QRS Change Research Articles

QRS Duration After Pulmonary Valve Replacement in Adults with Repaired Tetralogy of Fallot: Association with Ventricular Arrhythmia and Correlation with Right Ventricular Size.

The aim of this study is to analyze the relationship between QRS duration after pulmonary valve replacement (PVR) and ventricular arrhythmias (VA) in patients with repaired tetralogy of Fallot (ToF). ToF patients may face complications such as heart failure and VA after primary repair, often mitigated by PVR. Prior studies have shown a decrease in QRS duration and right ventricular (RV) size following PVR. It remains unclear whether a lack of QRS duration reduction identifies patients at risk of VA. We retrospectively identified adult patients with repaired ToF who underwent surgical or transcatheter PVR. EKG data (pre-PVR, 30 days to 1-year post-PVR, and closest to CMR) was collected. The primary endpoint was sustained ventricular tachycardia (VT), ICD shock for sustained VT, or inducible VT on EP study. 85 patients were included (median follow-up 3.6 years; median age 34 years; 51% females). The primary outcome was noted in 8 patients. Mean QRS duration decreased by 5 ms following PVR (p = 0.0001). Increased age at PVR, QRS ≥ 180 ms post-PVR, no reduction in QRS after PVR, and a history of VT were associated with higher risk of the primary endpoint. The change in QRS was linearly correlated with the change in RVEDVi (R = 0.66). Adults with repaired ToF experience a reduction in QRS duration post-PVR that correlates with the change of the RV size. Patients with QRS ≥ 180 ms post-PVR, no reduction in QRS, increased age at repair, and a history of VT are at risk for recurrent VT and warrant closer monitoring/ICD consideration.

Sodium bicarbonate treatment for QRS widening in bupropion overdoses

Introduction Bupropion cardiotoxicity widens QRS complexes by inhibiting cardiac gap junctions. Sodium bicarbonate is the standard treatment for QRS widening from sodium channel blockade, but its effect on QRS widening in bupropion cardiotoxicity is not well-studied. Methods This is a retrospective cohort study of bupropion overdoses from 10 hospitals between January 2010 and June 2022. Patients with documented administration of sodium bicarbonate and QRS duration > 100 milliseconds on pre-bicarbonate electrocardiogram were included. Patients with no electrocardiogram within four hours of treatment or with baseline pre-overdose wide QRS and < 10 milliseconds widening from baseline were excluded. The primary outcome was a change in QRS duration between the pre-bicarbonate electrocardiogram and the first electrocardiogram after initial bicarbonate administration. Secondary outcomes included prevalence of post-bicarbonate QRS < 100 milliseconds, change in electrocardiogram intervals after total bicarbonate administration, and change in metabolic parameters and hemodynamics. Wilcoxon signed-rank testing was performed on the primary outcome. Linear regression modeling was performed to test for an association between change in QRS and bicarbonate dosing. Results Thirteen patients were included for final analysis. The median age was 32 years, and 54% were male. Six patients developed seizures; one developed ventricular tachycardia, and four received vasopressors. The median QRS and QTc pre-bicarbonate were 116 and 495 milliseconds, respectively. The median change in QRS duration was −2.0 milliseconds, which was not statistically significant (P = 0.42). The median bicarbonate dose administered before the first post-bicarbonate electrocardiogram was 100 milliequivalents. We did not identify an association between QRS change and bicarbonate dosing (P = 0.9, R-squared = 0.001). No patient had a QRS duration < 100 milliseconds after the initial bicarbonate dose. There was minimal change in QTc, electrolytes, heart rate, or blood pressure; alkalemia post-bicarbonate was achieved in eight patients. Conclusion Sodium bicarbonate did not significantly decrease QRS duration in this small retrospective cohort of bupropion overdoses.

Abstract 14051: QRS Duration After Pulmonary Valve Replacement in Adults With Repaired Tetralogy of Fallot: Prediction of Ventricular Arrhythmias and Correlation With Right Ventricular Size

Background: Tetralogy of Fallot (ToF) patients face complications such as heart failure and ventricular arrhythmias (VA) after early repair which may be mitigated by pulmonary valve replacement (PVR). Prior studies have shown significant decreases in QRS duration and right ventricular (RV) size following PVR. We aimed to determine whether QRS duration reduction independently identifies patients at lower risk of VA and/or correlates with a decrease of RV size on cardiac magnetic resonance imaging (CMR) with long-term follow-up. Methods: We retrospectively identified patients ≥18 years old with repaired ToF who underwent surgical or transcatheter PVR, respectively, at our tertiary care center. Demographics, imaging, and ECGs (pre-PVR, 30 days to 1-year post-PVR, and closest to follow up CMR) were collected. Patients with ventricularly paced rhythm were excluded. The composite primary outcome was defined as sustained VT, ICD shock for sustained VT or inducible VT on EP study. Results: During the study period, 85 patients were included (median follow-up 3.6 years; median age 34 years; 51% females, 68% surgical PVR and median LVEF 56%). The primary outcome was observed in 8 (9.6%) patients. QRS duration decreased by 5 ms (pre-PVR mean 154±28 ms to 149±28ms post-PVR; p=0.0001). Increased age at PVR (OR 1.1 per year), QRS≥180ms post-PVR, no reduction in QRS after PVR (ΔQRS ≤ 0ms), and a history of VT were significantly associated with the composite outcome. (Table) The change in QRS was linearly correlated with the change in RVEDVi (R = 0.66; p=0.002). Conclusion: In conclusion, adults with repaired ToF experience a reduction in QRS duration post-PVR. This change correlates with the change in the RV size post-operatively. A QRS ≥180ms post-PVR, no reduction in QRS, increased age at repair, and a history of VT independently predict the occurrence of VT post-PVR. Patients with these risk factors may warrant closer monitoring and/or ICD consideration.

Simple electrophysiological predictor of QRS change induced by cardiac resynchronization therapy: A novel marker of complete left bundle branch block.

QRS complex shortening by cardiac resynchronization therapy (CRT) has been associated with improved outcomes. We hypothesized that the absence of QRS duration (QRSd) prolongation by right ventricular mid-septal pacing (RVP) may indicate complete left bundle branch block (cLBBB). We prospectively collected 12-lead surface electrocardiograms (ECGs) and intracardiac electrograms during CRT implant procedures. Digital recordings were edited and manually measured. The outcome measure was a change in QRSd induced by CRT (delta CRT). Several outcome predictors were investigated: native QRSd, cLBBB (by using Strauss criteria), interval between the onset of the QRS complex and the local left ventricular electrogram (Q-LV), and a newly proposed index defined by the difference between RVP and native QRSd (delta RVP). One hundred thirty-three consecutive patients were included in the study. Delta RVP was 27 ± 25 ms, and delta CRT was -14 ± 28 ms. Delta CRT correlated with native QRSd (r = -0.65), with the presence of ECG-based cLBBB (r = -0.40), with Q-LV (r = -0.68), and with delta RVP (r = 0.72) (P < .00001 for all correlations). In multivariable analysis, delta CRT was most strongly associated with delta RVP (P < .00001), followed by native QRSd and Q-LV, while ECG-based cLBBB became a nonsignificant factor. Baseline QRSd, delta RVP, and LV electrical lead position (Q-LV) represent strong independent predictors of ECG response to CRT. The absence of QRSd prolongation by RVP may serve as an alternative and more specific marker of cLBBB. Delta RVP correlates strongly with the CRT effect on QRSd and outperforms the predictive value of ECG-based cLBBB.

QTc Prolongation in COVID-19 Patients Using Chloroquine.

Chloroquine is used in the treatment of patients with COVID-19 infection, although there is no substantial evidence for a beneficial effect. Chloroquine is known to prolong the QRS and QTc interval on the ECG. To assess the effect of chloroquine on QRS and QTc intervals in COVID-19 patients, we included all inpatients treated with chloroquine for COVID-19 in the Spaarne Gasthuis (Haarlem/Hoofddorp, the Netherlands) and had an ECG performed both in the 72 h before and during or at least 48 h after treatment. We analyzed the (change in) QRS and QTc interval using the one-sample t-test. Of the 106 patients treated with chloroquine, 70 met the inclusion criteria. The average change in QRS interval was 6.0 ms (95% CI 3.3–8.7) and the average change in QTc interval was 32.6 ms (95% CI 24.9–40.2) corrected with the Bazett’s formula and 38.1 ms (95% CI 30.4–45.9) corrected with the Fridericia’s formula. In 19 of the 70 patients (27%), the QTc interval was above 500 ms after start of chloroquine treatment or the change in QTc interval was more than 60 ms. A heart rate above 90 bpm, renal dysfunction, and a QTc interval below 450 ms were risk factors for QTc interval prolongation. Chloroquine prolongs the QTc interval in a substantial number of patients, potentially causing rhythm disturbances. Since there is no substantial evidence for a beneficial effect of chloroquine, these results discourage its use in COVID-19 patients.Electronic supplementary materialThe online version of this article (10.1007/s12012-020-09621-2) contains supplementary material, which is available to authorized users.

Baseline Framingham risk score does not predict future ECG-derived QRS duration over an average of 3.3\xa0years

BackgroundProlonged electrocardiogram (ECG) QRS duration has been associated with increased cardiovascular risk. It is unclear whether the main predictor of cardiovascular risk, the Framingham risk score also predicts short-term changes in ECG QRS duration. Our aim is to determine whether baseline Framingham risk score is associated with baseline or changes in QRS duration.MethodsA retrospective cross-sectional analysis was performed using observational data obtained from two hundred two participants. Framingham risk score was calculated using an online risk calculator. QRS duration was obtained using a 10 s trace from a Welch Allyn PC-based 12-lead ECG system.ResultsAverage follow-up duration was 3.3 ± 1.1 years. Mean QRS change was 1.8 ± 11.4 ms. Specifically, among two hundred two participants, there are 104 subjects with a greater QRS duration at follow-up, while 98 subjects had the same or a shorter follow-up QRS duration. Baseline Framingham risk score did not significantly predict an increase in QRSd with an odds ratio of 1.04 (P = 0.230). Regression analysis of QRS duration at baseline and Framingham risk at baseline had a weak association (R2 = 0.020; P = 0.043). The Framingham risk score at follow-up was likewise has a weak association with follow-up QRS duration (R2 = 0.045; P = 0.002).ConclusionsOur results do not demonstrate a statistically significant association between Framingham risk parameters and future QRS duration changes over longitudinal time. QRS duration had variable changes between baseline and follow-up. This might suggest that a longer period of follow-up is required to document more stable increases in QRS duration associated with ventricular pathology. A larger population study is needed to confirm our observations.

Both baseline Selvester QRS score and change in QRS score predict prognosis in patients with acute ST-segment elevation myocardial infarction after percutaneous coronary intervention

Background:We aimed to demonstrate the prognostic value of Selvester QRS scores in patients with acute ST-segment elevation myocardial infarction (STEMI).Methods:In this prospective, observational study, we screened 289 patients with acute STEMI who underwent percutaneous coronary intervention (PCI) from 1 January 2014 to 1 June 2015 at the Second Hospital of Dalian Medical University. Selvester QRS scores were calculated at the time of hospital admission and within 24 h after treatment for PCI. The primary endpoint was the 2-year mortality rate, and the secondary endpoint was any nonfatal major adverse cardiovascular event (MACE).Results:Of the 289 patients, the QRS score increased in 115 (39.8%), and the 2-year mortality and MACE rates were significantly higher in these patients than in those in whom the QRS score decreased or remained unchanged after the treatment of PCI. Multivariable Cox regression analysis revealed that both baseline QRS scores and changes in QRS scores were independently associated with the 2-year mortality rate [hazard ratio (HR) 1.462, 95% confidence interval (95% CI) 1.279–1.671 and HR 5.122, 95% CI 2.128–12.328, respectively), MACE rate (HR 1.119, 95% CI 1.019–1.229 and HR 2.585, 95% CI 1.260–5.303, respectively) and composite endpoint (HR 1.137, 95% CI 1.047–1.236 and HR 3.152, 95% CI 1.704–5.829, respectively) after adjusting for other risk factors.Conclusion:In conclusion, both baseline Selvester QRS scores and changes in QRS scores independently predicted poor outcomes in patients with acute STEMI who underwent PCI.

P5428QRS narrowing more than 15 ms after CRT implantation is strongly associated with the long-term survival

Abstract Background Cardiac resynchronization therapy (CRT) is used in selected heart failure patients with electrical cardiac dyssynchrony with a prolonged QRS duration and a left ventricle ejection fraction (LVEF) ≤35%. QRS duration post CRT implantation can probably predict responders and survivors. The aim of our study is to investigate the effect of QRS change on long-term survival post CRT implantation. Methods We performed a retrospective cohort study in patients receiving a CRT device in our tertiary referral center between January 2009 and January 2018. Clinical and electrocardiographic (ECG) data were collected at baseline, one week after CRT implantation, six months, and yearly during follow-up. The primary endpoint was death, left ventricle assisting device implantation, or heart transplantation. At the end, the cohort was dichotomized to the cut-off value of ≥15ms according current literature. Results The study population consisted of 219 patients of whom 145 (66%) patients were survivors and 74 (34%) non-survivors. Non-survivors were significantly older (63 vs. 68 years, p=0.001), male gender (67% vs. 82%, p=0.015), had more often diabetes mellitus (20% vs. 39%, p=0.002), chronic obstructive pulmonary disease (12% vs. 28%, p=0.003), an ischemic etiology of heart failure (42% vs. 61%, p=0.009) with previous myocardial infarction (29% vs 53%, p=0.001), previous revascularization (32% vs. 49%, p=0.019), atrial fibrillation (21% vs. 39%, p=0.004), worser NYHA class (p=0.008), and amiodarone use (10% vs. 22%, p=0.024). Blood urea nitrogen (BUN) (8.1 mmol/L vs. 10.4 mmol/L, p&lt;0.001) and creatinine levels (96 μmol/L vs. 114 μmol/L, p=0.001) were also higher in the non-survivors group. Median QRS duration (168 ms IQR [154 to 182]) at baseline was comparable between survivors and non-survivors (170 ms vs. 166 ms, p=0.17). However, median QRS change one week after CRT implantation was significantly better in the survivors (−19 ms IQR [−30 to −2] vs. −6 ms IQR [−24 to +12], p=0.004). The QRS change at the last FU (median 5.1 years IQR [2.9 to 7.8] was consistently higher in the survivor group (−16 ms IQR [−29 to 0] vs. +1 ms IQR [−27 to +20], p=0.004). Dichotomized to ΔQRS narrowing of ≥15 ms after CRT implantation showed significantly better long-term survival (figure). Kaplan-Meier curve Conclusion QRS narrowing cut-off of ≥15 ms post CRT implantation is strongly associated with the long term survival in chronic heart failure patients with reduced LVEF.

Correction of the QRS duration for heart rate

ObjectiveTo determine the clinical value of correcting the QRS duration for heart rate. BackgroundWe recently observed [1] that the QRS duration shortens during spontaneous increases in heart rate. In the current study, we analyzed ECG and pharmacokinetic data of 21 subjects who received quinidine in a recent study [2]. They experienced the expected post-quinidine increase in heart rate, allowing us to determine if quinidine's well-known QRS prolongation might be attenuated due to the concomitant rate increase. MethodsIn a crossover-designed study, after baseline ECG recording, the subjects received quinidine 400 mg orally or placebo, and ECGs and quinidine plasma concentrations were then obtained at 15 prespecified timepoints over 24 h. The previously determined QRS-RR regression slope (0.0125) [1] was used to rate-correct QRS. Change in QRS from baseline (dQRS) and rate-corrected change in QRS from baseline (dQRSc) over time were plotted with the mean quinidine concentration and the correlation of plasma concentration with dQRS and dQRSc was assessed by pairwise correlation and linear regression. ResultsThere was a statistically significantly greater increase in heart rate at all timepoints combined in the quinidine arm compared with the placebo arm (9.9 ± 6.80 vs. 5.2 ± 7.42, respectively, p < 0.0001). dQRSc was significantly greater at all timepoints combined compared with dQRS (1.99 ± 4.824 vs −0.68 ± 4.640 msec, respectively, p < 0.0001). dQRS correlated poorly with quinidine plasma concentration (p = 0.127), with no clear change in QRS observed. On the other hand, dQRSc correlated well with quinidine concentration (p = 0.010), with a clear rise and fall in dQRSc that mirrored the rise and fall of quinidine concentration. ConclusionRate correction of the QRS duration improves detection of QRS prolongation in the presence of heart rate change. Condensed abstractUsing the mean QRS – RR slope determined previously in normal volunteers [1], we corrected the QRS duration for its known dependency on heart rate in 21 subjects who received quinidine and experienced the expected post-quinidine increase in heart rate in a recent clinical trial [2]. We found that uncorrected QRS did not correlate with quinidine concentration (p = 0.127), while rate-corrected QRS correlated well (p = 0.010) and mirrored the rise and fall of quinidine concentration. Rate correction of the QRS duration improves detection of QRS prolongation in the presence of heart rate change.

Abstract 145: Efficacy of ECG Waveform to Predict Outcome in Patients With Out-of-Hospital Cardiac Arrest

Introduction: Neurological intact survival of pulseless electrical activity (PEA) has extremely poor outcome when compared with ventricular fibrillation. In Japan, the all patients with out-of-hospital cardiac arrest received CPR is transferred to emergency hospitals. To determine termination of resuscitation, it is necessary to predict their outcome. Therefore, we analyzed the relationship between ECG changes during prehospital resuscitation and outcome. Method: This study is a retrospective observational study for out-of-hospital PEA in April 2012 - April 2017 which was transported to the emergency medical center in Shizuoka General Hospital. We examined consecutive PEA cases where recorded by emergency medical services. The QRS width and RR interval were measured in ECG recording in the initial check pulse phase and arrival hospital. The primary outcome was survival admission and the secondary outcome was good neurologic outcome defined as cerebral performance score (CPC) of 1, 2. ECG changes determined as QRS width and RR interval in initial rhythm minus those at hospital arrival. Results: Eighty-four patients were analyzed and the average age was 77.3 years old, male 52.0%. There were 44 cases (52%) with survival admission (ROSC cases) and 7 (8%) with CPC 1-2. ROSC cases showed significantly narrower QRS width than non-ROSC cases in the initial waveform (139.1±61.9 vs 165.5±57.5msec, P&lt;0.05). Regarding ECG waveform changes, RR interval was significantly shortened in ROSC cases(-356.0±1256.0 vs 386.8±1258.6msec, P&lt;0.01). Comparing CPC1-2 cases and CPC3-5 cases, QRS width is significantly narrower in CPC1-2 cases(108.6±44.51 vs 155.6±60msec, P&lt;0.05), and there were no significant differences in ECG waveform changes. Multivariate analysis revealed that Initial QRS width and RR interval change are the independent factors associated with survival admission. Conclusion: Those findings suggested that analyzing QRS width and change of RR intervals during prehospital resuscitation predict survival admission in PEA cases.

The electrical axis of the heart in patients with atrial fibrillation before and after radiofrequency ablation

Aim – to study changes of the electrical axis of the heart in patients with atrial fibrillation before and after radiofrequency ablation with pulmonary veins isolation. Materials and methods. Data from the study of heart electrical axis (HEA) position in 40 patients (24 men and 16 women) with atrial fibrillation before and during acute postoperative period (3–7 days) after performed radiofrequency ablation with pulmonary vein isolation (RFA PVI) were presented. The values of vector α angle of HEA (αF QRS) and its projections to the frontal (αQRS max F), the sagittal (αQRS max Si) and the horizontal plane (αQRS max H) were determined for the averaged complex in 5 seconds. Patients were divided into 3 groups: the group 1 – normal position of HEA α = 30–70 (n = 10), the group 2 – deviations of HEA to the left α 70 (n = 7). The analysis of the changes reliability after the operation was carried out using the Wilcoxon test. Results. It has been established that the initially bimodal distribution of resultant vector with maxima in the groups 1 and 2 changed to a unimodal asymmetric with a maximum value displacement to the group 1region. The changes in aF QRS max projections on a plane yielded little information. There was a change in the resultant aF QRS in all patients after RFA PVI and in one third (32.5 %) of the patients normalizing of the HEA position took place, and in 5 % – an increase in aF QRS with the transition to the group 3. Conclusions. A further study of aF QRS changes, a comparison of aF QRS and the atrial vector are required.

The impact of trans-catheter aortic valve replacement induced left-bundle branch block on cardiac reverse remodeling

BackgroundLeft bundle branch block (LBBB) is common following trans-catheter aortic valve replacement (TAVR) and has been linked to increased mortality, although whether this is related to less favourable cardiac reverse remodeling is unclear. The aim of the study was to investigate the impact of TAVR induced LBBB on cardiac reverse remodeling.Methods48 patients undergoing TAVR for severe aortic stenosis were evaluated. 24 patients with new LBBB (LBBB-T) following TAVR were matched with 24 patients with a narrow post-procedure QRS (nQRS). Patients underwent cardiovascular magnetic resonance (CMR) prior to and 6 m post-TAVR. Measured cardiac reverse remodeling parameters included left ventricular (LV) size, ejection fraction (LVEF) and global longitudinal strain (GLS). Inter- and intra-ventricular dyssynchrony were determined using time to peak radial strain derived from CMR Feature Tracking.ResultsIn the LBBB-T group there was an increase in QRS duration from 96 ± 14 to 151 ± 12 ms (P < 0.001) leading to inter- and intra-ventricular dyssynchrony (inter: LBBB-T 130 ± 73 vs nQRS 23 ± 86 ms, p < 0.001; intra: LBBB-T 118 ± 103 vs. nQRS 13 ± 106 ms, p = 0.001). Change in indexed LV end-systolic volume (LVESVi), LVEF and GLS was significantly different between the two groups (LVESVi: nQRS -7.9 ± 14.0 vs. LBBB-T -0.6 ± 10.2 ml/m2, p = 0.02, LVEF: nQRS +4.6 ± 7.8 vs LBBB-T -2.1 ± 6.9%, p = 0.002; GLS: nQRS -2.1 ± 3.6 vs. LBBB-T +0.2 ± 3.2%, p = 0.024). There was a significant correlation between change in QRS and change in LVEF (r = -0.434, p = 0.002) and between change in QRS and change in GLS (r = 0.462, p = 0.001). Post-procedure QRS duration was an independent predictor of change in LVEF and GLS at 6 months.ConclusionTAVR-induced LBBB is associated with less favourable cardiac reverse remodeling at medium term follow up. In view of this, every effort should be made to prevent TAVR-induced LBBB, especially as TAVR is now being extended to a younger, lower risk population.

Meta-Analysis of the Usefulness of Change in QRS Width to Predict Response to Cardiac Resynchronization Therapy

The existing data regarding the role of QRS duration (QRSd) change on cardiac resynchronization therapy (CRT) response show some inconsistent results. We conducted a meta-analysis of data obtained from observational studies to examine the impact of QRS change after CRT device implantation on the clinical and/or echocardiographic response. We searched the PubMed and EMBASE databases for relevant studies published before January 2016. Twenty-seven studies were retrieved for detailed evaluation of which 12studies with a total population of 1,545 patients met our eligibility criteria. The analysis demonstrated that QRSd narrowing was a positive predictor of response to CRT (mean difference [MD]=-19.24ms, 95% CI=-24.00 to-14.48ms, p <0.00001). Thiseffectwas consistent in the studies using clinical criteria (MD=-19.91ms, 95% CI= -27.20to-12.62ms, p <0.00001) and in those that used echocardiographic criteria (MD=-19.51ms, 95% CI=-25.78 to-13.25ms, p <0.00001). The heterogeneity test showed moderate differences among the individual studies (I2= 42%). Subgroup analysis showed that QRSd change was more pronounced in studies having a follow-up ≤6months. We did not find significant differences in studies measuring postimplantation QRSd after a certain follow-up period compared with studies measuring QRSd immediately after CRT device implantation. Further studies should clarify the exact timing of QRSd assessments during follow-up. In conclusion, QRSd shortening after CRT device implantation is associated with a favorable clinical and echocardiographic response.

39 The Impact of New Left Bundle Branch Block Following Trans-Catheter Aortic Valve Impantation. Is There a TAVI LBBB-induced Cardiomyopathy? Insights from Cardiovascular Magnetic Resonance Imaging

Introduction Left bundle branch block (LBBB) is common following trans-catheter aortic valve implantation (TAVI) and has been linked to increased mortality, although whether this is due to the development of a TAVI-induced LBBB cardiomyopathy is unclear. Methods 48 patients undergoing TAVI for severe aortic stenosis were evaluated. 24 patients with TAVI-induced LBBB (LBBB-T) were matched with 24 patients with a narrow post-procedure QRS (nQRS). Patients underwent comprehensive Cardiovascular Magnetic Resonance (CMR) imaging prior to and 6m post-TAVI. Measured cardiac reverse remodelling parameters included left ventricular ejection fraction (LVEF), global longitudinal strain (GLS) and left sided chamber size. Inter and intraventricular dyssynchrony was determined using time to peak radial strain derived from CMR Feature Tracking. Results In the nQRS group there was no change in QRSd (93 ± 17 to 96 ± 11 ms, p = 0.098). In the LBBB-T group, QRSd increased by a mean of 55 ms from 96 ± 14 to 151 ± 12 (p= 18.6 ± 5.8 mm, p = 0.773). Post-procedure aortic regurgitant fraction was similar between groups (nQRS 5.4 ± 5.7 vs LBBB-T 5.5 ± 3.3%, p = 0.948). There was an inverse correlation between QRS duration and change in LVEF (r=-0.46, p = 0.001) and QRS duration and change in LV GLS (r=-0.37, p = 0.010). Conclusion LBBB-T is associated with less favourable cardiac reverse remodelling at medium term follow up. In view of this, every effort should be made to prevent TAVI-induced LBBB, especially as TAVI is extended to a younger, lower risk population.

Prognostic Impact of Implementation of QRS Characteristics in the Seattle Heart Failure Model in ICD and CRT-D Recipients.

The Seattle Heart Failure Model (SHFM) provides accurate estimates of survival in heart failure (HF) patients. The model is, however, not developed for HF patients with cardiac resynchronization therapy (CRT). The aim of this study was to assess the prognostic value of SHFM combined with QRS morphology and CRT-related change in QRS duration in implantable cardioverter defibrillator (ICD) and CRT defibrillator (CRT-D) recipients. All patients who underwent prophylactic ICD implantation at the Leiden University Medical Center since 1996 were included. Baseline SHFM, QRS morphology, and duration before and after device implantation were determined. The regression coefficients of the QRS characteristics derived from a Cox regression analysis were implemented in the SHFM. SHFM-estimated survival was compared with Kaplan-Meier observed survival. The current study includes 1,834 defibrillator recipients (63 ± 11 years; 79% male; 53% CRT-D). In 585 (60%) CRT-D recipients a left bundle branch block was present, the mean QRS duration was 147 ± 31 ms before and 151 ± 27 ms after device implantation. After a median follow-up of 4.4 years (25(th) -75(th) percentile 2.7-6.4 years), 285 (29%) CRT-D recipients had died. CRT-related decrease in QRS duration adjusted for QRS morphology was associated with improved survival (hazard ratio 1.05/10 ms; 95% confidence interval [CI]: 1.01-1.09; P = 0.02). The estimated 5-year survival of CRT-D recipients after implementation of the QRS characteristic was 70%, and comparable with the observed 5-year survival of 68% (95% CI: 65-72). Implementation of native QRS morphology and change in QRS duration due to CRT in the SHFM improves the prognostic value of this model in HF patients with CRT-D.

Electrocardiographic changes during acute mental stress

Background: Electrocardiogram (ECG) waveforms are influenced by physiological, pathological, and psychological factors. Acute mental stress affects the hypothalamic–pituitary–adrenal axis resulting in alterations in various physiological functions of the body particularly the cardiovascular system. Objective: To study the ECG changes during acute mental stress and also to understand the reasons for the changes in ECG caused by acute mental stress. Materials and Methods: ECG was recorded in relaxed state and in acute stress state in healthy male subjects in the age group of 18–24 years. ECG recordings in relaxed state were compared with those in acute stress state. Result: Increased heart rate, decreased PR interval, decreased QT interval, and prolonged QTc interval were observed in ECGs in acute stress state which were statistically significant. Also an increase in QRS duration and change in QRS axis were observed during acute stress which were statistically not significant. Conclusion: Increased sympathetic activity caused by acute mental stress may be the cause for this altered electrical activity of the heart.

Activation Pattern of the Polymorphic Ventricular Tachycardia and Ventricular Fibrillation on Body Surface Mapping in Patients With Brugada Syndrome.

Clinical and experimental studies have shown the existence of an arrhythmogenic substrate in the right ventricular outflow tract (RVOT) in patients with Brugada syndrome (BrS). To evaluate the importance of the RVOT, we evaluated the activation pattern of induced ventricular tachyarrhythmias using body surface mapping (BSM) in patients with BrS. We examined 14 patients with BrS in whom ventricular tachyarrhythmias were induced by programmed electrical stimulation. The 87-lead BSM was recorded during induced ventricular tachyarrhythmias, and an activation map and an isopotential map of QRS complexes every 5 ms were constructed to evaluate the activation pattern of ventricular tachyarrhythmias. BSM during 20 episodes of ventricular tachyarrhythmias induced at the RVOT showed that repetitive excitation was generated at the RVOT and propagated to the inferior RV and left ventricle, and then returned to the RVOT. Polymorphic QRS change during ventricular tachyarrhythmias was associated with migration of the earliest activation site and rotor. BSM during 4 episodes of ventricular fibrillation (VF) showed that the excitation front moved randomly with formation of multiple wavefronts. Programmed stimulation initiated repetitive firing from the RVOT. Migration and competition of the earliest activation site and rotor and local conduction delay changed the QRS morphology. Degeneration of the reentrant circuit into multiple wavefronts resulted in VF. (Circ J 2016; 80: 1734-1743).

QRS prolongation after cardiac resynchronization therapy is a predictor of persistent mechanical dyssynchrony.

Prolonged QRS duration is the main selection criterion for cardiac resynchronization therapy (CRT) which ameliorates left ventricular mechanical dyssynchrony (MD). However, consequences of post-CRT QRS prolongation and residual MD have been poorly evaluated. We aimed to define the predictors of persistent MD and hypothesized that CRT-induced QRS change (ΔQRS) might have an impact on residual MD after CRT. A total of 80 patients receiving CRT were included in the study. ΔQRS was calculated as the difference between the baseline and paced QRS intervals. Residual MD was assessed early after device implantation with a longitudinal dyssynchrony index (Yu index). Significant MD was defined as a Yu index ≥ 33msec. Two groups were created based on residual MD and compared according to clinical, electrocardiographic and echocardiographic features. Patients with persistent MD had longer paced QRS durations (182.5 ± 16.2 vs. 165.4 ± 22.5msec, p = 0.03) and were less likely to have left ventricular (LV) leads located in the posterolateral vein (53% vs. 85%, p = 0.002). The linear correlation between the ΔQRS and the Yu index values was modest (Spearman's rho = -0.341, p = 0.002); additionally, a prolonged QRS was strongly associated with MD after CRT (p = 0.00008). Both LV lead localization and CRT-induced QRS prolongation emerged as the significant predictors of persistent MD. A biventricularly paced QRS more than 10msec longer than the pre-paced QRS width was predictive of persistent MD after CRT (sensitivity = 80%, specificity = 62%). ΔQRS was found to be associated with residual MD after CRT. Ten milliseconds of QRS prolongation predicted persistent MD after CRT.

Effects of Cardiac Resynchronization Therapy on Ventricular Electrical Remodeling in Patients With Heart Failure.

Cardiac resynchronization therapy (CRT) reverses structural remodeling of the left ventricle. We investigated whether CRT reverses left-ventricular electrical remodeling.Eighty patients were enrolled and implanted with CRT-devices. Echocardiography and electrocardiography data were obtained from each patient prior to implantation and two years after implantation. At two years after implantation, the patients were classified into a responder group and a non-responder group based on echocardiography.Over the next 2 years, 75 patients completed follow-up, and 5 patients had died. Echocardiography results showed that 23 patients could be classified as non-responders and 52 as responders. Larger numbers of non-responders were diagnosed with either ischemic cardiomyopathy (ICM) or nonspecific intraventricular conduction delay (NICD). The intrinsic QRS duration was not changed in responders, patients with dilated cardiomyopathy, or in the patient categories of male and female. However, the intrinsic QRS duration was significantly prolonged in non-responders and patients with ischemic cardiomyopathy (P = 0.041). The mean left ventricular end-diastolic diameter in the responder group was significantly decreased by CRT (P < 0.05), while there was no significant change in intrinsic QRS duration.While CRT does not reduce the intrinsic QRS duration, it can delay negative ventricular electrical remodeling. Continuous CRT is necessary.

QRS Duration Changes in Patients with Hypoplastic Left Heart Syndrome Undergoing Hybrid Palliation: Prehybrid to Post‐Fontan

QRS prolongation has been shown to be a predictor of mortality in patients with certain forms of congenital heart disease. QRS changes have not been well described in patients with single ventricle physiology, particularly in those undergoing the hybrid procedure. To describe QRS changes in a cohort of patients with hypoplastic left heart syndrome (HLHS) who underwent hybrid palliation and to evaluate if QRS duration is associated with mortality. Chart review of 54 patients with HLHS who underwent hybrid procedure between 2002 and 2009 was performed. Patients awaiting surgical palliation were excluded. Patients who survived Fontan completion (HLHS-S, n = 30) were compared to non-survivor (HLHS-NS, n = 24). Electrocardiograms were reviewed for maximal QRS duration (ms) at three pre- and postsurgical stages: (1) hybrid procedure, (2) comprehensive stage 2 procedure, and (3) Fontan procedure. In HLHS-S, there was a significant increase in QRS from birth to Fontan completion (15.6 ± 9.3 ms). QRS duration increased 8.5 ± 8.9 ms between posthybrid to precomprehensive stage 2, and 5.4 ± 9.7 ms between postcomprehensive stage 2 to Fontan. Following Fontan procedure, mean QRS decreased 4.3 ± 8.5 ms. There was no significant mean difference in QRS change between HLHS-S and HLHS-NS following hybrid procedure. Pre- and posthybrid and pre- and postcomprehensive stage 2 QRS durations were not different between HLHS-S and HLHS-NS who underwent a comprehensive stage 2 procedure. There was a significant difference in QRS difference following comprehensive stage 2 in HLHS-S (0.9 ± 7.1 ms) compared to HLHS-NS (-7.1 ± 10.0 ms). QRS duration significantly increased from hybrid to Fontan completion in HLHS-S. There was a significant decrease in QRS duration in patients who died following comprehensive stage 2 procedure. Larger studies are needed to assess the significance of these QRS changes.