Cardiology

Bapat, V., V. Rajagopal, C. Meduri, R. S. Farivar, A. Walton, S. J. Duffy, R. Gooley, A. Almeida, M. J. Reardon, N. S. Kleiman, K. Spargias, S. Pattakos, M. K. Ng, M. Wilson, D. H. Adams, M. Leon, M. J. Mack, S. Chenoweth and P. Sorajja (2017). “Early experience with new transcatheter mitral valve replacement.” J Am Coll Cardiol: 2017 Oct [Epub ahead of print].

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BACKGROUND: Transcatheter mitral valve replacement (TMVR) is a potential therapy for patients with symptomatic, severe mitral regurgitation (MR). The feasibility of this therapy remains to be defined. OBJECTIVE: We report our early experience with TMVR using a new valve system. METHODS: The valve is a self-expanding, nitinol valve with bovine pericardial leaflets that is placed using a transapical delivery system. Patients with symptomatic MR who were deemed high or extreme risk by the local heart teams were enrolled in a global pilot study at 14 sites (U.S., Australia, and Europe). RESULTS: 50 consecutively enrolled patients (mean age, 73+/-9 years; 58.0% men; 84% secondary MR) underwent TMVR with the valve. The mean STS score was 6.4+/-5.5%; 86% of patient were NYHA class III or IV, and the mean left ventricular ejection fraction was 43+/-12%. Device implant was successful in 48 patients with a median deployment time of 14 (IQR, 12, 17) minutes. The 30-day mortality was 14%, with no disabling strokes, or repeat interventions. Median follow-up was 173 (IQR, 54, 342) days. At latest follow-up, echocardiography confirmed mild or no residual MR in all implanted patients. Improvements in symptom class (79% in NYHA I or II at follow-up; p<0.0001 vs. baseline), and Minnesota heart failure questionnaire scores (56.2+/-26.8 vs. 31.7+/-22.1; p=0.011) were observed. CONCLUSIONS: TMVR with the valve was feasible in a population at high-or extreme-risk for conventional mitral valve replacement. These results inform trial design of TMVR in lower-risk patients with severe mitral valve regurgitation.

Cleland, J. G. F., K. V. Bunting, M. D. Flather, D. G. Altman, J. Holmes, A. J. S. Coats, L. Manzano, J. J. V. McMurray, F. Ruschitzka, D. J. van Veldhuisen, T. G. von Lueder, M. Bohm, B. Andersson, J. Kjekshus, M. Packer, A. S. Rigby, G. Rosano, H. Wedel, A. Hjalmarson, J. Wikstrand and D. Kotecha (2017). “Beta-blockers for heart failure with reduced, mid-range, and preserved ejection fraction: An individual patient-level analysis of double-blind randomized trials.” Eur Heart J: 2017 Oct [Epub ahead of print].

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Aims: Recent guidelines recommend that patients with heart failure and left ventricular ejection fraction (LVEF) 40-49% should be managed similar to LVEF >/= 50%. We investigated the effect of beta-blockers according to LVEF in double-blind, randomized, placebo-controlled trials. Methods and results: Individual patient data meta-analysis of 11 trials, stratified by baseline LVEF and heart rhythm (Clinicaltrials.gov: NCT0083244; PROSPERO: CRD42014010012). Primary outcomes were all-cause mortality and cardiovascular death over 1.3 years median follow-up, with an intention-to-treat analysis. For 14 262 patients in sinus rhythm, median LVEF was 27% (interquartile range 21-33%), including 575 patients with LVEF 40-49% and 244 >/= 50%. Beta-blockers reduced all-cause and cardiovascular mortality compared to placebo in sinus rhythm, an effect that was consistent across LVEF strata, except for those in the small subgroup with LVEF >/= 50%. For LVEF 40-49%, death occurred in 21/292 [7.2%] randomized to beta-blockers compared to 35/283 [12.4%] with placebo; adjusted hazard ratio (HR) 0.59 [95% confidence interval (CI) 0.34-1.03]. Cardiovascular death occurred in 13/292 [4.5%] with beta-blockers and 26/283 [9.2%] with placebo; adjusted HR 0.48 (95% CI 0.24-0.97). Over a median of 1.0 years following randomization (n = 4601), LVEF increased with beta-blockers in all groups in sinus rhythm except LVEF >/=50%. For patients in atrial fibrillation at baseline (n = 3050), beta-blockers increased LVEF when < 50% at baseline, but did not improve prognosis. Conclusion: Beta-blockers improve LVEF and prognosis for patients with heart failure in sinus rhythm with a reduced LVEF. The data are most robust for LVEF < 40%, but similar benefit was observed in the subgroup of patients with LVEF 40-49%.

Filardo, G., B. D. Pollock and J. Edgerton (2017). “Categorizing body mass index biases assessment of the association with post-coronary artery bypass graft mortality.” Eur J Cardiothorac Surg 52(5): 924-929.

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OBJECTIVES: The high prevalence of obesity makes accurately estimating the impact of anthropometric measures on cardiac surgery outcomes critical. The Society of Thoracic Surgeons coronary artery bypass graft (CABG) surgery risk model includes body surface area (as a continuous variable, using spline functions), but most studies apply various categorizations of body mass index (BMI)-contributing to the contradictory published findings. We assessed the association between BMI (modelled as a continuous variable without assumptions of linearity) and CABG operative mortality and examined the impact of applying previous studies’ BMI modelling strategies. METHODS: We identified 25 studies investigating the BMI-operative mortality association: 22 categorized BMI, 2 as a linear continuous variable,1 used spline functions. Our cohort of 12 715 consecutive patients underwent isolated CABG at 32 cardiac surgery programmes in North Texas from 1 January 2008-31 December 2012. BMI was modelled using restricted cubic spline functions in a propensity-adjusted model (controlling for Society of Thoracic Surgeons risk factors) estimating operative mortality. The analysis was repeated using each categorization identified and modelling BMI as a linear continuous variable. RESULTS: BMI (modelled with a restricted cubic spline) was significantly associated with operative mortality (P < 0.0001). Risk was lowest for BMI near 30 kg/m2 and highest below 20 kg/m2 and above 40 kg/m2. No categorization, nor the linear continuous model, fully captured this association. CONCLUSIONS: BMI is strongly associated with CABG operative mortality. Categorizing BMI (or assuming a linear relationship) heavily biases estimates of its association with post-CABG mortality. In general, smoothing techniques should be used for all continuous risk factors to avoid bias.

Packer, M. (2017). “Will long-acting glucagon-like peptide-1 analogues recapitulate our agonizing experience with cyclic amp-dependent positive inotropic agents in heart failure?” Eur J Heart Fail: 2017 Oct [Epub ahead of print].

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Over the past three decades, substantial changes have taken place regarding our understanding of the role of cyclic AMP. It is now understood that cyclic AMP may be compartmented and that changes in subcellular pools may not have implications for cardiac contractility or cardiotoxicity.3 Treatments that increase cyclic AMP in the heart have been reported to have favourable effects on myocardial viability and angiogenesis as well as on cardiac remodelling.4,5 Phosphodiesterase inhibitors (i.e. cilostazol) have been developed for the treatment of patients with claudication, even though peripheral vascular disease and heart failure frequently coexist.

Kovesdy, C. P., L. J. Appel, M. E. Grams, L. Gutekunst, P. A. McCullough, B. F. Palmer, B. Pitt, D. A. Sica and R. R. Townsend (2017). “Potassium homeostasis in health and disease: A scientific workshop cosponsored by the national kidney foundation and the american society of hypertension.” J Am Soc Hypertens: 2017 Oct [Epub ahead of print].

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While much emphasis, and some controversy, centers on recommendations for sodium intake, there has been considerably less interest in recommendations for dietary potassium intake, in both the general population and patients with medical conditions, particularly acute and chronic kidney disease. Physiology literature and cohort studies have noted that the relative balance in sodium and potassium intakes is an important determinant of many of the sodium-related outcomes. A noteworthy characteristic of potassium in clinical medicine is the extreme concern shared by many practitioners when confronted by a patient with hyperkalemia. Fear of this often asymptomatic finding limits enthusiasm for recommending potassium intake and often limits the use of renin-angiotensin-aldosterone system blockers in patients with heart failure and chronic kidney diseases. New agents for managing hyperkalemia may alter the long-term management of heart failure and the hypertension, proteinuria, and further function loss in chronic kidney diseases. In this jointly sponsored effort between the American Society of Hypertension and the National Kidney Foundation, 3 panels of researchers and practitioners from various disciplines discussed and summarized current understanding of the role of potassium in health and disease, focusing on cardiovascular, nutritional, and kidney considerations associated with both hypo- and hyperkalemia.