Cardiology

Joseph, S. and M. R. Costanzo (2016). “A novel therapeutic approach for central sleep apnea: Phrenic nerve stimulation by the remede system.” International journal of cardiology 206 Suppl: S28-34.

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Central sleep apnea is a devastating disease which occurs in approximately 40% of patients with heart failure as well as patients with a history of stroke, opioid use and neurological conditions. It is associated with increased morbidity and mortality in heart failure likely due to the recurrent episodes of hypoxia and nor-epinephrine release. There have historically been few therapeutic options; positive airway pressure therapies have been the most common treatment to date. However, the adoption of positive airway pressure therapies has been limited due to poor patient adherence and acceptance and recent evidence of increased cardiovascular mortality in low ejection fraction heart failure patients with CSA. The remede System, utilizing transvenous stimulation of the phrenic nerve, offers a novel physiologic approach to therapy that eliminates the need for positive airway pressure and patient adherence. Studies have shown that this therapy improves sleep, oxygenation, and quality of life and ongoing trials are expected to give additional randomized data to support the therapeutic benefit of the remede System.

Tecson, K. M., M. A. Silver, S. D. Brune, C. Cauthen, M. D. Kwan, J. M. Schussler, A. Vasudevan, J. A. Watts and P. A. McCullough (2016). “Impact of Enhanced External Counterpulsation on Heart Failure Rehospitalization in Patients With Ischemic Cardiomyopathy.” Am J Cardiol 117(6): 901-905.

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Heart failure (HF) affects millions of Americans and causes financial burdens because of the need for rehospitalization. For this reason, health care systems and patients alike are seeking methods to decrease readmissions. We assessed the potential for reducing readmissions of patients with postacute care HF through an educational program combined with enhanced external counterpulsation (EECP). We examined 99 patients with HF who were referred to EECP centers and received heart failure education and EECP treatment within 90 days of hospital discharge from March 2013 to January 2015. We compared observed and predicted 90-day readmission rates and examined results of 6-minute walk tests, Duke Activity Status Index, New York Heart Association classification, and Canadian Cardiovascular Society classification before and after EECP. Patients were treated with EECP at a median augmentation pressure of 280 mm Hg (quartile 1 = 240, quartile 3 = 280), achieved as early as the first treatment. Augmentation ratios varied from 0.4 to 1.9, with a median of 1.0 (quartile 1 = 0.8, quartile 3 = 1.2). Only 6 patients (6.1%) had unplanned readmissions compared to the predicted 34%, p <0.0001. The average increase in distance walked was 52 m (18.4%), and the median increase in Duke Activity Status Index was 9.95 points (100%), p values <0.0001. New York Heart Association and Canadian Cardiovascular Society classes improved in 61% and 60% of the patients, respectively. In conclusion, patients with HF who received education and EECP within 90 days of discharge had significantly lower readmission rates than predicted, and improved functional status, walk distance, and symptoms.

Sorajja, P., M. Mack, S. Vemulapalli, D. R. Holmes, Jr., A. Stebbins, S. Kar, D. S. Lim, V. Thourani, P. McCarthy, S. Kapadia, P. Grayburn, W. A. Pedersen and G. Ailawadi (2016). “Initial Experience With Commercial Transcatheter Mitral Valve Repair in the United States.” J Am Coll Cardiol 67(10): 1129-1140.

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BACKGROUND: Transcatheter mitral valve (MV) repair with the MitraClip received approval in 2013 for the treatment of prohibitive-risk patients with primary mitral regurgitation (MR). OBJECTIVES: The aim of this study was to report the initial U.S. commercial experience with transcatheter MV repair. METHODS: Data from the Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy Registry on patients commercially treated with this percutaneous mitral valve repair device were analyzed. RESULTS: Of 564 patients (56% men, median age 83 years), severe symptoms were present in 473 (86.0%). The median Society of Thoracic Surgeons Predicted Risk of Mortality scores for MV repair and replacement were 7.9% (interquartile range: 4.7% to 12.2%) and 10.0% (interquartile range: 6.3% to 14.5%), respectively. Frailty was noted in 323 patients (57.3%). Transcatheter MV repair was performed for degenerative disease, present in 90.8% of patients. Overall, MR was reduced to grade

McCullough, P. A. and W. C. Roberts (2016). “Influence of Chronic Renal Failure on Cardiac Structure.” J Am Coll Cardiol 67(10): 1183-1185.

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It has been long recognized that patients with end-stage renal disease (ESRD) have an approximate 10-fold increase in mortality compared to age-matched individuals in the general population. Approximately one-half of this mortality is attributable to cardiovascular disease in the large domains of coronary artery disease, valvular abnormalities, arrhythmias, and cardiomyopathy. Our understanding of “structural heart disease” among those with ESRD has come from autopsy studies describing abnormalities including increased cardiac and left ventricular (LV) mass, mitral and aortic calcium, and marked calcific deposits in atherosclerotic plaques in the coronary arteries, aorta, and peripheral arteries. Morphological studies have also demonstrated high rates of pericardial disease (thickening and calcium) as well as myocardial hemosiderosis in ESRD. Physiological derangements over the course of many years, including pressure overload, volume overload, and derangements in myocyte function, also play a central role in the development of morphological abnormalities seen in ESRD. Cardiac ultrasonography has added to our understanding that these morphological changes have physiological consequences including impairment in LV systolic and diastolic function, chamber dilation and wall thickening, abnormal flow acceleration, and in some cases valvular stenosis. Coronary angiographic analysis has found in general that epicardial coronary arterial disease is more diffuse with more extensive calcium than those with normal renal function. The rate of coronary calcific deposition is more rapid than in the general population and is not reversible or able to be attenuated with any form of therapy we are presently aware of. (Excerpt from text, p. 1183; no abstract.)

Baumgarten, H., J. J. Squiers, M. Arsalan, J. M. Dimaio and M. J. Mack (2016). “Defining the clinical need and indications: who are the right patients for transcatheter mitral valve replacement?” J Cardiovasc Surg (Torino). Mar 30. [Epub ahead of print]

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Mitral regurgitation (MR) can be divided into two major etiologies, primary and secondary MR. Primary MR, also termed degenerative or organic MR, is a disease of the valve itself and is treated routinely by surgical repair in all but prohibitive risk patients. In these patients, transcatheter repair techniques, including edge to edge repair with the MitraClip device have been largely successful and widely adopted. Transcatheter placement of artificial chords has also been performed. The potential role for transcatheter mitral valve replacement (TMVR) in primary MR will likely be quite limited. Secondary or functional MR is due to a disease of the left ventricle and not the valve itself. The MR is a result of dilation of the left ventricle causing distraction of the papillary muscles with tethering of the mitral leaflets and lack of leaflet coaptation. Medical therapy is the mainstay treatment, with resynchronization used in appropriate patients. Surgical repair, usually with an undersized annuloplasty, is used in a limited number of patients. Transcatheter edge to edge repair is used extensively outside the US in secondary MR and is the subject of a pivotal trial in the US. However, it is in this group of patients with secondary MR that there is the largest clinical unmet need and, hence, the greatest potential opportunity for transcatheter mitral valve replacement (TMVR). At least ten TMVR platforms are in early feasibility, first in human, or preclinical trial stages. Four devices have cumulative early human experience in <100 patients. In this article, we discuss those patients most likely to benefit from TMVR and detail lessons learned from the first human studies regarding patient selection.