Leway Chen

Extended Mechanical Circulatory Support With a Continuous-Flow Rotary Left Ventricular Assist Device

OBJECTIVESnThis study sought to evaluate the use of a continuous-flow rotary left ventricular assist device (LVAD) as a bridge to heart transplantation.nnnBACKGROUNDnLVAD therapy is an established treatment modality for patients with advanced heart failure. Pulsatile LVADs have limitations in design precluding their use for extended support. Continuous-flow rotary LVADs represent an innovative design with potential for small size and greater reliability by simplification of the pumping mechanism.nnnMETHODSnIn a prospective, multicenter study, 281 patients urgently listed (United Network of Organ Sharing status 1A or 1B) for heart transplantation underwent implantation of a continuous-flow LVAD. Survival and transplantation rates were assessed at 18 months. Patients were assessed for adverse events throughout the study and for quality of life, functional status, and organ function for 6 months.nnnRESULTSnOf 281 patients, 222 (79%) underwent transplantation, LVAD removal for cardiac recovery, or had ongoing LVAD support at 18-month follow-up. Actuarial survival on support was 72% (95% confidence interval: 65% to 79%) at 18 months. At 6 months, there were significant improvements in functional status and 6-min walk test (from 0% to 83% of patients in New York Heart Association functional class I or II and from 13% to 89% of patients completing a 6-min walk test) and in quality of life (mean values improved 41% with Minnesota Living With Heart Failure and 75% with Kansas City Cardiomyopathy questionnaires). Major adverse events included bleeding, stroke, right heart failure, and percutaneous lead infection. Pump thrombosis occurred in 4 patients.nnnCONCLUSIONSnA continuous-flow LVAD provides effective hemodynamic support for at least 18 months in patients awaiting transplantation, with improved functional status and quality of life. (Thoratec HeartMate II Left Ventricular Assist System [LVAS] for Bridge to Cardiac Transplantation; NCT00121472).

Renal and Hepatic Function Improve in Advanced Heart Failure Patients During Continuous-Flow Support With the HeartMate II Left Ventricular Assist Device

Background— The effects of continuous blood flow and reduced pulsatility on major organ function have not been studied in detail. Methods and Results— We evaluated renal (creatinine and blood urea nitrogen) and hepatic (aspartate transaminase, alanine transaminase, and total bilirubin) function in 309 (235 male, 74 female) advanced heart failure patients who had been supported with the HeartMate II continuous-flow left ventricular assist device for bridge to transplantation. To determine whether patients with impaired renal and hepatic function improve over time with continuous-flow left ventricular assist device support or whether there are any detrimental effects in patients with normal organ function, we divided patients into those with above-normal and normal laboratory values before implantation and measured blood chemistry over time during left ventricular assist device support. There were significant improvements over 6 months in all parameters in the above-normal groups, with values in the normal groups remaining in the normal range over time. Mean blood urea nitrogen and serum creatinine in the above-normal groups decreased significantly from 37±14 to 23±10 mg/dL (P<0.0001) and from 1.8±0.4 to 1.4±0.8 mg/dL (P<0.01), respectively. There were decreases in aspartate transaminase and alanine transaminase in the above-normal groups from 121±206 and 171±348 to 36±19 and 31±22 IU (P<0.001), respectively. Total bilirubin for the above-normal group was 2.1±0.9 mg/dL at baseline; after an acute increase at week 1, it decreased to 0.9±0.5 mg/dL by 6 months (P<0.0001). Both renal and liver values from patients in the normal groups remained normal during support with the left ventricular assist device. Conclusions— The HeartMate II continuous-flow left ventricular assist device improves renal and hepatic function in advanced heart failure patients who are being bridged to transplantation, without evidence of detrimental effects from reduced pulsatility over a 6-month time period. Clinical Trial Registration Information— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00121472.

Comparison of outcomes in women versus men using a continuous-flow left ventricular assist device as a bridge to transplantation.

BACKGROUNDnThe use of large, pulsatile left ventricular assist devices (LVADs) has been limited in women because of their small body size.nnnMETHODSnWe compared the survival outcomes, quality of life, and adverse events in 465 patients (104 women, 361 men) with advanced systolic heart failure in their first 18 months of support with the HeartMate II (Thoratec Corp, Pleasanton, CA) continuous-flow LVAD for bridge to transplantation.nnnRESULTSnDuring the first 18 months, there were no differences in survival between women and men while on LVAD support (73% ± 3% vs 73% ± 5%, p = 0.855) but fewer women (40%) underwent heart transplantation than did men (55%; p = 0.001). More women continued on support after 18 months (p = 0.007). Median duration of support was 238 days for women and 184 days for men (p = 0.003). Mortality was 20% for women and 19% for men (p = 0.89). Adverse events were similar, with the exception of hemorrhagic stroke, which occurred more frequently in women (0.10 vs 0.04 events/patient-year, p = 0.02), and device-related infections, which occurred less frequently in women (0.23 vs 0.44, p = 0.006). Functional capacity and quality of life at 6 months improved significantly in women and men.nnnCONCLUSIONSnContinuous-flow left ventricular assistance as a bridge to transplantation is associated with similar survival rates in women and men. Differences observed in higher stroke rates and fewer infections among women require further study.

Montreal Cognitive Assessment and Mini-Mental Status Examination compared as cognitive screening tools in heart failure

BACKGROUNDnHeart failure (HF) patients run four times the risk of developing cognitive impairment than does the general population, yet cognitive screening is not routinely performed.nnnMETHODSnThis cross-sectional study enrolled 90 community-dwelling adults with HF aged 50 years and above. Participants took the Mini Mental Status Examination (MMSE) and Montreal Cognitive Assessment (MoCA), to measure cognitive function in persons with HF. Participants were predominately men (66%) and Caucasian (78%), aged 50-89 years (62 SD, 9 years), and 77% had an ejection fraction <40%.nnnRESULTSnFifty-four percent of participants scored ≤26 on the MoCA, suggesting mild cognitive impairment (MCI), and 17% scored ≤22, suggesting moderate cognitive impairment, compared with 2.2% on the MMSE. The MoCA scores were lowest for visuospatial/executive domain, short-term memory, and delayed recall. These findings were similar to those in published reports.nnnCONCLUSIONnThese preliminary findings support the use of MoCA for cognitive screening in stable HF.

Antecedent Hypertension Confers Increased Risk for Adverse Outcomes After Initial Myocardial Infarction

Several studies have examined the association of blood pressure (BP) after myocardial infarction (MI) with a risk for adverse outcome; however, few studies have investigated prognosis after MI as a function of BP before MI. Our goal was to examine the relation of antecedent hypertension to risk of adverse outcomes after initial MI. From 1967 to 1990, 404 subjects followed at the Framingham Heart Study developed an initial MI. These subjects were classified on the basis of preinfarction BP into normotensive (BP<140/90 mm Hg and not receiving antihypertensive treatment; n=118), stage I-untreated hypertension (BP 140 to 159/90 to 99 mm Hg; n=89), and stage II to IV or treated hypertension (BP > or =160/100 mm Hg or treated hypertension; n=197). Cox models were used to adjust for age, sex, smoking, glucose intolerance, total cholesterol, and prior cardiovascular disease. Antecedent hypertension was related to risk of adverse outcome after MI. Compared with normotensive individuals, stage II to IV hypertensives were at increased risk for reinfarction (hazard ratio [HR], 2.20; 95% confidence interval [CI], 1.20 to 4.04). A similar but nonsignificant association was seen in stage I hypertensives (HR, 1.91; 95% CI, 0.97 to 3.77). Stage II to IV hypertensives were at increased risk for all-cause mortality compared with normotensive persons (HR, 1.45; 95% CI, 1.07 to 1.98). Thus, even after MI, a history of antecedent hypertension remains predictive of adverse outcome. These findings are consistent with beneficial effects of BP control in primary and secondary prevention settings. Effective BP control may both reduce the risk for an initial MI and improve outcome in the event that an MI occurs.

Risk factors for syncope in a community-based sample (the Framingham Heart Study).

The epidemiology of syncope has not been well described. Prior studies have examined risk factors for syncope in hospital-based or other acute or long-term care settings. To determine risk factors for syncope in a community-based sample, we performed a nested case-control study. We examined reports of syncope in Framingham Heart Study participants who underwent routine clinic visits from 1971 to 1990. For each syncope case (n = 543) 2 controls were matched for age, sex, and examination period. Mean age of subjects was 67 years (range 25 to 95); 59% were women. History of stroke or transient ischemic attack, history of myocardial infarction, high blood pressure, use of antihypertensive medication, use of other cardiac medication, smoking, alcohol intake, body mass index, systolic blood pressure, diastolic blood pressure, heart rate, atrial fibrillation, PR interval prolongation, interventricular block, and diabetes or elevated glucose level were examined as potential predictors. Using conditional logistic regression analysis, the predictors of syncope included a history of stroke or transient ischemic attack (odds ratio [OR] 2.56, 95% confidence interval [CI] 1.62 to 4.04), use of cardiac medication (OR 1.67, 95% CI 1.21 to 2. 30), and high blood pressure (OR 1.46, 95% CI 1.14 to 1.88). Lower body mass index was marginally associated with syncope (OR per 4 kg/m(2) decrement 1.10, 95% CI 0.99 to 1.22), as were increased alcohol intake (OR per 5 oz/week 1.11, 95% CI 0.99 to 1.26), and diabetes or an elevated glucose level (OR 1.29, 95% CI 0.96 to 1.75). To our knowledge, this study represents the first community-based study of risk factors for syncope.

Relation among body mass index, exercise training, and outcomes in chronic systolic heart failure.

Exercise training (ET) in patients with heart failure (HF), as demonstrated in the Heart Failure: A Controlled Trial Investigating Outcomes of Exercise TraiNing (HF-ACTION), was associated with improved exercise tolerance and health status and a trend toward reduced mortality or hospitalization. The present analysis of the HF-ACTION cohort examined the effect of ET in overweight and obese subjects compared to normal weight subjects with HF. Of 2,331 subjects with systolic HF randomized to aerobic ET versus usual care in the HF-ACTION, 2,314 were analyzed to determine the effect of ET on all-cause mortality, hospitalizations, exercise parameters, quality of life, and body weight changes by subgroups of body mass index (BMI). The strata included normal weight (BMI 18.5 to 24.9 kg/m(2)), overweight (BMI 25.0 to 29.9 kg/m(2)), obese I (BMI 30 to 34.9 kg/m(2)), obese II (BMI 35 to 39.9 kg/m(2)), and obese III (BMI ≥40 kg/m(2)). At enrollment, 19.4% of subjects were normal weight, 31.3% were overweight, and 49.4% were obese. A greater BMI was associated with a nonsignificant increase in all-cause mortality or hospitalization. ET was associated with nonsignificant reductions in all-cause mortality and hospitalization in each weight category (hazard ratio 0.98, 0.95, 0.92, 0.89, and 0.86 in the normal weight, overweight, obese I, obese II, and obese III categories, respectively; all p >0.05). Modeled improvement in exercise capacity (peak oxygen consumption) and quality of life in the ET group was seen in all BMI categories. In conclusion, aerobic ET in subjects with HF was associated with a nonsignificant trend toward decreased mortality and hospitalization and a significant improvement in quality of life across the range of BMI categories.

Cognitive profile in persons with systolic and diastolic heart failure.

Persons with heart failure (HF) have four times the risk of having cognitive impairment compared with the general population and display different patterns of cognitive impairment. This secondary analysis of a published cross-sectional study of 90 community-dwelling adults examined the Montreal Cognitive Assessment (MoCA) scores and HF differentiated as systolic and diastolic HF. Mean MoCA score was 22.9 (standard deviation±2.31) in persons with systolic HF (n=69) and 24.8 (standard deviation±2.76) in persons with diastolic HF (n=21) with statistically significant mean difference between groups (t=-2.025, P=.030). Independent t test on the eight MoCA domain scores and systolic and diastolic HF indicated significance on visuo-spatial/executive function (P=.026), attention (P=.049), abstraction (P=.014), and delayed recall (P=.048). Findings from this study support the need for including persons with systolic and diastolic HF in future researches on identifying varying cognitive profiles to plan tailored cognitive intervention.

Lack of significant de novo HLA allosensitization in ventricular assist device recipients transfused with leukoreduced, ABO identical blood products

Ventricular assist devices provide support for a failing heart and often serve as a bridge to transplantation. The use of these devices has also been associated with allosensitization to HLA antigens because of transfusion of blood products. Our program established a protocol mandating the use of leukoreduced, irradiated and ABO identical products, including platelets, in patients receiving initial implantations of VADs as a bridge to transplantation. Recipients were tested for anti-HLA antibodies before VAD implantation and monthly post-implantation by cytotoxicity and solid phase assays. We observed minimal de novo anti-HLA sensitization (<10%) in this population of 55 patients, each receiving a mean of 90 blood components, using this approach. No patient developed broad sensitization (PRA>50%). In conclusion, The use of leukoreduced, irradiated, ABO identical blood products abrogates broad allosensitization in this highly transfused population.

Non-invasive flow measurement of a rotary pump ventricular assist device using quantitative contrast echocardiography.

BACKGROUNDnMany implantable ventricular assist devices (VADs) have no direct measurement of pump output. The aim of this study was to test the hypothesis that quantitative contrast echocardiography can be used to measure VAD output.nnnMETHODSnContrast-enhanced Doppler velocity-time integral (VTI) was measured in the VAD inlet and outlet cannulae. Doppler flow (Doppler Q=Doppler VTIxcannula area) was compared with measured flow (Q). A total of 130 flow measurements were made (at 6400 and 12,000 rpm).nnnRESULTSnDoppler Q in the outflow and inflow cannulae showed an excellent correlation with measured Q (outlet Doppler Q=1.0052 xQ+0.048, R2=0.9865; inlet Doppler Q=1.5043 xQ+0.003, R2=0.9904), but inlet Doppler Q was 50% higher. Correcting for the flow profile of the conical inlet tube yielded excellent correlation (inlet Doppler Q=1.0029 xQ+0.002, R2=0.9904).nnnCONCLUSIONnNoninvasive Doppler flow techniques can be used to accurately measure VAD flow, but the flow profile in the cannula needs to be taken into account.