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Introduction: cardiac resynchronization therapy (CRT) may improve prognosis in patients with chronic right ventricular (RV) pacing, and optimal lead position can decrease nonresponders. We evaluated the clinical and echocardiographic response to CRT in patients with previous chronic RV pacing, using pressure-volume loop analyses to determine the optimal left ventricular (LV) lead position during implantation., Methods and Results: In this single-blinded, randomized, controlled crossover study, 40 patients with chronic RV apical pacing and symptoms of heart failure, decreased LV ejection fraction (LVEF) or dyssynchrony were included. During implantation, stroke work (SW), LVEF, cardiac output, and LV dP/dt(max) were assessed by a conductance catheter. Clinical and echocardiographic response was studied during a 3-month period of RV pacing (RV period, LV lead inactive) and a 3-month period of biventricular pacing (CRT period). At the optimal LV lead position, SW (37 ± 41%), LVEF (16 ± 13%), cardiac output (29 ± 16%), and LV dP/dt(max) increased (11 ± 11%) significantly during biventricular pacing compared to baseline. Additional benefit could be achieved by pressure-volume loop guided selection of the best left-sided pacing location. RV outflow tract pacing did not improve hemodynamics. During follow-up, symptoms improved during CRT, VO(2,max) increased 10% and significant improvements in LVEF, LV volumes, and mitral regurgitation were observed as compared to the RV period., Conclusions: CRT in patients with chronic RV pacing causes significant improvement of both LV function as measured by pressure-volume loops during implantation and clinical and echocardiographic improvement during follow-up. Pressure-volume loops during implantation may facilitate selection of the most optimal pacing site., (© 2010 Wiley Periodicals, Inc.)

Objectives: We sought to evaluate the impact of the left ventricular (LV) pacing site on hemodynamic response to cardiac resynchronization therapy (CRT)., Background: CRT reduces morbidity and mortality in heart failure patients. However, 20% to 40% of eligible patients may not fully benefit from CRT device implantation. We hypothesized that selecting the optimal LV pacing site could be critical in this issue., Methods: Thirty-five patients with nonischemic dilated cardiomyopathy referred for CRT device implantation were studied. Intraventricular dyssynchrony and latest activated LV wall were defined by tissue Doppler imaging analysis before the study. Eleven predetermined LV pacing sites were systematically assessed in random order: basal and mid-cavity (septal, anterior, lateral, inferior), apex, coronary sinus (CS), and the endocardial site facing the CS pacing site. For each patient, +dP/dT(max), -dP/dT(min), pulse pressure, and end-systolic pressure during baseline (AAI) and DDD LV pacing were compared. Two atrioventricular delays were tested., Results: Major interindividual and intraindividual variations of hemodynamic response depending on the LV pacing site were observed. Compared with baseline, LV DDD pacing at the best LV position significantly improved +dP/dT(max) (+31 +/- 26%, p < 0.001) and was superior to pacing the CS (+15 +/- 23%, p < 0.001), the lateral LV wall (+18 +/- 22%, p < 0.001), or the latest activated LV wall (+11 +/- 17%, p < 0.001)., Conclusions: The pacing site is a primary determinant of the hemodynamic response to LV pacing in patients with nonischemic dilated cardiomyopathy. Pacing at the best LV site is associated acutely with fewer nonresponders and twice the improvement in +dP/dT(max) observed with CS pacing., (Copyright 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Cardiac resynchronization therapy produces both short-term hemodynamic and long-term symptomatic/mortality benefits in symptomatic heart failure patients with a QRS duration >120 ms. This is conventionally believed to be due principally to relief of dyssynchrony, although we recently showed that relief of external constraint to left ventricular filling may also play a role. In this study, we evaluated the short-term hemodynamic effects in symptomatic patients with a QRS duration <120 ms and no evidence of dyssynchrony on conventional criteria and assessed the effects on contractility and external constraint., Methods and Results: Thirty heart failure patients (New York Heart Association class III/IV) with a left ventricular ejection fraction < or =35% who were in sinus rhythm underwent pressure-volume studies at the time of pacemaker implantation. External constraint, left ventricular stroke work, dP/dtmax, and the slope of the preload recruitable stroke work relation were measured from the end-diastolic pressure-volume relation before and during delivery of biventricular and left ventricular pacing. The following changes were observed during delivery of cardiac resynchronization therapy: Cardiac output increased by 25+/-5% (P<0.05), absolute left ventricular stroke work increased by 26+/-5% (P<0.05), the slope of the preload recruitable stroke work relation increased by 51+/-15% (P<0.05), and dP/dtmax increased by 9+/-2% (P<0.05). External constraint was present in 15 patients and was completely abolished by both biventricular and left ventricular pacing (P<0.05)., Conclusions: Cardiac resynchronization therapy results in an improvement in short-term hemodynamic variables in patients with a QRS <120 ms related to both contractile improvement and relief of external constraint. These findings provide a potential physiological basis for cardiac resynchronization therapy in this patient population.

Aims: To evaluate the clinical utility of pressure-volume loop analyses during pacemaker/implantable cardioverter defibrillator (ICD) implantations to assess the optimal right ventricular (RV) and/or left ventricular (LV) lead position., Methods and Results: 29 patients with heart failure and chronic RV apical pacing were studied. Stroke work (SW), LV ejection fraction (LVEF), cardiac output (CO), and LV dP/dt(max) were assessed using a conductance catheter in the LV during RV apical, RV outflow tract, single-site LV, and biventricular pacing at different left-sided pacing locations. Left ventricular ejection fraction was 34.3 +/- 9.8%. Compared with baseline, RV outflow tract pacing showed a small increase of 4.0 +/- 6.4% in LV dP/dt(max) and no improvement in SW, LVEF, or CO. In the optimal biventricular configuration, SW increased 39 +/- 41%, LVEF increased 22 +/- 13%, CO increased 16 +/- 16%, and LV dP/dt(max) increased 10 +/- 11% (all P < 0.05). In 45% of the patients, the optimal LV lead position was found at a different location as the 'first choice' postero-lateral or lateral target vein., Conclusion: Pressure-volume loop analysis during pacemaker/ICD implantations facilitates to determine the optimal LV pacing site. Patients with chronic RV pacing showed a significant acute improvement in LV function when LV pacing or biventricular pacing is applied.

Aims: At present, 20-30% of patients do not respond to cardiac resynchronization therapy (CRT). In this study, the relation between the extent of viable myocardium and scar tissue vs. response to CRT was evaluated. In addition, the presence of scar tissue in the left ventricular (LV) lead position was specifically related to response to CRT., Methods and Results: A total of 51 consecutive patients with ischaemic heart failure and substantial LV dyssynchrony undergoing CRT were included. All patients underwent gated SPECT before CRT implantation to determine the extent of scar tissue and viable myocardium. Clinical and echocardiographic parameters were assessed at baseline and after 6 months of CRT. The results demonstrated direct relations between the response to CRT and the extent of viable myocardium and scar tissue. In addition, the 15 patients (29%) with transmural scar tissue (< 50% tracer activity) in the region of the LV pacing lead showed no improvement after 6 months of CRT., Conclusion: The extent of scar tissue and viable myocardium were directly related to the response to CRT. Furthermore, scar tissue in the LV pacing lead region may prohibit response to CRT. Evaluation for viability and scar tissue may be considered in the selection process for CRT.

M-mode echocardiography (using the septal-to-posterior wall motion delay [SPWMD]) and color-coded tissue Doppler imaging (TDI; using the septal-to-lateral delay in peak systolic velocity) have been proposed for assessment of left ventricular (LV) dyssynchrony and prediction of response to cardiac resynchronization therapy (CRT). In this study, a head-to-head comparison between M-mode echocardiography and color-coded TDI was performed for assessment of LV dyssynchrony and prediction of response to CRT. Consecutive (n = 98) patients with severe heart failure (New York Heart Association class III/IV), LV ejection fraction < or =35%, and QRS duration >120 ms underwent CRT. Before pacemaker implantation, LV dyssynchrony was assessed by M-mode echocardiography (SPWMD) and color-coded TDI (septal-to-lateral delay). At baseline and 6 months after implantation, clinical and echocardiographic parameters were evaluated. SPWMD measurement was not feasible in 41% of patients due to akinesia of the septal and/or posterior walls or poor acoustic windows. Conversely, the septal-to-lateral delay could be assessed in 96% of patients. At 6-month follow-up, 75 patients (77%) were classified as responders to CRT (improvement > or =1 New York Heart Association class). The sensitivity and specificity of SPWMD were lower compared with those of septal-to-lateral delay (66% vs 90%, p <0.05; 50% vs 82%, p = NS, respectively). In conclusion, LV dyssynchrony assessment was feasible in 59% of patients with M-mode echocardiography compared with 96% (p <0.05) when color-coded TDI was used. Color-coded TDI was superior to M-mode echocardiography for prediction of response to CRT.

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.

Unlabelled: The response to cardiac resynchronization therapy (CRT) varies significantly among individuals. Preliminary data suggest that the presence of myocardial viability may be important for response to CRT. The aim of this study was to evaluate whether the extent of viability could predict response to CRT after 6 mo., Methods: Sixty-one consecutive patients with advanced heart failure, left ventricular ejection fraction < 35%, QRS duration > 120 ms, and chronic coronary artery disease were included. To determine the extent of viability all patients underwent nuclear imaging with 18F-FDG SPECT before implantation. Clinical and echocardiographic parameters were assessed at baseline and after 6 mo of follow-up., Results: The presence of myocardial viability was directly related to an increase in left ventricular ejection fraction after 6 mo of CRT. Furthermore, the extent of viability in responders (n = 38) was significantly larger compared with that of nonresponders (n = 23; 12 +/- 3 vs. 7 +/- 3 viable segments, P < 0.01). Moreover, the optimal cutoff value to predict clinical response to CRT was identified at an extent of 11 viable segments or more (in a 17-segment model), yielding a sensitivity of 74% and a specificity of 87%., Conclusion: The presence of myocardial viability is directly related to response to CRT in patients with ischemic heart failure. Interestingly, using a cutoff level of 11 viable segments or more, the extent of viability could be used to predict response. Therefore, evaluation for myocardial viability may be considered in the selection process for CRT.

Cardiac resynchronization therapy (CRT) is beneficial in selected patients with moderate to severe heart failure (New York Heart Association [NYHA] classes III to IV). Patients with mildly symptomatic heart failure (NYHA class II) are currently not eligible for CRT and the potential beneficial effects in these patients have not been well studied. Fifty consecutive patients in NYHA class II heart failure and 50 consecutive patients in NYHA classes III to IV (control group) were prospectively included. All patients had left ventricular (LV) ejection fraction120 ms. The effects of CRT in NYHA class II patients were compared with the results obtained in both groups. The severity of baseline LV dyssynchrony (assessed with color-coded tissue Doppler imaging) was comparable between patients in NYHA class II versus those in NYHA classes III to IV (83+/-49 vs 96+/-51 ms, p=NS); resynchronization was achieved in all patients. NYHA class II patients showed a significant improvement in LV ejection fraction (from 25+/-7% to 33+/-10%, p<0.001) and reduction in LV end-systolic volume (from 168+/-55 to 132+/-51 ml, p<0.001) after CRT, similar to patients in NYHA classes III to IV. In addition, only 8% of NYHA class II patients had progression of heart failure symptoms. In conclusion, CRT had comparable effects in patients in NYHA class II and in NYHA classes III to IV heart failure in terms of LV resynchronization, improvement in LV ejection fraction, and LV reverse remodeling.

Background: Acute hemodynamic effects of cardiac resynchronization therapy (CRT) were reported previously, but detailed invasive studies showing hemodynamic consequences of long-term CRT are not available., Methods and Results: We studied 22 patients scheduled for implantation of a CRT device based on conventional criteria (New York Heart Association class III or IV, left ventricular [LV] ejection fraction <35%, left bundle-branch block, and QRS duration >120 ms). During diagnostic catheterization before CRT, we acquired pressure-volume loops using conductance catheters during atrial pacing at 80, 100, 120, and 140 bpm. Studies were repeated during biventricular pacing at the same heart rates after 6 months of CRT. Our data show a significant clinical benefit of CRT (New York Heart Association class change from 3.1+/-0.5 to 2.1+/-0.8; quality-of-life score change from 44+/-12 to 31+/-16; and 6-minute hall-walk distance increased from 260+/-149 to 396+/-129 m; all P<0.001), improved LV ejection fraction (from 29+/-10% to 40+/-13%, P<0.01), decreased end-diastolic pressure (from 18+/-8 to 13+/-6 mm Hg, P<0.05), and reverse remodeling (end-diastolic volume decreased from 257+/-67 to 205+/-54 mL, P<0.01). Previously reported acute improvements in LV function remained present at 6 months: dP/dtmax increased 18%, -dP/dtmin increased 13%, and stroke work increased 34% (all P<0.01). Effects of increased heart rate were improved toward more physiological responses for LV ejection fraction, cardiac output, and dP/dtmax. Moreover, our study showed improved ventricular-arterial coupling (69% increase, P<0.01) and improved mechanical efficiency (44% increase, P<0.01)., Conclusions: Hemodynamic improvements with CRT, previously shown in acute invasive studies, are maintained chronically. In addition, ventricular-arterial coupling, mechanical efficiency, and chronotropic responses are improved after 6 months of CRT. These findings may help to explain the improved functional status and exercise tolerance in patients treated with CRT.

Background: Currently, one third of patients treated with cardiac resynchronization therapy (CRT) do not respond. Nonresponse to CRT may be explained by the presence of scar tissue in the posterolateral left ventricular (LV) segments, which may result in ineffective LV pacing and inadequate LV resynchronization. In the present study, the relationship between transmural posterolateral scar tissue and response to CRT was evaluated., Methods and Results: Forty consecutive patients with end-stage heart failure (NYHA class III/IV), LV ejection fraction < or =35%, QRS duration >120 ms, left bundle-branch block, and chronic coronary artery disease were included. The localization and transmurality of scar tissue were evaluated with contrast-enhanced MRI. Next, LV dyssynchrony was assessed at baseline and immediately after implantation with tissue Doppler imaging. Clinical parameters, LV volumes, and LV ejection fraction were assessed at baseline and at a 6-month follow-up. Fourteen patients (35%) had a transmural (>50% of LV wall thickness) posterolateral scar. In contrast to patients without posterolateral scar tissue, these patients showed a low response rate (14% versus 81%; P<0.05) and did not show improvement in clinical or echocardiographic parameters. In addition, LV dyssynchrony remained unchanged after CRT implantation (84+/-46 versus 78+/-41 ms; P=NS). Patients without posterolateral scar tissue and severe baseline dyssynchrony (> or =65 ms) showed an excellent response rate of 95% compared with patients with a posterolateral scar and/or absent LV dyssynchrony (11%)., Conclusions: CRT does not reduce LV dyssynchrony in patients with transmural scar tissue in the posterolateral LV segments, resulting in clinical and echocardiographic nonresponse to CRT.

Objectives: The purpose of this research was to evaluate right ventricular (RV) remodeling after six months of cardiac resynchronization therapy (CRT)., Background: Cardiac resynchronization therapy is beneficial in patients with end-stage heart failure. The effect of CRT on RV size is currently unknown. Accordingly, the effects of CRT on RV size, severity of tricuspid regurgitation, and pulmonary artery pressure were evaluated., Methods: Fifty-six consecutive patients with end-stage heart failure (52% ischemic cardiomyopathy), left ventricular (LV) ejection fraction (EF) < or =35%, QRS duration >120 ms, and left bundle branch block were included. Clinical parameters, LV volumes, LVEF, LV dyssynchrony, and RV chamber size were assessed at baseline and after six months of CRT; LV dyssynchrony was assessed using tissue Doppler imaging., Results: Clinical parameters improved significantly; LV dyssynchrony was acutely reduced after CRT and remained unchanged at six-month follow-up. Left ventricular EF improved significantly from 19 +/- 6% to 26 +/- 8% (p < 0.001), and LV end-diastolic volume decreased from 257 +/- 98 ml to 227 +/- 86 ml (p < 0.001). Right ventricular annulus decreased significantly from 37 +/- 9 mm to 32 +/- 10 mm, RV short-axis from 29 +/- 11 mm to 26 +/- 7 mm, and RV long-axis from 89 +/- 11 mm to 82 +/- 10 mm (all p < 0.001). Left ventricular and RV reverse remodeling were only observed in patients with substantial LV dyssynchrony at baseline. Finally, significant reductions in severity of tricuspid regurgitation and pulmonary artery pressure were observed., Conclusions: Cardiac resynchronization therapy results in significant reverse LV and RV remodeling after six months of CRT in patients with LV dyssynchrony. Moreover, CRT leads to a reduction of the severity of tricuspid regurgitation and a decrease in pulmonary artery pressure.

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.

In the present study, the effects of cardiac resynchronization therapy (CRT) in elderly patients were evaluated. The study included 170 consecutive patients whose clinical and echocardiographic improvements were evaluated after 6 months of follow-up. Survival was evaluated up to 2 years. The effects of CRT in elderly patients (age > or =70 years) were compared with those in younger patients (age <70 years).

Unlabelled: Long-term follow-up of cardiac resynchronization therapy., Introduction: Cardiac resynchronization therapy (CRT) has been introduced to treat patients with end-stage heart failure, and results of this technique are promising. The aim of our study was to assess the sustained benefit of CRT in a large patient cohort with end-stage heart failure at long-term follow-up. In addition, the prognosis of responders and nonresponders was evaluated., Methods and Results: 125 patients with end-stage heart failure, NYHA class III or IV, LVEF<35%, QRS duration>120 msec and left bundle branch block morphology received a biventricular device. At baseline and 6 months after implantation the following parameters were evaluated: NYHA class, Minnesota Quality of life score, QRS duration on surface ECG, 6-minute walking distance and LVEF. Follow-up was obtained up to 3 years. After 6 months, patients were divided in clinical responders and nonresponders according to improvement in NYHA class. All clinical parameters improved significantly at 6-month follow-up. Hospitalization for heart failure was 3.8+/-4.9 days/year before and 0.7+/-1.6 days/year after CRT. Survival at 1-, 2-, and 3-year follow-up was 93%, 88%, and 85%, respectively. Responders (78%) showed a significantly better survival than nonresponders at 2- and 3-year follow-up (96% and 93% for responders versus 81% and 73% for nonresponders, P<0.05)., Conclusion: The improvement in functional status and symptoms after CRT is maintained at long-term follow-up (up to 3 years). The clinical improvement was associated with a significant reduction in hospitalization rate which was also maintained over the years. Preimplantation selection of responders may result in even better long-term survival.

We evaluated whether long-term cardiac resynchronization therapy affects the inducibility of ventricular tachyarrhythmias in relation to reverse remodeling in cardiac arrest survivors with either ischemic or idiopathic dilated cardiomyopathy. Clinical, electrophysiologic, and echocardiographic data of 18 patients were obtained before and after 6 months of cardiac resynchronization.

Cardiac resynchronization therapy (CRT) is a new therapeutic option for patients who have drug-refractory end-stage heart failure. Much information has been obtained from patients who have sinus rhythm, but the use of CRT in patients who have chronic atrial fibrillation (AF) has not been studied extensively. Accordingly, we evaluated the clinical response and long-term survival rate of CRT in patients who had heart failure and chronic AF, and the results were compared with those in patients who had sinus rhythm and who underwent CRT. Sixty patients who had end-stage heart failure (30 had sinus rhythm and 30 had chronic AF), New York Heart Association classes III to IV, left ventricular ejection fraction <35%, QRS interval >120 ms, and a left bundle branch block received a biventricular pacemaker. New York Heart Association class, Minnesota Quality of Life score, and 6-minute walking distance were evaluated at baseline and after 6 months of CRT. Long-term follow-up was

Objectives: This study was designed to predict the response and prognosis after cardiac resynchronization therapy (CRT) in patients with end-stage heart failure (HF)., Background: Cardiac resynchronization therapy improves HF symptoms, exercise capacity, and left ventricular (LV) function. Because not all patients respond, preimplantation identification of responders is needed. In the present study, response to CRT was predicted by the presence of LV dyssynchrony assessed by tissue Doppler imaging. Moreover, the prognostic value of LV dyssynchrony in patients undergoing CRT was assessed., Methods: Eighty-five patients with end-stage HF, QRS duration >120 ms, and left bundle-branch block were evaluated by tissue Doppler imaging before CRT. At baseline and six months follow-up, New York Heart Association functional class, quality of life and 6-min walking distance, LV volumes, and LV ejection fraction were determined. Events (death, hospitalization for decompensated HF) were obtained during one-year follow-up., Results: Responders (74%) and nonresponders (26%) had comparable baseline characteristics, except for a larger dyssynchrony in responders (87 +/- 49 ms vs. 35 +/- 20 ms, p < 0.01). Receiver-operator characteristic curve analysis demonstrated that an optimal cutoff value of 65 ms for LV dyssynchrony yielded a sensitivity and specificity of 80% to predict clinical improvement and of 92% to predict LV reverse remodeling. Patients with dyssynchrony >/=65 ms had an excellent prognosis (6% event rate) after CRT as compared with a 50% event rate in patients with dyssynchrony <65 ms (p < 0.001)., Conclusions: Patients with LV dyssynchrony >/=65 ms respond to CRT and have an excellent prognosis after CRT.

Cardiac resynchronization therapy (CRT) is a recently introduced therapeutic option for patients with severe heart failure and intraventricular conduction disturbances. However, it is estimated that 20% to 30% of patients may not respond to CRT. Patients with ischemic cardiomyopathy (IC) may respond less favorably to CRT compared with patients with idiopathic dilated cardiomyopathy (IDC). Accordingly, the beneficial effects of CRT were evaluated in 2 subsets of patients (IC and IDC). Seventy-four patients with end-stage heart failure, New York Heart Association (NYHA) class III or IV, left ventricular (LV) ejection fraction <35%, QRS >120ms, and left bundle branch block received a biventricular pacemaker. At baseline and 6 months after implantation these parameters were evaluated: NYHA class, Minnesota quality-of-life score, QRS duration, and 6-minute walking distance. LV ejection fraction and severity of mitral regurgitation were assessed before and 6 months after CRT using 2-dimensional echocardiography. Long-term follow-up and hospitalization rates were obtained up to 2 years. Of the 74 patients, 46% (n = 34) had IC and 54% (n = 40) IDC. At 6 months follow-up all clinical parameters, QRS duration, LV ejection fraction, and mitral regurgitation improved significantly in both groups. Long-term (2-year) follow-up showed a survival rate of 87.5% for patients with IDC and 88.3% for patients with IC. The percentages of responders to CRT (defined as an improvement in NYHA class >or=1 grade) were comparable in both groups (65% vs 71%). Therefore, the underlying etiology of heart failure (IC vs IDC) was not related to the response to CRT.

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.

We evaluated patients with end-stage heart failure who have a high likelihood of response to cardiac resynchronization therapy (biventricular pacing). It appears that 20% of patients do not respond to this expensive therapy despite the use of selection criteria (dilated cardiomyopathy, heart failure, New York Heart Association class II or IV, left ventricular ejection fraction <35%, left bundle branch block, and QRS >120 ms). The presence of left ventricular dyssynchrony is needed to result in improvement after cardiac resynchronization therapy.

Biventricular pacing has been introduced to treat patients with end-stage heart failure, and short-term results of this technique are promising. Because data on longer follow-up are limited to 3-month follow-up, the sustained effect of biventricular pacing is unclear and long-term survival is unknown. Forty patients with end-stage heart failure in New York Heart Association (NYHA) functional class III or IV with left ventricular (LV) ejection fraction (EF) <35%, QRS duration >120 ms, and left bundle branch block morphology received a biventricular pacemaker. At baseline, and at 3 and 6 months after implantation, the following parameters were evaluated: NYHA class, Minnesota quality-of-life score, QRS duration on surface electrocardiogram, 6-minute walking distance, and LVEF. Long-term follow-up was obtained for up to 2 years. All clinical parameters improved significantly at 3 months and remained unchanged at 6-month follow-up. LVEF increased from 24 +/- 9% to 34 +/- 11%. Before implantation, patients were hospitalized (for congestive heart failure) an average of 3.9 +/- 5.3 days/year compared with 0.5 +/- 1.5 days/year after implantation. Long-term follow-up showed a survival of 87.5% at 2 years. Thus, biventricular pacing resulted in improvement of symptoms and quality of life, accompanied by improvement in 6-minute walking distance and LVEF. These effects were observed at 3 months after implantation and were maintained at 6-month follow-up. Moreover, 2-year survival was excellent.