Biventricular pacing and transmural dispersion of the repolarization.
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Publications and source records attributed to Gabe B Bleeker.
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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.
OBJECTIVES: This study was designed to evaluate the value of 64-slice computed tomography (CT) to visualize the cardiac veins and evaluate the relation between variations in venous anatomy and history of infarction. BACKGROUND: Cardiac resynchronization therapy (CRT) is an attractive treatment for selected heart failure patients. Knowledge of venous anatomy may help in identifying candidates for successful left ventricular lead implantation. METHODS: The 64-slice CT of 100 individuals (age 61 +/- 11 years, 68% men) was studied. Subjects were divided into 3 groups: 28 control patients, 38 patients with significant coronary artery disease (CAD), and 34 patients with a history of infarction. Presence of the following coronary sinus (CS) tributaries was evaluated: posterior interventricular vein (PIV), posterior vein of the left ventricle, and left marginal vein (LMV). Vessel diameters were also measured. RESULTS: Coronary sinus and PIV were identified in all individuals. Posterior vein of the left ventricle was observed in 96% of control patients, 84% of CAD patients, and 82% of infarction patients. In patients with a history of infarction, a LMV was significantly less observed as compared with control patients and CAD patients (27% vs. 71% and 61%, respectively, p < 0.001). None of the patients with lateral infarction and only 22% of patients with anterior infarction had a LMV. Regarding quantitative data, no significant differences were observed between the groups. CONCLUSIONS: Non-invasive evaluation of cardiac veins with 64-slice CT is feasible. There is considerable variation in venous anatomy. Patients with a history of infarction were less likely to have a LMV, which may hamper optimal left ventricular lead positioning in CRT implantation.
OBJECTIVES: We attempted to assess the efficacy of combined cardiac resynchronization therapy-implantable cardioverter-defibrillator (CRT-ICD) in heart failure patients with and without ventricular arrhythmias. BACKGROUND: Because CRT and ICDs both lower all-cause mortality in patients with advanced heart failure, combination of both therapies in a single device is challenging. METHODS: A total of 191 consecutive patients with advanced heart failure, left ventricular ejection fraction <35%, and a QRS duration >120 ms received CRT-ICD. Seventy-one patients had a history of ventricular arrhythmias (secondary prevention); 120 patients did not have prior ventricular arrhythmias (primary prevention). During follow-up, ICD therapy rate, clinical improvement after 6 months, and mortality rate were evaluated. RESULTS: During follow-up (18 +/- 4 months), primary prevention patients experienced less appropriate ICD therapies than secondary prevention patients (21% vs. 35%, p < 0.05). Multivariate analysis revealed, however, no predictors of ICD therapy. Furthermore, a similar, significant, improvement in clinical parameters was observed at 6 months in both groups. Also, the mortality rate in the primary prevention group was lower than in the secondary prevention group (3% vs. 18%, p < 0.05). CONCLUSIONS: As 21% of the primary prevention patients and 35% of the secondary prevention patients experienced appropriate ICD therapy within 2 years after implant, and no predictors of ICD therapy could be identified, implantation of a CRT-ICD device should be considered in all patients eligible 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 fraction 120 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.
OBJECTIVES: This study sought to compare tissue Doppler imaging (TDI) with velocity-encoded (VE) magnetic resonance imaging (MRI) for left ventricular (LV) dyssynchrony assessment. BACKGROUND: Cardiac resynchronization therapy (CRT) is proposed for patients with heart failure, depressed LV function, and a wide QRS complex. Selection is based mainly on electrocardiogram criteria, but recent data suggest that intraventricular dyssynchrony may be preferred for selection. An LV dyssynchrony can adequately be assessed with TDI, but this has not been compared directly with other imaging modalities. A VE MRI potentially allows direct myocardial wall motion measurements similar to TDI. METHODS: Twenty patients with heart failure, systolic LV dysfunction, and a wide QRS complex were included, as well as 10 normal individuals with normal QRS duration and LV function. The TDI and VE MRI data were acquired to study intraventricular dyssynchrony. RESULTS: Left ventricular dyssynchrony was not observed in normal individuals (mean dyssynchrony -2 +/- 15 ms on TDI; mean -5 +/- 17 ms on MRI, p = NS). In patients, mean LV dyssynchrony was 55 +/- 37 ms on TDI; 49 +/- 38 ms on MRI (p = NS). Good correlation between both modalities was observed (linear regression TDI = 0.99 x MRI - 5, n = 30, r = 0.98, p < 0.01). The MRI showed a small, nonsignificant underestimation of 5 +/- 8 ms compared with TDI. Agreement between MRI and TDI for classification according to severity of LV dyssynchrony (minimal, intermediate, and extensive) was excellent (kappa +/- SE = 0.96 +/- 0.07, p < 0.01) with 95% of patients classified identical. CONCLUSIONS: Both MRI and TDI yield comparable information on LV dyssynchrony; MRI is useful in the selection of patients for CRT.
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.
BACKGROUND: Surgical ventricular restoration is increasingly applied in patients with ischemic dilated cardiomyopathy. Previous studies show promising results with regard to survival and clinical outcome. However, a comprehensive midterm analysis of this approach on left ventricular (LV) and right ventricular function is not yet available. We investigated biventricular function and clinical status at 6-month follow-up. METHODS: We investigated the effects of surgical ventricular restoration on clinical variables, LV volume, right ventricular reverse remodeling, LV dyssynchrony, tricuspid regurgitation, and pulmonary artery pressure in 21 patients with ischemic dilated cardiomyopathy (New York Heart Association class III or IV) who underwent surgical ventricular restoration and coronary artery bypass grafting. Additional surgery included mitral annuloplasty (n = 14) and tricuspid valve annuloplasty (n = 8). Clinical variables (New York Heart Association class, quality-of-life questionnaire, 6-minute hall-walk test) and echocardiographic variables were assessed at baseline and at 6 months. RESULTS: At 6-month follow-up, all clinical variables were significantly improved. Left ventricular ejection fraction improved from 0.27 +/- 0.10 to 0.36 +/- 0.11 (p < 0.01), LV end-diastolic volume decreased from 248 +/- 78 mL to 152 +/- 50 mL (p < 0.001), and LV end-systolic volume decreased from 186 +/- 77 mL to 101 +/- 50 mL (p < 0.001). Left ventricular dyssynchrony decreased from 61 +/- 41 ms to 12 +/- 12 ms (p < 0.001). Right ventricular annular diameter decreased from 30 +/- 7 mm to 27 +/- 6 mm, right ventricular short-axis from 30 +/- 9 mm to 27 +/- 7 mm, and right ventricular long-axis from 90 +/- 7 mm to 79 +/- 10 mm (all p < 0.05). Finally, significant reductions in severity of tricuspid regurgitation (from 1.3 +/- 1.1 to 0.9 +/- 0.6; p = 0.001) and pulmonary artery pressure (42 +/- 11 mm Hg to 28 +/- 10 mm Hg; p = 0.015) were observed. CONCLUSIONS: Surgical ventricular restoration resulted in improvement of clinical variables, significant LV volume reduction, and reduced LV dyssynchrony at 6-month follow-up. In addition, right ventricular reverse remodeling was noted with reductions in tricuspid regurgitation and pulmonary artery pressure.
The number of patients with chronic heart failure is increasing rapidly in the Western world. Despite the introduction of new pharmacologic therapies, the prognosis of these patients remains poor. Left ventricular (LV) dyssynchrony is a frequently observed feature in patients with heart failure, and is recognized as an important predictor of poor outcome if left untreated. The presence of LV dyssynchrony leads to inefficient LV contraction with a decreased cardiac output. Moreover, patients with LV dyssynchrony are at increased risk of adverse cardiac events. New therapeutic options targeted at restoring normal mechanical synchrony, such as cardiac resynchronization therapy, have been shown to improve clinical symptoms and prognosis in patients with heart failure. The beneficial effects of cardiac resynchronization therapy are predominantly mediated by this treatment's ability to reduce LV dyssynchrony. Given these results, adequate identification of LV dyssynchrony in patients with heart failure is of paramount importance. Several new imaging techniques are proving useful for diagnosis of LV dyssynchrony. In particular, advanced echocardiographic techniques (e.g. tissue Doppler imaging) and conductance catheter techniques are two accurate methods for quantification of LV dyssynchrony. In this review, we discuss the pathophysiology, diagnosis and treatment of LV dyssynchrony in patients with heart failure.
Cardiac resynchronization therapy (CRT) has been proposed to improve hemodynamics in patients with heart failure and left bundle branch block (LBBB) by resynchronization of left ventricular (LV) dyssynchrony. The current report concerns a patient with narrow QRS complex without LV dyssynchrony who experienced an acute exacerbation of heart failure following exercise. Careful analysis revealed that an increase of heart rate induced acceleration-dependent LBBB with severe LV dyssynchrony and mitral regurgitation followed by acute heart failure and hemodynamic collapse. CRT prevented these adverse reactions. Accordingly, optimal evaluation for CRT may include testing for LV dyssynchrony during exercise.
In large cardiac resynchronization therapy (CRT) trials, approximately 20-30% of patients did not respond to CRT. Recent studies indicated that left ventricular (LV) dyssynchrony is needed for response to CRT. However, the presence of LV dyssynchrony may not be the only determinant of response, because some patients with LV dyssynchrony do not benefit from CRT. In the current case report, we present a patient with ischemic cardiomyopathy, NYHA class III heart failure symptoms, and substantial LV dyssynchrony on tissue Doppler imaging who underwent CRT implantation but did not respond. Following CRT, LV dyssynchrony was not reduced and the patient did not improve in clinical symptoms or LV function. The lack of LV resynchronization was explained by the presence of extensive scar tissue in the region of the tip of the LV pacing lead resulting in ineffective LV pacing. In patients with ischemic cardiomyopathy and history of previous infarction, assessment of scar tissue should be considered before CRT implantation.
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.
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.
Currently, a clear definition of response to cardiac resynchronization therapy (CRT) is still lacking, and clinical and echocardiographic end points are used. It is also unclear whether patients with clinical responses also improve in echocardiographic end points (and vice versa). To better understand and define response to CRT, the relation between improvement in clinical and echocardiographic parameters was evaluated in 144 patients.
BACKGROUND: In patients with severe heart failure and dilated cardiomyopathy, cardiac resynchronization therapy (CRT) improves left ventricular (LV) systolic function associated with LV reverse remodeling and favorable 1-year survival. However, it is unknown whether LV reverse remodeling translates into a better long-term prognosis and what extent of reverse remodeling is clinically relevant, which were investigated in this study. METHODS AND RESULTS: Patients (n=141) with advanced heart failure (mean+/-SD age, 64+/-11 years; 73% men) who received CRT were followed up for a mean (+/-SD) of 695+/-491 days. The extent of reduction in LV end-systolic volume (LVESV) at 3 to 6 months relative to baseline was examined for its predictive value on long-term clinical outcome. The cutoff value for LV reverse remodeling in predicting mortality was derived from the receiver operating characteristic curve. Then the relation between potential predictors of mortality and heart failure hospitalizations were compared by Kaplan-Meier survival analysis, followed by Cox regression analysis. There were 22 (15.6%) deaths, mostly due to heart failure or sudden cardiac death. The receiver operating characteristic curve found that a reduction in LVESV of > or =9.5% had a sensitivity of 70% and specificity of 70% in predicting all-cause mortality and of 87% and 69%, respectively, for cardiovascular mortality. With this cutoff value, there were 87 (61.7%) responders to reverse remodeling. In Kaplan-Meier survival analysis, responders had significantly lower all-cause morality (6.9% versus 30.6%, log-rank chi2=13.26, P=0.0003), cardiovascular mortality (2.3% versus 24.1%, log-rank chi2=17.1, P<0.0001), and heart failure events (11.5% versus 33.3%, log-rank chi2=8.71, P=0.0032) than nonresponders. In the Cox regression analysis model, the change in LVESV was the single most important predictor of all-cause (beta=1.048, 95% confidence interval=1.019 to 1.078, P=0.001) and cardiovascular (beta=1.072, 95% confidence interval=1.033 to 1.112, P<0.001) mortality. Clinical parameters were unable to predict any outcome event. CONCLUSIONS: A reduction in LVESV of 10% signifies clinically relevant reverse remodeling, which is a strong predictor of lower long-term mortality and heart failure events. This study suggests that assessing volumetric changes after an intervention in patients with heart failure provides information predictive of natural history outcomes.