Baseline Right Ventricular Dysfunction Predicts Worse Outcomes in Patients Undergoing Cardiac Resynchronization Therapy Implantation

IntroductionCardiac resynchronization therapy (CRT) has been shown to improve survival in patients with systolic heart failure, wide QRS duration, and left-bundle-branch-block. However, CRT outcomes stratified by right ventricular (RV) function at implant have not been well studied.MethodsWe retrospectively reviewed patients at Cleveland Clinic who underwent CRT implantation (n = 777) from 2003 to 2011 with a diagnosis of heart failure, echocardiography with both pre-CRT left ventricular ejection fraction (LVEF) ≤35% and available post-CRT echocardiography at 6 months post-implant. CRT response was defined as LVEF improvement ≥5%. Patients were separated into 2 groups: normal or mild RV dysfunction (n = 570) labeled Normal RV; moderate to severe dysfunction (n = 207) labeled RV DYSFXN based on qualitative echocardiography assessment. Survival was calculated as time from CRT implant to death, left ventricular assist device implant, or heart transplant.ResultsCRT response was significantly higher in patients with Normal RV (67%) compared with patients with RV DYSFXN (56%; P = .006). Kaplan–Meier analysis showed that CRT patients with Normal RV had significantly greater survival compared with patients with RV DYSFXN (P < .001). In multivariable Cox regression accounting for a priori covariates, RV DYSFXN was associated with worse survival (HR 1.41 [95% CI: 1.14–1.75], P = .002) and lower CRT response (HR 0.66 [95% CI: 0.44–0.97], P = .03).ConclusionBaseline RV dysfunction at CRT implant is an important predictor of worsened left ventricular remodeling and survival in CRT patients.     

Cardiac Resynchronization Therapy as Rescue Therapy in End‐Stage Heart Failure: Illustration by Three‐Dimensional Speckle Tracking Strain Echocardiography

We report the case of a 73‐year‐old man admitted for refractory heart failure following implantation of a dual‐chamber pacemaker. Three‐dimensional (3D) echocardiography with speckle tracking area strain identified severe left ventricular (LV) dysfunction and LV dyssynchrony following right ventricular pacing. As the patient's clinical condition rapidly worsened despite optimal medical treatment, a cardiac resynchronization therapy (CRT) pacemaker was successfully implanted as rescue therapy. Symptoms rapidly regressed and echocardiographic assessment following CRT demonstrated an immediate improvement in LV systolic function, confirmed at 9‐month follow‐up with evidence of reverse remodeling. New imaging technologies such as 3D echocardiography with speckle tracking area strain may help to identify and follow up patients who will benefit from CRT as rescue therapy.     

Patient selection for cardiac resynchronization therapy: from the Council on Clinical Cardiology Subcommittee on Electrocardiography and Arrhythmias and the Quality of Care and Outcomes Research Interdisciplinary Working Group, in collaboration with the Heart Rhythm Society

Cardiac resynchronization therapy (CRT) is a relatively new therapy for patients with symptomatic heart failure resulting from systolic dysfunction. CRT is achieved by simultaneously pacing both the left and right ventricles. Biventricular pacing resynchronizes the timing of global left ventricular depolarization and improves mechanical contractility and mitral regurgitation. Published clinical trials have demonstrated that CRT results in improved clinical status and lower mortality rate when selected patients with systolic ventricular dysfunction and heart failure are treated with CRT. This advisory identifies appropriate candidates for CRT on the basis of the inclusion criteria and results from the published clinical trials.     

Improved Right Ventricular Systolic Function After Cardiac Resynchronization Therapy in Patients With Heart Failure

BackgroundSince the introduction of cardiac resynchronization therapy (CRT) to improve left ventricular function, the effect of CRT on the right ventricle in patients with heart failure has not been well described.MethodsWe evaluated the effect of CRT on right ventricular systolic function in 20 patients (80% men; mean [SD] age, 58.5 [9.8] y) with cardiomyopathy and right ventricular systolic dysfunction (New York Heart Association class III or IV, left ventricular ejection fraction ≤35%, and QRS interval ≥120 ms). The median follow-up time was 15 months. Right ventricular systolic function, defined as a tricuspid annular plane systolic excursion (TAPSE) index of 16 mm or less, was evaluated in patients before and after CRT.ResultsTwelve (60%) patients had ischemic cardiomyopathy, and 12 (60%) patients had left bundle branch block detected using surface electrocardiogram. The mean (SD) QRS duration was 160.5 (24.4) ms. From before CRT to the time of follow-up after CRT, the mean (SD) ejection fraction increased significantly from 22.5% (5.6%) to 29.4% (7.4%) (P < .001). The mean (SD) TAPSE index also increased significantly from 13.70 (1.78) mm to 16.50 (4.77) mm (P = .018). Eleven (55%) patients showed improved right ventricular systolic function (TAPSE ≥16 mm) after CRT. Patients with a favorable right ventricular response to CRT were significantly older (64.6 [8.2] y vs 53.6 [8.4] y, respectively) and more likely to have nonischemic origin of cardiomyopathy than were patients with unimproved right ventricular function (66.7% vs 18.2%, respectively).ConclusionOur findings indicate that CRT is associated with improved right ventricular systolic function in patients with heart failure and right ventricular systolic dysfunction. Patients with nonischemic heart disease more often show improved right ventricular function after CRT.     

Should Patients who have Persistent Severe Symptoms Receive a Left Ventricular Assist Device or Cardiac Resynchronization Therapy as the Next Step?

Currently, cardiac resynchronization therapy (CRT) should be considered before a left ventricular assist device for most patients who have moderate or severe left ventricular systolic dysfunction and have not responded symptomatically to conventional pharmacologic measures. There is little evidence that the severity of cardiac dyssynchrony as measured using current techniques is useful in predicting the benefits of CRT. QRS duration on the surface ECG is a surrogate marker of the severity of the left ventricular ejection fraction as well as of several types of dyssynchrony. More clinical trials are required to determine whether excluding patients who have QRS duration less than 120 msec or those who have no evidence of dyssynchrony from implantation of CRT is appropriate. Perhaps all patients who have moderate or severe left ventricular systolic dysfunction should be considered for CRT, either to improve symptoms if they are persistent or relapsing, or to improve outcome. In the longer-term future, it is possible that the development of less expensive, small, and safe left ventricular assist devices will supplant the role of both CRT and CRT-defibrillator devices.     

Inhibition of left ventricular stimulation due to left ventricular lead failure and the left ventricular T‐wave protection algorithm in patient with cardiac resynchronization therapy and pacemaker dependency

The electrocardiogram (ECG) interpretation in patients with cardiac resynchronization therapy (CRT) is often a perplexing problem. The difficulty in the device evaluation increases in the presence of unfamiliar timing cycles and a lead dysfunction. Authors describe a special function of a Biotronik CRT devices called the left ventricle T‐wave protection (LVTP), and demonstrate its behavior in a patient with left ventricular (LV) lead failure. This report shows that sometimes it might be difficult to understand the loss of resynchronization in 12‐lead ECG when LVTP feature is on, and a malfunction of left ventricular lead sensing occurs.     

Multicenter Automatic Defibrillator Implantation Trial–Cardiac Resynchronization Therapy (MADIT‐CRT): Design and Clinical Protocol

The planned MADIT‐CRT trial is designed to determine if CRT‐D will reduce the risk of mortality and HF events by approximately 25% in subjects with ischemic (NYHA class I‐II) and non‐ischemic (NYHA class II) cardiomyopathy, left ventricular dysfunction (EF ≤ 0.30), and prolonged intraventricular conduction (QRS duration ≥ 130 ms).     

Short-term effects of cardiac resynchronization therapy on sleep-disordered breathing in patients with systolic heart failure

OBJECTIVES: We evaluated the short-term effect of cardiac resynchronization therapy (CRT) on sleep apnea in patients with systolic heart failure. BACKGROUND: Sleep-disordered breathing is common in patients with left ventricular systolic dysfunction. METHODS: Twelve patients (mean [+/-SE] age, 59.6+/-7.8 years; mean left ventricular ejection fraction, 28.0+/-2.8%) with an implanted atrial-synchronized biventricular pacemaker for the treatment of left ventricular systolic dysfunction were selected and studied. Each subject underwent polysomnography on 3 consecutive nights with CRT on the first night, CRT off the second night, and CRT on the third night. Echocardiography was performed prior to each polysomnogram. RESULTS: The central sleep event index (ie, the number of central sleep apneas [CSAs] and hypopneas per hour of sleep) score was lower with CRT compared to that without CRT (mean central sleep event index score with CRT on, 6.9+/-1.7 events per hour of sleep; mean central sleep event index score with CRT off, 14.3+/-2.9 events per hour of sleep; mean central sleep event index score with CRT on, 8.1+/-1.5 events per hour of sleep; p<0.001). Similarly, the cumulative duration of central sleep events (the number of minutes per hour of sleep during CRT) was one half that observed without CRT (CRT on, 2.8+/-0.7 min per hour of sleep; CRT OFF 6.2+/-1.2 min per hour of sleep; CRT ON 3.1+/-0.7 min per hour of sleep; p<0.001). There was a significant correlation between mitral regurgitant volume and central sleep event index on all three nights (r>or=0.77; p<0.01). CONCLUSIONS: CRT reduces CSA severity in the short term. This reduction correlated significantly with the CRT-mediated reduction of mitral regurgitation.     

Resynchronization therapy for congestive heart failure

Opinion statement Ventricular contraction is achieved by the coordinated electrical activation of the ventricles through the action of the cardiac conduction system. In the presence of left bundle branch block (LBBB) or interventricular conduction delay (IVCD), the ventricular contraction pattern is desynchronized and the stroke volume is reduced as a consequence. In patients with congestive heart failure (CHF) due to systolic dysfunction, the presence of LBBB or IVCD further degrades ventricular function, contributing directly to the severity of their CHF symptoms. Cardiac resynchronization therapy (CRT) through biventricular pacing relieves CHF symptoms and improves functional status in patients with medically refractory heart failure due to left ventricular systolic dysfunction and LBBB or IVCD. The benefits of CRT are due to improvement in the ventricular activation sequence, resulting in a more coordinated and efficient ventricular contraction. In addition to symptomatic benefits, available data support the hypothesis that CRT alters the natural history of CHF in patients with intraventricular conduction delay.     

Doppler echocardiographic methods for optimization of the atrioventricular delay during cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is beneficial for a majority of patients with medically refractory heart failure due to severe left ventricular (LV) systolic dysfunction and prolonged interventricular conduction to improve symptoms and LV performance. An optimally programmed atrioventricular delay (AVD) during CRT can be also important to maximize the response in left ventricular function. Several Doppler echocardiographic methods have been reported to be useful for determination of the optimal AVD. This review will discuss the various Doppler-based approaches to program the AVD in patients that receive CRT.     

Elevated red cell distribution width is associated with impaired reverse ventricular remodeling and increased mortality in patients undergoing cardiac resynchronization therapy

Elevated red cell distribution width (RDW) has been associated with poor long-term outcomes in patients with systolic dysfunction. The relationship between baseline RDW and reverse ventricular remodeling in advanced heart failure patients undergoing cardiac resynchronization therapy (CRT) has not been established. The authors reviewed the pre-implant and follow-up echocardiograms of 233 patients undergoing the new implantation of a CRT device at the Cleveland Clinic between December 2001 and November 2006. Patients were included in the final cohort if they had an RDW level within 7 days of CRT implantation, a left ventricular ejection fraction (LVEF) ≤40%, and New York Heart Association class II to IV symptoms. Patients with a reduction in left ventricular end-systolic volume ≥15% following CRT were considered "responders." Multivariate models were created to assess the relationship between baseline RDW elevation with progressive remodeling and all-cause mortality. Of 233 patients, 217 patients met inclusion criteria. Patients in the highest RDW quartile (>16.1) derived significantly less improvement in LVEF (3.5%±9.3% vs 10.1%±10.9%, P=.001) than patients in the lowest quartile (<13.6). In multivariate analysis, elevated RDW was inversely associated with response (odds ratio, 0.83; 95% confidence interval, 0.69-0.99; P=.047). The presence of elevated RDW is associated with less reverse left ventricular remodeling in patients with advanced heart failure undergoing CRT.     

Chronic Right Ventricular Pacing in the Heart Failure Population

Purpose of Review

We review the trials that have demonstrated potentially harmful effects from right ventricular (RV) apical pacing as well as reviewing the evidence of alternative RV pacing sites and cardiac resynchronization therapy (CRT) for patients who have heart failure and atrioventricular (AV) block.

Recent Findings

The role of CRT in patients with AV block and impaired left ventricular function remains an important consideration. The BLOCK HF trial demonstrated better outcomes with CRT pacing over RV pacing in patients with left ventricular systolic dysfunction (LVSD) and AV block who were expected to have a high RV pacing burden, but failed to demonstrate a mortality benefit.

Summary

CRT seems to have a beneficial effect on left ventricular reverse remodeling, systolic function, and clinical outcomes in patients with New York Heart Association (NYHA) functional class I–III heart failure, moderate to severe LVSD, and AV block compared to RV pacing. However, it is less clear whether there is a similar benefit from CRT in patients with a high percentage of RV pacing who have normal or mild LVSD in the treatment of AV block.

     

Echo determinants of dyssynchrony (atrioventricular and inter- and intraventricular) and predictors of response to cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) has revolutionized not only the treatment of chronic heart failure but also how we assess left ventricular (LV) dysfunction on echo. Increasingly, it has become clear that identifying and quantifying delays in events during the cardiac cycle is an important assessment in LV dysfunction as it has prognostic implications for patients undergoing CRT. The delays in atrioventricular, right-to-left ventricular, and LV segmental contraction have been shown to be important components in cardiac performance, and this review provides an overview of the commonest methods used for these assessments and their implications for selecting patients for biventricular pacing.     

Echocardiographic evaluation of cardiac dyssynchrony: Does it still matter?

Cardiac resynchronization therapy (CRT) is an established treatment for patients with heart failure and left ventricular systolic dysfunction. For many years, cardiac mechanical dyssynchrony assessed by echocardiography has been considered as a key evaluation to characterize CRT candidates and predict CRT response. In current guidelines, however, CRT implant indications rely only on electrical dyssynchrony. The aim of this article was to clarify whether and how the evaluation of cardiac mechanical dyssynchrony should be performed today by echocardiography.     

Pivotal trials of cardiac resynchronization therapy: evolution to therapy in mild heart failure

Cardiac resynchronization therapy (CRT) has traditionally been reserved for patients with left ventricular (LV) dysfunction in the setting of advanced heart failure. Early clinical trials clearly demonstrated reverse ventricular remodeling and clinical benefits following CRT in this population. More recently, with the publication of the REVERSE, MADIT-CRT, and RAFT trials, the benefits of CRT have been demonstrated in patients with LV dysfunction and mild heart failure calling into question the optimal timing for biventricular pacemaker implantation. With the expanded indications for CRT arising from these studies, significant questions remain specifically with regards to the economic impact on health care systems and to the added risk of future morbidity due to device infection and malfunction.     

Brain natriuretic peptide levels and response to cardiac resynchronization therapy in heart failure patients

The authors used brain natriuretic peptide (BNP) as a reliable marker to identify nonresponders to cardiac resynchronization therapy (CRT) in patients with advanced heart failure. The study included 70 patients with left ventricular dysfunction (mean ejection fraction, 21+/-4%) and left bundle branch block (QRS duration, 164+/-25 milliseconds) treated with CRT. The authors reviewed data on New York Heart Association functional class, baseline ejection fraction, sodium, creatinine, QRS duration, and BNP levels 3 months before and after CRT therapy. The authors compared results of 42 patients who survived (973+/-192 days) after CRT implantation (responders) to those of 28 patients (nonresponders) who either expired (n=21) or underwent heart transplantation (n=5) or left ventricular assist device implantation (n=2) after an average of 371+/-220 days. Mean BNP levels after 3 months of CRT decreased in responders from 758+/-611 pg/mL to 479+/-451 pg/mL (P=.044), while in nonresponders there was increase in BNP levels from 1191+/-466 pg/mL to 1611+/-1583; P=.046. A rise in BNP levels was associated with poor response (death or need for transplantation or left ventricular assist device and impaired long-term outcome), which makes it a good predictor to identify such patients.     

Transcatheter ablation through the cardiac veins in a patient with a biventricular device and left ventricular epicardial arrhythmias.

Left ventricular outflow tract (LVOT) may be a source of repeated premature ventricular complexes (PVCs). In symptomatic patients, radiofrequency catheter ablation (RFCA) can be effective, either from endocardial or from epicardial sites. A 50-year-old patient, with dilated cardiomyopathy (DCM) and severe left ventricular (LV) dysfunction, left bundle branch block (LBBB), New York Heart Association (NYHA) class IV, received a biventricular implantable cardioverter/defibrillator (ICD) in 2002. Despite drug therapy, PVCs were frequent (21.019/24 h) including prolonged runs, prompting ICD intervention. Premature ventricular complexes showed an inferior axis morphology, with an R/S ratio in V3>1, suggesting an LVOT origin. Despite the cardiac resynchronization therapy (CRT) device, successful RFCA was performed through the anterior venous branch, with a favourable clinical outcome. To our knowledge, this is the first case describing epicardial RFCA of a PVC focus from cardiac veins in the presence of a CRT device.     

Cardiac Resynchronization Therapy is an Important Advance in the Management of Congestive Heart Failure

Cardiac resynchronization therapy (CRT) is an emerging therapy that improves symptoms and exercise tolerance in patients with advanced heart failure, left ventricular systolic dysfunction, and intraventricular conduction delay. By correcting the AV, interventricular, and intraventricular dyssynchrony induced by conduction disorders, controlled studies have shown that CRT improved functional status, decreased heart failure hospitalization rate, and might have a positive effect on left ventricular remodeling. Recent and preliminary data from the COMPANION trial suggest that CRT alone or in association with defibrillator capacity significantly reduced total mortality and hospitalization and that total mortality was significantly reduced only in the CRT plus implantable cardioverter defibrillator (ICD) group. Many questions remain unanswered, particularly the selection of responder patients. (J Cardiovasc Electrophysiol, Vol. 14, pp. S27-S29, September 2003, Suppl.)     

Minimally invasive video-assisted thoracoscopic left ventricular epicardial lead implantation for biventricular pacing in a patient with persistent left superior vena cava

Cardiac resynchronization therapy (CRT) by biventricular pacing reduces symptoms and improves left ventricular function in many patients with heart failure due to left ventricular systolic dysfunction and cardiac dyssynchrony. Implantation of the biventricular pacing lead in association with persistent left superior vena cava is technically challenging. We report a successful case of minimally invasive video-assisted thoracoscopic left ventricular epicardial lead implantation for biventricular pacing in a patient with persistent left superior vena cava.     

6 VENTRICULAR INTER‐ AND LEFT VENTRICULAR INTRA VENTRICULAR SYSTOLIC ASYNCHRONY IN PATIENTS WITH DILATED CARDIOMYOPATHY AND THE EFFECT OF CARDIAC RESYNCHRONIZATION THERAPY

Aim: Data dealing with the effect of cardiac resynchronization therapy (CRT) on myocardial or interventricular systolic asynchrony derived by pulsed Doppler tissue imaging (PDTI) and pulsed flow Doppler imaging are scare. The purpose of this study was to evaluate ventricular inter‐ and left ventricular intraventricular systolic asynchrony and to describe the effects of CRT on Doppler imaging in patients with dilated cardiomyopathy (DCM) and reduced left ventricular ejection fraction (LVEF). Methods: 217 consecutive patients (96 patients with left bundle branch bloc[LBBB]) with DCM underwent a standard and PDTI echocardiography examination. We measured the interval between Q wave in the electrocardiogram and the beginning of the systolic velocity profile (Q ‐ Sb) recorded from the right and left ventricular outflow tract by pulsed Doppler imaging (PWD) and from 5 basal segments (right ventricle, septal‐, lateral‐, anterior‐, inferior left ventricle) by PDTI from an apical approach. In 18 patients a biventricular pacing system was implanted and the effect of the cardiac resynchronization therapy was evaluated 1 month after implantation by echo examination. Results: A high‐grade interventricular systolic asynchrony (> 60 ms) was measured in 3 patients (2.5%) without LBBB versus 33 patients (16%) with LBBB. A severe left ventricular intraventricular systolic asynchrony (> 60 ms) was documented in 33 patients (27%) without LBBB versus 27 patients (28%) with LBBB. CRT in 18 patients reduced the interventricular systolic asynchrony from 52 ± 29 (20–116) ms to 14 ± 10 (0–32) ms (p < 0.01). Left ventricular intraventricular systolic asynchrony was reduced from 87 ± 35 (42–168) ms to 29 ± 14 (4–52) ms (p < 0.001). All patients with CRT showed an improvement in NYHA functional status. Conclusions: Patients with LBBB and DCM showed a significant intense degree of interventricular systolic asynchrony compared with patients without LBBB. The incidence of high‐grade left ventricular intraventricular systolic asynchrony was not influenced by LBBB. CRT is able to reduce inter‐ and left ventricular intraventricular systolic asynchrony. We recommend the use of PWD and PDTI in all patients with DCM as an additional important selection criteria for CRT.