ABSTRACT: Objective. To evaluate the safety and efficacy of rotational atherectomy (RA) in patients with severe left ventricular (LV) dysfunction. Background. RA, using a rotating diamond-crystal burr, is most commonly used to open lesions with severe calcification or diffuse disease that may prove difficult to cross or dilate. However, RA generates microparticular debris that may attenuate the coronary microcirculation, inducing transient myocardial stunning and LV dysfunction. In fact, the manufacturer does not support RA use in patients with severe LV dysfunction. Methods. We retrospectively identified patients with a LV ejection fraction < 30% who underwent RA in our institution over a 4-year period. The medical records were reviewed and risk factors for cardiac disease were recorded. The procedural reports and subsequent hospitalization records were reviewed to identify predetermined positive and negative outcomes. Results. Twenty-three patients (17 males) who underwent RA with severe LV dysfunction (mean LVEF 21.3%) were identified. The majority of these patients had multivessel coronary artery disease, hypertension, hyperlipidemia and/or tobacco use. Also, a substantial subset had diabetes, renal insufficiency and/or in-stent restenosis. RA was 100% successful in opening the lesions without any in-hospital procedure-related mortality. Three patients experienced periprocedural myocardial infarctions; 1 patient died from malignancy during hospitalization. There were no major adverse cardiac events at 30 days. Conclusion. The transient effect of RA on ventricular function did not adversely affect short-term outcomes in our study population. These results suggest that RA, when performed by experienced operators, is safe and feasible in patients with severe LV dysfunction.

       Over the past decade there have been tremendous advancements in the technique and procedural success rates in the field of interventional cardiology. Many of these advancements have addressed percutaneous coronary interventions (PCI) on lesions with high-risk characteristics.^1,2 For example, high-speed rotational atherectomy (RA), first described in 1989,³ is performed using a rotating abrasive burr that is designed to debulk atherosclerotic plaque by producing small particles (approximately 7–15 microns in diameter) that are washed away across the capillary bed and filtered by the reticuloendothelial system.⁴ Early studies evaluating the efficacy of RA revealed very high procedural success rates with low complication rates.⁵ But more recent data regarding RA have been unable to replicate these early clinical successes; although the clinical practice in these studies^6–12 (e.g., RA followed by low-pressure balloon inflation without stent implantation) is strikingly different from the current practice of RA use.⁵ Presently, RA is being used in patients with complex coronary lesions,¹³ such as those with severely calcified, diffuse coronary artery lesions or diffuse, severe in-stent restenosis that may prove difficult to cross or dilate,¹⁴ and is followed by high-pressure inflation with stent implantation.
       Further studies have suggested that RA diminishes plaque volume with abrasion, as opposed to fracturing plaque, and therefore has the potential to minimize acute vessel injury and avoid disruption of soft elastic tissue.¹⁵ Therefore, RA can possibly reduce some types of complications including restenosis in smaller vessels,⁸ heavily calcified or diffuse high-risk lesions. However, RA is not without its dangers: previous research suggests that specific procedural complications including myocardial infarction via direct platelet activation¹⁶ and coronary artery perforation may occur more frequently with RA.^17,18 Also, in patients undergoing RA (compared to balloon angioplasty), wall motion abnormalities occurred with similar severity (mean wall motion abnormality ~30%), but with much higher frequency and persisted much longer.¹⁹ In fact (according to the device manufacturer), RA is not recommended to be used in patients with severe left ventricular dysfunction (defined as LVEF < 30%). But unfortunately, patients with severe left ventricular dysfunction frequently have extensive, diffuse and heavily calcified coronary artery disease that is not amenable to standard surgical or percutaneous revascularization.
       Therefore, our study attempted to further elucidate the clinical feasibility, safety, efficacy and applicability of RA in patients with severe left ventricular dysfunction.

Materials and Methods
       All patients who underwent RA at our institution over a 4-year period were retrospectively identified. These patients’ medical records were reviewed and only patients with severe left ventricular dysfunction (defined by left ventricular ejection fraction < 30% as assessed by transthoracic echocardiogram or left ventriculogram) were included in the study. Standard risk factors for coronary artery disease were recorded. The procedural reports, diagnostic and interventional angiograms, and subsequent hospitalization records were reviewed to identify defined positive and negative outcomes.
       Lesion type, according to the ACC/AHA (American College of Cardiology/American Heart Association) classification, and morphologic characteristics were evaluated using standard criteria.²⁰ Procedural success was defined as: (1) asymptomatic and hemodynamically stable patient at the conclusion of the procedure; (2) successful crossing of the lesion with the rotational atherectomy burr; (3) no evidence of coronary artery dissection or perforation; and (4) residual diameter stenosis < 10% (after stent placement). Major adverse cardiac events (MACE) were defined as death, periprocedural myocardial infarction (MI: defined as a significant electrocardiographic ischemic changes, and not cardiac biomarkers), cerebrovascular accident (CVA), target vessel revascularization (TVR) performed by either coronary artery bypass grafting (CABG) or repeat PCI at 30 days. Further endpoints including significant bleeding, need for blood transfusion, worsening congestive heart failure (e.g., as evidenced by pulmonary edema) or left ventricular systolic function (e.g., as evidenced by reduced ejection fraction by transthoracic echocardiography), acute renal insufficiency, and length of hospital stay were also noted.
       The interventional cardiologist performed the RA procedure according to standard practice at our institution: All patients received periprocedural intravenous glycoprotein IIb/IIIa inhibitors (GP IIb/IIIa); all patients who were undergoing intervention to a right coronary artery or dominant left circumflex artery lesion received a temporary pacemaker; all patients deemed hemodynamically unstable had preprocedural intraaortic balloon pump placement. All patients, who were not taking clopidogrel prior to the procedure were given 300 mg of clopidogrel at the start of the case. During the procedure, unfractionated heparin was administered in all patients in order to maintain a partial prothrombin time (PTT) > 300 seconds. All patients received sirolimus drug-eluting stents. Following the procedure, the patient was monitored on telemetry for at least 12 hours for signs of ischemia, congestive heart failure or other procedural complications. Electrocardiographic evaluation of all patients was completed postprocedure, and serum cardiac biomarkers were drawn only when clinically indicated by the patient’s symptoms and clinical presentation. If no complications arose, the patient was discharged home in stable condition with standard 2-week cardiology outpatient follow up. Clopidogrel (75 mg/daily) and aspirin were prescribed to all patients for at least 3 months following the procedure unless contraindicated.

Results
       During the 4-year period, 27 lesions were treated with RA in 23 patients (17 males) with a LVEF < 30%. All 23 patients were deemed to have significant medical comorbidities and/or coronary artery disease that was heavily calcified, diffuse, and/or involving small vessels which made them unsuitable for standard surgical or percutaneous revascularization. Clinical baseline characteristics (Table 1), angiographic appearance of the lesions (Table 2), procedural techniques (Table 3), and clinical endpoints (Table 4) of these selected patients and procedures are shown.
       A majority of the study patients had a prior diagnosis of hypertension (74%), hyperlipidemia (83%), diabetes (30%), chronic renal insufficiency (30.4%; mean serum creatinine 2.2 mg/dL) and/or previous tobacco use (69%). The average LVEF was 21.3% (range 15–30%), and 87% had significant multivessel coronary artery disease. Review of the procedural reports and angiograms revealed that the most common culprit vessel lesion was in the proximal LAD (59.3%), and based on the AHA/ACC classification, most often were Type C lesions (74%), while 26% had Type B lesions. In addition, the lesions treated with RA were “high-risk” complex lesions defined as ostial (33%), bifurcation (40.7%), calcified (74.1%), or sites of severe, diffuse in-stent restenosis (29.6%). RA was used most frequently to debulk the target lesion (82.6% of cases). Other indications for RA use were the inability to cross the target lesion (8.7%) or dilate the target lesion (8.7%) with standard PTCA technique. The average reference vessel size was 3.2 mm (range 2.5–4.1 mm), the average RA burr size used was 1.87 mm (range 1.50–2.38 mm), and therefore the average vessel-to-burr size ratio was 0.60 (range 0.40–0.94). The average lesion was diffuse (defined as lesion length greater than 20 mm). The mean left ventricular end-diastolic pressure (LVEDP) was 24 mmHg (range 14–35 mmHg) at the start of the procedure.
       During the procedure, there was no emergent placement of an IABP, and 35% of patients had either a previously implanted permanent pacemaker or a prophylactic temporary pacemaker placed prior to the procedure. On average, there were 1.7 different burr sizes used per patient (43.4% patients underwent “step-up” burr technique), 3.5 burr runs per patient at an average duration of 22 seconds, at a burr speed of 167,000 rpm. During the intervention, there were no clinically significant coronary artery perforations/dissections, no “no-reflow” episodes, abrupt vessel closures, hypotension, arrhythmias or episodes of heart block noted. The angiographic success rate was 100% in all patients. Three patients experienced a periprocedural MI based on electrocardiographic ischemic criteria (2 patients with > 1 mm ST-segment elevation in 2 contiguous leads, and 1 with > 2 mm ST-segment depression in at least 2 contiguous leads) — none of whom required repeat revascularization. The average postprocedural troponin was 4.12 ng/mL (range 0–27) in the 10 patients whose clinical presentation dictated serum biomarker evaluation. No patients necessitated emergency coronary artery bypass. There were no in-hospital mortalities related to the procedure. Only 1 patient died during hospitalization; this patient initially was admitted with AML blast crisis, underwent cardiac catheterization with RA solely for relief of refractory angina and died after all medical therapy and life-support for the hematologic emergency were withdrawn. Therefore, in-hospital MACE were observed in 4 patients (17.4%). There were no postdischarge deaths or MACE after 30 days. Further endpoints included 1 patient with significant bleeding requiring transfusions (4.3%) and another with acute renal insufficiency (4.3%). There were no patients with worsening dyspnea or congestive heart failure (e.g., as evidenced by pulmonary edema) or progressive decline of left ventricular function assessed by transthoracic or transesophageal echocardiography, and the average length of hospital stay was 3.2 days (range 1–15 days).

Discussion
       Presently, RA is being used with more frequency in patients with complex coronary lesions. RA is designed to debulk complex atherosclerotic plaque by producing small particles of atheromatous debris which initially was proposed to pass harmlessly through the coronary capillary bed and then be filtered from the bloodstream by the reticuloendothelial system.^21–23 However, Friedman et al disputed this claim by demonstrating histological evidence of myocardial microinfarctions after intracoronary infusion of atherectomized debris.²⁴ Other studies have investigated the clinical consequences of the “shower” of debris by performing simultaneous echocardiography during and following RA. A study showed in patients undergoing RA that wall motion abnormalities occurred with much higher frequency, developed in predictable territories related to the target artery, and were unrelated to cardiac biomarker release or electrocardiographic changes. More importantly, these wall motion abnormalities persisted much longer than in those patients undergoing balloon angioplasty (153 minutes compared to 3 minutes).¹⁹ This prolonged segmental LV dysfunction can possibly be explained by the distal embolization of atherosclerotic debris,^24,25 production of microcavitation with microbubbles²⁶ in the target coronary artery, induction of coronary artery spasm at the site of RA and resultant low-flow^1,27 and/or increased platelet activation and aggregation.²⁸
       Therefore, it seems reasonable to suggest that patients with severe LV dysfunction may have a higher likelihood of hemodynamic instability during RA. And although in our small case series there were no detected coronary artery perforations or dissections, it seems reasonable to also assume that this patient subgroup would have little cardiac function reserve to tolerate significant coronary artery damage. In our experience, this was not necessarily the case: controversy still exists on predicting hemodynamic instability during PCI, therefore no formal clinical guidelines exist on intra-aortic balloon pump (IABP) placement during PCI.²⁹ Elective high-risk PCI often can be performed without placement of an IABP.²⁹ However, it is appropriate to consider elective IABP placement prior to the intervention in patients who have high-risk characteristics: ejection fraction < 35%, > 50% myocardium at risk, PTCA performed on the last remaining vessel or cardiogenic shock.^29–31 IABP placement preceding or during PCI in these patient populations have been shown to improve clinical outcomes.^32,33 Specifically, recent literature has suggested RA is feasible in patients with varying degrees of LV dysfunction (only 31% of these patients had a LVEF < 35%) or complex coronary lesions when used in the setting of elective preprocedural placement of an IABP.³⁴
       However, no study to date has specifically addressed the role of RA and its clinical efficacy and safety in patients with severe LV dysfunction. The current study is a small, retrospective study reporting our clinical experience with RA in patients with severe LV dysfunction undergoing PCI. Our results support the notion that RA in patients with severe LV dysfunction is a safe and feasible technique for revascularization when no other therapeutic options are available and when performed by experienced operators at medical centers with on-site surgical backup.
       Study limitations. Although these data are encouraging, there are a few limitations that must be acknowledged. First, this study was completed at only one tertiary medical center, which makes the accuracy of extrapolating these conclusions to community hospitals unknown. Second, there was not a standard protocol for cardiac biomarker assessment for postprocedural MI. Instead, cardiac biomarker evaluation was only done when the clinical scenario or patients’ symptoms suggested ischemia or infarction. Although this may underestimate the total number of postprocedural MIs, it may not affect the reported event rate of clinically significant infarctions.

Conclusions
       It is certain that in the era of drug-eluting stents, we are intervening on more complex coronary lesions and treating sicker patients who previously were deemed poor candidates for any revascularization. Recent reviews of patient registries have revealed no decrease in procedural success with RA, despite increasing complexity in patients’ medical illness or coronary lesions.¹³ This suggests that RA may allow PCI in patients who were previously deemed poor candidates for revascularization. However, it is crucial to evaluate a patient’s likelihood of tolerating a time-consuming procedure while lying supine and receiving moderate-to-large amounts of intravenous fluids and nitrates prior to undergoing RA. Therefore, it is imperative that we have a clear understanding of the subset of patients in which RA is effective and when concomitant IABP use is necessary. Our small, retrospective study suggests that RA is safe and effective in patients with severe LV dysfunction when performed by experienced operators (with extensive knowledge in determining burr size, burr speed, number of runs and number of vessels to be safely treated) and at centers with on-site surgical backup and IABP support. Further studies involving a larger patient population are needed to validate our clinical experience with a standard protocol involving postprocedure cardiac biomarker assessment and objective evaluation with postprocedure LV systolic function (e.g., cardiac magnetic resonance imaging or multiple gated acquisition [MUGA] testing). Also, studies are needed to evaluate the long-term clinical outcomes of RA with patients who have severe LV dysfunction to further confirm the importance of the use of this interventional technique in high-risk patient populations.