Wireless pulmonary artery haemodynamic monitoring in chronic heart failure: a randomised controlled trial

BACKGROUND

Results of previous studies support the hypothesis that implantable haemodynamic monitoring systems might reduce rates of hospitalisation in patients with heart failure. We undertook a single-blind trial to assess this approach.

METHODS

Patients with New York Heart Association (NYHA) class III heart failure, irrespective of the left ventricular ejection fraction, and a previous hospital admission for heart failure were enrolled in 64 centres in the USA. They were randomly assigned by use of a centralised electronic system to management with a wireless implantable haemodynamic monitoring (W-IHM) system (treatment group) or to a control group for at least 6 months. Only patients were masked to their assignment group. In the treatment group, clinicians used daily measurement of pulmonary artery pressures in addition to standard of care versus standard of care alone in the control group. The primary efficacy endpoint was the rate of heart-failure-related hospitalisations at 6 months. The safety endpoints assessed at 6 months were freedom from device-related or system-related complications (DSRC) and freedom from pressure-sensor failures. All analyses were by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00531661.

FINDINGS

In 6 months, 83 heart-failure-related hospitalisations were reported in the treatment group (n=270) compared with 120 in the control group (n=280; rate 0·31 vs 0·44, hazard ratio [HR] 0·70, 95% CI 0·60-0·84, p<0·0001). During the entire follow-up (mean 15 months [SD 7]), the treatment group had a 39% reduction in heart-failure-related hospitalisation compared with the control group (153 vs 253, HR 0·64, 95% CI 0·55-0·75; p<0·0001). Eight patients had DSRC and overall freedom from DSRC was 98·6% (97·3-99·4) compared with a prespecified performance criterion of 80% (p<0·0001); and overall freedom from pressure-sensor failures was 100% (99·3-100·0).

INTERPRETATION

Our results are consistent with, and extend, previous findings by definitively showing a significant and large reduction in hospitalisation for patients with NYHA class III heart failure who were managed with a wireless implantable haemodynamic monitoring system. The addition of information about pulmonary artery pressure to clinical signs and symptoms allows for improved heart failure management.

FUNDING

CardioMEMS.

Intrathoracic impedance vs daily weight monitoring for predicting worsening heart failure events: results of the Fluid Accumulation Status Trial (FAST)

The relative sensitivity and unexplained detection rate of changes in intrathoracic impedance has not been compared with standard heart failure (HF) monitoring using daily weight changes. The Fluid Accumulation Status Trial (FAST) prospectively followed 156 HF patients with implanted cardioverter-defibrillator or cardiac resynchronization therapy defibrillator devices modified to record daily changes in intrathoracic impedance in a blinded fashion for 537±312 days. Daily impedance changes were used to calculate a fluid index that could be compared with a prespecified threshold. True positives were defined as adjudicated episodes of worsening HF occurring within 30 days of a fluid index above threshold or an acute weight gain. Unexplained detections were defined as threshold crossings or acute weight gains not associated with worsening HF. Impedance measurements were performed on >99% of follow-up days, compared with only 76% of days for weight measurements. Sixty-five HF events occurred during follow-up (0.32/patient-year). Forty HF events were detected by impedance but not weight, whereas 5 were detected by weight but not impedance. Sensitivity was greater (76% vs 23%; P<.0001) and unexplained detection rate was lower (1.9 vs 4.3/patient-year; P<.0001) for intrathoracic impedance monitoring at the threshold of 60Ω days compared with acute weight increases of 3 lbs in 1 day or 5 lbs in 3 days and also over a wide range of fluid index and weight thresholds. The sensitivity and unexplained detection rate of intrathoracic impedance monitoring was superior to that seen for acute weight changes. Intrathoracic impedance monitoring represents a useful adjunctive clinical tool for managing HF in patients with implanted devices.

Safety and accuracy of a wireless pulmonary artery pressure monitoring system in patients with heart failure

BACKGROUND

Implantable hemodynamic monitoring to guide heart failure (HF) therapy is a promising area of active research. The goal of this investigation was to evaluate the safety and technical performance of a novel wireless pulmonary artery pressure monitoring system in 17 patients with symptomatic HF.

METHODS

The monitoring system consists of a sensor, delivery catheter, interrogator, and home monitoring device. The HF sensor was implanted into a distal branch of the pulmonary artery. Pulmonary artery pressures were monitored using the external device, which powers the HF sensor and transmits the hemodynamic data from the patient's home to a secure Internet database. The accuracy of the system was assessed by comparison with standard right heart catheterization (RHC).

RESULTS

The HF sensor was safely and successfully implanted in all patients. Agreement between the HF sensor and RHC for systolic, diastolic, and mean pulmonary artery pressures was excellent, with correlation coefficients of 0.94, 0.85, and 0.95, respectively (all P < .0001). Using Bland-Altman plots, the average differences for systolic, diastolic, and mean pulmonary artery pressures for the HF sensor vs RHC were -4.4 ± 0.3, 2.5 ± 1.0, and -0.8 ± 1.3 mm Hg, respectively. There were no serious device-related adverse events. A postmortem analysis of the HF sensor in a patient who died 12 months after implant demonstrated complete endothelialization and no evidence of thrombosis.

CONCLUSIONS

This trial supports the safety and accuracy of this pulmonary artery pressure monitoring system in patients with HF and the conduct of randomized trials of implantable hemodynamic monitoring in HF, using this system.

Wireless pulmonary artery haemodynamic monitoring in chronic heart failure: a randomised controlled trial

BACKGROUND

Results of previous studies support the hypothesis that implantable haemodynamic monitoring systems might reduce rates of hospitalisation in patients with heart failure. We undertook a single-blind trial to assess this approach.

METHODS

Patients with New York Heart Association (NYHA) class III heart failure, irrespective of the left ventricular ejection fraction, and a previous hospital admission for heart failure were enrolled in 64 centres in the USA. They were randomly assigned by use of a centralised electronic system to management with a wireless implantable haemodynamic monitoring (W-IHM) system (treatment group) or to a control group for at least 6 months. Only patients were masked to their assignment group. In the treatment group, clinicians used daily measurement of pulmonary artery pressures in addition to standard of care versus standard of care alone in the control group. The primary efficacy endpoint was the rate of heart-failure-related hospitalisations at 6 months. The safety endpoints assessed at 6 months were freedom from device-related or system-related complications (DSRC) and freedom from pressure-sensor failures. All analyses were by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00531661.

FINDINGS

In 6 months, 83 heart-failure-related hospitalisations were reported in the treatment group (n=270) compared with 120 in the control group (n=280; rate 0·31 vs 0·44, hazard ratio [HR] 0·70, 95% CI 0·60-0·84, p<0·0001). During the entire follow-up (mean 15 months [SD 7]), the treatment group had a 39% reduction in heart-failure-related hospitalisation compared with the control group (153 vs 253, HR 0·64, 95% CI 0·55-0·75; p<0·0001). Eight patients had DSRC and overall freedom from DSRC was 98·6% (97·3-99·4) compared with a prespecified performance criterion of 80% (p<0·0001); and overall freedom from pressure-sensor failures was 100% (99·3-100·0).

INTERPRETATION

Our results are consistent with, and extend, previous findings by definitively showing a significant and large reduction in hospitalisation for patients with NYHA class III heart failure who were managed with a wireless implantable haemodynamic monitoring system. The addition of information about pulmonary artery pressure to clinical signs and symptoms allows for improved heart failure management.

FUNDING

CardioMEMS.

A randomized controlled trial evaluating the safety and efficacy of cardiac contractility modulation in advanced heart failure

BACKGROUND

Cardiac contractility modulation (CCM) delivers nonexcitatory electrical signals to the heart during the absolute refractory period intended to improve contraction.

METHODS

We tested CCM in 428 New York Heart Association class III or IV, narrow QRS heart failure patients with ejection fraction (EF) ≤ 35% randomized to optimal medical therapy (OMT) plus CCM (n = 215) versus OMT alone (n = 213). Efficacy was assessed by ventilatory anaerobic threshold (VAT), primary end point, peak Vo₂ (pVo₂), and Minnesota Living with Heart Failure Questionnaire (MLWFQ) at 6 months. The primary safety end point was a test of noninferiority between groups at 12 months for the composite of all-cause mortality and hospitalizations (12.5% allowable delta).

RESULTS

The groups were comparable for age (58 ± 13 vs 59 ± 12 years), EF (26% ± 7% vs 26% ± 7%), pVo₂ (14.7 ± 2.9 vs 14.8 ± 3.2 mL kg⁻¹ min⁻¹), and other characteristics. While VAT did not improve at 6 months, CCM significantly improved pVo₂ and MLWHFQ (by 0.65 mL kg⁻¹ min⁻¹ [P = .024] and -9.7 points [P < .0001], respectively) over OMT. Forty-eight percent of OMT and 52% of CCM patients experienced a safety end point, which satisfied the noniferiority criterion (P = .03). Post hoc, hypothesis-generating analysis identified a subgroup (characterized by baseline EF ≥ 25% and New York Heart Association class III symptoms) in which all parameters were improved by CCM.

CONCLUSIONS

In the overall target population, CCM did not improve VAT (the primary end point) but did improve pVo₂ and MLWHFQ. Cardiac contractility modulation did not have an adverse affect on hospitalizations or mortality within the prespecified boundaries. Further study is required to clarify the role of CCM as a treatment for medically refractory heart failure.

Effects of low-dose oral enoximone administration on mortality, morbidity, and exercise capacity in patients with advanced heart failure: the randomized, double-blind, placebo-controlled, parallel group ESSENTIAL trials

Aims

Use of inotropic agents in patients with heart failure (HF) has been limited by adverse effects on outcomes. However, administration of positive inotropes at lower doses and concomitant treatment with beta-blockers might increase benefit–risk ratio. We investigated the effects of low doses of the positive inotrope enoximone on symptoms, exercise capacity, and major clinical outcomes in patients with advanced HF who were also treated with beta-blockers and other guideline-recommended background therapy.

Methods and results

The Studies of Oral Enoximone Therapy in Advanced HF (ESSENTIAL) programme consisted of two identical, randomized, double-blind, placebo-controlled trials that differed only by geographic location (North and South America: ESSENTIAL-I; Europe: ESSENTIAL-II). Patients with New York Heart Association class III–IV HF symptoms, left ventricular ejection fraction ≤30%, and one hospitalization or two ambulatory visits for worsening HF in the previous year were eligible for participation in the trials. The trials had three co-primary endpoints: (i) the composite of time to all-cause mortality or cardiovascular hospitalization, analysed in the two ESSENTIAL trials combined; (ii) the 6 month change from baseline in the 6 min walk test distance (6MWTD); and (iii) the Patient Global Assessment (PGA) at 6 months, both analysed in each trial separately. ESSENTIAL-I and -II randomized 1854 subjects at 211 sites in 16 countries. In the combined trials, all-cause mortality and the composite, first co-primary endpoint did not differ between the two treatment groups [hazard ratio (HR) 0.97; 95% confidence interval (CI) 0.80–1.17; and HR 0.98; 95% CI 0.86–1.12, respectively, for enoximone vs. placebo]. The two other co-primary endpoints were analysed separately in the two ESSENTIAL trials, as prospectively designed in the protocol. The 6MWTD increased with enoximone, compared with placebo, in ESSENTIAL-I (P = 0.025, not reaching, however, the pre-specified criterion for statistical significance of P < 0.020), but not in ESSENTIAL-II. No difference in PGA was observed in either trial.

Conclusion

Although low-dose enoximone appears to be safe in patients with advanced HF, major clinical outcomes are not improved.

Nesiritide in acute decompensated heart failure: a pooled analysis of randomized controlled trials

BACKGROUND

Previous randomized controlled trials (RCTs) evaluating nesiritide for the treatment of acute decompensated heart failure (ADHF) have reported wide variances in mortality hazard ratios for nesiritide vs controls, but these individual trials were neither designed nor powered to evaluate mortality. This study used relevant data from all RCTs of nesiritide in ADHF completed as of June 2006 to independently estimate the effect of nesiritide on 30- and 180-day mortality.

HYPOTHESIS

Administration of nesiritide to treat patients with ADHF does not significantly increase mortality at 30 or 180 days.

METHODS

Six trials met prespecified criteria for inclusion in this analysis. Primary data from these trials were obtained from Scios Inc. (Fremont, CA). Statistical models were fitted to estimate 4 effects: dose response, differing control groups, vulnerable subgroup interactions, and time of death relative to nesiritide administration. All models included 4 baseline covariates that were significantly and independently associated with mortality.

RESULTS

Complete covariate data were available in 1472 of 1538 subjects (96%). The risk-adjusted hazard ratio for mortality was 1.05 (95% confidence interval [CI]: 0.85-1.30) at 30 and 1.00 (95% CI: 0.88-1.14) at 180 days with no clear relationship to nesiritide dose. In addition to consistent results across 2 time points, no significant evidence of sensitivity to control group or baseline risk factors was found.

CONCLUSIONS

Currently available data suggest nesiritide does not significantly increase mortality at 30 or 180 days.

Chronic baroreflex activation: a potential therapeutic approach to heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is a substantial public health issue, equal in magnitude to heart failure with reduced ejection fraction. Clinical outcomes of HFpEF patients are generally poor, related annual accrual of health care expenses amount to billions of dollars, and no therapy has been shown to be effective in randomized clinical trials. Baroreflex activation therapy (BAT) produced by stimulating the carotid sinuses using an implanted device (Rheos) is being studied for the treatment of hypertension, the primary comorbidity of HFpEF. Other potential benefits include regression of left ventricular hypertrophy, normalization of the sympathovagal balance, inhibition of the renin-angiotensin-aldosterone system, arterio- and venodilation, and preservation of renal function. This paper reviews the evidence suggesting that BAT may be a promising therapy for HFpEF and introduces the HOPE4HF trial (ClinicalTrials.gov Identifier: NCT00957073), a randomized outcomes trial designed to evaluate the clinical safety and efficacy of BAT in the HFpEF population.

Direct left atrial pressure monitoring in severe heart failure: long-term sensor performance

We report the stability, accuracy, and development history of a new left atrial pressure (LAP) sensing system in ambulatory heart failure (HF) patients. A total of 84 patients with advanced HF underwent percutaneous transseptal implantation of the pressure sensor. Quarterly noninvasive calibration by modified Valsalva maneuver was achieved in all patients, and 96.5% of calibration sessions were successful with a reproducibility of 1.2 mmHg. Absolute sensor drift was maximal after 3 months at 4.7 mmHg (95% CI, 3.2–6.2 mmHg) and remained stable through 48 months. LAP was highly correlated with simultaneous pulmonary wedge pressure at 3 and 12 months (r = 0.98, average difference of 0.8 ± 4.0 mmHg). Freedom from device failure was 95% (n = 37) at 2 years and 88% (n = 12) at 4 years. Causes of failure were identified and mitigated with 100% freedom from device failure and less severe anomalies in the last 41 consecutive patients (p = 0.005). Accurate and reliable LAP measurement using a chronic implanted monitoring system is safe and feasible in patients with advanced heart failure.

Chronic Ambulatory Intracardiac Pressures and Future Heart Failure Events

Background—

Intracardiac pressures in heart failure (HF) have been measured in patients while supine in the hospital but change at home with posture and activity. The optimal level of chronic ambulatory pressure is unknown. This analysis compared chronic intracardiac pressures to later HF events and sought a threshold above which higher pressures conferred worse outcomes.

Methods and Results—

Median pressures were measured every 24 hours from continuous 8-minute segments for 6 months after implantation of hemodynamic monitors in 261 patients with New York Heart Association class III-IV HF in the Chronicle Offers Management to Patients with Advanced Signs and Symptoms of Heart Failure Study. Baseline and chronic daily medians of estimated pulmonary artery diastolic, right ventricular systolic, and right ventricular end-diastolic pressures were compared with HF event rate. The group median for chronic 24-hour estimated pulmonary artery diastolic pressure was 28 mm Hg (excluding 7 days before and after events). Despite weight-guided management, events occurred in 100 of 261 (38%) patients. Event risk increased progressively with higher chronic 24-hour estimated pulmonary artery diastolic pressure, from 20% at 18 mm Hg to 34% at 25 mm Hg and 56% at 30 mm Hg, with similar relations for right ventricular pressures. Among patients with baseline day median estimated pulmonary artery diastolic pressures of ≥25 mm Hg, event risk was 1.10/6 mo when they remained chronically ≥25 mm Hg, but risk fell to 0.47 when 24-hour pressures declined to <25 mm Hg for more than half of the days.

Conclusions—

Despite current management, many patients with advanced HF live on a plateau of high filling pressures from which later events occur. This risk is progressively higher with higher chronic ambulatory pressures. It is not known whether more targeted intervention could maintain lower chronic ambulatory pressures and better outcomes.

Sleep apnea testing and outcomes in a large cohort of Medicare beneficiaries with newly diagnosed heart failure

RATIONALE

Previous studies have demonstrated a high prevalence of sleep apnea (SA) in patients with chronic heart failure (HF), which is associated with higher rates of morbidity, mortality, and health care use.

OBJECTIVES

To investigate the reported incidence, treatment, outcomes, and economic cost of SA in new-onset HF in a large U.S. database.

METHODS

This retrospective cohort study used the 2003 to 2005 Medicare Standard Analytical Files and included subjects with newly diagnosed HF from the first quarter of 2004, without prior diagnosis of SA, stratified by testing, diagnosis, and treatment status.

MEASUREMENTS AND MAIN RESULTS

Among a study population of 30,719 incident subjects with HF, only 1,263 (4%) were clinically suspected to have SA. Of these, 553 (2% of the total cohort) received SA testing, and 545 received treatment. After adjustment for age, sex, and comorbidities, subjects with HF who were tested, diagnosed, and treated for SA had a better 2-year survival rate compared with subjects with HF who were not tested (hazard ratio, 0.33 [95% confidence interval, 0.21-0.51], P < 0.0001). Similarly, among subjects who were tested and diagnosed, those who were treated had a better 2-year survival rate than those who were not treated (hazard ratio, 0.49 [95% confidence interval, 0.29-0.84], P = 0.009).

CONCLUSIONS

In Medicare beneficiaries with HF, comorbid SA is most often not tested and consequently subjects are underdiagnosed and not treated. Meanwhile, in the few subjects in whom a diagnosis of SA is established and treatment is executed, survival improves significantly. These results support the importance of SA testing and treatment for patients newly diagnosed with HF.

Rationale and design of a randomized clinical trial to assess the safety and efficacy of frequent optimization of cardiac resynchronization therapy: the Frequent Optimization Study Using the QuickOpt Method (FREEDOM) trial

OBJECTIVE

The aim of the study was to describe the rationale, design, and end points of a randomized, double-blind, controlled trial evaluating frequent systematic optimization of atrioventricular (AV) and interventricular (VV) delays in patients receiving cardiac resynchronization therapy (CRT).

METHODS

One thousand five hundred eighty heart failure patients, with standard clinical indications for CRT, were enrolled at 178 sites in 16 countries. Within 2 weeks after implantation of a CRT system capable of using a new device-based algorithm for AV and VV optimization, patients were randomly assigned to frequent optimization arm versus empiric device programming or any other non-device-based method of CRT optimization (standard of care arm). In patients in the frequent optimization arm, the AV and VV delays were calculated, reevaluated, and, if necessary, reprogrammed every 3 months. In patients in the standard of care arm, device programming was left to the implanting physician's discretion and remained unchanged throughout the trial unless mandated by a change in clinical status. The primary end point of the trial is the heart failure clinical composite, which classifies patients as worsened, unchanged, or improved based on prespecified definitions. Secondary end points include hospitalizations for cardiovascular reasons and all-cause mortality. End points are adjudicated by an independent committee blinded to study assignment.

CONCLUSIONS

The FREEDOM trial, expected to conclude late in 2009, will determine whether frequent optimization of CRT, using a new device-based algorithm, is associated with better clinical outcomes than current standard of care. In addition to improving patient care, this approach might alleviate the workload and economic burden imposed by current approaches to optimization of CRT devices.

Upgrading to resynchronization therapy after chronic right ventricular pacing improves left ventricular remodelling

AIMS

Chronic right ventricular (RV) pacing may impose ventricular dyssynchrony leading to LV remodelling and is associated with increased morbidity and mortality. Upgrading patients with chronic RV pacing to cardiac resynchronization therapy (CRT) may be considered to restore synchronicity and prevent these deleterious effects.

METHODS AND RESULTS

A total of 172 patients from two tertiary centres were analysed over a mean follow-up of 21.7 and 23.5 months after primary CRT implantation (n = 102) and CRT upgrade (n = 70), respectively. In the latter group, mean duration of RV pacing before CRT upgrade was 80.3 months, and ventricular stimulation was >95%. A significant improvement in left ventricular (LV) ejection fraction (10 and 11% absolute increase in primary CRT vs. upgrades, respectively), LV end-diastolic diameter index (-0.15 cm/m(2) vs. -0.2 cm/m(2)), and LV end-systolic diameter (-6.0 vs. -7.0 mm) was observed in both groups, which did not differ between primary CRT recipients and CRT upgrades. Response to CRT upgrade was independent of the underlying rhythm, QRS duration, duration of prior RV pacing, or LV function and size at baseline. Of note, even seven of nine patients with RV pacing >12 years responded favourably to CRT.

CONCLUSION

The current study demonstrates that CRT reverses LV remodelling in heart failure patients with chronic RV pacing in a similar way as in primary CRT recipients, even after very long periods of RV pacing. Our data, therefore, may have important implications for the treatment of pacemaker-dependent patients with heart failure, and support the use of CRT in this setting.

Physician-directed patient self-management of left atrial pressure in advanced chronic heart failure

BACKGROUND

Previous studies suggest that management of ambulatory hemodynamics may improve outcomes in chronic heart failure. We conducted a prospective, observational, first-in-human study of a physician-directed patient self-management system targeting left atrial pressure.

METHODS AND RESULTS

Forty patients with reduced or preserved left ventricular ejection fraction and a history of New York Heart Association class III or IV heart failure and acute decompensation were implanted with an investigational left atrial pressure monitor, and readings were acquired twice daily. For the first 3 months, patients and clinicians were blinded as to these readings, and treatment continued per usual clinical assessment. Thereafter, left atrial pressure and individualized therapy instructions guided by these pressures were disclosed to the patient. Event-free survival was determined over a median follow-up of 25 months (range 3 to 38 months). Survival without decompensation was 61% at 3 years, and events tended to be less frequent after the first 3 months (hazard ratio 0.16 [95% confidence interval 0.04 to 0.68], P=0.012). Mean daily left atrial pressure fell from 17.6 mm Hg (95% confidence interval 15.8 to 19.4 mm Hg) in the first 3 months to 14.8 mm Hg (95% confidence interval 13.0 to 16.6 mm Hg; P=0.003) during pressure-guided therapy. The frequency of elevated readings (>25 mm Hg) was reduced by 67% (P<0.001). There were improvements in New York Heart Association class (-0.7+/-0.8, P<0.001) and left ventricular ejection fraction (7+/-10%, P<0.001). Doses of angiotensin-converting enzyme/angiotensin-receptor blockers and beta-blockers were uptitrated by 37% (P<0.001) and 40% (P<0.001), respectively, whereas doses of loop diuretics fell by 27% (P=0.15).

CONCLUSIONS

Physician-directed patient self-management of left atrial pressure has the potential to improve hemodynamics, symptoms, and outcomes in advanced heart failure. Clinical Trial Registration Information- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00547729.

Cardiac resynchronization therapy may benefit patients with left ventricular ejection fraction >35%: a PROSPECT trial substudy

AIMS

Cardiac resynchronization therapy (CRT) is currently limited to those with left ventricular ejection fraction (LVEF) < or =35%. To evaluate whether patients with LVEF >35% might benefit from CRT, we performed a retrospective analysis of the predictors of response to CRT (PROSPECT) database.

METHODS AND RESULTS

PROSPECT was a prospective, multicentre study that enrolled CRT patients based on enrolling centre-evaluated LVEF <35%, but all echocardiograms were subsequently analysed by a core laboratory. Patients with core laboratory-measured LVEF >35% (OVER35) were compared with those whose LVEF was <35% (UNDER35). Clinical composite score (CCS) and change in LV end systolic volume (LVESV) were analysed from baseline to 6-month follow-up. Of 361 patients, 86 (24%) had LVEF >35%. At entry, OVER35 had smaller LV volumes, shorter QRS duration, shorter 6-min walk distance, and were more likely to have ischaemic aetiology than UNDER35. Outcomes were comparable between the groups, with 62.8% of OVER35 improved in CCS (70.2% in UNDER35) and 50.8% of OVER35 improved in LVESV (57.8% in UNDER35).

CONCLUSION

Patients with LVEF >35%, New York heart association functional Class III-IV status, and QRS >130 ms appear to derive clinical and structural benefit from CRT. As CRT may offer a valuable option for these patients, this hypothesis should be formally tested in a prospective, randomized multicentre trial.

An α 2C -Adrenergic Receptor Polymorphism Alters the Norepinephrine-Lowering Effects and Therapeutic Response of the β-Blocker Bucindolol in Chronic Heart Failure

Background— Adrenergic activation is an important determinant of outcomes in chronic heart failure. Adrenergic activity is regulated in part by prejunctional α 2C -adrenergic receptors (ARs), which exhibit genetic variation in humans. Bucindolol is a novel β-AR blocking agent that also lowers systemic norepinephrine and thus is also a sympatholytic agent. This study investigated whether α 2C -AR polymorphisms affect sympatholytic effects of bucindolol in patients with heart failure.

Methods and Results— In the β-Blocker Evaluation of Survival Trial, adrenergic activation was estimated by systemic venous norepinephrine measured at baseline, 3 months, and 12 months posttreatment in patients treated with placebo or bucindolol. In the β-Blocker Evaluation of Survival Trial AR polymorphism substudy, DNA was collected from 1040 of the 2708 randomized patients, and α 2C -AR gene polymorphisms (α 2C Del322-325 or the wild-type counterpart) were measured by polymerase chain reaction and gel electrophoresis. Patients who were α 2C Del carriers (heterozygotes or homozygotes) exhibited a much greater sympatholytic response to bucindolol (decrease in norepinephrine at 3 months of 153±57 pg/mL, P =0.012 compared with placebo versus decrease of 50±13 pg/mL in α 2C wild type, P =0.0005 versus placebo; P =0.010 by interaction test). α 2C Del carriers had no evidence of a favorable survival benefit from bucindolol (mortality compared with placebo hazard ratio, 1.09; 95% CI, 0.57 to 2.08; P =0.80), whereas bucindolol-treated subjects who were wild type for the α 2C -AR had a 30% reduction in mortality (hazard ratio, 0.70; 95% CI, 0.51 to 0.96; P =0.025).

Conclusions— In the β-Blocker Evaluation of Survival Trial AR polymorphism substudy, the norepinephrine lowering and clinical therapeutic responses to bucindolol were strongly influenced by α 2C receptor genotype.