The benefits of biventricular pacing in heart failure patients with narrow QRS, NYHA class II and right ventricular pacing

OBJECTIVE: To identify subgroups of heart failure patients who might benefit from biventricular pacing. BACKGROUND: Cardiac resynchronization therapy (CRT) improves the quality of life, New York Heart Association (NYHA) functional class, and exercise capacity and decreases hospitalizations for heart failure for patients who have severe heart failure and a wide QRS. It is unclear if other populations of heart failure patients would benefit from CRT. METHODS: One hundred forty-four consecutive heart failure patients who underwent CRT and completed 3 months of follow-up were reviewed. Demographic, echocardiographic, electrocardiographic, and clinical outcome data were analyzed to assess the relationship of functional class and QRS duration before device implantation to postimplant outcomes. RESULTS: There were 20, 88, and 36 patients in NYHA functional class II, III, and IV, respectively. Thirty-four patients had right ventricular pacing and another 29 patients had a QRS duration < or = 150 ms. Patients who were in NYHA functional class II at baseline had significant improvement in left ventricular ejection fraction and indices of left ventricular remodeling after CRT. Similar significant findings were seen in the subgroup with right ventricular pacing at baseline after CRT. However, in the subgroup with a narrow QRS duration, there were no significant changes in the indices of left ventricular remodeling or in the NYHA functional class and there was a significant increase in the QRS duration. For the study cohort as a whole, an improvement in NYHA functional class after CRT correlated with a significant decrease in adverse clinical outcomes. CONCLUSIONS: Heart failure patients who were in NYHA functional class II and those with right ventricular pacing appeared to benefit from CRT.     

Predictors of a positive response to biventricular pacing in patients with severe heart failure and ventricular conduction delay

BACKGROUND: Cardiac resynchronization therapy (CRT) is recommended in patients with ejection fraction <35%, QRS width> 120 ms, and New York Heart Association (NYHA) functional class III or IV despite optimal medical therapy. We aimed to define demographic, clinical, and electrocardiographic predictors of positive clinical response to CRT. METHODS AND RESULTS: Hundred consecutive patients fulfilling the recommended criteria were implanted with a CRT device. Demographic, clinical, two-dimensional echocardiographic and electrographic parameters were measured at baseline and after 6 months of simultaneous biventricular pacing. A positive response to CRT included an improvement of at least one NYHA functional class associated with an absence of hospitalization for worsening heart failure. At the end of follow-up, 12 patients were dead and 71% of the patients were classified as responders. After 6 months of CRT, the ejection fraction was significantly higher (P = 0.035) in responders versus nonresponders. Multivariate analysis identified three independent predictors of positive response to CRT: an idiopathic origin of the cardiomyopathy (P = 0.043), a wider QRS before implantation (P = 0.017), and a narrowing of the QRS after implantation (P = 0.037). CONCLUSION: An idiopathic origin of the cardiomyopathy, a wider QRS before implantation, and a narrowing of the QRS width after implantation were identified as independent predictors of clinical positive response to CRT.     

Poster Session 2–3: Cardiac Resynchronization Therapy Monday, April 3, 2006, 4:00–5:30pm

Dr. Gabe Bleeker ¹ , Martin Schalij ¹ , Eduard Holman ¹ , Paul Steendijk ¹ , Ernst van der Wall ¹ , Jeroen Bax ^{1   1} Cardiology, Leiden University Medical Center, Leiden, The Netherlands
Background: Cardiac resynchronization therapy (CRT) is beneficial in selected patients with moderate-to-severe heart failure (New York Heart Association (NYHA) class III/IV). Patients with mildly symptomatic heart failure (NYHA class II) are currently not eligible for CRT and potential beneficial effects in these patients are not well studied. Methods: Fifty consecutive patients with NYHA class II heart failure and 50 consecutive NYHA class III/IV patients (control group) were prospectively included. All patients had left ventricular ejection fraction (LVEF) ≤ 35% and QRS duration >120 ms. The effects of CRT in NYHA class II patients were compared to results obtained in the control group. Results: The severity of baseline LV dyssynchrony was comparable between patients in NYHA class II vs NYHA class III/IV (83 ± 49 ms vs 96 ± 51 ms, ns), and resynchronization was achieved in both groups. NYHA class II patients showed a significant improvement in LVEF (from 25 ± 7% to 33 ± 10%, P < 0.001) and reduction in LV end-systolic volume (from 168 ± 55 ml to 132 ± 51 ml, P < 0.001) following CRT, similar to patients in NYHA class III/IV. In addition, only 8% of NYHA class II patients showed progression in heart failure symptoms. Conclusions: CRT has comparable effects in patients with NYHA class II and NYHA class III/IV heart failure in terms of LV resynchronization, improvement in LVEF, and LV reverse remodeling.     

SPECT and Cardiac Resynchronization Therapy

Cardiac resynchronization therapy (CRT) has proven benefits in patients with refractory heart failure including improved symptoms, exercise capacity, quality of life, and left ventricular (LV) function, and mortality benefits. At present, CRT is recommended in patients with severe refractory heart failure (New York Heart Association class III or IV), LV ejection fraction ≤ 35%, QRS duration ≥ 120 ms, and sinus rhythm. When selected based on these standard indications, 20% to 40% of patients fail to respond to CRT. Important parameters for predicting CRT response, such as LV mechanical dyssynchrony, myocardial scar, and LV pacing lead position, have been studied using phase analysis of gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). This review aims to describe the role of gated SPECT MPI for the comprehensive assessment of those parameters for selection of patients for CRT.     

How Many Patients with Dilated Cardiomyopathy May Potentially Benefit from Cardiac Resynchronization Therapy?

GRIMM, W., et al .: How Many Patients with Dilated Cardiomyopathy May Potentially Benefit from Cardiac Resynchronization Therapy? The clinical and electrocardiographic Marburg Cardiomyopathy database was analyzed to identify potential candidates for cardiac resynchronization therapy (CRT) with biventricular or left ventricular pacing among 566 patients with dilated cardiomyopathy (DCM). All of the following restrictive selection criteria were fulfilled by 38 patients (7%): NYHA functional class ≥ 3 (   n = 193   , 34%), left ventricular ejection fraction (LVEF) <30% (n = 238, 42%), sinus rhythm (   n = 437   , 77%), left bundle branch block (LBBB,   n = 142   , 25%), and QRS duration ≥ 150 ms (   n = 136   , 24%). In 78 of the 566 patients (14%) all of the following less restrictive selection criteria were fulfilled: NYHA functional class ≥3 (   n = 193   , 34%), LVEF < 35% in presence of any underlying rhythm (n = 326, 58%), QRS duration ≥ 120 ms with right or left bundle branch block (   n = 223   , 39%). Thus, between 7% and 14% of patients with DCM were candidates for CRT depending on the application of strict versus less restrictive selection criteria.(PACE 2003; 26[Pt. II]:155–157)     

Prevalence of mechanical dyssynchrony in heart failure patients with different QRS durations

BACKGROUND: Cardiac resynchronization therapy (CRT) has emerged as an established therapy for congestive heart failure. However, up to 30% of patients fail to respond to CRT despite prolonged QRS. OBJECTIVES: This study aimed at defining the prevalence of interventricular and intraventricular dyssynchrony in heart failure patients with different QRS durations. METHODS: A total of 123 consecutive patients with severe heart failure (LVEF < 35% and NYHA class III-IV) were prospectively evaluated using 12-lead electrocardiogram and complete echocardiographic examination including tissue Doppler imaging. RESULTS: According to the QRS duration, 56 patients had a QRS duration < or = 120 ms (Group 1), 33 patients had a QRS duration between 120 and 150 ms (Group 2), and 34 patients had a QRS duration > or = 150 ms (Group 3). Intraventricular dyssynchrony was present in 36% of Group 1 patients, in 58% of Group 2 patients, and in 79% of Group 3 patients (P < 0.000). Linear regression demonstrated a weak relation between QRS and intraventricular dyssynchrony. A greater proportion of patients with interventricular dyssynchrony was observed in Group 3 or Group 2 compared to patients with normal QRS duration (32% in Group 1 vs. 51.5% in Group 2 vs. 76.5% in Group 3, P < 0.000). Linear regression demonstrated a significant relation between QRS duration and interventricular mechanical delay. CONCLUSIONS: Although both interventricular and intraventricular dyssynchrony increased with the increasing QRS duration, the correlation between intraventricular mechanical and electrical dyssynchrony was weak. The lack of intraventricular dyssynchrony in a fraction of patients with standard CRT indication by QRS duration may provide us insight into the nonresponders rates.     

Does a Gender Difference in Response to Cardiac Resynchronization Therapy Exist?

BACKGROUND: Cardiac resynchronization therapy (CRT) has a beneficial effect on clinical symptoms, exercise capacity, and systolic left ventricular (LV) performance in patients with heart failure. The aim of the current study was to evaluate whether a gender difference exists in response to CRT. METHODS: Consecutive patients with end-stage heart failure (New York Heart Association, NYHA, class III-IV), LV ejection fraction (LVEF) < or =35%, QRS duration >120 ms, and left bundle branch block configuration underwent CRT. At baseline and 6 months post-CRT, clinical and echocardiographic parameters were evaluated; follow-up was obtained up to 5 years. The effects of CRT were compared between women and men. RESULTS: The study population comprised 137 men and 36 women (mean age 66 +/- 11 years). No differences in baseline characteristics were observed except that nonischemic cardiomyopathy was more frequent in women than men (67% vs 38%, P < 0.05). In all patients, clinical and echocardiographic parameters improved significantly at 6-month follow-up. The magnitude of improvement in different parameters was similar between women and men, e.g., the improvement in NYHA Class was 0.9 +/- 0.6 in women and 1.0 +/- 0.7 in men (NS) and the increase in LVEF was 8 +/- 8% in women as compared to 7 +/- 9% in men (NS). The percentage of individual responders was not different between women and men (76% vs 80%, NS) and 2-year survival was comparable for women and men (84% vs 80%, NS). CONCLUSION: No gender differences were observed in response to CRT and long-term survival after CRT.     

Evidence for electrical remodeling of the native conduction system with cardiac resynchronization therapy

BACKGROUND: Cardiac resynchronization therapy (CRT) improves hemodynamics and decreases heart failure symptoms. However, the potential of CRT to bring about electrical remodeling of the heart has not been investigated. METHODS AND RESULTS: We studied 25 patients, of whom 17 had a nonischemic cardiomyopathy, and 8 had an ischemic cardiomyopathy; 16 had left bundle branch block (LBBB), 1 right bundle branch block (RBBB), and 8 nonspecific intraventricular conduction delay. During routine device clinic visits, patients with chronic biventricular pacing (>6 months) were reprogrammed to VVI 40 to allow for native conduction to resume. After 5 minutes of native rhythm, a surface electrocardiogram (ECG) was recorded, and then the previous device settings were restored. This ECG was compared to the preimplant ECG. Preimplant mean ejection fraction was 19% (range, 10%-35%), and follow-up mean ejection fraction was 35% (12.5%-65%). Mean time from implant to follow-up ECG was 14 months (range, 6-31). The QRS interval prior to CRT was 155 +/- 29 ms, and shortened to 144 +/- 31 ms (P = 0.0006), and the QRS axis shifted from -1 +/- 59 to -26 +/- 53 (P = 0.03). There was no significant change in PR or QTc interval, or in heart rate. CONCLUSION: CRT leads to a decrease in the surface QRS duration, without affecting other surface ECG parameters. The reduced electrical activation time may reflect changes in the specialized conduction system or in intramyocardial impulse transmission.     

Male gender and chronic obstructive pulmonary disease predict a poor clinical response in patients undergoing cardiac resynchronisation therapy

Aims: Current guidelines advocate cardiac resynchronisation therapy (CRT) in patients with class III/IV New York Heart Association (NYHA) heart failure, depressed left ventricular function and a broad QRS. However, a significant proportion of patients do not derive any benefit from CRT. The aim of this study was to identify clinical, electrocardiographic and echocardiographic predictors of response to CRT. Methods: A retrospective analysis of patients undergoing CRT in our institution was performed. A favourable clinical response to CRT was defined as an improvement in NYHA Heart failure class of ≥ 1 and lack of hospitalisation with heart failure. Comparisons were made between responders and non‐responders in terms of baseline characteristics and potential predictors of CRT response (QRS width, presence of left bundle branch block, atrial fibrillation, evidence of mechanical dyssynchrony on echocardiography and LV lead position). Results: A total of 164 patients had full follow‐up data. The mean follow‐up was 293 days. Of patients undergoing CRT, 90 (58.9%) had a favourable clinical response to CRT. Predictors of a lack of clinical response to CRT were male gender (p = 0.012) and chronic obstructive pulmonary disease (COPD) (0.008). Pre‐implant echocardiographic dyssynchrony assessment appeared not to predict response to CRT (p = 0.87); however, there was a trend towards a positive response in those patients with significant dyssynchrony (p = 0.09) defined as interventricular delay > 40 ms or maximal LV delay of > 80 ms. Conclusion: Male gender and coexisting COPD were shown to be independent predictors of non‐response to CRT in this cohort of patients fulfilling current criteria for CRT.     

Cardiac resynchronization therapy response is associated with shorter duration of atrial fibrillation

BACKGROUND: Atrial fibrillation (AF) is commonly associated with heart failure. The benefit of cardiac resynchronization therapy (CRT) on atrial remodeling has been demonstrated. However, biventricular pacing did not reduce the global incidence of AF. We evaluated the relationship between CRT response and AF duration. METHODS: We retrospectively analyzed data from 96 patients (59 +/- 15 years; 78% male) who underwent CRT. All patients had class III-IV New York Heart Association (NYHA) symptoms despite maximal medical therapy, left ventricular ejection fraction (LVEF) < or = 35%, QRS >130 ms, and sinus rhythm before implantation. CRT response in patients who survived at six months of follow-up was defined as: (1) no hospitalization for heart failure and (2) improvement of one or more grades in the NYHA classification. RESULTS: CRT responders (n = 54) and non-responders (n = 42) had similar baseline characteristics, including the incidence of persistent AF within six months before implantation. Six months after implantation, when compared to baseline, CRT responders exhibited a significant decrease in left atrial size (47.5 +/- 7.1 mm vs 44.6 +/- 7.7 mm, P < 0.01) and in the incidence of persistent AF (17% vs 2%, P = 0.02). At six months, CRT responders demonstrated shorter mean AF duration (7.5 +/- 43.3 hours vs 48.8 +/- 129.0 hours, P = 0.03) and lower incidence of persistent AF (2% vs 19%, P = 0.004) compared to nonresponders. CONCLUSION: CRT response is associated with a reversal of atrial remodeling and a shorter AF duration.     

Cardiac Resynchronization Therapy in Patients with Mildly Impaired Left Ventricular Function

Aims: We sought to determine the unknown effects of cardiac resynchronization therapy (CRT) in patients with a left ventricular ejection fraction (LVEF) >35%. Because of its technical limitations, echocardiography (Echo) may underestimate LVEF, compared with cardiovascular magnetic resonance (CMR).
Methods: Of 157 patients undergoing CRT (New York Heart Association [NYHA] functional class III or IV, QRS ≥ 120 ms), all of whom had a preimplant Echo-LVEF ≤35%, 130 had a CMR-LVEF ≤35% (Group A, 19.7 ± 7.0%[mean ± standard deviation]) and 27 had a CMR-LVEF >35% (Group B, 43.6 ± 7.7%). All patients underwent a CMR scan at baseline and a clinical evaluation, including a 6-minute walk test and a quality of life questionnaire, at baseline and after CRT.
Results: Both groups derived similar improvements in NYHA functional class (A =−1.3, B =−1.2, [mean]), quality of life scores (A =−21.6, B =−33.0; all P < 0.0001 for changes from baseline), and 6-minute walking distance (A = 64.5, B = 70.1 m; P < 0.001 and P < 0.0001, respectively). Symptomatic response rates (increase by ≥1 NYHA classes or 25% 6-minute walking distance) were 79% in group A and 92% in group B. Over a maximum follow-up period of 5.9 years for events, patients in group A were at a higher risk of death from any cause, hospitalization for major cardiovascular events (P = 0.0232), or cardiovascular death (P = 0.0411). There were borderline differences in the risk of death from any cause (P = 0.0664) and cardiovascular death or hospitalization for heart failure (P = 0.0526).
Conclusions: This observational study suggests that the benefits of CRT extend to patients with a LVEF > 35%.     

Time course of effects of cardiac resynchronization therapy in chronic heart failure: benefits in patients with preserved exercise capacity

Objectives: To assess in patients with chronic heart failure the effect of cardiac resynchronization therapy (CRT) over 12 months' follow-up the time course of the changes in functional and neurohormonal indices and to identify responders to CRT.
Methods: Eighty-nine patients (74.1 ± 1 years, left ventricular ejection fraction [LVEF] < 35%), QRS complex duration >150 ms, in stable New York Heart Association (NYHA) class III or IV on optimal medical treatment were prospectively randomized either in a control (n = 45) or CRT (n = 44) group and underwent clinical evaluation, cardiopulmonary exercise testing (CPET), 2D-Echo, heart rate variability (HRV), carotid baroreflex (BRS), and BNP assessments before and at 6- and 12-month follow-up.
Results: In the CRT group, improvement of cardiac indices and BNP concentration were evident at medium term (over 6 months) follow-up, and these changes persisted on a longer term (12 months) (all P < 0.05). Instead CPET indices and NYHA class improved after 12 months associated with restoration of HRV and BRS (all P < 0.05). We identified 26 responders to CRT according to changes in LVEF and diameters. Responders presented less depressed hemodynamic (LVEF 25 ± 1.0 vs 22 ± 0.1%), functional (peak VO₂ 10.2 ± 0.2 vs 6.9 ± 0.3 ml/kg/min), and neurohormonal indices (HRV 203.6 ± 15.7 vs 147.6 ± 10.ms, BRS 4.9 ± 0.2 vs 3.6 ± 0.3 ms/mmHg) (all P < 0.05). In the multivariate analysis, peak VO₂ was the strongest predictor of responders.
Conclusions: Improvement in functional status is associated with restoration of neurohormonal reflex control at medium term. Less depressed functional status (peak VO₂) was the strongest predictor of responders to CRT.     

Biventricular pacing for treating heart failure in children: A case report and review of the literature

BACKGROUND Cardiac resynchronization therapy(CRT) can be used as an escalated therapy to improve heart function in patients with cardiac dysfunction due to long-term right ventricular pacing. However, guidelines are only targeted at adults. CRT is rarely used in children.CASE SUMMARY This case aimed to implement biventricular pacing in one child with heart failure who had a left ventricular ejection fraction < 35% at 4 years after implantation of an atrioventricular sequential pacemaker due to atrioventricular block.Postoperatively, echocardiography showed atrial sensing ventricular pacing and QRS wave duration of 120-130 ms, and cardiac function significantly improved after upgrading pacemaker.CONCLUSION Patients whose cardiac function is deteriorated to a level to upgrade to CRT should be upgraded to reverse myocardial remodeling as soon as possible.     

Greater three-dimensional ventricular lead tip separation is associated with improved outcome after cardiac resynchronization therapy

Background: Effective cardiac resynchronization therapy (CRT) is more likely with widely separated left ventricular (LV) and right ventricular (RV) pacing leads tips. We hypothesized that lead separation is an important factor in determining the clinical response to CRT. Methods: A retrospective study of 86 consecutive patients age 71 ± 10 years, male (74%), coronary disease (71%), atrial fibrillation (23%), LV ejection fraction (22 ± 9%), QRS duration (160 ± 27 ms), New York Heart Association (NYHA) class III (81%), NYHA class IV (19%) undergoing CRT from January 2006 to September 2008. The median follow‐up was 12 months and clinical response to CRT was defined as reduction of NYHA class by one or more. The three‐dimensional separation between RV and LV pacing lead tips was calculated using measurements obtained from orthogonal posteroanterior and lateral chest radiographs performed the day after implantation. Results: Fifty‐nine patients (69%) responded to CRT. There was a statistically significant association between increased three‐dimensional lead separation and clinical response to CRT (P= 0.005). Stronger association was obtained when lead separation was corrected for cardiac size (P= 0.001). A significantly higher response rate of 88% was achieved in patients with QRS duration of 160 ms or more, and lead separation of 100 mm or more compared with 60% when lead separation was less than 100 mm and QRS duration remained the same (P = 0.027). Conclusions: Greater three‐dimensional separation of LV‐to‐RV leads is associated with improved response to CRT. A prospective multicenter trial is needed to assess lead separation as a predictor for response. (PACE 2010; 33:1490–1496)     

Treatment of heart failure with decreased left ventricular ejection fraction

Original Article Class I recommendations for treating patients with current or prior symptoms of heart failure with reduced left ventricular ejection fraction (LVEF) include using diuretics and salt restriction in individuals with fluid retention. Use angiotensin-converting enzyme (ACE) inhibitors, beta blockers, and angiotensin II receptor blockers if intolerant to ACE inhibitors because of cough or angioneurotic edema. Nonsteroidal anti-inflammatory drugs, most antiarrhythmic drugs, and calcium channel blockers should be avoided or withdrawn. Exercise training is recommended. Implant cardioverter-defibrillator (ICD) is recommended in individuals with a history of cardiac arrest, ventricular fibrillation, or hemodynamically unstable ventricular tachycardia. ICD is indicated in patients with ischemic heart disease for at least 40 d post-myocardial infarction or nonischemic cardiomyopathy, an LVEF of 30% or less, New York Heart Association (NYHA) class II or III symptoms on optimal medical therapy, and an expectation of survival of at least 1 yr. Cardiac resynchronization therapy should be used in individuals with an LVEF of 35% or below, NYHA class III or IV symptoms despite optimal therapy, and a QRS duration greater than 120 ms. An aldosterone antagonist can be added in selected patients with moderately severe to severe symptoms of heart failure who can be carefully monitored for renal function and potassium concentration (serum creatinine should be ≶2.5 mg/dL in men and ≶2.0 mg/dL in women; serum potassium should be <5.0 mEq/L).     

CRT治疗患者心室复极异质性指标的变化及不同起搏部位的影响

目的探讨心脏再同步化治疗患者心室复极异质性指标的变化以及不同部位起搏对心室复极异质性指标的影响。方法22例难治性心力衰竭患者,纽约心功能协会(NYHA)心功能分级Ⅲ~Ⅳ级,左心室射血分数(LVEF)≤35%,左心室舒张末内径(LVEDD)>55 mm,QRS波时限>120 ms,组织多普勒显像(TDI)证实心脏机械活动不同步,且经最优化药物治疗无效,行心脏再同步化治疗(CRT)后定期随访。以常规体表12导联心电图QT离散度及Tpeak-end间期以及Tpeak-end离散度作为心室复极异质性的指标。于CRT术前、术后1、3、6、12个月,分别在右室起搏、左室起搏、双室起搏三种不同起搏模式下测量心室复极异质性指标。结果QT离散度及Tpeak-end、Tpeak-end离散度在双室起搏时最小,左室起搏时最大,双室起搏与右室起搏之间没有统计学差异;CRT治疗后心室复极异质性指标明显改善,并且随着时间延长,心室复极异质性指标逐渐变小。结论CRT治疗可以明显改善心室复极异质性,右室起搏下心室复极异质性指标与双室起搏相似,但左室起搏则明显增加心室复极异质性指标。     

Use of beta-blockers in congestive heart failure

While beta-adrenergic blockers have been used for decades in a variety of cardiovascular illnesses, they have traditionally been avoided in chronic heart failure. In spite of significant advances in management, mortality in patients suffering from heart failure remains unacceptably high and new therapies are urgently needed. Recently, several large clinical trials have shown a significant reduction in both morbidity and mortality in heart failure patients when beta-blockers are added to standard therapy. While further investigation is warranted in certain subgroups, the use of beta-adrenergic blockers in New York Heart Association (NYHA) class II to IV heart failure should now be considered routine. The purpose of this article is to outline and review the five major clinical trials of beta-blocker therapy in chronic heart failure; the US Carvedilol heart failure Program (USCP), the Cardiac Insufficiency Bisoprolol Study II (CIBIS-II), the Metoprolol CR/XL Randomized Intervention Trial in chronic Heart Failure (MERIT-HF), the Beta-blocker Evaluation of Survival Trial (BEST) and the Carvedilol Prospective Randomized Cumulative Survival trial (COPERNICUS), and to aid the reader in the selection of appropriate candidates for beta-blocker therapy.     

Three Years of Cardiac Resynchronization Therapy: Could Superior Benefits be Obtained in Patients with Heart Failure and Narrow QRS?

Aim of the study: To examine the long-term effects of cardiac resynchronization therapy (CRT) in patients presenting with heart failure (HF) and QRS ≤120 ms.
Methods: This was a prospective, longitudinal study of 376 patients [mean age = 65 years, mean left ventricular (LV) ejection fraction (EF) = 29%, mean QRS duration =165 ms, mean distance covered during a 6-minute hall walk (6-MHW) = 325 m], who underwent successful implantation of CRT systems. The QRS duration at baseline was ≤120 ms in 45 patients (12%) who were not pre-selected by echocardiographic criteria of dyssynchrony, and >120 ms in the remaining 331 patients. The baseline characteristics of the 2 groups were similar. We evaluated indices of cardiac function, percentage of responders, and survival rates over a mean 28-month follow-up.
Results: Both groups experienced similar long-term increases in 6-MHW, and decreases in New York Heart Association functional class and LV end-systolic volume (all comparisons P < 0.0001 in both groups). Time interaction of changes in LVEF and percentage of responders were significantly different (P = 0.03 and P = 0.004, respectively), in favor of the narrow QRS group, where the changes were sustained and persisted at 2 and 3 years. The long-term death rate from HF was lower in the group with narrow than in the group with wide QRS complex (P = 0.04; log-rank test).
Conclusions: CRT confers considerable long-term clinical, functional, and survival benefits in patients presenting with HF and narrow QRS, not preselected by echocardiographic criteria of dyssynchrony. Caution is advised before denying CRT to these patients on the basis of QRS width only.     

Effect of posterolateral left ventricular scar on mortality and morbidity following cardiac resynchronization therapy

OBJECTIVES: To determine the effect of a posterolateral (PL) left ventricular scar on mortality and morbidity following cardiac resynchronization therapy (CRT). METHODS: Sixty-two patients with heart failure (age 67.3 +/- 9.6 yrs [mean +/- SD], 45 males, New York Heart Association class [NYHA] class III or IV, left ventricular ejection fraction [LVEF]= 35%, left bundle branch block, QRS > or = 120 ms) underwent late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) for scar imaging. Patients were followed up for 741 (75-1602) days (mean [range]). RESULTS: The presence of a PL scar emerged as an independent predictor of the composite endpoint of cardiovascular death or hospitalization for worsening heart failure (HR: 3.06 [1.63, 7.7, P < 0.0001]) as well as the endpoint of cardiovascular death (HR: 2.63 [1.39, 6.65], P = 0.0016). A transmural PL scar was the strongest predictor of these endpoints (both P < 0.0001). The symptomatic responder rate (improvement by > or =1 NYHA classes or > or =25% in 6-min walking distance) was 83% in the group with non-PL scars, but only 47% in the group with transmural PL scars (P < 0.0001). Pacing over the scar was associated with a higher mortality and morbidity than pacing outside the scar (all P < 0.05). CONCLUSIONS: A PL scar is associated with a worse clinical outcome following CRT, particularly if it is transmural. Pacing scarred left ventricular myocardium carries a greater risk of mortality and morbidity than pacing nonscarred myocardium.     

Long-Term Survival in Patients Treated with Cardiac Resynchronization Therapy: A 3-Year Follow-Up Study from the InSync/InSync ICD Italian Registry

Background: Studies reporting the long-term survival of patients treated with cardiac resynchronization therapy (CRT) outside the realm of randomized controlled trials are still lacking. The aim of this study was to quantify the survival of patients treated with CRT in clinical practice and to investigate the long-term effects of CRT on clinical status and echocardiographic parameters.
Methods: The study population consisted of 317 consecutive patients with implanted CRT devices from eight Italian University/Teaching Hospitals. The patients were enrolled in a national observational registry and had a minimum follow-up of 2 years. A visit was performed in surviving patients and mortality data were obtained by hospital file review or direct telephone contact.
Results: During the study period, 83 (26%) patients died. The rate of all-cause mortality was significantly higher in ischemic than nonischemic patients (14% vs 8%, P = 0.002). Multivariate analysis showed that ischemic etiology (HR 1.72, CI 1.06–2.79; P = 0.028) and New York Heart Association (NYHA) class IV (HR 2.87, CI 1.24–6.64; P = 0.014) were the strongest predictors of all-cause mortality. The effects of CRT persisted at long-term follow-up (for at least 2 years) in terms of NYHA class improvement, increase of left ventricular ejection fraction, decrease of QRS duration (all P = 0.0001), and reduction of left ventricular end-diastolic and end-systolic diameters (P = 0.024 and P = 0.011, respectively).
Conclusions: During long-term (3 years) follow-up after CRT, total mortality rate was 10%/year. The outcome of ischemic patients was worse mainly due to a higher rate of death from progressive heart failure. Ischemic etiology along with NYHA class IV was identified as predictors of death. Benefits of CRT in terms of clinical function and echocardiographic parameters persisted at the time of long-term follow-up.