Cardiac resynchronization therapy in patients with narrow QRS

Conduction delay affecting 30-50% of patients with NYHA class III-IV heart failure (HF) mainly results from left bundle branch block and leads to deterioration of cardiac contractility through intra- and interventricular dyssynchrony. Cardiac resynchronization therapy (CRT) has class I recommendation for the treatment of patients with severe systolic HF who have left ventricular ejection fraction less or equal to 35%, QRS duration greater than or equal to 120 ms. Nevertheless some studies have shown that systolic asynchrony is present in 27-43% of HF patients with narrow QRS complexes (defined as <120 ms). We present here results of CRT in 20 patients (13 male, 7 female). Main indication for CRT was ventricular dyssynchrony during basic cardiac rhythm or cardiac pacing independently of QRS width. In 4 patients width of QRS complex was less than 120 ms, in 3 QRS varied from 120 to 149 ms pts and in 13 it was equal to or exceeded 150 ms. CRT in patients with narrow QRS resulted in clinical improvement associated with increase of cardiac contractility and decrease of left ventricular end systolic volume. This allows to conclude that CRT can be beneficial for HF patients with narrow QRS and ventricular dyssynchrony.     

Cardiac resynchronization therapy in patients with a narrow QRS complex.

OBJECTIVES: The purpose of this study was to evaluate the effects of cardiac resynchronization therapy (CRT) in heart failure patients with narrow QRS complex (<120 ms) and evidence of left ventricular (LV) dyssynchrony on tissue Doppler imaging (TDI). BACKGROUND: Cardiac resynchronization therapy is beneficial in selected heart failure patients with wide QRS complex (> or =120 ms). Patients with narrow QRS complex are currently not eligible for CRT, and the potential effects of CRT are not well studied. METHODS: Thirty-three consecutive patients with narrow QRS complex and 33 consecutive patients with wide QRS complex (control group) were prospectively included. All patients needed to have LV dyssynchrony > or =65 ms on TDI, New York Heart Association (NYHA) functional class III/IV heart failure, and LV ejection fraction < or =35%. RESULTS: Baseline characteristics, particularly LV dyssynchrony, were comparable between patients with narrow and wide QRS complex (110 +/- 8 ms vs. 175 +/- 22 ms; p = NS). No significant relationship was observed between baseline QRS duration and LV dyssynchrony (r = 0.21; p = NS). The improvement in clinical symptoms and LV reverse remodeling was comparable between patients with narrow and wide QRS complex (mean NYHA functional class reduction 0.9 +/- 0.6 vs. 1.1 +/- 0.6 [p = NS] and mean LV end-systolic volume reduction 39 +/- 34 ml vs. 44 +/- 46 ml [p = NS]). CONCLUSIONS: Cardiac resynchronization therapy appears to be beneficial in patients with narrow QRS complex and severe LV dyssynchrony on TDI, with similar improvement in symptoms and comparable LV reverse remodeling to patients with wide QRS complex. The current results need confirmation in larger patient cohorts.     

Cardiac resynchronization in narrow QRS and less affected exercise capacity

Cardiac resynchronization (CRT) through atrio-biventricular pacemaker therapy is now a well established treatment option for severely symptomatic patients with advanced systolic heart failure (HF) and intraventricular conduction delay, especially left bundle branch block. The purpose of this article is to address possible applications of biventricular pacing beyond the classical CRT indication. In particular, a summary is given of available information on CRT in patients with symptomatic systolic HF, but narrow QRS complex, and those with wide QRS, but less pronounced or even absent clinical HF signs.     

窄QRS波心力衰竭的心脏再同步化治疗

心脏再同步化治疗(CRT)对于伴QRS波时限延长的心力衰竭(心衰)患者有良好的效果,但对于伴窄QRS波心衰患者能否获益尚无定论.虽然多数临床试验表明,窄QRS心衰伴心室收缩不同步患者在CRT后临床症状改善、生活质量提高、死亡率下降,但尚缺乏大规模临床试验证实.组织多普勒技术可用于评价窄QRS波心衰患者的心室收缩同步性,...     

心脏再同步治疗在窄QRS波慢性心力衰竭患者的疗效观察

目的:观察窄QRS波慢性心力衰竭(CHF)患者的双心室再同步治疗的临床疗效。方法:筛选16例窄QRS波CHF患者行双心室再同步治疗,所有病例均经冠状静脉窦植入左心室导线至心脏静脉,术后平均随访1～43个月,平均13个月,观察心功能、左心室射血分数、二尖瓣反流面积、左心室舒张末和收缩末内径等的变化。结果:16例患者治疗后心功能明显改善,有效率75%,心功能从Ⅲ～Ⅳ级(NYHA分级)改善为Ⅱ～Ⅲ级,左心室射血分数从(0.31±0.11)%提高至(0.38±0.10)%,P0.05,每搏输出量从(74±8)ml提高至(96±4)ml,P0.05,二尖瓣反流面积从(8±4)cm2减少至(6±3)cm2,P0.05,左心室舒张末内径、收缩末内径虽有缩小趋势但没有显著差异[(69±7)mmvs.(68±9)mm;(59±10)mmvs.(56±11)mm]。结论:双心室再同步治疗对某些窄QRS波CHF患者同样有效。     

组织多普勒超声评价窄QRS间期患者心脏再同步治疗效果

目的组织多普勒超声（TDI）指导下评价窄QRS间期合并心室不同步患者行心脏再同步治疗（CRT）对临床预后的影响。方法91例经超声心动图和TD[确诊为心脏收缩不同步的慢件心力衰竭患者,按是否接受CRT分为CRT组（窄QRS间期21例,宽QRS间期22例）和对照组（宽QRS间期25例,窄QRS间期23例）。对所有患者进行1年的随访,评价心功能及生存率。结果CRT组6min步行试验、生活质量积分、心功能（NYHA分级）明显改善。超声心动图及TDI结果显示,CRT组左心室收缩未容积、左心室舒张末容积明显减少,射血分数明显增加。与各对照组亚组相比,CRT组中窄QRS亚组心功能改善,6min步行试验距离、左心室射血分数、生活质量积分明垃增加,左心室收缩末容积和左心窀舒张末容积明显减少。结论在TDI指导下,窄QRS间期慢性心力衰竭可以从CRT中获益。     

Beta-blocker therapy induces ventricular resynchronization in dilated cardiomyopathy with narrow QRS complex.

OBJECTIVES: We sought to evaluate the effects of beta-blocker therapy on regional and global myocardial mechanics in addition to ventricular synchrony in patients with heart failure and normal QRS by using tissue Doppler and strain echocardiography. BACKGROUND: It is unknown whether beta-blocker therapy can influence mechanical synchrony. METHODS: Conventional and strain echocardiography were performed in 15 healthy age-matched volunteers and in 25 patients with idiopathic dilated cardiomyopathy (IDC). Of these, 15 IDC patients on standard heart failure therapy were studied prior to and at 1 and 6 months after initiation of carvedilol therapy and compared to the controls. RESULTS: There was significant mechanical dyssynchrony in IDC compared with control patients. Patients placed on carvedilol demonstrated a significant decrease in the inferoseptal to lateral wall delay in peak strain (normalized to the R-R interval) between baseline and 1 month and between baseline and 6 months. Similarly, global time to peak segmental strain (455 +/- 51 ms vs. 423 +/- 59 ms, respectively, p = 0.02, and 455 +/- 51 ms vs. 415 +/- 50 ms, respectively, p = 0.01) and the coefficient of variation of the time to peak segmental strain decreased (17 +/- 4% vs. 15 +/- 5%, respectively, p = 0.02, and 17 +/- 4% vs. 14 +/- 5%, respectively, p = 0.03), from baseline to 1 month and between baseline and 6 months, respectively. Global strain significantly increased from baseline to 1 month (-8.2 +/- 1.8 to -10.4 +/- 3.9, respectively, p = 0.01) and between baseline and 6 months (-8.2 +/- 1.8% to -12.0 +/- 3.2%, respectively, p = 0.008). Improvements in left ventricular ejection fraction and reverse remodeling were coincident with reductions in mechanical dyssynchrony. CONCLUSIONS: The use of carvedilol improves contractile function and dyssynchrony in heart failure patients with normal QRS.     

Long-term effectiveness of cardiac resynchronization therapy in patients with refractory heart failure and "narrow" QRS

OBJECTIVES: The aim of the study was to evaluate the effectiveness of cardiac resynchronization therapy (CRT) in patients with refractory heart failure (HF) and incomplete left bundle branch block ("narrow" QRS), together with echocardiographic evidence of interventricular and intraventricular asynchrony. BACKGROUND: Cardiac resynchronization therapy has been proven effective in patients with HF and wide QRS by ameliorating contraction asynchrony. METHODS: Fifty-two patients with severe HF received biventricular pacing. The patients were eligible in the presence of echocardiographic evidence of interventricular and intraventricular asynchrony, regardless of QRS duration. The patient population was divided into group 1 (n = 38), with a QRS duration >120 ms, and group 2 (n = 14), with a QRS duration < or =120 ms. RESULTS: The baseline parameters considered in the study were similar in both groups. At follow-up, CRT determined narrowing of the QRS interval in the entire population and in group 1 (p < 0.001), whereas a small increase in QRS duration was observed in group 2 (p = NS); in all patients and within groups, we observed improvement of New York Heart Association functional class (p < 0.001 in all), left ventricular ejection fraction (p < 0.001 in all), left ventricular end-diastolic and end-systolic diameter (p < 0.05 within groups), mitral regurgitation area (p < 0.001 in all), interventricular delay (p < 0.001 in all), and deceleration time (group 1: p < 0.001, group 2: p < 0.05), with no significant difference between groups. The 6-min walking test improved in both groups (group 1: p < 0.001; group 2: p < 0.01). CONCLUSIONS: Cardiac resynchronization therapy determined clinical and functional benefit that was similar in patients with wide or "narrow" QRS. Cardiac resynchronization therapy may be helpful in patients with echocardiographic evidence of interventricular and intraventricular asynchrony and incomplete left bundle branch block.     

Cardiac resynchronization therapy in patients with chronic atrial fibrillation

Heart failure (HF) and atrial fibrillation (AF), 2 of the most common cardiovascular disorders, often coexist in the same patient, as 1 condition can lead to the other. The best approach to AF management in patients with HF is currently under investigation, but there seems to be an abundance of evidence in support of cardiac resynchronization therapy (CRT) in this group of patients. In addition, CRT is emerging as a superior option to stand-alone right ventricular pacing in patients with structural heart disease. However, in patients with AF, an adequate rate control is critical for this therapy to be highly effective. As control of the ventricular response can be difficult to achieve in many of those patients, often a nonpharmacologic intervention is required, such as ablation of the atrioventricular node to create heart block. The definitive role for CRT with or without atrioventricular nodal ablation in patients with AF and HF is yet to be studied in large, well-designed, randomized, controlled clinical trials.     

心脏再同步化治疗窄QRS波心力衰竭疗效研究

心力衰竭是大多数心血管疾病的最终归宿,心脏再同步化治疗(CRT)以其明显的疗效逐渐成为一种行之有效且具代表性的治疗手段。2008年ACC/AHA/HRS将CRT作为符合条件的心力衰竭患者治疗的Ⅰa类适应证(最佳药物治疗基础上NY-HA心功能Ⅲ级或Ⅳ级的心力衰竭患者,符合LVEF≤35%、QRS时限≥120ms、窦性心律),其中QRS时限要求≥120ms。窄QRS波心力衰竭患者是否也能从CRT中获益,目前仍存在很大争议。文章就CRT治疗窄QRS波心力衰竭的疗效研究作一概述。     

心力衰竭心脏再同步治疗

慢性心力衰竭的传统治疗为药物治疗，随着血管紧张素转化酶抑制剂、血管紧张素受体拮抗剂、β受体阻滞剂和醛固酮受体拮抗剂的广泛应用，心力衰竭患者的心功能有所改善，但其病死率仍居高不下。有文献报道，心力衰竭患者5年存活率与恶性肿瘤相似。近年来心力衰竭的非药物治疗，尤其是心脏再同步治疗（CRT）应用于中至重度患者，