The MGH Multispecialty Cardiac Resynchronization Therapy Clinic

Introduction The high prevalence of heart failure (HF) and the increasing patient population eligible for device therapy has created a new genre of ambulatory HF patients with implanted devices. The complex nature of these patients often requires participation of their internist, primary cardiologist, electrophysiologist (EP) and HF specialist with echocardiography support. Unfortunately, in most centers there is no structured cross talk between the cardiac subspecialties, and several weeks may pass between individual evaluations, resulting in disjointed and often less than optimal medical care. Current post-device implant care is lacking on many fronts, namely: attention to device diagnostic information and use of such data to titrate medications, evaluating and maximizing device response in patients, and more importantly, identifying and treating non-responders. Currently, non-responsive patients usually come to attention via a heart failure exacerbation or a hospitalization. Therefore, one of the goals of a multidisciplinary health care delivery program is to detect problems early, with proactive modification of the drug regimen or device settings to prevent disease decompensation. The Massachusetts General Hospital CRT Program brings together a team inclusive of the electrophysiology, heart failure and echocardiography services to provide coordinated care for this ailing patient population. The MGH CRT Program The MGH Multispecialty CRT Clinic was launched as a part of the Heart Center initiative in November 2005. This clinic provides an integrated approach to facilitate optimal patient selection and implantation strategies, CRT device optimization, and careful titration of the medical therapy in the post-implantation period. Each subspecialty plays an important independent role in the care of these patients (Figure 1). The electrophysiologist implants and interrogates the CRT device, while the heart failure specialist assesses the volume and functional status of the patient, optimizes the medical regimen, and provides the necessary HF education and options for additional novel pharmacological and interventional strategies. The interdependence of the specialties is exemplified by the fact that the adjustment of the medications can often be guided by using the longitudinal diagnostic data (e.g., transthoracic impedance, mean heart rate, mode-switch episodes) obtained from the device interrogation. The program also has a dedicated CRT nurse practitioner who is cross-trained across both subspecialties. Response to therapy is assessed via clinical improvement and echocardiographic evidence of reduction in ventricular dyssynchrony, positive ventricular remodeling and improved contractility. Non-responsive patients have their device programming optimized through adjustment of certain parameters (the atrio-ventricular and inter-ventricular timings) with echocardiographic guidance. Typically, every CRT implant patient is seen at one, three and six months post implant. During each visit, the patient gets a six-minute walk test, quality of life questionnaire, and device check, evaluation by an EP and/or HF physician or nurse practitioner, followed by device optimization under echocardiographic guidance. During device optimization, evaluation of reverse remodeling and dyssynchrony patterns are also made. During each of these visits, HF education is reinforced and the medical regimen is further adjusted. CRT devices record and provide detailed information pertaining to patient activity, heart rate, autonomic activity, and transthoracic impedance; in the near future they will also provide real-time hemodynamic data (Table 1). Our multidisciplinary clinic provides an ideal structure for consultation between different specialties to allow these data to be used more efficiently in the care of these patients. This program provides the opportunity to implement optimization protocols to treat non-responders, maximize device benefit (even in responders) and integrate echocardiography and device diagnostic information into the clinical care of these patients. This closed-circuit approach (Figure 1) also provides feedback to the device-implanting physician, which in turn enhances ventricular lead implantation and positioning strategies. Unfortunately, there is no one size fits all strategy, and peri-implant care needs to be individualized based upon the clinical characteristics and cardiac substrate of the patient. Also of importance is that, post-device implantation, the hemodynamic status changes and the heart remodels, which in turn impacts the ventricular filling and contractility patterns. In order to keep pace with this evolving pattern, it appears intuitive that one needs to proactively institute medication and device programming changes on an individualized basis. However, such care would be possible only through an integrated health care delivery setup. Our dedicated multidisciplinary program has enhanced this collaborative care model and facilitated cross-training among the specialties. MGH - CRT Program Research Recent studies from our center (and others) have shown that several factors are involved in predicting patient response. These include appropriate patient selection, optimal placement of the LV lead, and individualized programming of the CRT device in the post-implantation period. Currently we have ongoing research work in the field of patient selection, device implantation strategies and follow-up protocols. On the patient selection front, we have echocardiographic protocols looking at innovative measures and lability of mechanical dyssynchrony with provocative agents in predicting response to CRT. We are about to commence an MRI study to evaluate strain, with its possible role in patient selection, LV lead pacing site choice and response evaluation. Substantial effort at our center has been directed toward improving our understanding of the coronary venous anatomy and better quantifying ventricular dyssynchrony. At MGH, a state-of-the-art rotational venography system allows for multi-angle visualization of the origin, course, and tortuosity of each branch of the cardiac venous system (Figure 2). The Echocardiography Service employs a variety of imaging modalities, including M-mode, two-dimensional, Tissue Doppler Imaging (TDI) and three-dimensional echocardiography (3DE) to provide a better understanding of the anatomical and functional aspects of the cardiac substrate and to quantify the synchrony of contraction (Figure 3). Recently, we have integrated mechanical information from 3DE with anatomical data obtained from 3DE reconstructions of the coronary venous tree (Figure 4). The aim of this integration, which provides pertinent information about the ventricular segment with mechanical dyssynchrony and details of the coronary venous anatomy in its proximity, is to improve patient selection and lead-implantation strategies. We also have a lead implantation protocol examining interactions between the right and left ventricular leads in determining response to CRT. This protocol involves choosing the best pacing sites with intra-procedural cardiac output measurements. The MGH CRT Program plays a significant role in several national and international multi-center CRT-related studies. Our work with the MADIT II study group showed that HF progression was associated with a high incidence of appropriate ICD therapy for ventricular tachycardia/ventricular fibrillation and death, suggesting that earlier intervention with CRT may be useful. The MADIT-CRT is specifically addressing the question whether prophylactic CRT, in combination with a defibrillator, can prevent the progression of HF and reduce all-cause mortality in subjects with only mild HF. The Massachusetts General Cardiac Arrhythmia Service is the primary site for studying coronary venography and lead position for the multi-center MADIT-CRT and WBC (Who Benefits from Cardiac Resynchronization) trial. Our CRT Program is a participant in the RethinQ Study (St. Jude Medical), which is examining the benefit of CRT in patients with HF and narrow QRS duration. We are also participants in remote monitoring studies such as DeCode (Boston Scientific) and soon to start PRECEDE-HF (Medtronic) and TRIAGE-CRT (Biotronik). The CRT clinic is prospectively collecting data on all our patients and eventually will enable us to answer many questions pertinent to follow-up strategies, usage of device diagnostics and optimization protocols. Although it appears intuitive that this multi-specialty model would translate into better patient care, the impact of such integrated services still needs to be prospectively assessed. Besides hard endpoints such as cardiovascular events, hospitalization for heart failure and total mortality, other measures such as quality of life, cost-effectiveness, patient satisfaction, and physician efficiency are currently being evaluated. Our experience has been extremely positive, and we are in the process of prospectively acquiring additional data to determine if the enhanced physician efficiency and patient satisfaction we have observed truly translates into better long-term care for this ailing group of patients. The Future The clear benefit of device therapy in the symptomatic patient refractory to conventional medical therapy has brought up the possibility of expanding its role to the well-controlled heart failure patients (NYHA Class I and II), as well as to some subjects with a narrow QRS but with echocardiographic evidence of mechanical dyssynchrony. As the population eligible for device therapy rapidly expands, the need to be more cognizant of its cost-effectiveness and to refine the selection criteria will become more important. In order to ensure that we accurately select the patient most likely to respond, recognize early the non-responder and accordingly make changes to the drug-device therapy, communication lines between the electrophysiologist, echocardiographer and HF specialist need to be facilitated. The multidisciplinary CRT clinic enables this structured cross-talk among the different specialties, enabling better patient care. As remote monitoring becomes more commonly used and device-sensor strategies get more sophisticated, the demands on each of the subspecialties will continue to evolve.