend toward an increase in the rate of myocardial infarction at 30 days (OR 1.39), and a significant increase in major adverse cardiac events at one year (OR 1.32).

In contemporary percutaneous coronary intervention, interest in excimer laser has been renewed for treatment of certain complex lesions prior to definitive stenting, such as severe diffuse lesions, especially if heavily calcified and not well suited for rotational atherectomy; undilatable lesions; and diffuse in-stent restenosis [23].

Efficacy for in-stent restenosis — Excimer laser coronary angiography (ELCA) followed by adjunct PTCA has been evaluated for treatment of in-stent restenosis, followed by repeat stenting with drug-eluting stents in most patients. (See "Intracoronary stent restenosis".)

ELCA is associated with a high rate of procedural success and a low rate of periprocedural complications in patients with in-stent restenosis [24]. Data supporting long-term efficacy come from observational studies comparing ELCA and PTCA to PTCA alone. The relevant studies show a tendency for less frequent need for repeat target vessel revascularization [25], similar rates of revascularization [26], or higher rates of recurrent stenosis and reintervention [27,28].

The American College of Cardiology/American Heart Association/Society for Cardiovascular Angiography and Interventions (ACC/AHA/SCAI) guideline update concluded that there is no evidence that ELCA improves late outcomes in lesions that can be safely treated with stenting or angioplasty alone [14,15].

SUMMARY — A specialized revascularization device is an uncommonly needed tool with specialized functions that can be used at the time of percutaneous coronary intervention (generally before the stent is placed) that either allows for optimal placement of a stent or improved outcomes.

Neither short- nor long-term benefits have been shown consistently with routine use of these revascularization devices. In particular, atherectomy devices have generally failed to improve patient survival or the durability of the revascularization. These findings indicate that routine use of specialized device therapies (over the combination of balloon dilation and stent implantation) is not justified in most cases.

The following summarizes the current use of these devices:

●Rotational atherectomy – This may be used prior to stenting when a proximal calcified segment prevents stent delivery or when there is a large plaque burden, which may interfere with optimal stent expansion. (See 'Rotational atherectomy' above.)

●Cutting balloon angioplasty – This can be used to avoid slipping-induced vessel trauma during percutaneous coronary intervention (PCI) of in-stent restenosis. (See 'Cutting balloon angioplasty' above.)

●Excimer laser angioplasty – There is no evidence that excimer laser angioplasty improves late outcomes in lesions that can be safely treated with stenting or angioplasty alone, but some of our experts use it in certain lesion subsets before definitive stenting. (See 'Excimer laser angioplasty' above.)

●Several devices that can mechanically aspirate thrombus are available. These devices have been studied for their use in saphenous vein grafts and before primary PCI. (See "Coronary artery bypass graft surgery: Prevention and management of vein graft stenosis", section on 'Thrombolysis and thrombectomy' and "Suboptimal reperfusion after primary percutaneous coronary intervention in acute ST-elevation myocardial infarction", section on 'Prevention'.)