Percutaneous Support Devices for Percutaneous Coronary Intervention

Abstract

S ince the start of percutaneous coronary intervention (PCI), the field has seen a rapid explosion in technology from initial catheters, balloons, to metallic, now drug-coated stents. However, unique to the field of coronary intervention in comparison with other areas of technological advances in medicine, the iterative advances have been progressively tested, and when possible, randomized against control groups to determine the best and most appropriate care. In fact, the field has matured in such rapid fashion over the 40 years since inception, 1 in part, because of the scientific culture started by the initial report of angioplasty from Grüntzig et al 1 in which they concluded "A prospective randomized trial will be necessary to evaluate it usefulness in comparison with surgical and medical management." Hence, each new therapy has been, in general, vetted and tested for improvements in patient outcomes from technologies such as coronary pressure wires, drug-eluting stents, to strategies such as primary PCI for acute myocardial infarc-tion (MI). It is with these therapies and, more importantly, advances in effective medical therapy including antiplatelet and antithrombotic therapy, lipid-lowering drugs, and overall preventive care that cardiovascular mortality rates have fallen by 22% over the past decade. 2 However, in parallel with the maturation of coronary intervention has been the baby boom and aging population living with coronary heart disease and multiple comorbidities and more complex coronary anatomy. In fact, despite the noted improvements, patients presenting between 2011 and 2013 with acute MI and cardiogenic shock were significantly more likely to have comorbidities, including diabetes mellitus, dyslipidemia, previous PCI, and end-stage renal disease in comparison with similar patients between 2005 and 2006. 3 It is in this context that, as the clinical community attempts to determine how to best use percutaneous support devices, Kapur et al 4 provide the initial findings of the Door-to-Unload in STEMI Pilot trial in Circulation. Based on prior preclinical studies demonstrating that mechanically unloading the left ventricle for 30 minutes before reperfusion leads to biological myocardial protective mechanisms reducing infarct size, 5-7 patients (n=50) with anterior ST-segment-elevation myocardial infarction were randomly assigned at 14 centers in the United States to either mechanical left ventricular unloading with an Impella CP system and immediate percutaneous reperfusion or left ventricular unloading with a 30-minute delay to reperfusion. The evaluation was specifically aimed at determining whether the unloading and delay were feasible and safe with regard to any increase in infarct size. The Impella was explanted after a minimum of 3 hours of support. All patients were followed for major adverse cardiovascular events, and the protocol aimed to have the patients undergo cardiac magnetic resonance imaging for infarct size at day 3 to 5 and 30 days post-MI.