Cardiology

Brindis, R. G. and G. J. Dehmer (2016). “The volume-outcome relationship revisited: Does it matter for high-risk pci?” JACC Cardiovasc Interv 9(20): 2094-2096.

Full text of this article.

The National Cardiovascular Data Registry (NCDR) CathPCI registry collects clinical data from >90% of all PCIs performed in the United States. Excluding patients with ST-segment elevation myocardial infarctions, aggregate data from 2015 show an in-hospital mortality rate of 0.89%, while elective PCI mortality is 0.65% 5 and 6. The small number of deaths for a given operator, coupled with estimates of the case volume for operators in the United States (mean 59 cases annually, with 61% of operators performing <40 cases annually in 2008), results in a very wide confidence interval around the point estimate of PCI mortality for an operator (7). In addition, the interplay between facility and individual operator volumes, the operator’s lifetime experience, and the operator’s performance of non-PCI procedures (structural and peripheral arterial interventions) confound the assessment of a relationship between operator PCI case volume and outcomes (3). On the basis of these considerations, there are 2 possible approaches for a continuing examination of the relationship between operator volume and outcomes. One approach would require the collection of operator mortality data over many years to obtain a sample size that would allow meaningful differentiation among operators. For an individual operator, this would likely include mostly low-complexity, low-risk cases mixed with a few high-complexity, high-risk cases. Given the low and decreasing case volume for U.S. operators, the time required to obtain an adequate number of cases is impractical. The alternative approach is to focus on high-complexity, high-risk cases, for which the number of cases needed to discriminate among operators should be lower and obtainable. This latter approach was examined by Xu et al. (8) in a report in this issue of JACC: Cardiovascular Interventions.

Nickenig, G., C. Hammerstingl, R. Schueler, Y. Topilsky, P. A. Grayburn, A. Vahanian, D. Messika-Zeitoun, M. Urena Alcazar, S. Baldus, R. Volker, M. Huntgeburth, O. Alfieri, A. Latib, G. La Canna, E. Agricola, A. Colombo, K. H. Kuck, F. Kreidel, C. Frerker, F. C. Tanner, O. Ben-Yehuda and F. Maisano (2016). “Transcatheter mitral annuloplasty in chronic functional mitral regurgitation: 6-month results with the cardioband percutaneous mitral repair system.” JACC Cardiovasc Interv 9(19): 2039-2047.

Full text of this article.

OBJECTIVES: This study sought to show safety and efficacy of the Cardioband system during 6 months after treatment. BACKGROUND: Current surgical and medical treatment options for functional mitral regurgitation (FMR) are limited. The Cardioband system (Valtech Cardio, OrYehuda, Israel) is a novel transvenous, transseptal direct annuloplasty device. METHODS: Thirty-one patients (71.8 +/- 6.9 years of age; 83.9% male; EuroSCORE II: 8.6 +/- 5.9) with moderate to severe FMR, symptomatic heart failure, and depressed left ventricular function (left ventricular ejection fraction 34 +/- 11%) were prospectively enrolled. RESULTS: Procedural success rate, defined as delivery of the entire device, was 100%. There were no periprocedural deaths (0%), and mortality rate at 1 month or prior to hospital discharge and at 7 months was 5% and 9.7% respectively. Cinching of the implanted Cardioband reduced the annular septolateral dimension by >30% from 3.7 +/- 0.5 cm at baseline to 2.5 +/- 0.4 cm after 1 month and to 2.4 +/- 0.4 cm after 6 months, respectively (p < 0.001). Percentage of patients with FMR >/=3 was reduced from 77.4% to 10.7% 1 month after the procedure (p < 0.001) and 13.6% (p < 0.001) at 7 months. Percentage of patients with New York Heart Association functional class III/IV decreased from 95.5% to 18.2% after 7 months (p < 0.001); exercise capacity as assessed by 6-min walking test increased from 250 +/- 107 m to 332 +/- 118 m (p < 0.001) and quality of life (Minnesota Living With Heart Failure Questionnaire) was also significantly improved (p < 0.001). CONCLUSIONS: In this feasibility trial in symptomatic patients with FMR, transcatheter mitral annuloplasty with the Cardioband was effective in reducing MR and was associated with improvement in heart failure symptoms and demonstrated a favorable safety profile.

Bakris, G. L., J. M. Burkart, E. D. Weinhandl, P. A. McCullough and M. A. Kraus (2016). “Intensive hemodialysis, blood pressure, and antihypertensive medication use.” Am J Kidney Dis 68(5s1): S15-s23.

Full text of this article.

Hypertension is a cardinal feature of end-stage renal disease (ESRD). Hypertensive nephropathy is the primary cause of ESRD for nearly 30% of patients, and the prevalence of hypertension is >85% in new patients with ESRD. In contemporary hemodialysis (HD) patients, mean predialysis systolic blood pressure (SBP) is nearly 150mmHg, and about 70%, 50%, and 40% use beta-blockers, calcium channel blockers, and renin-angiotensin system inhibitors, respectively. Predialysis SBP generally exhibits a U-shaped association with mortality risk. Interdialytic ambulatory SBP is more strongly associated with risk. Hypertension is multifactorial; key causes include persistent hypervolemia and elevated peripheral resistance. With 3 HD sessions per week, blood pressure (BP) climbs during the interdialytic interval, in step with interdialytic weight gain, particularly among elderly patients and those with higher dry weight. Elevated peripheral resistance can be attributed to inappropriate activation of the sympathetic nervous system due to higher plasma norepinephrine concentrations. Multiple randomized clinical trials show that intensive HD reduces BP and the need for oral medications indicated for hypertension. In the first 2 months of the Frequent Hemodialysis Network trial, the short daily schedule reduced predialysis SBP by 7.7mmHg, whereas the nocturnal schedule reduced predialysis SBP by 7.3mmHg, both relative to 3 sessions per week. Improvements were sustained after 12 months. Both schedules reduced antihypertensive medication use relative to 3 sessions per week. In FREEDOM (Following Rehabilitation, Economics, and Everyday-Dialysis Outcome Measurements), a prospective cohort study of short daily HD, the mean number of prescribed antihypertensive agents decreased from 1.7 to 1.0 in 1 year, whereas the percentage of patients not prescribed antihypertensive agents increased from 21% to 47%. Nocturnal HD appears to markedly reduce total peripheral resistance and plasma norepinephrine and restore endothelium-dependent vasodilation. In conclusion, intensive HD reduces BP and the need for antihypertensive medications.

Copland, M., P. Komenda, E. D. Weinhandl, P. A. McCullough and J. A. Morfin (2016). “Intensive hemodialysis, mineral and bone disorder, and phosphate binder use.” Am J Kidney Dis 68(5s1): S24-s32.

Full text of this article.

Mineral and bone disorder is a common complication of end-stage renal disease. Notably, hyperphosphatemia likely promotes calcification of the myocardium, valves, and arteries. Hyperphosphatemia is associated with higher risk for cardiovascular mortality and morbidity along a gradient beginning at 5.0mg/dL. Among contemporary hemodialysis (HD) patients, mean serum phosphorus level is 5.2mg/dL, although 25% of patients have serum phosphorus levels of 5.5 to 6.9mg/dL; and 13%, >7.0mg/dL. Treatment of hyperphosphatemia is burdensome. Dialysis patients consume a mean of 19 pills per day, half of which are phosphate binders. Medicare Part D expenditures on binders for dialysis patients approached $700 million in 2013. Phosphorus removal with thrice-weekly HD (4 hours per session) is approximately 3,000mg/wk. However, clearance is unlikely to counterbalance dietary intake, which varies around a mean of 7,000mg/wk. Dietary restriction and phosphate binders are important interventions, but each has limitations. Dietary control is complicated by limited access to healthy food choices and unclear labeling. Meanwhile, adherence to phosphate binders is poor, especially in younger patients and those with high pill burden. Multiple randomized clinical trials show that intensive HD reduces serum phosphorus levels. In the Frequent Hemodialysis Network (FHN) trial, short daily and nocturnal schedules reduced serum phosphorus levels by 0.6 and 1.6mg/dL, respectively, relative to 3 sessions per week. A similar effect of nocturnal HD was observed in an earlier trial. In the daily arm of the FHN trial, intensive HD significantly lowered estimated phosphate binder dose per day, whereas in the nocturnal arm, intensive HD led to binder discontinuation in 75% of patients. However, intensive HD appears to have no meaningful effects on serum calcium and parathyroid hormone concentrations. In conclusion, intensive HD, especially nocturnal HD, lowers serum phosphorus levels and decreases the need for phosphate binders.

McCullough, P. A., C. T. Chan, E. D. Weinhandl, J. M. Burkart and G. L. Bakris (2016). “Intensive hemodialysis, left ventricular hypertrophy, and cardiovascular disease.” Am J Kidney Dis 68(5s1): S5-s14.

Full text of this article.

The prevalence of cardiovascular disease, including cardiac arrhythmia, coronary artery disease, cardiomyopathy, and valvular heart disease, is higher in hemodialysis (HD) patients than in the US resident population. Cardiovascular disease is the leading cause of death in HD patients and the principal discharge diagnosis accompanying 1 in 4 hospital admissions. Furthermore, the rate of hospital admissions for either heart failure or fluid overload is persistently high despite widespread use of beta-blockers and renin-angiotensin system inhibitors and attempts to manage fluid overload with ultrafiltration. An important predictor of cardiovascular mortality and morbidity in dialysis patients is left ventricular hypertrophy (LVH). LVH is an adaptive response to increased cardiac work, typically caused by combined pressure and volume overload, resulting in cardiomyocyte hypertrophy and increased intercellular matrix. In new dialysis patients, the prevalence of LVH is 75%. Regression of LVH may reduce cardiovascular risk, including the incidence of heart failure, complications after myocardial infarction, and sudden arrhythmic death. Multiple randomized clinical trials show that intensive HD reduces left ventricular mass, a measure of LVH. Short daily and nocturnal schedules in the Frequent Hemodialysis Network trial reduced left ventricular mass by 14 (10%) and 11 (8%) g, respectively, relative to 3 sessions per week. Comparable efficacy was observed in an earlier trial of nocturnal HD. Intensive HD also improves cardiac rhythm. Clinical benefits have been reported only in observational studies. Daily home HD is associated with 17% and 16% lower risks for cardiovascular death and hospitalization, respectively; admissions for cerebrovascular disease, heart failure, and hypertensive disease, which collectively constitute around half of cardiovascular hospitalizations, were less likely with daily home HD. Relative to peritoneal dialysis, daily home HD is likewise associated with lower risk for cardiovascular hospitalization. In conclusion, intensive HD likely reduces left ventricular mass and may lead to lower risks for adverse cardiac events.