斑点追踪显像对慢性心力衰竭患者心脏再同步化治疗短期疗效的评价

目的 探讨超声斑点追踪显像(STI)技术对慢性心力衰竭患者心脏再同步化治疗(CRT)短期疗效的评价价值.方法 16例慢性心力衰竭患者,获取心尖长轴观测量各节段收缩期纵向应变达峰时间、径向应变达峰时间,胸骨旁短轴观测环向应变达峰时间,计算CRT术后1个月、术后3个月18节段纵向、径向、环向应变达峰时间标准差(LS-SD18、RS-SD18、CS-SD18),左室各节段收缩期纵向、径向、环向应变达峰时间最大差值(LS-dif、RS-dif、CS-dif)作为应变非同步指标.将术后3个月、1个月18节段纵向、径向、环向应变达峰时间标准差与术前的差值(△LS-SD18、△RS-SD18、ACS-SD18)与术后3个月、1个月左室收缩末容积减少百分比(△ESV%)进行相关性分析.结果 CRT后1个月、术后3个月LS-SD18、RS-SD18、CS-SD18及RS-dif较术前显著减少,差异有统计学意义(P<0.05);术后3个月△RS-SD18与术后3个月△ESV%具有明显的相关性(r=0.694).结论 应变非同步指标对评价短期CRT后机械非同步性具有重要意义.     

三维斑点追踪成像技术预测心脏再同步化治疗短期疗效的研究

目的探讨三维斑点追踪成像（3DT）技术评价左心室收缩同步性,预测心脏再同步化治疗（CRT）短期疗效的临床价值。方法接受CRT治疗的心力衰竭患者18例,于CRT术前及术后1个月用常规超声测量左心室舒张末期容积（LVEDV）、收缩末期容积（LVESV）及射血分数（LVEF）。采用3DT技术分析左心室16节段面积应变达峰时间最大差（A—Max-Ts）和标准差（A—Ts—sD）。将术后LVESV缩小≥15％定义为CRT短期治疗有效。18例患者中,CRT短期治疗有效组11例,CRT短期治疗无效组7例。结果与术前比较,有效组术后LVEDV和LVESV减小,LVEF增高,A—Max—Ts和A-Ts-SD缩短（P〈0．05）;无效组各参数比较差异均无统计学意义。有效组术前A—Max—Ts和A—Ts-SD大于无效组（P〈0．05）,其余参数比较差异均无统计学意义。有效组术后LVEDV和LVESV较无效组减小,LVEF增高,A—Max—Ts和A—Ts-SD缩短（P〈0．05）。A—Ts—SD是预测LVESV≥15％的独立因素,A—Ts-SD为48．2ms时预测CRT短期疗效的敏感性和特异性分别为100％和83．3％。结论CRT短期即可改善左心室收缩同步性。3DT技术能准确评价左心室收缩同步性,预测CRT短期疗效。     

Prediction of response to cardiac resynchronization therapy using left ventricular pacing lead position and cardiovascular magnetic resonance derived wall motion patterns: a prospective cohort study

Background

Despite marked benefits in many heart failure patients, a considerable proportion of patients treated with cardiac resynchronization therapy (CRT) fail to respond appropriately. Recently, a “U-shaped” (type II) wall motion pattern identified by cardiovascular magnetic resonance (CMR) has been associated with improved CRT response compared to a homogenous (type I) wall motion pattern. There is also evidence that a left ventricular (LV) lead localized to the latest contracting LV site predicts superior response, compared to an LV lead localized remotely from the latest contracting LV site.

Methods

We prospectively evaluated patients undergoing CRT with pre-procedural CMR to determine the presence of type I and type II wall motion patterns and pre-procedural echocardiography to determine end systolic volume (ESV). We assessed the final LV lead position on post-procedural fluoroscopic images to determine whether the lead was positioned concordant to or remote from the latest contracting LV site. CRT response was defined as a ≥ 15 % reduction in ESV on a 6 month follow-up echocardiogram.

Results

The study included 33 patients meeting conventional indications for CRT with a mean New York Heart Association class of 2.8 ± 0.4 and mean LV ejection fraction of 28 ± 9 %. Overall, 55 % of patients were echocardiographic responders by ESV criteria. Patients with both a type II pattern and an LV lead concordant to the latest contracting site (T2CL) had a response rate of 92 %, compared to a response rate of 33 % for those without T2CL (p = 0.003). T2CL was the only independent predictor of response on multivariate analysis (odds ratio 18, 95 % confidence interval 1.6-206; p = 0.018). T2CL resulted in significant incremental improvement in prediction of echocardiographic response (increase in the area under the receiver operator curve from 0.69 to 0.84; p = 0.038).

Conclusions

The presence of a type II wall motion pattern on CMR and a concordant LV lead predicts superior CRT response. Improving patient selection by evaluating wall motion pattern and targeting LV lead placement may ultimately improve the response rate to CRT.     

Echo Doppler parameters predict response to cardiac resynchronization therapy

Background  Cardiac resynchronization therapy (CRT) has been shown to reduce heart failure related morbidity and mortality. However, approximately 30% of patients do not respond to CRT. We investigated the usefulness of Echo Doppler parameters to predict reverse remodelling, functional improvement and mortality following CRT.
Materials and methods  Our population consists of 200 consecutive heart failure patients evaluated for ventricular dyssynchrony by echocardiography between February 1999 and May 2007 who subsequently received CRT. Patients were reassessed for signs of reverse remodelling after a mean follow-up of 10 months. Information on vital status was obtained from local registration authorities.
Results  Three parameters significantly predicted reverse remodelling in the logistic regression analysis: the Q-to-E-wave-delay (QED) at a cutoff of 550 ms (odds ratio 4·5, P -value 0·001), the interventricular mechanical delay (IVMD) at a cutoff of 60 ms (odds ratio 2·4, P -value 0·02), and the aortic electromechanical delay (A-EMD) at a cutoff of 140 ms (odds ratio 2·9, P -value 0·004). Furthermore, the QED and the IVMD also predicted all-cause mortality (hazard ratio 0·36, P -value 0·02 and 0·21, P -value 0·004, respectively). Adjustment for confounders did not alter the results.
Conclusions  The QED and IVMD predict reverse remodelling and survival following CRT. These parameters are easy to obtain, provide valuable prognostic information, and should thus be measured in CRT candidates evaluated by echocardiography.     

A prospective evaluation of cardiovascular magnetic resonance measures of dyssynchrony in the prediction of response to cardiac resynchronization therapy

Background

Many patients with electrical dyssynchrony who undergo cardiac resynchronization therapy (CRT) do not obtain substantial benefit. Assessing mechanical dyssynchrony may improve patient selection. Results from studies using echocardiographic imaging to measure dyssynchrony have ultimately proved disappointing. We sought to evaluate cardiac motion in patients with heart failure and electrical dyssynchrony using cardiovascular magnetic resonance (CMR). We developed a framework for comparing measures of myocardial mechanics and evaluated how well they predicted response to CRT.

Methods

CMR was performed at 1.5 Tesla prior to CRT. Steady-state free precession (SSFP) cine images and complementary modulation of magnetization (CSPAMM) tagged cine images were acquired. Images were processed using a novel framework to extract regional ventricular volume-change, thickening and deformation fields (strain). A systolic dyssynchrony index (SDI) for all parameters within a 16-segment model of the ventricle was computed with high SDI denoting more dyssynchrony. Once identified, the optimal measure was applied to a second patient population to determine its utility as a predictor of CRT response compared to current accepted predictors (QRS duration, LBBB morphology and scar burden).

Results

Forty-four patients were recruited in the first phase (91% male, 63.3 ± 14.1 years; 80% NYHA class III) with mean QRSd 154 ± 24 ms. Twenty-one out of 44 (48%) patients showed reverse remodelling (RR) with a decrease in end systolic volume (ESV) ≥ 15% at 6 months. Volume-change SDI was the strongest predictor of RR (PR 5.67; 95% CI 1.95-16.5; P = 0.003). SDI derived from myocardial strain was least predictive. Volume-change SDI was applied as a predictor of RR to a second population of 50 patients (70% male, mean age 68.6 ± 12.2 years, 76% NYHA class III) with mean QRSd 146 ± 21 ms. When compared to QRSd, LBBB morphology and scar burden, volume-change SDI was the only statistically significant predictor of RR in this group.

Conclusion

A systolic dyssynchrony index derived from volume-change is a highly reproducible measurement that can be derived from routinely acquired SSFP cine images and predicts RR following CRT whilst an SDI of regional strain does not.     

斑点追踪显像对慢性心力衰竭患者心脏再同步化治疗短期疗效的评价

Objective To assess the short-term effect of cardiac resynchronization therapy (CRT) by speckle tracking strain imaging(STI). Methods Sixteen chronic heart failure patients(CHF) with CRT were enrolled. The time to peak systolic longitudinal strain and the time to peak systolic radial strain were derived from the LV apical views, and the time to peak systolic circumferential strain was derived from the parasternal short axis. The standard deviation for time to peak longitudinal, radial and circumferential strain in the 18 segments (LS-SD18, RS-SD18, CS-SD18) and the maximal temporal difference of any two segments(LS-dif, RS-dif, CS-dif) were calculated as a strain-derived dyssynchrony index. The difference of LS-SDIS, RS-SD18, CS-SD18 between 1 month,3 months after CRT and baseline (△LS-SD18, △RS-SD18, △CS-SD18) was calculated. The correlation between △LS-SD18,ARS-SD18,△CS-SD18 and the reduction of end-systolic volume at follow-up(△ESV%) were analyzed. Results The LS-SD18, RS-SD18,CS-SD18 and RS-dif were decreased significantly 1 month,3 months after CRT.△RS-SD18 was correlated with △ESV% 3 months after CRT(r = 0. 694). Conclusions The strain-derived dyssynchrony index is great significient for short-term effect of CRT.     

组织多普勒成像技术对心脏再同步化治疗的评价

目的探讨应用组织多普勒成像(TDI)技术评价心脏再同步化治疗(CRT)慢性心力衰竭患者的临床应用价值。方法选择拟行CRT的慢性心力衰竭患者31例,应用TDI测量收缩速度达峰时间判断左室收缩延迟部位,根据左室电极的位置是否与收缩延迟部位相符,将患者分为电极位置和收缩延迟部位符合者20例(A组)和不符合者11例(B组)。应用常规超声心动图及TDI技术观察两组术前及术后1,3,6个月左室收缩功能指标和心脏同步性参数的变化,评价CRT治疗效果。结果所有患者术前TDI技术评估均提示存在左室内收缩不同步,TDI技术能够指导左室电极植入理想靶静脉。术后1,3,6个月,患者的纽约心脏病协会心功能(NYHA)分级、6min步行距离、左室射血分数(LVEF)、左室舒张末期内径(LVEDd)、二尖瓣反流(MR)程度及室间机械延迟(IVMD)、左室12节段达峰时间标准差(Ts-SD)、左室内最晚收缩-最早收缩(Ts max-min)均较术前明显改善,术后6个月各参数改变最明显(P<0.05)。术后6个月,A,B组间NYHA分级、6min步行距离、LVEF、MR程度、IVMD、Tsmax-min及Ts-SD比较,差异均有统计学意义(均P<0.05)。结论 TDI技术可以用于慢性心力衰竭患者接受CRT的筛选,并能指导左室电极植入位置和评价疗效。     

实时三维超声和斑点追踪显像预测心脏再同步化治疗疗效的实验和临床研究

目的 应用实时三维超声心动图(RT-3DE)和斑点追踪显像(STI)评价左心室同步性,以探索检测心脏再同步化治疗(cardiac resynchronization therapy,CRT)疗效的有效方法。方法 动物实验对象为21条比格犬,随机分为A组(CRT组,10条),B组（心衰组,7条）和C组（对照组,4条）三组,临床研究对象为70例完成CRT术前及术后6个月随访的患者。以左室收缩末容积(LVESV)缩小15％为CRT治疗有效。评价同步性的超声参数包括RT-3DE评价左室16节段达最小收缩容积时间的标准差及其与心动周期的比值(Tmsv-16SD,SDI),STI评价犬左室乳头肌水平6节段QRS波起点至径向应变和圆周应变达峰时间的标准差与心动周期的比值(Trs-6SD、Tcs-6SD)。结果 动物实验的Tmsv-16SD、Trs-6SD、Tcs-6SD与左室射血分数(LVEF)呈负相关（r分别为-0.86、-0.75、-0.83,P均＜0.01）,Trs-6SD对CRT疗效最有预测价值,当Trs-6SD≥12.2％时,预测CRT有效的敏感性和特异性分别为83.3％和100％。临床研究显示,SDI最有预测价值,当其临界值为6.55％时,预测CRT有效的敏感性为80.0％,特异性为81.8％。结论 RT-3DE和STI能有效评价左室内不同步,有望成为预测CRT疗效的有效方法。     

常用超声指标不能预测心脏再同步化治疗的疗效

目的 比较和评价常用的M型超声、频谱多普勒和组织多普勒指标在预测心脏再同步化治疗(CRT)疗效中的价值.方法 29例完成随访的CRT患者,评价心脏同步性的常用超声心动图参数包括室间隔与左室后壁间的收缩延迟时间(SPWMD)、肺动脉射血前时间(PPEI)、主动脉射血前时间(APED、速度达峰时间的标准差(Ts-SD)、心室间机械延迟(IVMD).以CRT后6个月,左室收缩末容积较治疗前减小≥10%为治疗有效.结果 CRT的有效率为68.97%.术后CRT无效组的SPWMD、PPEI、APEI和Ts-SD均无显著改变(均P＞0.05),CRT有效组的SPWMD、APEI和Ts-SD显著缩短(P＜0.05或P＜0.001),SPWMD、PPEI、APEI、Ts-SD和IVMD预测CRT疗效的ROC曲线下面积在0.41～0.57之间,且差异均无统计学意义(均P＞0.05).结论 常用的M型超声、频谱多普勒和组织多普勒指标均不能预测CRT疗效,有必要进行实时三维超声和斑点追踪显像等新技术参数预测CRT疗效的研究.     

组织同步显像技术在扩张型心肌病心脏同步化治疗的临床应用

目的 探讨常规超声心动图及组织同步显像（TSI）技术在扩张型心肌病心脏同步化治疗（CRT）前、后的临床应用价值.方法 53例CRT治疗的扩张型心肌病患者,于CRT术前3d、术后1周、3个月和6个月在超声心动图指导下进行个体化参数程控,观察CRT前后不同起搏参数时各指标变化.结果 CRT治疗后左心室发生逆重构,其中术后3个月及6个月左心室舒张末期内径、左心室舒张末期容积明显小于术前（P＜0.01,P＜0.05）,左心室舒张充盈时间增加,二尖瓣反流量减少,LVEF明显提高（P＜0.01）,重度延迟节段数减少,节段数量由术前的3.1±1.3减少至6个月的1.5±1.4（P ＜0.01）,左心室起搏电极所在节段的达峰时间有的回复到正常范围,收缩峰值速度亦有改善,但仍没有到正常水平,12节段达峰时间标准差（Ts-SD）由术前的（139±33）ms缩短至（110±40）ms,差异有统计学意义（P＜o.01）.结论 常规超声心动图和TSI技术是预测评价CRT疗效的临床应用最简便有效的方法,是参与CRT全程的一种无创、准确的检查手段.     

组织同步显像技术评价心脏同步治疗扩张型心肌病的疗效

目的应用组织同步显像(TSI)技术评价心脏同步治疗扩张型心肌病后的疗效。方法采用TSI技术，在心电图监测下采集7例扩张型心肌病患者的心尖四腔观、心尖二腔观及心尖长轴观的组织速度成像，其中5例扩张型心肌病伴有左束支阻滞患者在心脏同步治疗1d后再采集心尖四腔观、心尖二腔观及心尖长轴观的组织速度成像。结果3例扩张型心肌病患者在心脏同步治疗后，心室的不同步收缩改善明显，而2例在心脏同步治疗后心室的不同步收缩改善不明显。2例扩张型心肌病患者在心脏同步治疗前作TSI检查，1例因不存在心室不同步收缩，故未进行心脏同步治疗；1例下壁收缩活动延迟，但左室射血分数较高，为42％，故暂时不考虑进行心脏同步治疗。结论TSI在心脏同步治疗扩张型心肌病适应证选择及疗效评价方面有较大的应用价值。     

超声心动图评价心脏再同步化治疗疗效

目的探讨超声心动图在慢性充血性心力衰竭患者心脏再同步化治疗疗效评价中的应用价值。方法 27例接受心脏再同步化治疗的慢性充血性心力衰竭患者,分别于术前及术后6个月应用超声心动图测量左心室大小、左心室容积、左心室射血分数、二尖瓣反流面积、房室间、心室间及左心室内同步性。结果术后6个月患者左心室收缩末内径、左心室舒张末内径、左心室收缩末容积、左心室舒张末容积小于术前（P〈0.05或P〈0.01）,房室间、心室间、左心室内收缩同步性改善（P〈0.05或P〈0.01）。结论超声心动图可通过多项参数综合评价心脏再同步化治疗的效果。     

Detection of the cardiac activation sequence by novel echocardiographic tissue tracking method

Asynchronous cardiac activation leads to decreased pumping efficiency. Quantifying the activation sequence may optimize both the selection of patients for cardiac resynchronization therapy (CRT) and its efficacy. The feasibility of assessing the directivity and the degree of synchronous activation with ultrasound was examined. A tissue tracking method (CEB, GE-Ultrasound, AFI, GE Healthcare Inc., Wauwatosa, WI, USA) provided the regional strain profiles. The first maxima in systole of the regional circumferential strains were considered as the activation times. An integrative vector (SDV) describes the activation synchrony and directivity. In six open-chest sheep, activation maps and SDV were calculated in short-axis planes of the left ventricle for normal activation and induced pacings from the anterior and lateral free walls. Both magnitude and angle of the SDV were statistically different (p < 0.05) for the different pacings. Localization of the pacing site was 3 degrees +/- 18 degrees from true position. Conclusions were that motion analysis in echocardiograms provides insightful information regarding the activation process and may enhance procedures such as CRT.     

二维斑点追踪成像评价蒽环类抗肿瘤药对乳腺癌患者左房功能的影响

目的探讨二维斑点追踪成像(STI)评价蒽环类抗肿瘤药(ATC)对乳腺癌左房功能的影响。方法 40例乳腺癌患者术后行化疗为化疗组,30例乳腺癌患者术后未化疗为对照组。应用Simpson法在心尖双平面测量左房最小容积(LAVmin)、最大容积(LAVmax)及P容积(LAVp),计算左房总排空分数(LATEF)、被动射血分数(LAPEF)及主动射血分数(LAAEF)。应用STI于心尖四腔心切面测量左房收缩期峰值应变率(SRs)、舒张早期峰值应变率(SRe)、舒张晚期峰值应变率(SRa),并计算其平均峰值(m SRs、m SRe、m SRa)。结果化疗组LATEF、LAPEF、LAAEF、m SRs、m SRe、m SRa较对照组均减低(均P0.05)。两组LATEF与m SRs、LAPEF与m SRe、LAAEF与m SRa均呈正相关(r分别为0.859、0.866、0.882,P0.001)。结论使用ATC乳腺癌患者左房功能发生改变,表现为储备功能、管道功能及泵功能减低。STI与左房容积指标有良好的相关性,能够准确评价左房功能。     

QRS duration and shortening to predict clinical response to cardiac resynchronization therapy in patients with end-stage heart failure

Despite current selection criteria (NYHA Class III-IV, LVEF < 35%, QRS > 120 ms with LBBB), 30% of patients do not benefit from cardiac resynchronization therapy (CRT). The use of QRS duration as selection criteria for CRT has not been evaluated systematically yet. Accordingly, the value of QRS duration at baseline (and reduction in QRS duration after CRT) to predict responders was studied. Patients were evaluated at baseline and after 6 months of CRT for NYHA Class, quality of life score, and 6-minute walk test. QRS duration was evaluated before, directly after implantation, and after 6 months of CRT. Sixty-one patients were included; 45 (74%) patients were classified as responders (improvement of NYHA Class, 6-minute walking distance and quality of life score) and 16 (26%) as nonresponders. QRS duration at baseline was similar between the two groups: 179 +/- 30 ms versus 171 +/- 32 ms, NS. Directly after implantation, QRS duration was reduced from 179 +/- 30 ms to 150 +/- 26 ms (P < 0.01) in responders; nonresponders did not exhibit this reduction (171 +/- 32 ms vs 160 +/- 26 ms, NS). After 6 months of CRT, QRS shortening was only observed in responders (from 179 +/- 30 ms to 159 +/- 25 ms, P < 0.01). ROC curve analysis showed that a reduction in QRS duration > 10 ms had a high sensitivity (73%) with low specificity (44%); conversely, a > 50 ms reduction in QRS duration was highly specific (88%) but not sensitive (18%) to predict response to CRT. No optimal cutoff value could be defined. QRS duration at baseline is not predictive for response to CRT; responders exhibit a significant reduction in QRS duration after CRT, but individual response varies highly, not allowing adequate selection of responders.     

Adaptive cardiac resynchronization therapy device: a simulation report

We report the results of a simulation of an adaptive cardiac resynchronization therapy (CRT) device performing biventricular pacing in which the atrioventricular (AV) delay and interventricular (VV) interval parameters are changed dynamically in response to data provided by the simulated IEGMs and simulated hemodynamic sensors. A learning module, an artificial neural network, performs the adaptive part of the algorithm supervised by an algorithmic deterministic module, internally or externally from the implanted CRT or CRT-D. The simulated cardiac output obtained with the adaptive CRT device is considerably higher (30%) especially with higher heart rates than in the nonadaptive CRT mode and is likely to be translated into improvement in quality of life of patients with congestive heart failure.     

实时三维超声心动图指导心脏再同步化治疗左心室起搏电极靶向植入的临床研究

目的 探讨实时三维超声心动图(RT-3DE)指导心脏再同步化治疗(CRT)左心室起搏电极靶向植入对提高CRT疗效的影响.方法 连续入选慢性心力衰竭(CHF)拟行CRT患者48例,按1∶1的比例随机分为2组:靶向治疗组和常规治疗组,两组在术前均行RT-3DE检查,筛选出左心室收缩最延迟部位,指导靶向治疗组在术中左心室起搏电极尽可能植入到左心室收缩最延迟部位,常规治疗组按照常规方法选择左心室起搏电极位置.术后6月比较左室收缩末容积(LVESV)、左室射血分数(LVEF)、左室16节段收缩末期容积达峰时间标准差(Tmsv16-SD)以及各指标的手术前后变化率(△LVESV、△LVEF、△Tmsv16-SD)等指标.结果 与常规治疗组比较,靶向治疗组左心室电极植入到最佳位置成功率显著增高(P =0.022),植入到远离部位发生率显著减低(P=0.026);靶向治疗组术后6月LVESV以及Tmsv16-SD显著减低(P均＜0.05),LVEF显著增加(P=0.042),CRT术前后△LVESV、△LVEF以及△Tmsv16-SD均显著增加(P均＜0.05).结论 RT-3DE能够指导CRT左心室起搏电极植入到左心室最延迟部位,进而显著提高CRT疗效,使行CRT患者最大化获益.     

心脏再同步化治疗无反应原因荟萃分析

心脏再同步化治疗(CRT)已成为治疗中重度心力衰竭的有效治疗手段.然而,临床上仍有约30％～40％的CRT植入患者对其无反应.研究指出,QRS时限和形态、缺血性心肌病、右心功能不全、肾功能不全、左心室电极植入位置、药物治疗和起搏器参数设置均是影响CRT无反应的主要危险因素.本文就CRT无反应常见原因做一综述,旨在通过早期识别和控制上述危险因素以降低CRT无反应率,从而提高CRT疗效.     

应变率成像监测肿瘤患者蒽环类药物化疗后心脏毒性的研究

目的 探讨应变率成像早期检测和评估葸环类药物（ATC）对肿瘤患者心脏毒性的临床价值。方法比较52例恶性肿瘤患者ATC化疗前和化疗后3～6个月的常规超声心动图心肌缩短率（FS）、射血分数（EF）舒张早期最大流速和收缩期最大流速的比值（E／A）指标以及心肌基底段和中间段前间隔、左室后壁、后间隔和左室侧壁中间段和基底段8个位点的收缩期最大应变率（SRs）、舒张早期最大应变率（SRe）。结果与化疔前比较,化疗后所取8个位点的SRs、SRe降低,E／A降低,差异均有统计学意义（P〈0．05）,化疗前后Fs、EF差异无统计学意义（P〉0．05）。结论在早期评价ATC对肿瘤患者心脏功能损害方面,SRs、SRe是较敏感的指标,E／A也有一定参考意义。     

Relationship of baseline electrocardiographic characteristics with the response to cardiac resynchronization therapy for heart failure

Prospective identification of patients most and least likely to respond to cardiac resynchronization therapy (CRT) for congestive heart failure (CHF) will allow clinicians to target this intervention most efficiently. The authors hypothesized that ECG variables including RBBB and indicators of RV dysfunction and extensive prior myocardial infarction would correlate with diminished response to CRT. This study analyzed preimplantation ECGs in 110 patients with ICD indications and CHF due to left ventricular systolic dysfunction randomized to active biventricular pacing in the MIRACLE ICD trial. Clinical and ECG variables on the outcome of change in peak oxygen consumption from baseline to 6 months (Delta-VO2 ) were evaluated. For this cohort, average peak VO2 improved from 13.4 to 14.3 mL/kg per minute. Among clinical variables, the strongest predictors of increasing Delta-VO2 were reduced exercise time and peak VO2 at baseline. A dominant R wave in lead a VR, RBBB, and evidence of prior anterior infarction were each associated with significantly smaller average improvements in Delta-VO2 than their absence in univariate analysis. Alternative ECG criteria, including QRS duration, had no relationship with the outcome. In a multivariate model, only baseline VO2 (beta=-0.3, P=0.001) and ECG evidence of prior anterior infarction (beta=-1.3, P=0.03) were associated with the outcome. ECG markers of anterior infarction and RV dilation may help identify CHF patients unlikely to benefit from biventricular pacing. Further assessment is needed of these and other predictors of therapeutic response to CRT.