Characteristics of heart failure patients associated with good and poor response to cardiac resynchronization therapy: a PROSPECT (Predictors of Response to CRT) sub-analysis

Heart Size Difference Drives Sex-Specific Response to Cardiac Resynchronization Therapy: A Post Hoc Analysis of the MORE-MPP CRT Trial

BACKGROUND

Studies have reported that female sex predicts superior cardiac resynchronization therapy (CRT) response. One theory is that this association is related to smaller female heart size, thus increased relative dyssynchrony at a given QRS duration (QRSd). Our objective was to investigate the mechanisms of sex-specific CRT response relating to heart size, relative dyssynchrony, cardiomyopathy type, QRS morphology, and other patient characteristics.

METHODS AND RESULTS

This is a post hoc analysis of the MORE-CRT MPP (More Response on Cardiac Resynchronization Therapy with Multipoint Pacing)  trial (n=3739, 28% women), with a subgroup analysis of patients with nonischemic cardiomyopathy and left bundle-branch block (n=1308, 41% women) to control for confounding characteristics. A multivariable analysis examined predictors of response to 6 months of conventional CRT, including sex and relative dyssynchrony, measured by QRSd/left ventricular end-diastolic volume (LVEDV). Women had a higher CRT response rate than men (70.1% versus 56.8%, P<0.0001). In subgroup analysis, regression analysis of the nonischemic cardiomyopathy left bundle-branch block subgroup identified QRSd/LVEDV, but not sex, as a modifier of CRT response (P<0.0039). QRSd/LVEDV was significantly higher in women (0.919) versus men (0.708, P<0.001). CRT response was 78% for female patients with QRSd/LVEDV greater than the median value, compared with 68% with QRSd/LVEDV less than the median value (P=0.012). The association between CRT response and QRSd/LVEDV was strongest at QRSd <150 ms.

CONCLUSIONS

In the nonischemic cardiomyopathy left bundle-branch block population, increased relative dyssynchrony in women, who have smaller heart sizes than their male counterparts, is a driver of sex-specific CRT response, particularly at QRSd <150 ms. Women may benefit from CRT at a QRSd <130 ms, opening the debate on whether sex-specific QRSd cutoffs or QRS/LVEDV measurement should be incorporated into clinical guidelines.

Determining whether LV filling time contributes to HF symptoms in different widths of QRS in LBBB patients: A clinical study

OBJECTIVES

Accurate assessment of left ventricular (LV) function is essential for managing patients with left bundle branch block (LBBB). This study aimed to evaluate the relationship between LV systolic function, left ventricular diastolic filling time (LVFT), QRS duration, and heart failure symptoms in patients with LBBB.

METHODS

This study was conducted between June 2021 and June 2022. Patients with LBBB and sinus rhythm who were referred to the echocardiography department were included in the study. All the patients underwent electrocardiogram-gated echocardiography using the same machine. In this study, the LVFT value was measured in absolute terms and as a ratio to the R-R interval (LVFT/RR).

RESULTS

A total of sixty-five patients were included, forty-two (64.6%) were women, and the mean age was 60.71 ± 8.72. We performed three one-way ANOVA tests that showed that LV filling time/RR ratio, QRS duration, and ejection fraction were significantly different between heart failure classes (p = 0.008, p = 0.001, and p < 0.001, respectively). A weak correlation was observed between LVEF and LVFT/RR (r = 0.349, p = 0.004). Additionally, QRS duration was negatively correlated with LVEF (r =  - 0.395, p = 0.004) and LVFT/RR (r =  - 0.350, p = 0.004), although these correlations were weak.

CONCLUSION

We showed that LVFT/RR ratio differed significantly between HF functional classes and was lower in patients with more severe HF symptoms. Additionally, QRS duration was negatively correlated with LVEF and LVFT/RR, and patients with more severe HF symptoms had longer QRS durations.

Heart size disparity drives sex-specific response to cardiac resynchronization therapy: a post-hoc analysis of the MORE-MPP CRT trial

Background

Studies have reported that female sex predicts superior cardiac resynchronization therapy (CRT) response. One theory is that this association is related to smaller female heart size, thus increased "relative dyssynchrony" at given QRS durations (QRSd).

Objective

To investigate the mechanisms of sex-specific CRT response relating to heart size, relative dyssynchrony, cardiomyopathy type, QRS morphology, and other patient characteristics.

Methods

A post-hoc analysis of the MORE-CRT MPP trial (n=3739, 28% female), with a sub-group analysis of patients with non-ischaemic cardiomyopathy (NICM) and left bundle branch block (LBBB) (n=1308, 41% female) to control for confounding characteristics. A multivariable analysis examined predictors of response to 6 months of conventional CRT, including sex and relative dyssynchrony, measured by QRSd/LVEDV (left ventricular end-diastolic volume).

Results

Females had a higher CRT response rate than males (70.1% vs. 56.8%, p<0.0001). Subgroup analysis: Regression analysis of the NICM LBBB subgroup identified QRSd/LVEDV, but not sex, as a modifier of CRT response (p<0.0039). QRSd/LVEDV was significantly higher in females (0.919) versus males (0.708, p<0.001). CRT response was 78% for female patients with QRSd/LVEDV>median value, compared to 68% < median value (p=0.012). Association between CRT response and QRSd/LVEDV was strongest at QRSd<150ms.

Conclusions

In the NICM LBBB population, increased relative dyssynchrony in females, who have smaller heart sizes than their male counterparts, is a driver of sex-specific CRT response, particularly at QRSd <150ms. Females may benefit from CRT at a QRSd <130ms, opening the debate on whether sex-specific QRSd cut-offs or QRS/LVEDV measurement should be incorporated into clinical guidelines.

Predictors of long-term survival in Japanese patients with heart failure with reduced ejection fraction (HFrEF) treated with cardiac resynchronization therapy-defibrillators (CRT-D)

BACKGROUND

Reports on the factors predicting long-term survival of CRT-D cases from Western countries are increasing, however, those from Asia including Japan are still sparse. We aimed to clarify the factors predicting long-term survival of Japanese CRT-D cases.

METHODS

We retrospectively analyzed consecutive 133 patients who underwent CRT-D implantation between 2006 and 2021. We compared clinical factors between patients who died within 5 years after implantation (short-survival group: n = 31) and who had survived for more than 5 years (long-survival group: n = 36) after implantation.

RESULTS

Major underlying heart diseases were dilated cardiomyopathy (45%) and ischemic heart disease (12%). There was no difference between the short-survival group and the long-survival group in incidence of CLBBB (32% vs. 30%), whereas CRBBB was more common in the short-survival group (26% vs. 0%, p = .004). Mechanical dyssynchrony at implantation was more frequent in the long-survival group (48% vs. 78%, p = .02). The incidence of response to CRT at 1 year after implantation was higher in long-survival group (19% vs. 50%, p = .02). Multiple logistic regression analysis identified NYHA class, mechanical dyssynchrony at implantation, and response at one year as predictors of long-term survival.

CONCLUSIONS

In Japanese CRT-D cases, lower NHYA class, preexisting mechanical dyssynchrony, and 1-year response to CRT predict long-term survival.

Electrical Resynchronization and Clinical Outcomes During Long-Term Follow-Up in Intraventricular Conduction Delay Patients Applied Left Bundle Branch Pacing-Optimized Cardiac Resynchronization Therapy

BACKGROUND

Left bundle branch-optimized cardiac resynchronization therapy (LOT-CRT) has shown encouraging results for QRS duration reduction and heart function improvement. However, the feasibility and efficacy of LOT-CRT have not been well established in intraventricular conduction delay patients. This study aims to assess and compare the efficacy and clinical outcome of CRT based on left bundle branch pacing, combined with coronary sinus left ventricular pacing (LOT-CRT) with CRT via biventricular pacing (BiV-CRT) in intraventricular conduction delay patients indicated for CRT.

METHODS

Consecutive patients with intraventricular conduction delay and CRT indications were assigned nonrandomized to LOT-CRT (n=30) or BiV-CRT (n=55). Addition of the left bundle branch pacing (or coronary venous) lead was at the discretion of the implanting physician guided by suboptimal paced QRS complex and on clinical grounds. Echocardiographic parameters and clinical characteristics were accessed at baseline and during 2-years' follow-up.

RESULTS

Success rate for LOT-CRT and BiV-CRT was 96.8% and 96.4%. LOT-CRT had greater reduction of QRS duration compared with BiV-CRT (42.7±17.4 ms versus 21.9±21.5 ms; P<0.001). Higher left ventricular ejection fraction was also achieved in LOT-CRT than BiV-CRT at 6-month (36.7±9.8% versus 30.5±6.4%; P<0.05), 12-month (34.8±7.6% versus 30.3±6.2%; P<0.05), 18-month (36.3±7.9% versus 28.1±6.6%; P<0.005), and 24-month follow-up (37±9.5% versus 30.5±7%; P<0.05). Adverse clinical outcomes including heart failure rehospitalization and mortality were lower in LOT-CRT group for 24 months follow-up (hazard ratio, 0.33; P=0.035).

CONCLUSIONS

LOT-CRT improves ventricular electrical synchrony and may provide greater clinical outcomes as compared with BiV-CRT in intraventricular conduction delay patients. These findings need further evaluation in future randomized controlled trials.

Comparison of electrocardiographic parameters between left bundle optimized cardiac resynchronization therapy (LOT-CRT) and left bundle branch pacing-cardiac resynchronization therapy (LBBP-CRT)

BACKGROUND

In patients undergoing cardiac resynchronization therapy using left bundle branch area pacing (LBBP-CRT), the addition of a coronary sinus lead, that is, Left bundle optimized CRT (LOT-CRT) might confer additional benefits.

OBJECTIVES

To compare the electrocardiographic characteristics between LBBP-CRT and LOT-CRT MATERIALS AND METHODS: Patients with non-ischemic cardiomyopathy (NICMP) and left bundle branch block (LBBB) with left ventricular ejection fraction <35% who underwent implantation of an atrial lead, a left bundle lead, and a coronary sinus lead were included in this prospective study. Digital 12-lead electrocardiograms were recorded in three pacing modes-AAI, DDD with pacing from the LBB lead (LBBP-CRT), and DDD with pacing from both left bundle and coronary sinus leads (LOT-CRT). QRS duration (QRSd), QRS area, QT interval, and T peak-T end (TpTe) intervals were compared.

RESULTS

Among 24 patients, QRSd reduced from 167 ± 21.2 ms to 134.5 ± 23.6 ms with LBBP-CRT (p < .001) and 129.5 ± 18.6 ms with LOT-CRT (p < .001) without a significant difference between LBBP-CRT and LOT-CRT (p = .15). Patients with QRS duration with LBBP-CRT > 131 ms showed a significant reduction in QRSd with LOT-CRT (p = .03). QT interval was reduced with both modes of CRT. LOT-CRT was associated with a greater reduction in QRS area (p = .001), TpTe interval (p = .03), and TpTe/QT ratio (p = .013) compared to LBBP-CRT.

CONCLUSIONS

In patients with NICMP and LBBB, there was no significant difference in QRSd with LOT-CRT compared to LBBP-CRT. However, in patients with QRSd > 131 ms after LBBP-CRT, LOT-CRT resulted in a significantly narrower QRS.

Aconitum carmichaelii Debx. Attenuates Heart Failure through Inhibiting Inflammation and Abnormal Vascular Remodeling

Heart failure (HF) is the most common complication following myocardial infarction, closely associated with ventricular remodeling. Aconitum carmichaelii Debx., a traditional Chinese herb, possesses therapeutic effects on HF and related cardiac diseases. However, its effects and mechanisms on HF-associated cardiac diseases are still unclear. In the present study, a water extraction of toasted Aconitum carmichaelii Debx. (WETA) was verified using UPLC-Q/TOF-MS. The heart function of HF rats was assessed by echocardiography and strain analysis, and myocardial injury was measured by serum levels of CK-MB, cTnT, and cTnI. The pathological changes of cardiac tissues were evaluated by 2,3,5-triphenyltetrazolium chloride (TTC) staining, hematoxylin and eosin (H&E) staining, and Masson's trichrome staining. Additionally, the levels of inflammation-related genes and proteins and components related to vascular remodeling were detected by RT-qPCR, Western blot, and immunofluorescence. WETA significantly inhibited the changes in echocardiographic parameters and the increase in heart weight, cardiac infarction size, the myonecrosis, edema, and infiltration of inflammatory cells, collagen deposition in heart tissues, and also mitigated the elevated serum levels of CK-MB, cTnT, and cTnI in ISO-induced rats. Additionally, WETA suppressed the expressions of inflammatory genes, including IL-1β, IL-6, and TNF-α and vascular injury-related genes, such as VCAM1, ICAM1, ANP, BNP, and MHC in heart tissues of ISO-induced HF rats, which were further confirmed by Western blotting and immunofluorescence. In summary, the myocardial protective effect of WETA was conferred through inhibiting inflammatory responses and abnormal vascular remodeling in ISO-treated rats.

Predicting factors of echocardiographic super-response to cardiac resynchronization therapy

PURPOSE

To investigate the clinical and echocardiographic predictors of echocardiographic super-response to cardiac resynchronization therapy (CRT) in heart failure patients.

METHODS

We retrospectively collected data from 97 patients, who underwent CRT and were followed up (median time = 20.33 months). All had left ventricular ejection fraction (LVEF) ≤35%, New-York-Heart-Association class 3 or 4, and Q wave, R wave and S wave (QRS) duration >120 ms. Time-to-peak systolic velocity was measured for individual LV segments by tissue Doppler imaging prior to CRT. Two-dimensional echocardiography was carried out before and at follow-up, and ≥12.5% increase in LVEF was defined as super-response.

RESULTS

From the 97 patients, 23 (23.7%) were super-responders. Super-responders were more frequently female (52.2% vs. 24.3%, respectively; p value = 0.012). Among super-responders, the mean of LV end-diastolic and end-systolic volumes were significantly lower. According to dyssynchrony indices, time delay between anteroseptal and posterior wall and SD of all LV segments timing showed significantly higher values in super-responders. By multivariate analysis, LV end-systolic volume and anteroseptal-to-posterior wall delay remained independently associated with echocardiographic super-response to CRT.

CONCLUSION

About one-fourth of our patients with CRT were super-responder in that they had ≥12.5% increase in LVEF by echocardiography. Among all the clinical and echocardiographic measures, only lower LV end-systolic volume and higher anteroseptal-to-posterior wall delay predicted super-response.

Association of left ventricular remodeling with cardiac resynchronization therapy outcomes

BACKGROUND

Cardiac resynchronization therapy (CRT) response stratified by left ventricular (LV) remodeling revealed differing mortality profiles for distinct patient cohorts. Measuring functional end points, as well as mortality, may better assess CRT efficacy and inform patient management. However, the association between LV remodeling and functional outcomes after CRT is not well understood.

OBJECTIVE

The purpose of this study was to evaluate long-term CRT outcomes by extent of LV remodeling.

METHODS

REsynchronization reVErses Remodeling in Systolic Left vEntricular dysfunction (ClinicalTrials.gov identifier NCT00271154) was a prospective, double-blind, randomized trial of CRT. Subjects were classified on the basis of LV end-systolic volume (LVESV) change from baseline to 6 months post-CRT: worsened (increase), stabilized (0%-≤15% reduction), responder (>15%-<30% reduction), and super-responder (≥30% reduction). Subjects were evaluated annually for 5 years.

RESULTS

The analyses included 353 subjects randomized to CRT-ON arm. All-cause mortality was higher in the worsened group than in the other 3 response groups (29.8% vs 8.0%; P < .0001), with no difference in survival among those groups (P = .87). A significant interaction between the LVESV group and time was observed for health status and quality of life (P = .02 for both). The interaction was not significant for 6-minute hall walk (P = .79); however, super-responders had increased walk distance compared with the other 3 response groups (P = .03).

CONCLUSION

Preventing further increase in LVESV with CRT was associated with reduced mortality, whereas functional measure improvement was associated with LV remodeling magnitude. These results support the consideration of functional and mortality end points to assess CRT efficacy and provide further evidence that the dichotomous "responder and nonresponder" classification should be modified.

Dyssynchrony and Response to Cardiac Resynchronization Therapy in Heart Failure Patients With Unfavorable Electrical Characteristics

BACKGROUND

Among heart failure (HF) patients undergoing cardiac resynchronization therapy (CRT), those with unfavorable electrical characteristics (UEC) are less frequently CRT responders.

OBJECTIVES

In this study, the authors sought to evaluate the relationship between preprocedural echocardiographic parameters of electromechanical dyssynchrony (EMD) and outcome following CRT.

METHODS

Among 551 patients receiving CRT, 121 with UEC, defined as atypical left bundle branch, presence of right bundle branch block, or unspecified intraventricular conduction disturbance, were enrolled. Indices of EMD were presence of septal flash, apical rocking, septal deformation patterns, and global wasted work (GWW), determined with the use of speckle-tracking strain echocardiography. Endpoints were response to CRT, defined as a relative decrease in left ventricular end-systolic volume ≥15% at 9-month postoperative follow-up, and all-cause death or HF hospitalization during follow-up.

RESULTS

Among the 121 patients, 68 (56%) were CRT responders. In multivariate analysis, GWW ≥200 mm Hg% (adjusted odds ratio [aOR]: 4.17 [95% CI: 1.33-14.56]; P = 0.0182) and longitudinal strain septal contraction patterns 1 and 2 (aOR: 10.05 [95% CI: 2.82-43.97]; P < 0.001) were associated with CRT response. During a 46-month follow-up (IQR: 42-55 months), survival free from death or HF hospitalization increased with the number of positive criteria (87% for 2, 59% for 1, and 27% for 0). After adjustment for established predictors of outcome in patients receiving CRT, absence of either of the 2 criteria remained associated with a considerable increased risk of death and/or HF hospitalization (adjusted HR: 4.83 [95% CI: 1.84-12.68]; P = 0.001).

CONCLUSIONS

In patients with UEC, echocardiographic assessment of EMD may help to select patients who will derive benefit from CRT.

Nonischemic Super-Responders in Fusion CRT Pacing with Normal Atrioventricular Conduction

Background: Fusion CRT pacing (FCRT) is noninferior to biventricular pacing, according to the current data. The aim of this study is to assess the response to FCRT and to identify predictors of super-responders (SRs) in a nonischemic population with normal AV conduction. Methods: LV-only CRT patients (pts) with a right atrium/left ventricle pacing system implanted in two CRT centers in Romania were included. Device interrogation, exercise tests, echocardiography, and individualized drug optimization were performed every 6 months during close follow-up. SRs pts were defined as those with left ventricular end-systolic volume (LVESV) improvement ≥30% and stable ejection fraction (LVEF) ≥45%. Results: A total of 25 out of 83 pts (31%) were SRs, with nonischemic LBBB low EF cardiomyopathy (50 male, 62 ± 9 y.o.) initially included. Mean follow-up was 5 years ± 27 months. Patients were divided in two groups: SRs and non-SRs (52 responders/6 hypo-responders). Two predictors were found in the SRs group: a higher baseline LVEF (SRs 29 ± 5% vs. non-SRs 26 ± 5%, p = 0.02) and a lower pulmonary arterial systolic pressure (SRs 38 ± 11 mm Hg vs. non-SRs 50 ± 15 mmHg, p = 0.003). Baseline severe mitral regurgitation was found in 11% of SRs vs. 64% in the non-SRs group. Conclusions: SRs in the selected NICM-FCRT group are significative high. Higher baseline LVEF and mild pulmonary arterial hypertension were independently associated with super-response.

Tracking Early Systolic Motion for Assessing Acute Response to Cardiac Resynchronization Therapy in Real Time

An abnormal systolic motion is frequently observed in patients with left bundle branch block (LBBB), and it has been proposed as a predictor of response to cardiac resynchronization therapy (CRT). Our goal was to investigate if this motion can be monitored with miniaturized sensors feasible for clinical use to identify response to CRT in real time. Motion sensors were attached to the septum and the left ventricular (LV) lateral wall of eighteen anesthetized dogs. Recordings were performed during baseline, after induction of LBBB, and during biventricular pacing. The abnormal contraction pattern in LBBB was quantified by the septal flash index (SFI) equal to the early systolic shortening of the LV septal-to-lateral wall diameter divided by the maximum shortening achieved during ejection. In baseline, with normal electrical activation, there was limited early-systolic shortening and SFI was low (9 ± 8%). After induction of LBBB, this shortening and the SFI significantly increased (88 ± 34%, p < 0.001). Subsequently, CRT reduced it approximately back to baseline values (13 ± 13%, p < 0.001 vs. LBBB). The study showed the feasibility of using miniaturized sensors for continuous monitoring of the abnormal systolic motion of the LV in LBBB and how such sensors can be used to assess response to pacing in real time to guide CRT implantation.

ECG optimisation for CRT systems in the era of automatic algorithms: a comprehensive review

Cardiac resynchronisation therapy (CRT) may fail in up to one third of patients, mainly due to anatomical and procedural issues. In the daily practice, ECG optimisation is largely used to address CRT delivery. Ineffective CRT can be related to non-optimal pacing timing as well as inadequate pacing-capture. A rate-competitive atrial fibrillation (AF) or a high daily burden of premature ventricular contractions (PVC) may also affect CRT by means of fusion or pseudo-fusion captures. Growing observations suggest that in a subset of patients with typical left bundle branch block (LBBB), selected LV pacing may be more effective, producing a complete fusion between the left pacing and the intrinsic right bundle activation. The His-ventricular (HV) interval is an invasive measurement (derived from electrophysiological study), which mainly reflects the RV activation (and its contribution to QRS timing) and has been proposed by some authors when addressing LV-paced–RV-sensed fusion. In sinus rhythm CRT patients, with baseline typical LBBB criteria and preserved AV conduction, the “dromotropic” management to achieve RV intrinsic activation with LV fusion is also “AV delay dependent”. In this regard, the RV intrinsic activation (detected by RV sensing) and the A (paced/sensed)-RV (sensed) interval are also influenced by the RV lead position within the RV. The current families of CRT devices have implemented automatic algorithms to optimise AV and VV timing intervals. The proof of principle is again the evidence that fusion of an LV-paced beat with intrinsic rhythm may be more beneficial than standard biventricular pacing, provided a preserved AV conduction. In the present review, all the above issues are discussed.

The efficacy and safety outcomes of cardiac resynchronization therapy in patients with heart failure in Thailand: Phramongkutklao experience

BACKGROUND

Cardiac resynchronization therapy (CRT) is one of the crucial treatments in patients with symptomatic heart failure reduced ejection fraction. This study aimed to report the efficacy and safety of CRT implantation in treating patients with heart failure. The responders and related outcomes were also analyzed.

METHODS

Medical records of all patients with CRT implantation, because of heart failure treatment indication, in Phramongkutklao Hospital between 2008 and 2019 were reviewed. Free from death and heart failure hospitalization were analyzed as composited efficacy outcomes with survival analysis. Follow-up echocardiography was used to define a responder. The safety outcomes were reported using descriptive data. Cox-proportional hazard model analysis was used for the responder as a predictor of outcomes.

RESULTS

A total of 152 patients underwent CRT implantation because of heart failure. 77.63% were male, the mean age of 65.9 ± 13.19 years, 59.85% were diagnosed with ischemic cardiomyopathy, mean LVEF of 22.69 ± 7.51%, and QRS duration of 147 ± 21 ms. Mean Follow-up was 41 months. The composited efficacy outcomes were 91.7%, 54.8%, and 35.4% at 1, 5, and 10 years, respectively. CRT-related complications were found in 12 patients (7.89%). 71.30% of patients who were responders had lower death or heart failure hospitalization when compared to non-responders (HR: 0.43, 95% CI: 0.24-0.78).

CONCLUSION

The efficacy and safety in CRT treating patients in our center were consistent with the previous randomized and observational studies. The responder rate remained the same as in previous trials but was a strong predictor for better outcomes.

Determinants of left ventricular function improvement for cardiac resynchronization therapy candidates

AIMS

A waiting period of more than 3 months is recommended for patients before undergoing cardiac resynchronization therapy (CRT). However, due to an anticipated high mortality rate, early implementation of CRT might be beneficial for some patients. We aimed to evaluate the rate and the probability of left ventricular (LV) function improvement and their predictors in patients with heart failure (HF) with indications for CRT.

METHODS AND RESULTS

From March 2011 to February 2014, a total of 5625 hospitalized patients for acute HF were consecutively enrolled in 10 tertiary hospitals. Among them, we analysed 1792 patients (mean age 63.96 ± 15.42 years, female 63.1%) with left ventricular ejection fraction (LVEF) ≤ 35% at the baseline echocardiography and divided them into three groups: 144 with left bundle branch block (LBBB), 136 with wide QRS complexes without LBBB, and 1512 not having these findings (control). We compared and analysed these three groups for improvement of LV function at follow-up echocardiography. In patients who met CRT indications (patients with LBBB or wide QRS complexes without LBBB), logistic regression was performed to identify risk factors for no improvement of LV. No improvement of LV was defined as LVEF ≤ 35% at follow-up echocardiography or the composite adverse outcomes: death, heart transplantation, extracorporeal membrane oxygenation, or use of a ventricular assist device before follow-up echocardiography. A classification tree was established using the binary recursive partitioning method to predict the outcome of patients who met CRT indications. In a median follow-up of 11 months, LVEF improvement was observed in 24.3%, 15.4%, and 40.5% of patients with LBBB, wide QRS complexes without LBBB, and control, respectively. Patients meeting CRT indications had higher 3 month mortality rates than the control (24.6% vs. 17.7%, P = 0.002). Multivariable logistic regression analysis revealed that large LV end-systolic dimension [odds ratio (OR) 1.10, 95% confidence interval (CI) 1.05-1.15, P < 0.001], low LVEF (OR 0.92, 95% CI 0.87-0.98, P = 0.006), diabetes requiring insulin (OR 6.49, 95% CI 2.53-19.33, P < 0.001), and suboptimal medical therapy (OR 6.85, 95% CI 3.21-15.87, P < 0.001) were significant factors predictive of no improvement. A decision tree analysis was consistent with these results.

CONCLUSIONS

Patients with CRT indications had higher mortality during their follow-up compared with control. LV function improvement was rare in this population, especially when they had some risk factors. These results suggest that the uniform waiting period before CRT implantation could be reconsidered and individualized.

Improvement of LV Reverse Remodeling Using Dynamic Programming of Fusion-Optimized Atrioventricular Intervals in Cardiac Resynchronization Therapy

Background: The patient-tailored SyncAV algorithm shortens the QRS duration (QRSd) beyond what conventional biventricular (BiV) pacing can. However, evidence of the ability of SyncAV to improve the cardiac resynchronization therapy (CRT) response is lacking. The aim of this study was to evaluate the impact of CRT enhanced by SyncAV on echocardiographic and clinical responses.

Methods and Results: Consecutive heart failure (HF) patients from three centers treated with a quadripolar CRT system (Abbott) were enrolled. The total of 122 patients were divided into BiV+SyncAV (n = 68) and BiV groups (n = 54) according to whether they underwent CRT with or without SyncAV. Electrocardiographic, echocardiographic, and clinical data were assessed at baseline and during follow-up. Echocardiographic response to CRT was defined as a ≥15% decrease in left ventricular end-systolic volume (LVESV), and clinical response was defined as a NYHA class reduction of ≥1. At the 6-month follow-up, the baseline QRSd and LVESV decreased more significantly in the BiV+SyncAV than in the BiV group (QRSd −36.25 ± 16.33 vs. −22.72 ± 18.75 ms, P < 0.001; LVESV −54.19 ± 38.87 vs. −25.37 ± 36.48 ml, P < 0.001). Compared to the BiV group, more patients in the BiV+SyncAV group were classified as echocardiographic (82.35 vs. 64.81%; P = 0.036) and clinical responders (83.82 vs. 66.67%; P = 0.033). During follow-up, no deaths due to HF deterioration or severe procedure related complications occurred.

Conclusion: Compared to BiV pacing, BiV combined with SyncAV leads to a more significant reduction in QRSd and improves LV remodeling and long-term outcomes in HF patients treated with CRT.

Levels of Trimethylamine N-Oxide Remain Elevated Long Term After Left Ventricular Assist Device and Heart Transplantation and Are Independent From Measures of Inflammation and Gut Dysbiosis

BACKGROUND

Trimethylamine N-oxide (TMAO)-a gut-derived metabolite-is elevated in heart failure (HF) and linked to poor prognosis. We investigated variations in TMAO in HF, left ventricular assist device (LVAD), and heart transplant (HT) and assessed its relation with inflammation, endotoxemia, oxidative stress, and gut dysbiosis.

METHODS

We enrolled 341 patients. TMAO, CRP (C-reactive protein), IL (interleukin)-6, TNF-α (tumor necrosis factor alpha), ET-1 (endothelin-1), adiponectin, lipopolysaccharide, soluble CD14, and isoprostane were measured in 611 blood samples in HF (New York Heart Association class I-IV) and at multiple time points post-LVAD and post-HT. Gut microbiota were assessed via 16S rRNA sequencing among 327 stool samples. Multivariable regression models were used to assess the relationship between TMAO and (1) New York Heart Association class; (2) pre- versus post-LVAD or post-HT; (3) biomarkers of inflammation, endotoxemia, oxidative stress, and microbial diversity.

RESULTS

ln-TMAO was lower among HF New York Heart Association class I (1.23 [95% CI, 0.52-1.94] µM) versus either class II, III, or IV (1.99 [95% CI, 1.68-2.30], 1.97 [95% CI, 1.71-2.24], and 2.09 [95% CI, 1.83-2.34] µM, respectively; all P<0.05). In comparison to class II-IV, ln-TMAO was lower 1 month post-LVAD (1.58 [95% CI, 1.32-1.83] µM) and 1 week and 1 month post-HT (0.97 [95% CI, 0.60-1.35] and 1.36 [95% CI, 1.01-1.70] µM). ln-TMAO levels in long-term LVAD (>6 months: 1.99 [95% CI, 1.76-2.22] µM) and HT (>6 months: 1.86 [95% CI, 1.66-2.05] µM) were not different from symptomatic HF. After multivariable adjustments, TMAO was not associated with biomarkers of inflammation, endotoxemia, oxidative stress, or microbial diversity.

CONCLUSIONS

TMAO levels are increased in symptomatic HF patients and remain elevated long term after LVAD and HT. TMAO levels were independent from measures of inflammation, endotoxemia, oxidative stress, and gut dysbiosis.

Left ventricle pacing challenges in cardiac resynchronization therapy systems

Left ventricle (LV) pacing can be considered peculiar due to its different lead/tissue interface (epicardial pacing) and the small vein wedging lead locations with less reliable lead stability. The current technologies available for LV capture automatic confirmation adopt the evoked response (ER), as well as "LV pace to right ventricular (RV) sense" algorithms. The occurrence of anodal RV capture is today completely solved by the use of bipolar LV leads, while intriguing data are recently published regarding the unintentional LV anodal capture beside the cathodal one, which may enlarge the front wave of cardiac resynchronization therapy (CRT) delivery. The LV threshold behavior over time leading to ineffective CRT issues (subthreshold stimulation or concealed loss of capture), the extracardiac capture with phrenic nerve stimulation (PNS), the flexible electronic cathode reprogramming and the inadequate CRT delivery related to inadequate AV and VV pace timing (and its management by LV "dromotropic pace-conditioning") are discussed. Moreover, recently, His bundle pacing (HBP) and left bundle branch pacing (LBBP) have shown growing interest to prevent pacing-induced cardiomyopathy as well as for direct intentional CRT. The purpose of the present review is to explore these new challenges regarding LV pacing starting from old concepts.

Cardiovascular Imaging Applications in Clinical Management of Patients Treated with Cardiac Resynchronization Therapy

Cardiovascular imaging techniques, including echocardiography, nuclear cardiology, multi-slice computed tomography, and cardiac magnetic resonance, have wide applications in cardiac resynchronization therapy (CRT). Our aim was to provide an update of cardiovascular imaging applications before, during, and after implantation of a CRT device. Before CRT implantation, cardiovascular imaging techniques may integrate current clinical and electrocardiographic selection criteria in the identification of patients who may most likely benefit from CRT. Assessment of myocardial viability by ultrasound, nuclear cardiology, or cardiac magnetic resonance may guide optimal left ventricular (LV) lead positioning and help to predict LV function improvement by CRT. During implantation, echocardiographic techniques may guide in the identification of the best site of LV pacing. After CRT implantation, cardiovascular imaging plays an important role in the assessment of CRT response, which can be defined according to LV reverse remodeling, function and dyssynchrony indices. Furthermore, imaging techniques may be used for CRT programming optimization during follow-up, especially in patients who turn out to be non-responders. However, in the clinical settings, the use of proposed functional indices for different imaging techniques is still debated, due to their suboptimal feasibility and reproducibility. Moreover, identifying CRT responders before implantation and turning non-responders into responders at follow-up remain challenging issues.

Prognostic effects of longitudinal changes in left ventricular ejection fraction with cardiac resynchronization therapy

Aims

Left ventricular ejection fraction (LVEF) is considered an indicator of cardiac resynchronization therapy (CRT). Longitudinal studies on the predictive value of LVEF are scarce. We aimed to comprehensively evaluate the prognostic role of LVEF in the outcomes of Chinese patients with CRT.

Methods and results

Three hundred ninety‐two patients were divided into three tertiles of LVEF: ≤25%, 25–30%, and 30–35%, and four groups by LVEF changes: <0% (negative response); ≥0% and ≤5% (non‐response); >5% and ≤15% (response); and >15% (super‐response). One hundred six patients were super‐responders. During a median follow‐up of 3.6 years, 141 reached the composite endpoint. Odds ratios (ORs) for super‐response depicted a reversed U‐shaped relationship for baseline LVEF with a peak at 25–30%. Independent predictors of super‐response were smaller left atrial diameter [odds ratio 0.897, 95% confidence interval (CI) 0.844–0.955, P = 0.001], smaller left ventricular end‐diastolic diameter (OR 0.937, 95% CI 0.889–0.989, P = 0.018), and higher estimated glomerular filtration rate (OR 1.018, 95% CI 1.001–1.035, P = 0.042) in Tertile 1; atrial fibrillation (OR 0.278, 95% CI 0.086–0.901, P = 0.033), left bundle branch block (OR 4.096, 95% CI 1.046–16.037, P = 0.043), and left ventricular end‐diastolic diameter (OR 0.929, 95% CI 0.876–0.986, P = 0.016) in Tertile 2; while female sex (OR 2.778, 95% CI 1.082–7.132, P = 0.034) and higher systolic blood pressure (OR 1.045, 95% CI 1.013–1.079, P = 0.006) in Tertile 3. An inverse association with the composite endpoint was found in Tertile 1 vs. Tertile 2 (hazard ratio 1.934, 95% CI 1.248–2.996, P = 0.003). The prognostic effects of CRT response in Tertile 3 and Tertile 1 varied significantly (P for trend = 0.017 and <0.001). Among three tertiles in super‐responders, event‐free survival was similar (P for trend = 0.143).

Conclusions

Left ventricular ejection fraction of 25–30% is associated with a better prognosis of super‐response. Predictors of super‐response are different for LVEF tertiles. CRT responses would have better prognostic performance than LVEF tertiles at baseline, which should be considered when clinicians screening eligible patients for CRT.

Usefulness of Hemodynamic Device-Based Optimization in Heterogeneous Patients Implanted with Cardiac Resynchronization Therapy Defibrillator

Optimization of the atrioventricular (AV) and interventricular (VV) timings of the CRT is the most supposed correctable variable to improve the rate of CRT responder. The aim of the present study has been to evaluate if there is a specific subgroup of patients who can actually benefit the most from a hemodynamic optimization of AV. This is a prospective, observational single-center study that enrolled consecutive patients with clinical indication for CRT; all patients were implanted with CRT-D devices with SonR technology, able to automatically adjust AV and VV delay on a weekly basis. Among 57 patients, 39 (69%) showed a LVESV reduction > 15%. The SonR was able to modify the pacing parameters, but an increase of left atrial diameter was associated to a reduced AV variability, suggesting that an impaired left atrial function could potentially reduce the ability of the SonR algorithm to adjust the correct timing of pacing. Graphical abstract Patients with respectively a high (A) and low (B) AV timing variability, among several parameters that could potentially influence the AV timing, only left atrial dimensions demonstrated a significant impact. In fact an increase of left atrial diameter was associated to a reduced AV variability, suggesting that an impaired left atrial function could potentially reduce the ability of the SonR algorithm to adjust the correct timing of pacing.

A Predictive Model for Super-Response to Cardiac Resynchronization Therapy: The QQ-LAE Score

Objectives

It is important to identify super-responders who can derive most benefits from cardiac resynchronization therapy (CRT). We aimed to establish a scoring model that can be used for predicting super-response to CRT.

Methods

We retrospectively reviewed 387 CRT patients. Multivariate logistic regression analysis was performed to identify predictors for super-response (defined as an absolute increase in left ventricular ejection fraction of ≥15% at 6-month follow-up) and to create a score model. Multivariate Cox proportional-hazard regression analysis was conducted to assess associations with the long-term endpoint (defined as cardiac death/heart transplant, heart failure (HF) hospitalization, or all-cause death) across the score categories at follow-up.

Results

Among 387 patients, 109 (28.2%) met super-response. In multivariable analysis, 5 independent predictors (QQ-LAE) were identified: prior no fragmented QRS (odds ratio (OR) = 3.10 (1.39, 6.94)), QRS duration ≥170 ms (OR = 2.37 (1.35, 4.12)), left bundle branch block (OR = 2.57 (1.04, 6.37)), left atrial diameter <45 mm (OR = 3.27 (1.81, 5.89)), and left ventricular end-diastolic dimension <75 mm (OR = 4.11 (1.99, 8.48)). One point was attributed to each predictor, and three score categories were identified. The proportion of super-response after 6-month CRT implantation in patients with scores 0-3, 4, and 5 was 14.6%, 40.3%, and 64.1%, respectively (P < 0.001). Patients with score 5 had an 88% reduction in the risk of cardiac death/heart transplant (P=0.042), a 71% reduction in the risk of HF hospitalization (P=0.048), and an 89% reduction in the risk of all-cause mortality (P=0.028) compared to patients with scores 0-3.

Conclusions

The QQ-LAE score can be used for prediction of super-response to CRT and selection of most suitable patients in clinical practices.

Left ventricle automatic pacing threshold management in CRT systems: A comprehensive review

Modern cardiac resynchronization therapy (CRT) device-based threshold detection enables capture management and voltage output adjusting to combine consistent left ventricular (LV) pacing with acceptable battery drainage. The current technologies available for LV capture automatic confirmation in most cases require the evoked response, as well as "LV pace to right ventricular sense" algorithms. The LV pacing percentage counter may overestimate the CRT delivery which may be reduced due to pacing inhibition (by sensed LV activation) or inadequate capture due to subthreshold current or pacing into refractory tissue. Moreover, the LV threshold at implant and its behavior over time (as a marker of electrical viability) and the ineffective CRT issues (subthreshold stimulation or concealed loss of capture) are discussed. The purpose of the present review is to explore these new challenges regarding LV pacing automatic management.

Implantable cardioverter defibrillator and cardiac resynchronization therapy use in New Zealand (ANZACS-QI 33)

BACKGROUND

The ANZACS-QI Cardiac Implanted Device Registry (ANZACS-QI DEVICE) collects nationwide data on cardiac implantable electronic devices in New Zealand (NZ). We used the registry to describe contemporary NZ use of implantable cardioverter defibrillator (ICD) and cardiac resynchronization therapy (CRT).

METHODS

All ICD and CRT Pacemaker implants recorded in ANZACS-QI DEVICE between 1 January 2014 and 31 December 2017 were analyzed.

RESULTS

Of 1579 ICD implants, 1152 (73.0%) were new implants, including 49.0% for primary prevention and 51.0% for secondary prevention. In both groups, median age was 62 years and patients were predominantly male (81.4% and 79.2%, respectively). Most patients receiving a primary prevention ICD had a history of clinical heart failure (80.4%), NYHA class II-III symptoms (77.1%) and LVEF ≤35% (96.9%). In the secondary prevention ICD cohort, 88.4% were for sustained ventricular tachycardia or survived cardiac arrest from ventricular arrhythmia. Compared to primary prevention CRT Defibrillators (n = 155), those receiving CRT Pacemakers (n = 175) were older (median age 74 vs 66 years) and more likely to be female (38.3% vs 19.4%). Of the 427 (27.0%) ICD replacements (mean duration 6.3 years), 46.6% had received appropriate device therapy while 17.8% received inappropriate therapy. The ICD implant rate was 119 per million population with regional variation in implant rates, ratio of primary prevention ICD implants, and selection of CRT modality.

CONCLUSION

In contemporary NZ practice three-quarters of ICD implants were new implants, of which half were for primary prevention. The majority met current guideline indications. Patients receiving CRT pacemaker were older and more likely to be female.

[123 I-MIBG scintigraphy in the assessment of heart failure prognosis and effectiveness of cardiac resynchronization therapy]

Cardiac resynchronization therapy (CRT) is one of the methods of treating patients with chronic heart failure, which can reduce the mortality rate of this group. Scintigraphic assessment of sympathetic myocardial innervation allows us to evaluate the heart failure prognosis and the effectiveness of interventional treatment. The method is based on use of the radiopharmaceutical 123 I-methiodiobenzylguanidine (123 I-MIBG), which is a structural analogue of norepinephrine and is able to selectively accumulate in the sympathetic nerve endings. This review includes a brief description of norepinephrine metabolism and pharmacokinetics of 123 I-MIBG in the sympathetic nerve ending, a brief description of the study methodology and the clinical significance of this method in patients with heart failure. Particular attention is paid to the possibilities of using this method in patients with severe chronic heart failure before and after CRT.

Design and rationale for the Stimulation Of the Left Ventricular Endocardium for Cardiac Resynchronization Therapy in non-responders and previously untreatable patients (SOLVE-CRT) trial

BACKGROUND

Cardiac resynchronization therapy (CRT) improves outcomes, functional capacity and quality of life in patients with heart failure. Despite two decades of experience with CRT, the rate of non-response remains approximately 30%. CRT efficacy is impacted by pacing location, which is anatomically limited in conventional systems. A new wireless endocardial left ventricular (LV) pacing system allows CRT without such limitations and has shown promise in open-label studies. The purpose of this study is to evaluate its use in a patient population with poor therapeutic alternatives.

METHODS

The SOLVE CRT study is an international, multi-center, randomized, double-blind, sham-controlled trial of patients with Class I and IIa indications for CRT who have either failed to respond to or have been unable to receive conventional CRT. Enrollment will comprise 350 patients implanted with the wireless CRT system randomized 1:1 to therapy on (Treatment) or therapy off (Control) for the six-month period over which trial primary endpoints will be evaluated. The primary safety endpoint will measure the proportion of patients free from system- and procedure-related complications. Primary efficacy endpoints will assess absolute change in LV end-systolic volume LVESV, proportion of patients reducing LVESV by ≥15% and clinical composite score for Treatment versus Control patients. Primary endpoints will be evaluated on an intention-to-treat basis, though per-protocol and as-treated analysis will also be performed.

CONCLUSION

SOLVE-CRT will quantify the safety and effectiveness of wireless CRT in non-responders to conventional CRT and indicated patients who have been unable to receive CRT via the usual transvenous approach.

Full blood count as potential predictor of outcomes in patients undergoing cardiac resynchronization therapy

Almost a third of patients fulfilling current guidelines criteria have suboptimal responses following cardiac resynchronization therapy (CRT). Circulating biomarkers may help identify these patients. We aimed to assess the predictive role of full blood count (FBC) parameters in prognosis of heart failure (HF) patients undergoing CRT device implantation. We enrolled 612 consecutive CRT patients and FBC was measured within 24 hours prior to implantation. The follow-up period was a median of 1652 days (IQR: 837–2612). The study endpoints were i) composite of all-cause mortality or transplant, and ii) reverse left ventricular (LV) remodeling. On multivariate analysis [hazard ratio (HR), 95% confidence interval (CI)] only red cell count (RCC) (p = 0.004), red cell distribution width (RDW) (p < 0.001), percentage of lymphocytes (p = 0.03) and platelet count (p < 0.001) predicted all-cause mortality. Interestingly, RDW (p = 0.004) and platelet count (p = 0.008) were independent predictors of reverse LV remodeling. This is the first powered single-centre study to demonstrate that RDW and platelet count are independent predictors of long-term all-cause mortality and/or heart transplant in CRT patients. Further studies, on the role of these parameters in enhancing patient selection for CRT implantation should be conducted to confirm our findings.

Heart Failure Duration Combined with Left Atrial Dimension Predicts Super-Response and Long-Term Prognosis in Patients with Cardiac Resynchronization Therapy Implantation

Background

Response to cardiac resynchronization therapy (CRT) varies significantly among patients. This study aimed to identify baseline characteristics that could predict super-response to CRT and to evaluate the long-term prognosis in super-responders.

Methods

We retrospectively reviewed the data of 73 consecutive patients who received CRT. Patients were considered as super-responders after 6-month follow-up when NYHA class reduction to I or II combined with left ventricular ejection fraction (LVEF) ≥ 50% was observed. Patients were divided into super-responders group and non-super-responders group. All-cause mortality or hospitalization for heart failure (HF) was referred to the combined end point.

Results

17 (23.3%) patients were super-responders. HF duration, left atrial dimension (LAD), and left bundle branch block (LBBB) were independent predictors of super-response to CRT. The combination of HF duration and LAD could provide more robust prediction of super-response than standalone HF duration (0.899 versus 0.789, Z = 2.207, P = 0.027) or standalone LAD (0.899 versus 0.775, Z = 2.487, P = 0.013). super-responders had excellent LV reverse remodeling. The cumulative incidences of combined end point were significantly lower in the super-responders group, LAD ≤ 42mm group, and combination of HF duration ≤ 48 months and LAD ≤ 42mm group. LBBB remained associated with a lowered risk of the combined end point (HR: 0.19, 95% CI: 0.07-0.57, P = 0.003), whereas LAD was associated with a raised risk of the combined end point (HR: 1.09, 95% CI: 1.02-1.17, P = 0.014).

Conclusions

HF duration, LAD, and LBBB independently predicted super-response. The combination of HF duration and LAD makes more robust prediction of CRT super-response. Super-responders had excellent LV reverse remodeling and decreased the incidences of the combined end point. LBBB and LAD were independently associated with the combined end point.

Cardiac resynchronization therapy reprogramming to improve electrical synchrony in patients with existing devices

BACKGROUND

Optimal programming of cardiac resynchronization therapy (CRT) has not yet been fully elucidated. A novel algorithm (SyncAV) has been developed to improve electrical synchrony by fusion of the triple wavefronts: intrinsic, right ventricular (RV)-paced, and left ventricular (LV)-paced.

METHODS

Consecutive patients at a single tertiary care center with a previously implanted CRT device with SyncAV algorithm (programmable negative AV hysteresis) were evaluated. QRS duration (QRSd) was measured during 1) intrinsic conduction, 2) existing CRT pacing as chronically programmed by treating physician, 3) using the device-based QuickOpt™ algorithm for optimization of AV and VV delays, and 4) ECG-based optimized SyncAV programming. The paced QRSd was assessed and compared to intrinsic conduction and between the different modes of programming.

RESULTS

Of 64 consecutive, potentially eligible patients who underwent assessment, 34 patients who were able to undergo SyncAV programming were included. Mean intrinsic conduction QRSd was 163 ± 24 ms. In comparison, the mean QRSd was 152 ± 25 ms (-11.1 ± 19.0) during existing CRT pacing, 160 ± 25 ms (-4.1 ± 25.2) using the QuickOpt™ algorithm and 138 ± 23 (-24.9 ± 17.2) using ECG-based optimized SyncAV programming. SyncAV optimization resulted in significant reductions in QRSd compared to existing CRT pacing (P = 0.02) and QuickOpt™ (P < 0.001). Of the 32% of patients who did not have QRS narrowing with existing CRT, 72% experienced QRS narrowing with SyncAV.

CONCLUSION

ECG-based atrio-ventricular delay optimization using SyncAV significantly improved electrical synchrony in patients with a previously implanted CRT. Further studies are needed to assess the impact on long-term outcomes.

Machine Learning Prediction of Response to Cardiac Resynchronization Therapy: Improvement Versus Current Guidelines

BACKGROUND

Cardiac resynchronization therapy (CRT) has significant nonresponse rates. We assessed whether machine learning (ML) could predict CRT response beyond current guidelines.

METHODS

We analyzed CRT patients from Cleveland Clinic and Johns Hopkins. A training cohort was created from all Johns Hopkins patients and an equal number of randomly sampled Cleveland Clinic patients. All remaining patients comprised the testing cohort. Response was defined as ≥10% increase in left ventricular ejection fraction. ML models were developed to predict CRT response using different combinations of classification algorithms and clinical variable sets on the training cohort. The model with the highest area under the curve was evaluated on the testing cohort. Probability of response was used to predict survival free from a composite end point of death, heart transplant, or placement of left ventricular assist device. Predictions were compared with current guidelines.

RESULTS

Nine hundred twenty-five patients were included. On the training cohort (n=470: 235, Johns Hopkins; 235, Cleveland Clinic), the best ML model was a naive Bayes classifier including 9 variables (QRS morphology, QRS duration, New York Heart Association classification, left ventricular ejection fraction and end-diastolic diameter, sex, ischemic cardiomyopathy, atrial fibrillation, and epicardial left ventricular lead). On the testing cohort (n=455, Cleveland Clinic), ML demonstrated better response prediction than guidelines (area under the curve, 0.70 versus 0.65; P=0.012) and greater discrimination of event-free survival (concordance index, 0.61 versus 0.56; P<0.001). The fourth quartile of the ML model had the greatest risk of reaching the composite end point, whereas the first quartile had the least (hazard ratio, 0.34; P<0.001).

CONCLUSIONS

ML with 9 variables incrementally improved prediction of echocardiographic CRT response and survival beyond guidelines. Performance was not improved by incorporating more variables. The model offers potential for improved shared decision-making in CRT (online calculator: http://riskcalc.org:3838/CRTResponseScore ). Significant remaining limitations confirm the need to identify better variables to predict CRT response.

Super-response to cardiac resynchronization therapy may predict late phrenic nerve stimulation

Aims

Changes in the anatomical relationship between left phrenic nerve and coronary veins may occur due to the reverse remodelling observed in super-responders to cardiac resynchronization therapy (CRT) and might be the underlying mechanism in patients developing late-onset phrenic nerve stimulation (PNS) without evidence of lead dislodgement (LD). In this study, we sought to evaluate the role of super-response (SR) to CRT as a potential predictor of late-onset PNS.

Methods and results

Consecutive patients implanted with a left ventricular (LV) lead in a single centre were retrospectively analysed. Phrenic nerve stimulation was classified as 'early' when it occurred within 3 months of implantation and 'late' for occurrences thereafter. 'Late' PNS was considered related to LD (LD-PNS) when LV threshold differed by > 1 V or impedance >250 Ω from baseline values or in case of radiological displacement. Cases not meeting the former criteria were classified as 'non-LD-PNS'. Super-response was defined as a decrease ≥30% of the left ventricluar end-systolic volume at 1-year echocardiography. At 32 ± 7 months follow-up, PNS occurred in 20 of 139 patients. Late non-LD-PNS incidence was significantly higher in the SR group (8/61; 13.1%) when compared with the non-SR (1/78; 1.3%) (P = 0.010). Super-response remained the only predictor of non-LD-PNS at multivariate analysis (odds ratio: 11.62, 95% confidence interval 1.41-95.68, P = 0.023).

Conclusion

Incidence of late non-LD-PNS is higher among SR to CRT, suggesting a potential role of the changes in the anatomical relationship between left phrenic nerve and coronary veins.

Response to cardiac resynchronization therapy in non-ischemic cardiomyopathy is unrelated to medical therapy

INTRODUCTION

Current guidelines recommend at least 3 months of guideline-directed medical therapy (GDMT) for patients with a new onset of non-ischemic cardiomyopathy (NICM) and left bundle branch block (LBBB) prior to cardiac resynchronization therapy (CRT). For patients who do not receive optimal GDMT, response to CRT is unknown.

METHODS

Patients with NICM and LBBB with QRS ≥ 120 ms were identified among all patients who underwent CRT. Patients who received GDMT for ≥ 3 months before CRT were compared to those who did not. Among 38 patients who met inclusion criteria, 24 received optimal GDMT prior to implantation (Group 1) and 14 did not (Group 2).

RESULTS

QRS narrowing occurred in Group 1 (160 ± 9 ms to 138 ± 20 ms, P = 0.001) and Group 2 (160 ± 17 ms to 139 ± 30 ms, P = 0.021). Left ventricular ejection fraction (LVEF) improvement occurred in Group 1 (21.3 ± 5.9% to 34.4 ± 13.9%, P < 0.001) and Group 2 (18.8 ± 4.7% to 31.1 ± 13%, P = 0.010). QRS interval and LVEF changes were similar between groups (P = NS). There was a trend towards greater CRT response in women than in men, although differences did not reach statistical significance.

CONCLUSION

In patients with NICM and LBBB, CRT is associated with improvements in LV size and function independent of prior GDMT. The ability of resynchronization to improve LVEF without GDMT suggests that CRT without waiting 3 months for GDMT optimization may benefit some patients with NICM and LBBB.

Echocardiographic markers of dyssynchrony as predictors of super-response to cardiac resynchronisation therapy - a pilot study

Background

Some patients with congestive heart failure have greater improvement of cardiac remodelling after cardiac resynchronisation therapy (CRT) and they are identified as super-responders (SRs). It remains unclear if echocardiographic markers of dyssynchrony could accuratelly predict super-response to CRT. The aim of this study is to evaluate potential echocardiographic predictors associated with super-response to CRT.

Methods

Fifthy nine CRT patients (mean age 52.9 ± 9.0 years, 88% men) with congestive heart failure (54% ischaemic and 46% non-ischaemic aetiology) II-IV NYHA functional class were enrolled. To assess mechanical dyssynchrony we evaluated interventricular mechanical delay, the maximum delay between peak systolic velocities of the septal and posterior walls of left ventricle, duration of left ventricular pre-ejection period (LVPEP), left ventricular and interventricular dyssynchrony by tissue Doppler imaging and systolic dyssynchrony index by 3D echocardiography. After six months the patients were assessed for response and classified as SRs (reduction in left ventricular end-systolic volume (LVESV) ≥30%, n = 20) and non-SRs (reduction in LVESV < 30%, n = 39) and baseline data were analyzed to identify the predictors.

Results

Both groups demonstrated significant improvement in NYHA functional class, increase in left ventricular ejection fraction and reduction in LVESV. All parameters of mechanical dyssynchrony at baseline were significantly higher in SR group. Multiple logistic regression analysis showed that LVPEP (HR 1.031; 95% CI 1.007–1.055; p = 0.011) was an independent predictor for CRT super-response. In ROC curve analysis LVPEP with a cut-off value of 147 ms demonstrated 73.7% sensitivity and 75% specificity (AUC = 0.753; p = 0.002) for the prediction of super-response to CRT.

Conclusion

Greater mechanical dyssynchrony is associated with super-response to CRT in patients with congestive heart failure. It is probable that an LVPEP > 147 ms can be used as independent predictor of super-response.

Current role of echocardiography in cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is an established treatment for patients with heart failure and left ventricular systolic dysfunction. Patients are usually assessed by echocardiography, which provides a number of anatomical and functional information used for cardiac dyssynchrony assessment, prognostic stratification, identification of the optimal site of pacing in the left ventricle, optimization of the CRT device, and patient follow-up. Compared to other cardiac imaging techniques, echocardiography has the advantage to be non-invasive, repeatable, and safe, without exposure to ionizing radiation or nefrotoxic contrast. In this article, we review current evidence about the role of echocardiography before, during, and after the implantation of a CRT device.

Left ventricular dimensions predict risk of appropriate shocks but not mortality in cardiac resynchronization therapy-defibrillator recipients with left bundle-branch block and non-ischemic cardiomyopathy

Aims

Patients with non-ischaemic cardiomyopathy (NICM) and left bundle-branch block (LBBB) often benefit markedly from cardiac resynchronization therapy (CRT). Cardiac resynchronization therapy responders have a lower risk of appropriate device shocks from CRT-defibrillators (CRT-D) than do non-responders. Larger baseline left ventricular (LV) dimensions may be associated with less CRT response and thus greater risk of appropriate shocks.

Methods and results

We analysed all (n = 249; 55% female) primary prevention CRT-D recipients at our institution with LBBB, NICM, and measured LV dimensions prior to device implant for the outcomes of (i) appropriate shocks, (ii) any appropriate tachyarrhythmia therapies, and (iii) risk of death, transplant, or left ventricular assist device (LVAD). During 59 months (interquartile range 21.5-91.5) follow-up, 19 (8%) patients received ≥1 appropriate shock, and 67 (27%) patients died, received a transplant, or required LVAD. Receiver-operating characteristic analysis of LV end-diastolic diameter (LVEDD) per meter height vs. appropriate shock(s) revealed an area under the curve of 0.75 (95% CI 0.65-0.85; P < 0.001). No patient with indexed LVEDD <3.36 cm/m (n = 76) received a shock. There was no statistically significant difference in risk of death, transplant, or LVAD (corrected HR 1.67, 95% CI 0.90-3.03; P = 0.103) in patients with indexed LVEDD above this cut-off compared to those with smaller dimension. Among 102 patients with paired quantitative echocardiograms, there was no difference in LVEF change between patients with indexed LVEDD <3.36 cm/m (n = 27; median 11%) and larger (n = 75; median 14%).

Conclusion

Patients with LVEDD <3.36 cm/m height prior to CRT-D implant in the setting of NICM and LBBB have minimal risk of appropriate shocks but similar risk of death, transplant- and LVAD and similar extent of LV functional improvement as patients with larger LVEDD. CRT-pacemakers may be appropriate in such patients.

Improved patient selection for cardiac resynchronization therapy by normalization of QRS duration to left ventricular dimension

Aims

This study evaluates the relative importance of two components of QRS prolongation, myocardial conduction velocity and travel distance of the electrical wave front (i.e. path length), for the prediction of acute response to cardiac resynchronization therapy (CRT) in left bundle branch block (LBBB) patients.

Methods and results

Thirty-two CRT candidates (ejection fraction <35%, LBBB) underwent cardiac magnetic resonance (CMR) imaging to provide detailed information on left ventricular (LV) dimensions. Left ventricular end-diastolic volume (LVEDV) was used as a primary measure for path length, subsequently QRSd was normalized to LV dimension (i.e. QRSd divided by LVEDV) to adjust for conduction path length. Invasive pressure-volume loop analysis at baseline and during CRT was used to assess acute pump function improvement, expressed as LV stroke work (SW) change. During CRT, SW improved by +38 ± 46% (P < 0.001). The baseline LVEDV was positively related to QRSd (R = 0.36, P = 0.044). Despite this association, a paradoxical inverse relation was found between LVEDV and SW improvement during CRT (R = -0.40; P = 0.025). Baseline unadjusted QRSd was found to be unrelated to SW changes during CRT (R = 0.16; P = 0.383), whereas normalized QRSd (QRSd/LVEDV) yielded a strong correlation with CRT response (R = 0.49; P = 0.005). Other measures of LV dimension, including LV length, LV diameter, and LV end-systolic volume, showed similar relations with normalized QRSd and SW improvement.

Conclusion

Since normalized QRSd reflects myocardial conduction properties, these findings suggest that myocardial conduction velocity rather than increased path length mainly determines response to CRT. Normalizing QRSd to LV dimension might provide a relatively simple method to improve patient selection for CRT.

Impact of quadripolar LV leads on heart failure hospitalization rates among patients implanted with CRT-D: data from the Israeli ICD Registry

BACKGROUND

Cardiac resynchronization therapy (CRT) is an effective treatment for heart failure (HF); however, a third of patients are non-responders. The development of quadripolar left ventricular (LV) lead was shown, mainly in single manufactures' registry, to improve LV remodeling and overall mortality. However, limited reports exist on the impact of quadripolar LV leads on HF hospitalization rates in real-life cohorts. We evaluated the clinical outcomes associated with quadripolar LV leads in a large nation-wide registry including all patients implanted with a cardiac resynchronization therapy with defibrillator (CRT-D).

METHODS

Between July 2010 and October 2016, 2913 consecutive patients were implanted with a CRT-D and all were prospectively enrolled in the Israeli ICD Registry. Quadripolar LV leads were implanted in 973 (33.4%) patients during this period, and their clinical outcomes were compared to CRT-D recipients implanted with a bipolar LV lead. Primary endpoint was HF hospitalization rate.

RESULTS

Quadripolar leads were implanted more in patients with non-ischemic cardiomyopathy and for primary prevention indication and less in post-infarction patients and for secondary prevention of sudden death. Longer QRS duration was observed with quadripolar leads (147 ± 23 vs 143 ± 25; p < 0.001). Outcome event rate for 100 patient years revealed no difference in HF hospitalization rates between bipolar and quadripolar LV leads. Quadripolar lead implant led to lower cardiac mortality, with no influence on overall mortality. Multivariate analysis revealed no significant differences in study endpoints between bipolar and quadripolar LV leads.

CONCLUSION

In a large real-life registry, implantation of quadripolar LV leads in patients with CRT-D did not influence HF hospitalization rates.

What happens to non-responders in cardiac resynchronization therapy?

INTRODUCTION AND OBJECTIVES

Left ventricular reverse remodeling (LVRR) is strongly related to the long-term prognosis of patients undergoing cardiac resynchronization therapy (CRT). The aim of this study was to assess the long-term clinical outcome of patients without LVRR at six months after CRT implantation and to determine the prognostic impact of clinical response in this population.

METHODS

We analyzed 178 consecutive patients who underwent successful CRT device implantation (age 64±11 years; 69% male; 89% in New York Heart Association [NYHA] functional class III; 35% with ischemic cardiomyopathy). Clinical status and echocardiographic parameters were determined before and six months after CRT implantation. We identified those without criteria for LVRR (≥10% increase in left ventricular ejection fraction with ≥15% reduction in left ventricular end-systolic diameter compared to baseline). Clinical responders were defined by a sustained improvement of at least one NYHA functional class.

RESULTS

At six-month assessment after CRT, 109 (61%) patients showed LVRR. During a mean follow-up of 56±21 months, 47 (26%) patients died, with higher mortality in the group without LVRR (36% vs. 20%, p=0.023). Clinical response was greater in patients with LVRR (88% vs. 55%, p<0.001). In patients without LVRR, clinical response to CRT was the strongest independent predictor of survival (hazard ratio: 0.120; 95% confidence interval: 0.039-0.366; p<0.001).

CONCLUSION

Although patients without LVRR six months after CRT implantation had a worse prognosis, with higher all-cause mortality, clinical response can be an independent predictor of survival in this population.

Postimplantation ventricular ectopic burden and clinical outcomes in cardiac resynchronization therapy-defibrillator patients: a MADIT-CRT substudy

BACKGROUND

Frequent ventricular ectopy on preimplantation Holter has been associated with attenuated benefit from cardiac resynchronization therapy (CRT). However, it is unclear whether ectopic burden measured post-CRT implantation can be utilized to evaluate long-term prognosis. We aimed to describe the association between post-CRT implantation ectopic burden and subsequent risk of clinical outcomes.

METHODS

At the 12-month follow-up visit, 24-hour Holter recordings were performed in 698 CRT-D patients from the MADIT-CRT study. The mean number of ventricular premature complexes (VPCs/hour) was calculated. High ectopic burden was defined as >10 VPCs/hour and low burden as ≤10 VPCs/hour. Multivariate Cox proportional hazards models were utilized to assess the association between 12-month ectopic burden and the risk of the end points of heart failure (HF) or death and ventricular tachyarrhythmias (VT/VF).

RESULTS

At 12 months, 282 (40%) patients presented with low ectopic burden and 416 (60%) patients presented with high ectopic burden. The 3-year risk of HF/death and VT/VF was lower in patients with a low burden (7% and 8%) and significantly higher (25% and 24%) in patients with high burden. In multivariate analyses, patients with a high ectopic burden had approximately threefold increased risk of both HF/death (HR=2.76 [1.62-4.70], p < .001) and VT/VF (HR=2.79 [1.69-4.58], p < .001).

CONCLUSION

In CRT-D patients with mild heart failure, high ectopic burden at 12-month follow-up was associated with a high 3-year risk of HF/death and VT/VF and threefold increased risk as compared to patients with low burden. Ectopic burden at 12 months may be a valuable approach for evaluating long-term prognosis.

Utilization of cardiac resynchronization therapy in eligible patients hospitalized for heart failure and its association with patient outcomes

OBJECTIVES

We examined trends in CRT utilization overall and by sex and race and to assess whether CRT use is associated with a reduction in HF hospitalization and mortality.

BACKGROUND

It is unknown whether underutilization and race/sex-based differences in cardiac resynchronization therapy (CRT) use have persisted. The association between CRT and heart failure (HF) hospitalization and mortality in real-world practice remains unclear.

METHODS

We linked 72,008 HF patients from 388 hospitals participating in Get With The Guidelines HF eligible for CRT with Centers for Medicare & Medicaid Services data to assess CRT utilization trends, HF hospitalization rates, and all-cause mortality.

RESULTS

From 2005-2014, 18,935 (26.3%) eligible patients had CRT in place, implanted, or prescribed. The majority were male (60.0%) and white (61.9%). CRT utilization increased during the study period (P = .0002) especially in the early period. Women were less likely to receive CRT, and this difference increased over time (interaction P = .0037) despite greater mortality risk reduction (interaction P = .0043). Black patients were less likely than white patients to have CRT throughout the study period (adjusted hazard ratio (HR) 0.79; 95% CI 0.74-0.85). Patients with CRT implanted during the index hospitalization had lower mortality (adjusted HR 0.65; 95% CI 0.59-0.71) and were less likely to be readmitted for HF than patients without CRT (adjusted HR 0.64; 95% CI 0.58-0.71).

CONCLUSIONS/RELEVANCE

CRT use has increased in all populations, but it remains underutilized. CRT remains more common among white than black HF patients, and women were less likely than men to receive CRT despite deriving greater benefit.