Faculty Bibliography

Iron deficiency is common in heart failure (HF) patients, and is associated with increased risk of adverse clinical outcomes. Clinical trials of intravenous iron supplementation in iron-deficient HF patients have demonstrated short-term improvement in functional capacity and quality of life. In some trials, the benefits of iron supplementation were independent of the hemoglobin levels. Additional investigations of iron supplementation are needed to characterize the mechanisms contributing to clinical benefit and long-term safety in HF.

RATIONALE: Obesity is characterized by increased systemic and pulmonary blood volumes (pulmonary vascular congestion). Concomitant abnormal alveolar membrane diffusion suggests subclinical interstitial edema. In this setting, functional abnormalities should encompass the entire distal lung including the airways. OBJECTIVES: We hypothesize that in obesity: 1) pulmonary vascular congestion will affect the distal lung unit with concordant alveolar membrane and distal airway abnormalities; and 2) the degree of pulmonary congestion and membrane dysfunction will relate to the cardiac response. METHODS: 54 non-smoking obese subjects underwent spirometry, impulse oscillometry (IOS), diffusion capacity (DLCO) with partition into membrane diffusion (DM) and capillary blood volume (VC), and cardiac MRI (n = 24). Alveolar-capillary membrane efficiency was assessed by calculation of DM/VC. MEASUREMENTS AND MAIN RESULTS: Mean age was 45+/-12 years; mean BMI was 44.8+/-7 kg/m2. Vital capacity was 88+/-13% predicted with reduction in functional residual capacity (58+/-12% predicted). Despite normal DLCO (98+/-18% predicted), VC was elevated (135+/-31% predicted) while DM averaged 94+/-22% predicted. DM/VC varied from 0.4 to 1.4 with high values reflecting recruitment of alveolar membrane and low values indicating alveolar membrane dysfunction. The most abnormal IOS (R5 and X5) occurred in subjects with lowest DM/VC (r2 = 0.31, p<0.001; r2 = 0.34, p<0.001). Cardiac output and index (cardiac output / body surface area) were directly related to DM/VC (r2 = 0.41, p<0.001; r2 = 0.19, p = 0.03). Subjects with lower DM/VC demonstrated a cardiac output that remained in the normal range despite presence of obesity. CONCLUSIONS: Global dysfunction of the distal lung (alveolar membrane and distal airway) is associated with pulmonary vascular congestion and failure to achieve the high output state of obesity. Pulmonary vascular congestion and consequent fluid transudation and/or alterations in the structure of the alveolar capillary membrane may be considered often unrecognized causes of airway dysfunction in obesity.

Reduced parasympathetic modulation of heart rate is an independent predictor of mortality in heart failure. It is not known whether enhancing parasympathetic outflow to the heart impacts survival in these patients. Our aim was to evaluate whether the neck collar technique, a noninvasive method of stimulating the carotid baroreceptors, was a reliable and reproducible means to evaluate baroreflex control of heart rate in patients with heart failure. Twenty-five patients (20 males, mean age 54 +/-10-years) with symptomatic heart failure (NYHA class II-III) were studied on two separate days, one week apart. All were free of cholesterol plaques in the carotid arteries. Blood pressure and RR intervals were measured continuously in the seated position. Graded pressure (-70 to +70 mmHg) was administered to the neck during a held expiration using a custom-designed collar. Maximum change in RR intervals was determined during the onset of neck pressure. Stimulus response curves were plotted for changes in RR intervals against estimated-carotid sinus pressure. The technique was well tolerated and there were no adverse events. The maximal differential, used to estimate baroreflex gain, was tightly correlated between visits 1 and 2 (R2= 0.8063, p < 0.0001). The corresponding "set point" of the reflex was also significantly correlated between visits (R2=0.3324 p=0.049). To our knowledge, this is the first time the neck collar technique has been validated in a medically fragile population. The technique is safe and reproducible and maybe useful to help understand whether strategies that enhance parasympathetic activity change outcomes in heart failure

Physical activity and cardiac rehabilitation (CR) are components of heart failure (HF) self-care. The aims of this study were to describe patterns of physical activity in African Americans (n = 30) with HF and to explore experience in CR. This was a mixed method, concurrent nested, predominantly qualitative study. Qualitative data were collected via interviews exploring typical physical activity, and CR experience. It was augmented by quantitative data measuring HF severity, self-care, functional capacity and depressive symptoms. Mean age was 60 +/- 15 years; 65% were New York Heart Association (NYHA) class III HF. Forty-three percent reported that they did less than 30 min of exercise in the past week; 23% were told "nothing" about exercise by their provider, and 53% were told to do "minimal exercise". A measure of functional capacity indicated the ability to do moderate activity. Two related themes stemmed from the narratives describing current physical activity: "given up" and "still trying". Six participants recalled referral to CR with one person participating. There was high concordance between qualitative and quantitative data, and evidence that depression may play a role in low levels of physical activity. Findings highlight the need for strategies to increase adherence to current physical activity guidelines in this older minority population with HF.

Background: Comorbid diabetes is common in heart failure and associated with increased hospitalization and mortality. Nonetheless, the optimal treatment strategy for diabetes in heart failure patients remains poorly characterized, particularly among low income and minority populations. The purpose of this study was to evaluate the association between glycemic control and outcomes among patients with heart failure and diabetes who were seen in a safety net health care system. Methods: We performed a retrospective cohort study of outpatients with heart failure and diabetes in the New York City Health and Hospitals Corporation, the largest municipal health care system in the United States. Subjects with diagnoses of heart failure and diabetes mellitus were included if they had an outpatient visit in 2007-2010 with an HbA1c performed in the prior 90 days. HbA1c and covariates, including demographics, comorbidities, vital signs, labs, and prior utilization, were obtained from the HHC data warehouse, which was linked to the New York State Inpatient Database and to New York State Vital Statistics to ascertain hospitalization and mortality events, respectively. Cox proportional hazard models were used to measure the association between HbA1c levels and outcomes of all-cause hospitalization, heart failure hospitalization, and mortality. Results: Of 4,723 patients with heart failure and diabetes, 42.6% were black, 30.5% were Hispanic/ Latino, 31.4% were Medicaid beneficiaries and 22.9% were uninsured. As compared to patients with an HbA1c of 8.0-8.9%, patients with an HbA1c of <6.5%, 6.5-6.9%, 7.0-7.9%, and >9.0% had an adjusted hazard ratio (aHR) (95% CI) for all-cause hospitalization of 1.03 (0.90-1.17), 1.05 (0.91-1.22), 1.03 (0.90-1.17), and 1.13 (1.00-1.28), respectively. An HbA1c>9.0% was also associated with an increased risk of heart failure hospitalization (aHR 1.33; 95% CI 1.11- 1.59) and a non-significant increased risk in mortality (aHR 1.20; 95% CI 0.99-1.45) when compared to HbA1c of 8.0-8.9%. Conclusions: Among a cohort of primarily minority and low income patients with heart failure and diabetes, an increased risk of hospitalization was observed only for an HbA1c greater than 9%