Association of vectorcardiographic T-wave area with clinical and echocardiographic outcomes in cardiac resynchronization therapy

AIMS

Data on repolarization parameters in cardiac resynchronization therapy (CRT) are scarce. We investigated the association of baseline T-wave area, with both clinical and echocardiographic outcomes of CRT in a large, multi-centre cohort of CRT recipients. Also, we evaluated the association between the baseline T-wave area and QRS area.

METHODS AND RESULTS

In this retrospective study, 1355 consecutive CRT recipients were evaluated. Pre-implantation T-wave and QRS area were calculated from vectorcardiograms. Echocardiographic response was defined as a reduction of ≥15% in left ventricular end-systolic volume between 3 and 12 months after implantation. The clinical outcome was a combination of all-cause mortality, heart transplantation, and left ventricular assist device implantation. Left ventricular end-systolic volume reduction was largest in patients with QRS area ≥ 109 μVs and T-wave area ≥ 66 μVs compared with QRS area ≥ 109 μVs and T-wave area < 66 μVs (P = 0.004), QRS area < 109 μVs and T-wave area ≥ 66 μVs (P < 0.001) and QRS area < 109 μVs and T-wave area < 66 μVs (P < 0.001). Event-free survival rate was higher in the subgroup of patients with QRS area ≥ 109 μVs and T-wave area ≥ 66 μVs (n = 616, P < 0.001) and QRS area ≥ 109 μVs and T-wave area < 66 μVs (n = 100, P < 0.001) than the other subgroups. In the multivariate analysis, T-wave area remained associated with echocardiographic response (P = 0.008), but not with the clinical outcome (P = 0.143), when QRS area was included in the model.

CONCLUSION

Baseline T-wave area has a significant association with both clinical and echocardiographic outcomes after CRT. The association of T-wave area with echocardiographic response is independent from QRS area; the association with clinical outcome, however, is not.

Prognostic implications of invasive hemodynamics during cardiac resynchronization therapy: Stroke work outperforms dP/dtmax

Background

Invasive measurements of left ventricular (LV) hemodynamic performance can evaluate acute response to cardiac resynchronization therapy (CRT).

Objective

The study sought to determine which metric, maximum rate of LV pressure rise (LV dP/dtmax) or LV stroke work (LVSW), is more strongly associated with long-term prognosis.

Methods

CRT patients were prospectively included from 3 academic centers. Invasive pressure-volume loop measurements during implantation were performed, and LV dP/dtmax and LVSW were determined at baseline and during biventricular pacing (BVP) as well as their relative increase (%Δ). Hazard ratios (HRs) for the primary outcome of 8-year all-cause mortality were derived using Cox proportional hazards. The secondary endpoint was echocardiographic response, defined as 6-month LV end-systolic volume reduction ≥15%.

Results

Paired data from 82 patients were analyzed (67% male; age 66 ± 9 years; QRS duration 158 ± 22 ms, median survival time 72 months). Survival was better when LVSW during BVP was ≥4400 mL∙mm Hg (HR 0.21, 95% CI 0.08-0.58, P < .003) or when ΔLVSW% was ≥10% (HR 0.22, 95% CI 0.08-0.65, P = .006). In multivariate analysis, following direct comparison of continuous measures of acute ΔLV dP/dtmax% and ΔLVSW%, only ΔLVSW% remained associated with the primary endpoint (HR 0.982 per percentage point, P = .028). In contrast to LV dP/dtmax (all P > .05), significant associations with echocardiographic response were found for stroke work during BVP (area under the receiver-operating characteristic curve 0.745, P = .001) and ΔLVSW% (area under the receiver-operating characteristic curve 0.803, P < .001).

Conclusion

Stroke work, but not LV dP/dtmax, is consistently associated with long-term prognosis and response after CRT. Our results therefore favor the use of stroke work as the hemodynamic parameter to predict long-term outcome after CRT.

Comparison of the relation of the ESC 2021 and ESC 2013 definitions of left bundle branch block with clinical and echocardiographic outcome in cardiac resynchronization therapy

INTRODUCTION

We aimed to investigate the impact of the 2021 European Society of Cardiology (ESC) guideline changes in left bundle branch block (LBBB) definition on cardiac resynchronization therapy (CRT) patient selection and outcomes.

METHODS

The MUG (Maastricht, Utrecht, Groningen) registry, consisting of consecutive patients implanted with a CRT device between 2001 and 2015 was studied. For this study, patients with baseline sinus rhythm and QRS duration ≥ 130ms were eligible. Patients were classified according to ESC 2013 and 2021 guideline LBBB definitions and QRS duration. Endpoints were heart transplantation, LVAD implantation or mortality (HTx/LVAD/mortality) and echocardiographic response (LVESV reduction ≥15%).

RESULTS

The analyses included 1.202, typical CRT patients. The ESC 2021 definition resulted in considerably less LBBB diagnoses compared to the 2013 definition (31.6% vs. 80.9%, respectively). Applying the 2013 definition resulted in significant separation of the Kaplan-Meier curves of HTx/LVAD/mortality (p < .0001). A significantly higher echocardiographic response rate was found in the LBBB compared to the non-LBBB group using the 2013 definition. These differences in HTx/LVAD/mortality and echocardiographic response were not found when applying the 2021 definition.

CONCLUSION

The ESC 2021 LBBB definition leads to a considerably lower percentage of patients with baseline LBBB then the ESC 2013 definition. This does not lead to better differentiation of CRT responders, nor does this lead to a stronger association with clinical outcomes after CRT. In fact, stratification according to the 2021 definition is not associated with a difference in clinical or echocardiographic outcome, implying that the guideline changes may negatively influence CRT implantation practice with a weakened recommendation in patients that will benefit from CRT.

Electrocardiogram-based deep learning improves outcome prediction following cardiac resynchronization therapy

AIMS

This study aims to identify and visualize electrocardiogram (ECG) features using an explainable deep learning-based algorithm to predict cardiac resynchronization therapy (CRT) outcome. Its performance is compared with current guideline ECG criteria and QRSAREA.

METHODS AND RESULTS

A deep learning algorithm, trained on 1.1 million ECGs from 251 473 patients, was used to compress the median beat ECG, thereby summarizing most ECG features into only 21 explainable factors (FactorECG). Pre-implantation ECGs of 1306 CRT patients from three academic centres were converted into their respective FactorECG. FactorECG predicted the combined clinical endpoint of death, left ventricular assist device, or heart transplantation [c-statistic 0.69, 95% confidence interval (CI) 0.66-0.72], significantly outperforming QRSAREA and guideline ECG criteria [c-statistic 0.61 (95% CI 0.58-0.64) and 0.57 (95% CI 0.54-0.60), P < 0.001 for both]. The addition of 13 clinical variables was of limited added value for the FactorECG model when compared with QRSAREA (Δ c-statistic 0.03 vs. 0.10). FactorECG identified inferolateral T-wave inversion, smaller right precordial S- and T-wave amplitude, ventricular rate, and increased PR interval and P-wave duration to be important predictors for poor outcome. An online visualization tool was created to provide interactive visualizations (https://crt.ecgx.ai).

CONCLUSION

Requiring only a standard 12-lead ECG, FactorECG held superior discriminative ability for the prediction of clinical outcome when compared with guideline criteria and QRSAREA, without requiring additional clinical variables. End-to-end automated visualization of ECG features allows for an explainable algorithm, which may facilitate rapid uptake of this personalized decision-making tool in CRT.

Effects of lockdown on physical activity and arrhythmia burden in patients with an implantable cardioverter-defibrillator: the COVID-19 Lockdown ICD-Carelink (CLIC) study

Background

Both COVID-19 and the measures taken to control the pandemic may significantly affect cardiovascular health. The effects of a lockdown on physical activity and its potential consequences for arrhythmia burden remain largely unknown.

Purpose

In this study, we investigated the effect of the lockdown during the first COVID-19 wave on patients' physical activity and arrhythmia burden.

Methods

All patients with an ICD connected to a Carelink home-monitoring system from two Dutch hospitals were included. Anonymized data on physical activity, heart rate, and occurrence of ventricular tachycardia/fibrillation (VT/VF), and atrial fibrillation/tachycardia (AF/AT) were obtained and were compared between March-April 2020 (lockdown) and March-April 2019 (reference) within each patient. The study was approved by the local ethics committee.

Results

The ICDs of 531 patients registered significantly less activity during de lockdown period compared to the reference period (210±104 min vs 182±103 min, p<0.0001, Figure 1, panels A and B), while weather conditions improved (1A). Daytime and nighttime heart rates were significantly lower during lockdown compared to the reference period (71.3±9 bpm vs 72.6±9 bpm, p<0.0001 and 63.4±9 vs 63.8±9, p=0.02, respectively). AF/AT burden increased (Figure 2A) while number of VT/VF episodes decreased (2B). There was no significant difference in number of NSVT episodes.

Conclusion

During the lockdown in the first COVID-19 wave, the Carelink system revealed significantly less activity, increase in AF/AT burden and decrease in VT/VF episodes. Further investigation is needed to understand the relationship between physical activity and the occurrence of arrhythmias in ICD patients.

Funding Acknowledgement

Type of funding sources: None.

Explainable deep learning outperforms guideline criteria and QRSarea for prediction of outcome after cardiac resynchronization therapy

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Netherlands Organisation for Health Research and Development (ZonMw)

Background

Electrocardiogram-based prediction models for cardiac resynchronization therapy (CRT) response mainly focus on the QRS complex, but other information in the electrocardiogram (ECG) is neglected.

Purpose

We sought to identify and visualize ECG features using an explainable deep learning-based algorithm (FactorECG) to predict CRT outcome and echocardiographic response, and compare this to state-of-the-art parameters, including QRSarea.

Methods

Patients who underwent CRT implantation in three academic hospitals were analyzed for clinical outcome (death, left ventricular assist device implantation, or heart transplantation), and echocardiographic response (≥ 15% left ventricular end-systolic volume reduction at 6 months). Pre-implantation ECGs were converted into their respective FactorECG. By using a deep learning algorithm trained on 1.1 million ECGs, a compressed version of the median beat ECG was obtained, where all ECG features are summarized in only 21 explainable factors of variation (interactive tool: https://decoder.ecgx.ai). The 21 FactorECG values per patient were used in a Cox and logistic regression model, for outcome and response, respectively. Models were trained on data from two hospitals (n = 936 for outcome and n = 591 for response) and externally validated in a third hospital (n = 339 for outcome and n = 230 for response). Furthermore, ESC CRT guideline indications and vectorcardiographic QRSarea were used as a comparison.

Results

The deep learning-based approach was able to predict clinical outcome (AUC = 0.74 [95% confidence interval (CI) 0.69 - 0.80]) and echocardiographic response (AUC = 0.70 [95% CI 0.63 - 0.77]). Moreover, it significantly outperformed a model based on the ESC CRT guidelines for outcome (AUC = 0.57 [95% CI 0.50-0.63]) and response (AUC = 0.57 [95% CI 0.51 - 0.64]). In comparison with QRSarea, the deep learning-based approach performed significantly better for outcome (AUC = 0.61 [95% CI 0.53-0.69], but similar for response (AUC = 0.70 [95% CI 0.64-0.77]. Based on QRSarea and predicted probabilities of the deep learning approach, for both outcome at three years and response, four groups of similar size were identified and compared to the ESC CRT guidelines (Figure 1). Important ECG factors for poor response and clinical outcome were identified as anterior T-wave inversion (F9), increased heart rate (F10), non-LBBB morphology (F26) and increased PR-interval (F8, Figure 2).

Conclusion

Without compromising interpretability, the deep learning-based algorithm objectively identified CRT recipients with good clinical outcome and echocardiographic response. This approach outperformed QRSarea for outcome, and QRS morphology and duration as used in the ESC CRT guidelines for both outcome and echocardiographic response. Hence, most predictive information for CRT response is found within the QRS complex, whereas the complete median beat ECG provides additional predictive information for clinical outcome.

Effects of lockdown on physical activity and arrhythmia burden in patients with an implantable cardioverter-defibrillator: the Covid-19 Lockdown ICD-Carelink (CLIC) study

Funding Acknowledgements

Type of funding sources: None.

Background: Both COVID-19 and the measures taken to control the pandemic may significantly affect cardiovascular health. The effects of a lockdown on physical activity and its potential consequences for arrhythmia burden remain largely unknown.

Purpose: In this study, we investigated the effect of the lockdown during the first COVID-19 wave on patients’ physical activity and arrhythmia burden.

Methods: All patients with an ICD connected to a Carelink home-monitoring system from two Dutch hospitals were included. Anonymized data on physical activity, heart rate, and occurrence of ventricular tachycardia/fibrillation (VT/VF), and atrial fibrillation/tachycardia (AF/AT) were obtained and were compared between March-April 2020 (lockdown) and March-April 2019 (reference) within each patient. The study was approved by the local ethics committee.

Results: The ICDs of 531 patients registered significantly less activity during de lockdown period compared to the reference period (21,895±12,394min vs 25,173±12,532min, p&lt;0.0001, panel a). Daytime and nighttime heart rates were significantly lower during lockdown compared to the reference period (71.3±9bpm vs 72.6±9bpm, p&lt;0.0001 and 63.4±9 vs 63.8±9, p=0.02, respectively). 94 patients with VT/VF during the reference period did not show any VT/VF during lockdown, while only 4 patients without VT/VF during the reference period showed VT/VF during lockdown (p&lt;0.0001, panel B). There was no significant difference in the occurrence of NSVT or AF/AT.

Conclusion: During the lockdown in the first COVID-19 wave, the Carelink system revealed significantly less activity and lower heart rates. Moreover, there was a significant reduction in the occurrence of VT/VF.

Endocardial pacing results in better electrical resynchronization and hemodynamic improvement than epicardial pacing in CRT

Funding Acknowledgements

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): The original study was financially supported by Medtronic (Minneapolis, Minnesota). The investigation of the current abstract is unrelated to the original financial support.

Background

Cardiac resynchronization therapy (CRT) is conventionally applied by means of a transvenous epicardial left ventricular (LV) lead. Studies suggest that endocardial LV pacing may result in better resynchronization and LV function than epicardial LV pacing.

Purpose

To investigate whether endocardial pacing results in better electrical resynchronization and hemodynamic improvement compared to epicardial pacing.

Methods

Patients with an indication for CRT were prospectively included from two hospitals. In all patients, LV pacing was performed endocardially and epicardially in the postero-lateral region. QRS area was calculated from vectorcardiograms that were synthesized from 12-lead ECGs. Acute hemodynamic improvement was assessed as the change in maximum rate of rise of LV-pressure (%ΔLVdP/dtmax). We assessed the effects of endocardial and epicardial LV pacing on the change in QRS area (∆QRS area) and LVdP/dtmax (%ΔLVdP/dtmax).

Results

A total of 16 patients (age 66 ± 11 years, 56% male, 31% ischemic cardiomyopathy, QRS duration 166±18ms, LBBB in 88%) were included. Endocardial pacing resulted in greater ∆QRS area than epicardial pacing (-51 ± 34 µVs vs. -24 ± 37 µVs, p = 0.021, Panel A). In addition, endocardial pacing led to a larger %ΔLVdP/dtmax as compared to epicardial pacing (21 ± 12% vs. 18 ± 9%, p = 0.025, Panel B).

Conclusion

Compared to conventional epicardial LV pacing in CRT, endocardial LV pacing results in better electrical resynchronization and acute hemodynamic improvement.

Serial Assessment of Myocardial Injury Markers in Mechanically Ventilated Patients With SARS-CoV-2 (from the Prospective MaastrICCht Cohort)

Myocardial injury in COVID-19 is associated with in-hospital mortality. However, the development of myocardial injury over time and whether myocardial injury in patients with COVID-19 at the intensive care unit is associated with outcome is unclear. This study prospectively investigates myocardial injury with serial measurements over the full course of intensive care unit admission in mechanically ventilated patients with COVID-19. As part of the prospective Maastricht Intensive Care COVID cohort, predefined myocardial injury markers, including high-sensitivity cardiac troponin T (hs-cTnT), N-terminal pro-B-type natriuretic peptide (NT-proBNP), and electrocardiographic characteristics were serially collected in mechanically ventilated patients with COVID-19. Linear mixed-effects regression was used to compare survivors with nonsurvivors, adjusting for gender, age, APACHE-II score, daily creatinine concentration, hypertension, diabetes mellitus, and obesity. In 90 patients, 57 (63%) were survivors and 33 (37%) nonsurvivors, and a total of 628 serial electrocardiograms, 1,565 hs-cTnT, and 1,559 NT-proBNP concentrations were assessed. Log-hs-cTnT was lower in survivors compared with nonsurvivors at day 1 (β -0.93 [-1.37; -0.49], p <0.001) and did not change over time. Log-NT-proBNP did not differ at day 1 between both groups but decreased over time in the survivor group (β -0.08 [-0.11; -0.04] p <0.001) compared with nonsurvivors. Many electrocardiographic abnormalities were present in the whole population, without significant differences between both groups. In conclusion, baseline hs-cTnT and change in NT-proBNP were strongly associated with mortality. Two-thirds of patients with COVID-19 showed electrocardiographic abnormalities. Our serial assessment suggests that myocardial injury is common in mechanically ventilated patients with COVID-19 and is associated with outcome.

Reduction in QRS area correlates with hemodynamic response during CRT-device implantation

Funding Acknowledgements

Type of funding sources: None.

Background Previous studies have shown that reduction in QRS area after cardiac resynchronization therapy (CRT) is associated with improved long-term clinical outcome.

Purpose To investigate whether reduction in QRS area is associated with hemodynamic improvement and whether QRS area reduction could be used for CRT optimization, with respect to LV lead position and device programming in individual patients.

Methods A total of 78 patients with indication for CRT were prospectively included in 4 hospitals. QRS area was calculated from vectorcardiograms that were synthesized from 12-lead ECG’s. Acute hemodynamic response was assessed invasively as the maximum rate of percentual left ventricular (LV) pressure (%LVdP/dtmax) rise.  QRS area reduction was studied in relation to LV-lead position (n = 26), proximal versus distal LV lead position (n = 27), and VV-delay (n = 25).

Results Combining all measurements in all patients showed a significant correlation between QRS area reduction and %LVdP/dTmax increase (R = 0.49, P &lt; 0.0001).  Also, when one fixed routine implantation setting was used for each patient (lateral lead position, distal, AV-delay 120-150ms, VV-delay 0ms) this correlation was present (R = 0.45, p &lt; 0.0001, figure panel A). In 21 patients in which at least 3 lead positions were available there was also a significant correlation between QRS area reduction and %LVdP/dtmax increase (average R = 0.69, p &lt; 0.0001, panel B). For VV-delay, 25 other patients as well showed a significant correlation (average R = 0.53, p &lt; 0.0001).

Conclusion Within patients, QRS area reduction is associated with %LVdP/dtmax increase with various LV lead positions and VV-intervals. Therefore, QRS area, which is an easily obtainable and objective parameter, might be a promising tool for optimization of LV lead position and device programming in CRT. Abstract Figure.

Reduction in the QRS area after cardiac resynchronization therapy is associated with survival and echocardiographic response

INTRODUCTION

Recent studies have shown that the baseline QRS area is associated with the clinical response after cardiac resynchronization therapy (CRT). In this study, we investigated the association of QRS area reduction (∆QRS area) after CRT with the outcome. We hypothesize that a larger ∆QRS area is associated with a better survival and echocardiographic response.

METHODS AND RESULTS

Electrocardiograms (ECG) obtained before and 2-12 months after CRT from 1299 patients in a multi-center CRT-registry were analyzed. The QRS area was calculated from vectorcardiograms that were synthesized from 12-lead ECGs. The primary endpoint was a combination of all-cause mortality, heart transplantation, and left ventricular (LV) assist device implantation. The secondary endpoint was the echocardiographic response, defined as LV end-systolic volume reduction ≥ of 15%. Patients with ∆QRS area above the optimal cut-off value (62 µVs) had a lower risk of reaching the primary endpoint (hazard ratio: 0.43; confidence interval [CI] 0.33-0.56, p < .001), and a higher chance of echocardiographic response (odds ratio [OR] 3.3;CI 2.4-4.6, p < .0001). In multivariable analysis, ∆QRS area was independently associated with both endpoints. In patients with baseline QRS area ≥109 µVs, survival, and echocardiographic response were better when the ∆QRS area was ≥62 µVs (p < .0001). Logistic regression showed that in patients with baseline QRS area ≥109 µVs, ∆QRS area was the only significant predictor of survival (OR: 0.981; CI: 0.967-0.994, p = .006).

CONCLUSION

∆QRS area is an independent determinant of CRT response, especially in patients with a large baseline QRS area. Failure to achieve a large QRS area reduction with CRT is associated with a poor clinical outcome.