Hemodynamically Supported Percutaneous Coronary Revascularization Improves Left Ventricular Function

In Patients with Ischemic Dilated Cardiomyopathy at Very High Risk for Surgery: A Single-Center Experience

ABSTRACT: Background. Coronary artery bypass grafting is often considered for patients with ischemic cardiomyopathy, but age, comorbidities and depressed left ventricular function can increase surgical risk. Percutaneous left ventricular assist devices (pLVAD) may facilitate complex percutaneous coronary interventions (PCI) in the setting of severely impaired left ventricular function, thus providing a possible alternative to thoracotomy in high-risk patients. The long-term effects of hemodynamically-supported PCI on left ventricular function and clinical outcome in these patients are poorly understood. Objective. To determine the effect of hemodynamically-supported multivessel PCI on left ventricular ejection fraction (LVEF) in patients with severe ischemic cardiomyopathy at very high operative risk. Methods. Retrospective case-series analysis of patients with ischemic cardiomyopathy at very high surgical risk who underwent prophylactic pLVAD implantation for hemodynamic support during complex PCI between January 2004 and February 2007. The main outcome variable was change in LVEF assessed by echocardiography 90 days or more after PCI. Major in-hospital adverse cardiovascular events (MACE), vascular complications and all-cause mortality were secondary endpoints. Results. Eleven patients with prior myocardial infarction and ischemic cardiomyopathy (mean age 73 ± 14 years) underwent TandemHeart®-supported PCI. The indications for prophylactic support were depressed LVEF and a large myocardial mass at risk. Baseline LVEF was 25 ± 8%, increasing to 41 ± 9% at a mean follow-up time of 15 ± 15 months (p = 0.0004). There were no in-hospital MACE and only 1 vascular complication requiring blood transfusion. Conclusions. PLVAD-supported PCI in patients with ischemic cardiomyopathy at very high risk for surgery is feasible and relatively safe. In combination with medical therapy, it results in significant improvement in LVEF by echocardiography. J INVASIVE CARDIOL 2008;20:642–646 Despite advances in medical therapy, congestive heart failure (CHF) remains a leading cause of medical morbidity and healthcare expenditure in the United States.1 Largely due to an aging population, the prevalence of CHF has been steadily increasing.2 Optimal therapy for ischemic dilated cardiomyopathy (IDCM), a leading cause of CHF in the older patients, remains unsettled. In large randomized studies of patients with multivessel disease presenting with angina as opposed to heart failure, the benefits of coronary bypass graft (CABG) surgery over medical therapy increase with decreasing left ventricular function.3,4 Observational data from registries of patients presenting with IDCM have shown surgical coronary revascularization to be associated with improved survival compared to medical therapy alone, especially in patients with noninvasive imaging suggesting significant myocardial viability.5–7 However, these observations have yet to be confirmed by large randomized trials. Unfortunately, the risks of CABG also increase with age and decreased left ventricular function; comorbidities such as chronic obstructive lung disease, renal disease and peripheral vascular disease that are common in the older patients can further increase perioperative mortality.3,4,8 In patients with an unacceptably high risk of surgical coronary revascularization, multivessel percutaneous coronary intervention (PCI) represents a potential alternative. The recent introduction of percutaneous left ventricular assist devices (pLVADs) has facilitated complex coronary intervention in patients with severely impaired left ventricular function.9–12 While hemodynamically-supported multivessel PCI certainly represents an appealing alternative to thoracotomy in patients with very severe IDCM and high estimated surgical risk, long-term follow up demonstrating improved left ventricular function in patients treated with this strategy is lacking. In this retrospective case series, we sought to determine the outcome of pLVAD-supported multivessel PCI in patients with severe ischemic cardiomyopathy and very high estimated coronary bypass operative risk, including the long-term effect of revascularization on left ventricular function. Materials and Methods Eleven patients with severe ischemic cardiomyopathy at very high surgical risk underwent prophylactic pLVAD implantation for hemodynamic support during complex PCI. Patients were considered to be at excessive operative risk after evaluation by the cardiothoracic surgery team and were referred to our catheterization laboratory for PCI. Those presenting with acute ST-elevation myocardial infarction (STEMI) were excluded. Operative mortality was calculated by standard and logistic euroSCORE using the online interactive euroSCORE calculator (www.euroSCORE.org/calc).13–15 Assessment of myocardial viability was not consistently obtained in this series. A clinical decision to proceed with percutaneous revascularization was made in consultation with surgery and the heart failure/cardiac transplant team. Indications for the prophylactic use of pLVAD were depressed LVEF and a large amount of myocardium supplied by one or multiple complex lesions. The TandemHeart® pLVAD (Cardiac Assist, Inc., Pittsburgh, Pennsylvania) is an extracorporeal left atrial-to-femoral artery bypass system intended for short-term mechanical support in a variety of clinical situations. It is easily implanted in the cardiac catheterization laboratory via femoral arterial and venous access. The system is comprised of a 21 Fr inflow cannula, which is positioned in the left atrium via the standard transseptal approach, a 15–17 Fr arterial outflow cannula in the common femoral artery, and a compact external centrifugal pump delivering continuous flow at up to 4 L/minute.9,11,12,16,17 In this series of patients, the arteriotomy site for the outflow cannula was routinely preclosed using a 10 Fr Prostar XL device (Abbott Vascular, Abbott Park, Illinois).16–18 Immediately following the transseptal puncture, a heparin bolus was given to achieve an activated clotting time (ACT) of 400 seconds. Subsequently, heparin was administered continuously to maintain an ACT of 250 seconds. Coronary PCI was performed following pump activation, and the interventional strategy was left to the discretion of the operator and performed according to standard techniques.19 Following PCI, the arteriotomy site was sutured in the catheterization laboratory. When hemostasis was suboptimal, a Femostop® II Plus device was also used (Radi Medical Systems Inc., Wilmington, Massachusetts). The main outcome variable was improvement in left ventricular ejection fraction (LVEF) as assessed by echocardiography ≥ 90 days following percutaneous revascularization and 90-day survival. Major in-hospital adverse cardiovascular events (MACE: in-hospital death, Q-wave myocardial infarction, emergency revascularization and/or cerebrovascular accidents), 30-day mortality and vascular complications were secondary endpoints. In-hospital and 30-day mortality was defined as death due to any cause after PCI during the index hospitalization and in the following 30 days. Emergency revascularization was defined as the need for repeat PCI within 24 hours of the initial procedure. Q-wave MI was defined as a new pathological Q-wave on electrocardiography with creatine kinase more than twice the laboratory upper limit of normal as well as increased creatine kinase-MB fraction and troponin levels. Cerebrovascular accident was defined as a new neurological deficit appearing after the PCI and persisting at the time of patient discharge. All pLVAD implants and coronary interventions were performed by the authors in the cardiac catheterization laboratory at the University of Wisconsin Hospital in Madison. The study was approved by the Institutional Review Board of the University of Wisconsin. Participating patients or their families gave informed consent either before or following the index procedure. Data were collected at the time of the procedure and during subsequent review of charts or electronic medical records. Statistical Analysis. Categorical variables are described as counts and percentages. Continuous variables are reported as mean ± standard deviation. The magnitude of the change in LVEF was evaluated with the paired sample t-test. A two-sided p-value of 0.05 was considered significant. Kaplan-Meier survival curves were used to describe the survival rates in the sample. All statistical analyses were performed using MedCalc for Windows, version 9.5.2.0 (MedCalc Software, Mariakerte, Belgium). Results From January 2004 to February 2007, a total of 11 patients (10 males and 1 female) underwent PCI with prophylactic hemodynamic support using the TandemHeart® pLVAD. The patients’ baseline characteristics are shown in Table 1. Indications for coronary revascularization are listed in Table 2. The mean age was 73 ± 14 (range, 41–89) years. All patients had established coronary artery disease (CAD) and a history of prior myocardial infarction (MI). Four patients had a recent (≤ 30 days) NSTEMI and 1 presented with unstable angina without troponin level elevation. Nine patients had recent exacerbations of congestive heart failure; 1 of these remained refractory to medical therapy. One patient with NSTEMI also had multiple episodes of ventricular tachycardia refractory to amiodarone and sustained multiple implantable cardioverter-defibrillator shocks. Mean additive euroSCORE was 12 ± 2 (range, 9–16); mean logistic euroSCORE was 33 ± 17 (range, 16–67). All patients had evidence of ischemic cardiomyopathy, with pre-PCI LVEF of 25 ± 8%. Procedural details and outcomes. The number of stents used per intervention was 3.8 ± 1.7. A glycoprotein IIb/IIIa inhibitor (eptifibatide) was used in 2 cases (18%). Neither vasopressors nor mechanical ventilation was required for any of the patients. Two patients underwent rotational atherectomy of the left anterior descending artery (LAD) in the presence of right coronary artery (RCA) occlusion. All other patients underwent PCI of the left main artery (LM) or a LM-equivalent lesion. In four patients, a concomitant RCA lesion was treated. The choice to maximize revascularization during the same intervention was subjective. Mean total procedural duration, including placement of the pLVAD, was 171 ± 37 minutes. The time necessary to implant and activate the TandemHeart device, calculated from venous sheath insertion to pump activation, was 45 ± 6 minutes. The total duration of hemodynamic support ranged from 1–40 hours (mean = 5.5 ± 11 hours). There were no in-hospital deaths or deaths at 30 days. There were no in-hospital major adverse cardiovascular events. One patient’s hospital course was complicated by bleeding at the site of insertion of the pLVAD arterial cannula, epistaxis and hematuria, requiring multiple blood transfusions. Another patient developed transient worsening of renal function, which returned to baseline in 1 week. One patient’s right atrial pacemaker lead was displaced during pLVAD implantation; no other complications were encountered during his procedure and the patient subsequently underwent successful lead revision. A fourth patient with a logarithmic EuroSCORE of 54% presenting with syncope, NSTEMI, multiple implantable cardioverter defibrillator shocks and congestive heart failure, had a transient improvement in LVEF after PCI, and was weaned off percutaneous mechanical circulatory support. Unfortunately, he then developed multiorgan dysfunction syndrome (MODS) and worsening heart failure. He eventually recovered sufficiently to undergo implantation of a HeartMate XVE left ventricular assist device (LVAD) and was discharged to a rehabilitation facility after 49 days. The mean hospital length-of-stay (excluding the patient with surgically implanted LVAD, considered an outlier) was 5 ± 4 days. Follow-up echocardiographic evaluation of LVEF was obtained in 10 of 11 patients at 15 ± 15 months; the results are presented in Figure 1. There was a statistically significant increase in mean LVEF from 25 ± 8% to 41 ± 9% (p = 0.0004). One patient required readmission within a month from the index procedure due to decompensated heart failure; he was subsequently discharged on intravenous inotropes. His LVEF increased from 20–25%, although he expired 3 months later after presenting to our emergency room with severe, acute hyperkalemia. A second patient required readmission for Staphylococcal pneumonia but recovered after treatment with antibiotics. The Kaplan-Meier curve describing survival rate in the entire sample is displayed in Figure 2. Despite fairly dramatic intermediate-term improvement in LVEF, long-term survival in this high-risk population remained poor. Discussion Multiple randomized studies have demonstrated the superiority of CABG over medical therapy in patients with left main disease or 3-vessel CAD with proximal LAD involvement.20 Surgery also benefits patients with left ventricular dysfunction; however, as LVEF decreases, surgical morbidity and mortality rise. Whether surgery improves outcomes in all patients with severe left ventricular dysfunction is not clear. In the CASS study, patients with left ventricular dysfunction benefited from surgery only when presenting with angina but not heart failure.21 In contrast, a recent analysis of data from a single-center registry reported lower mortality in CABG regardless of the presence of angina, left ventricular function or functional class.7,22 The ongoing STICH trial will address the benefit of CABG in patients with heart failure and CAD, but for now definitive studies are lacking. Data on the role of PCI in patients with severe ischemic cardiomyopathy are also scant. PCI with stenting has resulted in good outcomes and low mortality in patients with left ventricular dysfunction, at least in nonrandomized studies.23 The AWESOME trial was a randomized study of PCI versus CABG patients felt to be at increased surgical risk, including those with multivessel disease and an EF Conclusions pLVAD-supported PCI in patients with ischemic cardiomyopathy at very high risk for surgery is feasible and relatively safe. In combination with medical therapy, it results in improved LVEF at follow up. Long-term survival in these very sick patients, however, remains low. Proper identification of patients most likely to benefit from prophylactic pLVAD support during PCI merits further investigation.

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