Relation of QRS Duration to Response to Cardiac Resynchronization Therapy in Patients With Left Bundle Branch Block

The role of fibrosis, inflammation, and congestion biomarkers for outcome prediction in candidates to cardiac resynchronization therapy: is "response" the right answer?

Background

Cardiac resynchronization therapy (CRT) is an established treatment in selected patients suffering from heart failure with reduced ejection fraction (HFrEF). It has been proposed that myocardial fibrosis and inflammation could influence CRT "response" and outcome. Our study investigated the long-term prognostic significance of cardiac biomarkers in HFrEF patients with an indication for CRT.

Methods

Consecutive patients referred for CRT implantation were retrospectively evaluated. The soluble suppression of tumorigenicity 2 (sST2), galectin-3 (Gal-3), N-terminal portion of the B-type natriuretic peptide (NT-proBNP), and estimated glomerular filtration rate (eGFR) were measured at baseline and after 1 year of follow-up. Multivariate analyses were performed to evaluate their correlation with the primary composite outcome of cardiovascular mortality and heart failure hospitalizations at a mean follow-up of 9 ± 2 years.

Results

Among the 86 patients enrolled, 44% experienced the primary outcome. In this group, the mean baseline values of NT-proBNP, Gal-3, and sST2 were significantly higher compared with the patients without cardiovascular events. At the multivariate analyses, baseline Gal-3 [cut-off: 16.6 ng/ml, AUC: 0.91, p < 0.001, HR 8.33 (1.88-33.33), p = 0.005] and sST2 [cut-off: 35.6 ng/ml AUC: 0.91, p < 0.001, HR 333 (250-1,000), p = 0.003] significantly correlated with the composite outcome in the prediction models with high likelihood. Among the parameters evaluated at 1-year follow-up, sST2, eGFR, and the variation from baseline to 1-year of Gal-3 levels showed a strong association with the primary outcome [HR 1.15 (1.08-1.22), p < 0.001; HR: 0.84 (0.74-0.91), p = 0.04; HR: 1.26 (1.10-1.43), p ≤ 0.001, respectively]. Conversely, the echocardiographic definition of CRT response did not correlate with any outcome.

Conclusion

In HFrEF patients with CRT, sST2, Gal-3, and renal function were associated with the combined endpoint of cardiovascular death and HF hospitalizations at long-term follow-up, while the echocardiographic CRT response did not seem to influence the outcome of the patients.

Clinical impacts of scar reduction on gated myocardial perfusion SPECT after cardiac resynchronization therapy

BACKGROUND

It had not been reported that myocardial scar shown on gated myocardial perfusion SPECT (GMPS) might reduce after cardiac resynchronization therapy (CRT). In this study, we aim to investigate the clinical impact and characteristic of scar reduction (SR) after CRT.

METHODS AND RESULTS

Sixty-one heart failure patients following standard indication for CRT received twice GMPS as pre- and post-CRT evaluations. The patients with an absolute reduction of scar ≥ 10% after CRT were classified as the SR group while the rest were classified as the non-SR group. The SR group (N = 22, 36%) showed more improvement on LV function (∆LVEF: 18.1 ± 12.4 vs 9.4 ± 9.9 %, P = 0.007, ∆ESV: - 91.6 ± 52.6 vs - 38.1 ± 46.5 mL, P < 0.001) and dyssynchrony (ΔPSD: - 26.19 ± 18.42 vs - 5.8 ± 23.0°, P < 0.001, Δ BW: - 128.7 ± 82.8 vs - 25.2 ± 109.0°, P < 0.001) than non-SR group (N = 39, 64%). Multivariate logistic regression analysis showed baseline QRSd (95% CI 1.019-1.100, P = 0.006) and pre-CRT Reduced Wall Thickening (RWT) (95% CI 1.016-1.173, P = 0.028) were independent predictors for the development of SR.

CONCLUSION

More than one third of patients showed SR after CRT who had more post-CRT improvement on LV function and dyssynchrony than those without SR. Wider QRSd and higher RWT before CRT were related to the development of SR after CRT.

Novel active fixation lead guided by electrical delay can improve response to cardiac resynchronization therapy in heart failure

AIMS

Cardiac resynchronization therapy (CRT) for heart failure (HF) recently has shown optimal results by targeting electrically delayed sites in coronary sinus (CS) branches. However this purpose often cannot be reached because of unstable left ventricular (LV) lead position. In current study were assessed the long-term effects of the novel active fixation LV lead in CS, guided by electrical delay (QLV), in patients with HF due to coronary artery disease.

METHODS

One hundred eighty-five consecutive patients underwent CRT with intraoperative evaluation of QLV in the target position of the LV lead. When the novel active fixation LV lead was available, 98 consecutive patients received it, composing the Fix group. They were compared with 87 patients with a conventional passive fixation lead (No Fix group). The final LV lead position was assessed by fluoroscopy. Clinical response to CRT was assessed within a period of about 3 years: patients experiencing HF rehospitalization and death due to HF were defined as non-responders.

RESULTS

There were no significant differences between groups in the final position of LV lead in left anterior oblique view (Pearson χ2  = 0.12; P = 0.73). In right anterior oblique view, a basal position was reached more in the Fix group (38%) than in the No Fix group (6.5%) (Pearson χ2  = 23.095; P < 0.001). QLV was significantly greater in the Fix group (122.6 ± 33.2 ms; SE = 3.6) than in the No Fix group (97.5 ± 37.8 ms; SE = 4.9) (t = 4.17; P < 0.001). Rehospitalizations for HF were 37 in the No Fix group and 14 in the Fix group. Deaths due to HF were 49 in the No Fix group and 18 in the Fix group. Survival analysis, assessed by Cox regression, showed that the Fix group had a better outcome both for HF rehospitalizations [hazard ratio (HR) = 0.48; 95% confidence interval (CI) = 0.25-0.9; P = 0.023] and death due to HF (HR = 0.55; 95% CI = 0.31-0.97; P = 0.04) in comparison with the No Fix group. Adjustment for baseline characteristics by multivariate analysis showed that an active fixation lead in CS, as a covariate, was still significant both for HF rehospitalizations (HR 0.46; 95% CI = 0.24-0.88; P = 0.019) and for death due to HF (HR 0.5; 95% CI = 0.28-0.9; P = 0.021).

CONCLUSIONS

The novel active fixation LV lead allowed to target sites with greater QLV. Often maximum QLV was documented in basal segments, were stability of conventional passive fixation leads is not enough. Patients receiving it experienced less HF rehospitalizations and less death due to HF. Active fixation lead in CS guided by QLV can improve long-term prognosis in patients with HF due to coronary artery disease undergoing to CRT.

Right ventricular dilatation and systolic dysfunction and relationship to QRS duration in patients with left bundle branch block and cardiomyopathy

BACKGROUND

Marked QRS widening in patients with left bundle branch block (LBBB) may reduce efficacy of cardiac resynchronization therapy (CRT). We hypothesized that extreme QRS prolongation may accompany right ventricular (RV) dilatation/systolic dysfunction (RVD/RVsD) as well as left ventricular dilatation/systolic dysfunction (LVD/LVsD).

METHODS

We assessed rates of both ventricular dilatation and systolic dysfunction according to widening of QRS duration (QRSd) in 100 consecutive cardiomyopathy patients with true LBBB (QRSd ≥ 130 ms in female or ≥140 ms in male, QS or rS in leads V1/V2, and mid-QRS notching/slurring in ≥2 contiguous leads of I, aVL, and V1/V2/V5/V6). Ventricular dimensions and function were measured by cardiac magnetic resonance imaging.

RESULTS

There was a trend toward an increase in the prevalence of LVD (13%, 20%, and 90%), LVsD (67%, 77%, and 90%), RVD (23%, 27%, and 50%), RVsD (27%, 27%, and 40%), RVD plus RVsD (13%, 17%, and 40%), or RVD/RVsD (37%, 37%, and 50%) according to the degree of QRS prolongation (<150 ms, n = 30; 150-180 ms, n = 60; and ≥180 ms, n = 10). Similarly, patients in the highest quartile of QRSd (QRSd ≥ 168 ms, n = 26) showed greater rates of RVD (23% vs. 44%, p = .069), RVsD (22% vs. 48%, p = .032), RVD plus RVsD (10% vs. 30%, p = .040), or RVD/RVsD (33% vs. 57%, p = .050) compared to those in the remaining quartiles (n = 74). QRSd ≥ 180 ms was identified as an independent predictor for the presence of RVD plus RVsD.

CONCLUSION

The rates of RVD and/or RVsD increased with QRS widening, particularly when QRSd exceeded 180 ms. This may diminish anticipated CRT response rates in cardiomyopathy patients with LBBB.

QRS Duration as a Predictor of Left Ventricular Outflow Tract Velocity Time Integral in Patient with Cardiac Resynchronization Therapy

Background

Cardiac resynchronization therapy (CRT) has a morbidity and mortality benefits in moderate to severe heart failure. It reduces mortality and hospitalization and improves cardiac function. It can be used according to the European guidelines in severely depressed left ventricular ejection fraction (i.e., ≤35%) and complete left bundle branch block. However, 30% of patients may show no benefit from CRT therapy. Therefore, prediction of CRT response seems to be an important subject for study in the current researches. We aimed to study the correlation between Surface ECG QRS complex duration (QRS) duration and cardiac output measured by ventricular outflow tract velocity time integral (LVOT VTI) as a predictor of response in patients with CRT implantation.

Methods

We studied 100 consecutive patients prospectively with biventricular pacing system. The patients were studied at the pacemaker follow-up clinic. Each patient was subjected to: Full medical history, general and local examination, a 12 lead electrocardiogram and QRS duration in ms was measured. All patients were subjected to a focused transthoracic echocardiographic examination in which a parasternal long axis view was obtained to measure the diameter of the LVOT diameter in mid-systole. The LVOT VTI was measured by pulsed-wave Doppler in the LVOT using a 2-mm sample volume positioned just proximal to the aortic valve in the apical five chamber view.

Results

We found a statistically significant difference between CRT responders and nonresponders as regards age, body surface area (BSA), time since CRT implantation and smoking status (P = 0.018, 0.039, 0.002, <0.001). There was negative significant correlation between QRS duration and LVOT VTI and stroke volume index. The optimal cut off values for optimal response to CRT using receiver operating characteristics curves were 130 ms for postimplant QRS duration and 17.1 cm for LVOT VTI. We also found a significant difference between responders and nonresponders as regard CO. It was higher in responders (5.97 vs. 3.34, P < 0.001).

Conclusion

CRT response is more in patients with lower BSA, and without previous history of ischemic heart disease or smoking. There is a significant negative correlation between QRS duration and LVOT VTI.

True complete left bundle branch block reveals dyssynchrony evaluated by semiconductor single-photon emission computed tomography

BACKGROUND

Conventional complete left bundle branch block (CLBBB) criteria sometimes result in a false-positive diagnosis that does not represent dyssynchrony. Recently, true CLBBB criteria have been proposed to detect responders to cardiac resynchronization therapy (CRT), although their correlation with severity of dyssynchrony or natural prognosis is unclear.

METHODS

Ninety-four consecutive patients (74 ± 9 years, 63 men) with conventional CLBBB during sinus rhythm underwent semiconductor SPECT. They were divided into two groups: patients with true CLBBB and others. True CLBBB was characterized by the mid-QRS notching/slurring and wide QRS duration (male, ≥140 milliseconds; female, ≥130 milliseconds). Multivariate analysis was performed to detect left ventricular dyssynchrony (LVD), defined as bandwidth ≥145° and/or phase standard deviation (SD) ≥43°. Primary endpoints (hospitalization for heart failure or cardiac death) were evaluated.

RESULTS

True CLBBB had wider bandwidth (145 ± 83° vs 110 ± 64°, P = 0.024) and higher phase SD (48 ± 26° vs 35 ± 19°, P = 0.007). Ejection fraction (EF), end-diastolic volume (EDV), summed rest score (SRS), and the presence of ischemic heart disease (IHD) showed no differences between groups (P = 0.401, 0.591, 0.165, and 0.212, respectively). Multivariate analysis revealed that true CLBBB, EF, and EDV were significant predictors of LVD (odds ratio, 12.6, 0.90, 1.03; P = 0.003, 0.002, 0.022, respectively). At 3-year follow-up (median 667 days), primary endpoints were comparable in both groups (log-rank, P = 0.92).

CONCLUSIONS

Patients with true CLBBB had more severe dyssynchrony on single-photon emission computed tomography than patients with nontrue CLBBB. On the other hand, the two groups showed no differences in EF, EDV, the presence of IHD, hospitalization for heart failure, and cardiac death.

Role of cardiovascular imaging in cardiac resynchronization therapy: a literature review

: Cardiac resynchronization therapy (CRT) is an established treatment in patients with symptomatic drug-refractory heart failure and broad QRS complex on the surface ECG. Despite the presence of either mechanical dyssynchrony or viable myocardium at the site where delivering left ventricular pacing being necessary conditions for a successful CRT, their direct assessment by techniques of cardiovascular imaging, though feasible, is not recommended in clinical practice by the current guidelines. Indeed, even though there is growing body of data providing evidence of the additional value of an image-based approach as compared with routine approach in improving response to CRT, these results should be confirmed in prospective and large multicentre trials before their impact on CRT guidelines is considered.

Echocardiography for the management of patients with biventricular pacing: Possible roles in cardiac resynchronization therapy implementation

Cardiac resynchronization therapy (CRT) is an established therapeutic option for the subset of patients with heart failure (HF), reduced ejection fraction (EF), and dyssynchrony evidenced by electrocardiography. Benefit from CRT has been proven in many clinical trials, yet a sizeable proportion of these patients with wide QRS do not respond to this intervention, despite the updated practice guidelines. Several echocardiographic indices, targeting mechanical rather than electrical dyssynchrony, have been suggested to address this issue, but research so far has not succeeded in providing a single and simple measurement with adequate sensitivity and specificity for identification of responders. While there is still ongoing research in this field, echocardiography proves helpful in other aspects of CRT implementation, such as site selection for left ventricular (LV) lead pacing and optimization of pacing parameters during follow-up visits.