Abstract
Congestive heart failure (CHF) secondary to ischemic cardiomyopathy is associated with significant morbidity and mortality despite currently available medical therapy. The Parachute TM device is a novel left ventricular partitioning device that is delivered percutaneously in the left ventricle (LV) in patients with anteroapical regional wall motion abnormalities, dilated LV and systolic dysfunction after anterior myocardial infarction with favorable clinical and LV hemodynamic improvements post-implantation. Here, we do review the current literature and present a case of the Parachute device implantation.
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Anteroapical myocardial infarction and left ventricular remodeling
Ischemic cardiomyopathy secondary to underlying coronary artery disease remains the most common cause of CHF in the United States (US) . Left ventricular systolic dysfunction is common after an anterior and apical myocardial infarction since this territory of LV is more vulnerable for LV dilatation because of its thinner wall and greater curvature . Following an acute myocardial infarction the LV undergoes remodeling with expansion and thinning, as well as increase in wall stress. This compensatory mechanism of LV remodeling is a vicious cycle and ultimately leads to inefficient pumping function of the LV with symptoms of CHF. Despite maximal medical therapy, some of these patients continue to have significant morbidity and mortality .
Although several treatment modalities are available to minimize associated symptoms and slow the disease progression, morbidity and mortality are important when LV anteroapical wall motion abnormality is present.
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Surgical approaches for LV remodeling
Several surgical approaches have been developed and tested for LV volume reduction such as surgical ventricular remodeling (Dor procedure) and partial left ventriculectomy (Batista procedure) . Although both procedures significantly reduce LV volumes, postprocedure improvement in functional capacity or quality of life has not been established. Favorable outcomes have only been reported in selected group of patients .
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Surgical approaches for LV remodeling
Several surgical approaches have been developed and tested for LV volume reduction such as surgical ventricular remodeling (Dor procedure) and partial left ventriculectomy (Batista procedure) . Although both procedures significantly reduce LV volumes, postprocedure improvement in functional capacity or quality of life has not been established. Favorable outcomes have only been reported in selected group of patients .
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Development of a novel percutaneous LV partitioning – the PARACHUTE – device
Recently, a novel percutaneous implantable device, the Parachute LV partitioning device (Cardiokinetix, Inc., Menlo Park, CA) has been developed to isolate the dysfunctional anteroapical region of the LV, reduce both systolic and diastolic volumes, decrease myocardial wall stress, and improve LV hemodynamics as well as functional capacity. The device is made of a self-expanding nitinol frame, a polytetrafluoroethylene (ePTFE) occlusive membrane, and a distal atraumatic foot ( Fig. 1 ). The device is delivered to the LV apex using a 16 French (Fr) special guide delivery catheter and a dilator ( Fig. 2 ). After the parachute implant is expanded using manual balloon inflation, the occlusive membrane provides a barrier to seal-off the static chamber on the distal side of the device. The ePTFE membrane allows the formation of an endothelial layer on both sides of the device.
Preclinical use of the device in animal models with acute myocardial infarction showed significant reduction in LV systolic and diastolic volumes, end-diastolic pressure with an increase in cardiac output and improvement in LV ejection fraction (LVEF) .
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PARACHUTE US and EU clinical trials
The initial PARACHUTE trial (Percutaneous Ventricular Restoration in Chronic Heart Failure) was a prospective, single-arm, multicenter trial performed in the United States and Europe . The study was designed to assess the safety and feasibility of this novel ventricular partitioning device (VPD). Patients were required to have antero-apical akinesis or dyskinesis due to prior myocardial infarction, and an LVEF ≤ 40%, with a diagnosis of New York Heart Association (NYHA) class II to IV CHF on stable doses of standard medical therapy for at least 3 months before enrollment. Although initial screening for the ideal LV apex anatomy was done by transthoracic echocardiogram (TTE), cardiac computed tomography (CT) was used as part of the enrollment screening process to prevent inaccurate estimates of LV size and for more optimal deployment of the device. The first Parachute device was implanted in Europe in 2005, and in US in 2008. Of the 39 patients enrolled in the trial, the device was safely and successfully implanted in 31 (91%) of the 34 patients who were anatomically suitable for implantation (79% of all enrolled patients). After implantation of the device, clinical and echocardiographic follow-up was performed at 1, 3, 6, 9, 12 months and annually thereafter up to 5 years. Patients had significant improvement in LV hemodynamics, functional class and exercise capacity in the 12 months following the procedure ( Figs. 3, 4 ). At 6 months, 5 (15%) of the treated patients had a device related major adverse cardiac event. Average procedural time was 80 min and fluoroscopy time 20 min with no device related death or stroke at 12 months. At 12 month follow up, there was a significant improvement in left ventricular volumes (both in LV end-systolic as well as end-diastolic volume indices) translating into a sustained improvement in NYHA class and quality of life scores ( Fig. 5 ). In a pooled analysis of the total 83 patients enrolled, the 1-year rate of death or repeat heart failure hospitalization was 16%. There was sustained improvement in NYHA class at 3 years, with 33% heart failure rehospitalization rate ( Fig. 6 ) . As a result, the device received CE market approval in Europe as of June 2011. Table 1 summarizes the current status of clinical trials with the Parachute device. PARACHUTE-IV pivotal randomized (medical therapy versus medical therapy + device implantation) clinical trial is under way in the US with active enrollment for the Phase 1 part of the study to randomize 50 patients at up to 15 clinical sites. The 30 day safety data on the first 30 patients enrolled will be reviewed by FDA prior to its expansion and hopefully its approval.
