Search

The normal physiologic range of QRS complex duration spans between 80 and 125 ms with known differences between females and males which cannot be explained by the anatomical variations of heart sizes. To investigate the reasons for the sex differences as well as for the wide range of normal values, a technology is proposed based on the singular value decomposition and on the separation of different orthogonal components of the QRS complex. This allows classification of the proportions of different components representing the 3-dimensional representation of the electrocardiographic signal as well as classification of components that go beyond the 3-dimensional representation and that correspond to the degree of intricate convolutions of the depolarisation sequence. The technology was applied to 382,019 individual 10-s ECG samples recorded in 639 healthy subjects (311 females and 328 males) aged 33.8 ± 9.4 years. The analyses showed that QRS duration was mainly influenced by the proportions of the first two orthogonal components of the QRS complex. The first component demonstrated statistically significantly larger proportion of the total QRS power (expressed by the absolute area of the complex in all independent ECG leads) in females than in males (64.2 ± 11.6% vs 59.7 ± 11.9%, p

Background Interest in permanent His bundle pacing (HBP) as a means of both preventing pacing-induced cardiomyopathy and providing physiological resynchronization by normalization of His-Purkinje activation is constantly growing. Current devices are not specifically designed for HBP, which gives rise to programming challenges. Purpose To evaluate the critical troubleshooting HBP options in patients with permanent atrial fibrillation (AF) and variable degree of atrio-ventricular block (AVB) who receive HBP through a lead connected to the atrial port, and an additional ventricular “backup”. Methods Between December 2018 and March 2021, 136 consecutive patients with indication for pacing underwent HBP. Among these, 24 had permanent AF with documented symptomatic pauses. Seven of them received a dual-chamber device which was used to place a backup right ventricle (RV) lead; in this scenario, the His lead is implanted in the right atrial (RA) port, the RV lead in the RV port. Depending on the presence of an additional left ventricle (LV) lead, either a dual-chamber and a CRT device can be used. Results In this context, the events marked as atrial sensed (As) or paced (Ap) are indeed ventricular, so that sensing is more complex. A clinical scenario is atrial activity oversensed on the His channel (As) leading to RV dyssynchronous pacing in the ventricular safety pacing (VSP) window. A second one is intrinsic QRS undersensing causing inappropriate His pacing with possible delivery of the RV pulse depending on capture of the His pulse. The interplay of intrinsic ventricular activity (rate, signal amplitude and slew rate on both the His and the ventricular channel) and of the HV interval may be of key importance to troubleshoot As-Vp (atrial sensed – ventricular paced) [Fig. 1A] as well as Vs-Ab (ventricular sensed – atrial blanking period) sequences [Fig. 1B]. Changing sensitivity and sensing configuration may help or fail to fix these issues depending on the abovementioned aspects, making it mandatory to check that the paced AV delay is appropriately set as to avoid inappropriate RV pacing on the T wave of an undersensed intrinsic event at the His channel. DVI(R) mode programming may indeed prove safer than DDD(R) in the setting of preserved intrinsic activity or in the event of intermittent His capture loss. Paced AV delay should be programmed slightly longer than H-V+QRS duration to avoid unnecessary RV pacing with pseudo-fusion (too short) and possibly R/T events (too long). Stability of H-V interval and of QRS duration must be verified at each device follow-up by decremental His pacing to ensure consistent sensitivity of the ventricular signal beyond stable His capture, that may be challenged by infra-hisian block. Conclusions Owing to the absence of HBP-specific devices, HBP shall be made safe and effective by careful troubleshooting, consisting of sensitivity setting, paced AV interval and mode programming. Funding Acknowledgement Type of funding sources: None. Different sensitivity settings for HBP

Background Immune checkpoint inhibitor (ICI)-associated myocarditis is associated with a markedly increased risk of morbidity and mortality. The occurrence of ventricular arrhythmias (VA) in patients with ICI-associated myocarditis has not been well characterized. Purpose The aim of this study was to determine the characteristics and risk factors for severe VA in patients with ICI myocarditis. Methods The cohort consisted of 202 patients with ICI myocarditis. Ventricular arrhythmias were defined as a composite of sustained ventricular tachycardia and ventricular fibrillation. We used a multivariable logistic regression model to test the association between clinical variables and the development of VA. Results From a cohort of 202 patients with ICI myocarditis (67±13 years, 35% female, 60% hypertension, 23% diabetes mellitus), 41 (20.3%) developed VA, of which, 33 had VT and 8 had VF. The median time from admission to VF was 144 hours and to VT was 72 hours. A VA occurred in 17.5% of patients with a normal LVEF, and 25% of patients with reduced LVEF. On univariate analysis, a QRS duration >110ms (OR 2.88, 95% CI 1.40 to 6.16, P=0.005) and a QTc duration >470ms were associated with an increased probability of VA (OR 2.58, 95% CI 1.23, 5.41, P=0.012). The association remained significant after adjustment for age and gender. Additionally, a longer time from admission to initiation of corticosteroids was associated with a higher probability of VA (OR 1.06, 95% CI 1.01 to 1.13, P=0.027). The association between the time from admission to administration of corticosteroids and probability of VA remained significant after adjustment for age, gender, and LVEF on admission (OR, 1.06, 95% CI 1.00, 1.13, P=0.037) where each 6-hour delay in the initiation of corticosteroids was associated with a 4% increase in the risk for VA. Conclusions Ventricular arrhythmias are common in the setting of ICI myocarditis and are observed in patients presenting with both a preserved and a reduced LVEF. Wider QRS and longer QT at presentation and longer time from admission to initiation of corticosteroids were associated with an increased risk of VA. Funding Acknowledgement Type of funding sources: None.

Background Various devices are available for electrocardiogram (ECG) based home monitoring and could facilitate early detection of arrhythmias in adult congenital heart disease (ACHD). However, the diagnostic accuracy of these devices in ACHD is unknown. Purpose We aimed to determine the accuracy of different ECG-based devices compared to the standard 12-lead ECG in ACHD. Methods We performed a single-center, prospective, cross-sectional study in consecutive ACHD patients. We determined diagnostic accuracy of the Withings Scanwatch (lead I), Eko DUO (precordial ECG) and Kardia 6L (six leads) compared to the 12-lead ECG on several parameters: 1) automatic atrial fibrillation (AF) detection, 2) QRS-morphology assessment (simplified into normal (120ms) or other wide complexes (>120ms)), and 3) conduction times (PR, QRS, QTc time). All 12-lead and device ECGs were evaluated by a single observer. Results A total of 176 patients (54% male, age 40±16.6 years, 24% severe ACHD, 84% previous correction, six patients with AF) enrolled in the study. The Withings algorithm classified only 5% of ECGs as inconclusive compared to 31% of Kardia 6L (p Conclusions This is the first study to examine diagnostic accuracy of different ECG-based devices in ACHD. Overall, Withings Scanwatch may be the most practical choice for continuous AF screening while Kardia 6L could be preferred to accurately capture symptomatic palpitations. These findings can inform both patients and caregivers for optimal choice of home monitoring. Funding Acknowledgement Type of funding sources: None.

Background Several electrocardiographic (ECG) indices have previously been proposed to diagnose left ventricular hypertrophy (LVH). Such indices utilize different criteria, including increased QRS voltage, prolonged QRS duration, left axis deviation, and LAFB and LBBB-like patterns in varying combinations. However, the inter-relationships of these different electrocardiographic indices of LVH with each otherare not fully understood. The purpose of this study is to estimate the relationships between the different LVH indices. Methods Electronic tracings of 12-lead ECGs recorded in 24,786 adult participants in the China Kadoorie Biobank recorded in 2014 were accessed to detect presence of LVH. ECG parameters of LVH, including individual and combinations of such parameters (voltage-only criteria such as Sokolov-Lyon, Cornell, Gubner as well as scores such as Romhilt-Estes point score) were estimated using customized computer software (Cardiolyse Oy, Finland) and compared proprietary LVH point score algorithms (Mortara, USA). Relationships between the different indices were assessed using a correlation matrix to explore associations between individual parameters and combined indices of such parameters. The matrices were used to construct heat maps and identify clustering of individual parameters. Results Overall, approximately 10% of the population had LVH assessed by Mortara algorithms. This graph shows that along with the free standing peaks, the rest are divided into two clusters of interconnected individual parameters. In the center of the largest cluster is the parameter, reflecting R-peak magnitude in aVL lead. In the center of another cluster was the left ventricular strain pattern, as described in Romhilt-Estes point score system. Overall, the Sokolov-Lyon index and LVH point score in Veritas algorithm had the strongest relationships with each other, but the Gubner and Cornell indices had relatively weak correlations with the other indices (Table 1). The mean correlation coefficient between five combined LVH indices was as follows: Veritas (Mortara) – 0.58, Sokolov-Lyon – 0.56, Romhilt-Estes – 0.45, Gubner – 0,32, Cornell – 0,3. Conclusions Parameters such as R-peak magnitude in aVL and left ventricular strain pattern were the most strongly related with each other. Aggregate indices, such as the Sokolov-Lyon index and LVH point score in Veritas algorithm were the most strongly related with all other indices, but the Gubner and Cornell indices were only weakly correlated. The results reinforce the utility of Sokolov-Lyon index and Mortara algorithms as the optimum measures of LVH. Funding Acknowledgement Type of funding sources: None.

Introduction Following cardiac resincronization therapy (CRT), QRS duration is the most important prognostic factor in the 12-lead electrocardiogram (ECG). However, there is little evidence regarding if the electrocardiographic pattern following CRT has impact on morbidity and mortality. Purpose In this historical cohort study we analysed if a certain pattern in three leads of the ECG (Rs in V1, Qr in aVL or rS in I) is associated with lower incidence of adverse outcomes in a population of CRT patients within 1 year of implant. Other variables previously associated with success or failure of CRT were analysed. Methods Patients with CRT devices (pacemaker or defibrillator) with left ventricle lead in the coronary sinus were included from January 2012 to April 2019. One year clinical follow-up was performed. The primary endpoint was a composite of death of any cause and heart failure hospitalization. Differences in categorical data were reported as frequencies then compared using χ2 tests. Continuous variables were reported as means ± standard deviation with differences between groups tested using independent samples t-tests. Survival analysis was performed using Kaplan-Meier test, comparing survival graphics through Log-Rank test. For multivariate analysis, Cox regression was performed. Variables that showed significance in the univariate analysis were included. Results 111 patients were included. Sample was divided into 2 groups according to the presence of the pattern in any of the three ECG leads. Two patients (1.8%) presented Rs in V1 and Qr in aVL simultanously and two patients (1.8%) presented Rs in V1 and rS in I. None of the patients presented all three patterns simultaneously. Baseline characteristics are reported in Table 1. Presence of any of the three patterns was independently associated with a lower incidence of the primary endpoint (2.3% vs. 17.6%, hazard ratio 0.1, 95% confidence interval 0.013–0.774, p=0.016). Previous atrial fibrillation was also independently associated with a higher incidence of the primary endpoint. QRS duration postimplantation did not showed prognostic value. Conclusion The presence of the patterns Rs in V1, Qr in aVL or rS in I is an independent predictor of good prognosis in patients with CRT. Funding Acknowledgement Type of funding sources: None. Baseline characteristicsKaplan Meier survival curves

ECG interpretation is a core skill for any healthcare practitioner that looks after children. The article aims to educate the reader in basic interpretation of paediatric ECG in a succinct, interactive, organised manner in a way that it can be easily referenced and applied in everyday clinical practice. We include clinical examples as well as age and sex-related reference ranges for QT intervals, P-wave duration, Q-wave amplitude, QRS complex duration, R-wave and S-wave amplitude, R/S ratio and PR intervals.

Accurate measurement of QRS complex duration (QRSd) remains crucial for the selection of patients for cardiac resynchronization therapy (CRT). However, assessment of QRSd on conventional surface electrocardiograms (ECG), especially when performed without computer assistance, may be challenging due to the limited accuracy of the human eye to discriminate differences in the range of 10 ms at 25 mm/s. The value and reproducibility of visual assessment of QRSd at 25 mm/s on conventional ECGs was compared to those obtained using an electrophysiology recording system (EPRS) with simultaneous 12 lead traces at 100 mm/s, which was considered the gold standard.The ECGs of 102 consecutive patients with left ventricular dysfunction undergoing electrophysiological evaluation were collected. Two sets of measurements were obtained: 1) QRSd-25 measured on conventional 12-lead ECGs printed at 25 mm/s with standard amplification (10 mm/mV) by 4 different observers, and 2) QRSd-100 measured on simultaneous 12-lead traces at 100 mm/s and 40 mm/mV by 2 different observers using electronic callipers.Significant differences were observed between QRSd-100 and QRSd-25 measurements (19.3 ± 9.9 ms, range 1.0-47.5, p 0.001). QRSd-25 showed significant inter and intra-observer variability. When categorizing individual ECGs in three QRSd-25 subgroups (120 ms, 120-149 ms and ≥150 ms), low concordance was observed between both techniques (kappa index 0.25, p 0.001). The sensitivity and specificity of QRSd-25 to detect QRSd-100 ≥ 150 ms was 36.6% and 100.0% respectively.Visual measurement of QRSd at 25 mm/s often underestimates its magnitude and presents significant inter and intraobserver variability.

We describe a case where ventricular overdrive pacing during a wide QRS complex supraventricular tachycardia demonstrated constant fusion by narrowing the QRS complex duration and diagnosing the tachycardia mechanism.

We examined the relationships between blood heavy metals [cadmium (B-Cd), mercury (B-Hg), and lead (B-Pb)] and heart rate-corrected QT interval (QTc), JT interval (JTc), and QRS complex duration (QRSc), electrocardiogram markers of ventricular repolarization and depolarization among 60 traffic enforcers in the MMDA traffic enforcers' health study. We fitted regression models to estimate the mean change effect on QTc, JTc, and QRSc, of B-Cd, B-Hg, and B-Pb concentrations, adjusted for potential confounding factors. We looked at effect modification by sex and smoking status. An interquartile range increase in B-Cd (0.9 μg/L) was related to a 6.6% increase in mean QRSc [95% confidence interval (CI): 2.5, 10.8], and a 1.7% increase in mean QTc (95% CI: 0.2, 3.3). We also found that the associations between B-Cd and QRSc and QTc were higher among participants who were never smokers than ever smokers. Moreover, the association between B-Cd and QRSc was also higher among males than females.

Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Netherlands Cardio Vascular Research Initiative (CVON): the Dutch heart foundation Background Mutations in phospholamban (PLN, most often PLNR14Del), a protein that regulates Ca2+ homeostasis in cardiomyocytes, are found in patients diagnosed with arrhythmogenic (ACM) and dilated cardiomyopathy (DCM). Fibrosis formation in the heart is one of the hallmarks in PLN patients, which compromises cardiac contractility and predisposes to arrhythmogenicity. Collagen type I is the most abundant type of collagen in the heart (85%). During continuous collagen synthesis propeptides, like procollagen type I carboxy-terminal propeptide (PICP) and during collagen breakdown, C-terminal telopeptide collagen type I (ICTP), are released into the circulation. Clinically, detection of fibrosis occurs via echo or MRI, however difficulties arise when patchy fibrosis has to be detected. Purpose To investigate if PICP and ICTP levels in blood are useful predictive biomarkers for clinical outcome in PLN patients. Methods 78 serum and EDTA blood samples were collected on the same day from ACM diagnosed (n = 12), DCM diagnosed (n = 14) or non-classified (n = 52) PLN patients. PICP levels were measured with an ELISA assay and ICTP with a RIA. Clinical data were subtracted two years around blood collection from Redcap, a Dutch database with medical records from PLN patients. Data were not normally distributed, so Spearman’s correlation coefficient and Mann-Whitney test were used. Results Gender, age and PICP/ICTP ratios were similarly distributed between the subgroups. First, we checked if clinical data subtracted two years around blood collection provided reliable results regarding clinical outcome. Patients who underwent clinical testing 5.5 weeks around blood collection revealed that clinical data were in line with the best-fitted line of the linear regression and therefore provide reliable results. Next, the potential correlation of fibrosis biomarkers with electrical parameters was assessed. Increased PICP/ICTP ratios suggest a higher collagen deposition. Although there was no correlation with prolonged QRS duration (Rs 0.13, n = 62, ns), subgroup analysis showed a significant weak correlation for non-classified patients (Rs 0.32, n = 38, p = 0.05). No significant correlation was found for ACM or DCM patients; however, groups were rather small. PICP/ICTP ratio was significantly higher in patients with T wave inversion and premature ventricular contractions (PVCs) during an exercise tolerance test. A weak inverted correlation was found with left ventricular ejection fraction and PICP/ICTP (Rs -0.28, n = 23, ns), while moderate correlations between the ratio and end diastolic volume, and end systolic volume exist (both Rs 0.40, n = 23, p = 0.06). Conclusion High PICP/ICTP ratios correlate with clinical outcome in PLN patients, such as T wave inversion and PVCs. However, the size and heterogeneity of the patient group resulted in weak to moderate correlation coefficients and might therefore currently precludes to use PICP and ICTP levels as biomarker.

Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Abbott Introduction Automatic adjustment of atrioventricular delay (AVD) with SyncAV has been shown to improve electrical synchronization. However, the effect of pacing configuration and right ventricular (RV) lead location on SyncAV programming is unknown. Purpose Evaluate the effect of pacing configuration and lead location on SyncAV optimization during biventricular (BiV) and LV-only pacing, with and without MultiPoint Pacing (MPP). Methods Patients with LBBB and QRS duration (QRSd) ≥ 150 ms scheduled for CRT-P/D device implantation with quadripolar LV lead were enrolled in this prospective study. RV lead location was classified at implant by the operator via fluoroscopy. QRSd was measured post-implant from 12-lead surface ECG by blinded experts during the following pacing modes: intrinsic conduction, BiV (BiV = RV + LV1), MPP (MPP = RV + LV1 + LV2), LV-only single-site (LVSS = LV1 only), and LV-only MPP (LVMPP = LV1 + LV2). For each mode, SyncAV was enabled (e.g. BiV + SyncAV) with the patient-tailored SyncAV offset that minimized QRSd. For BiV and LVSS, LV1 was the latest activating LV cathode; for MPP and LVMPP, LV1 + LV2 were the two LV cathodes with the widest possible separation (≥30mm). All modes used minimal RV-LV and LV1-LV2 delays. Results Fifty-three patients (68% male, 36% ischemic, 26% ejection fraction, 169 ms intrinsic QRSd) completed device implant and QRSd assessment. RV leads were implanted in either the septum (48%) or apex (52%), according to implanting physician preference. Relative to intrinsic conduction, BiV + SyncAV and MPP + SyncAV reduced QRSd by 23% and 27%, respectively (p Conclusion SyncAV improves acute electrical synchronization in CRT patients with LBBB, particularly with patient-specific SyncAV programming. Pacing configuration (RV + LV or LV only, with or without MPP) and RV lead location (apex or septum) could potentially influence optimal SyncAV programming. Abstract Figure.

Funding Acknowledgements Type of funding sources: None. Background and Purpose. To distinguish the origin of outflow tract ventricular arrhythmias (OTVAs) with a V3 precordial transition is still a challenge. To date, numerous diagnostic algorithms have been described, mainly by analysis of leads V1 and V2, while a complete study of lead V3 has never been conducted. Methods. The ECG characteristics of 45 patients (Pts) with a left bundle branch block pattern OTVAs (LVOT 51.1%, RVOT 48.9%) who underwent successful catheter ablation were retrospectively analyzed. The region where the radiofrequency delivery resulted in the persistent suppression of the arrhythmia was identified as the site of origin. For every duration or amplitude variable and for derivative indices, the comparison of means (U Mann Whitney or t-test), the determination of the AUC by ROC curves, and the correlation with BMI and BSA were performed. The odds ratio was calculated for every variable with an AUC ≥ 0.700. The three best results are described. Results. Pts with a LVOT origin were older (59.91 ± 10.48 vs 50.95 ± 15.48, p = 0.027) and predominantly males (82.6% vs 54.5%, p = 0.042) but they shared similar BMI (24.74 ± 2.76 vs 24.09 ± 2.94, p = 0.45) and BSA (1.83 ± 0.12 vs 1.77 ± 0.16, p = 0.157). In leads V1 – V2 the duration but not the amplitude of the R wave showed a significant correlation with the BSA; no variable, with the exception of the S wave amplitude, exhibited an AUC ≥ 0.700. Criteria based on the prevalence of the R wave in those leads were very specific but not sensitive as a V1 – V2 duration index ≥ 50% and a V1 – V2 amplitude ratio ≥ 30% were present only in 13.04 and 26.08% respectively of patients with a LVOT origin. No measurement in lead V3 showed any correlation with auxological characteristics. The three best ECG variables were: 1) the V3 R wave duration index (R wave \ QRS duration); AUC 0.905, LVOT origin if ≥ 50%, OR 74.80 95% CI [7.97 – 701.48], p < 0.001; 2) the V3 R wave duration; AUC 0.900, LVOT origin if ≥ 80 msec, OR 47.25 95% CI [7.73 – 288.82], p < 0.001; 3) the V3 R wave percentage (amplitude of the R wave with respect to the global amplitude of the QRS, expressed as a percentage); AUC 0.888, LVOT origin if ≥ 50%, OR 36 95% CI [6.19 – 209.06], p < 0.001. Based on the V2 transition ratio calculation formula, we calculated the V3 transition ratio (AUC 0.843, LVOT origin if ≥ 1) which was very sensitive but less specific; OR 30 CI [3.32 – 270.37], p = 0.002. To multivariate analysis, only a V3 R wave percentage ≥ 50% proved to be an independent predictor of LVOT origin; OR 9 CI [2.08 – 38.78], p = 0.003, even if the criterion with the highest accuracy was a V3 duration index ≥ 50% (88.89%). Conclusions. Although it has been poorly analyzed in previous studies on the origin of OTVAs, the morphological characteristics of lead V3 seem to provide valid elements for the creation of diagnostic algorithms. Abstract Figure. Comparison of ECG characteristics

Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): British Heart Foundation Background: His bundle pacing can be achieved in two ways selective His bundle pacing, where the His bundle is captured alone, and non-selective His bundle pacing, where local myocardium is also captured resulting a pre-excited ECG appearance. We assessed the impact of this ventricular pre-excitation on left and right ventricular dys-synchrony. Methods We recruited patients who displayed both selective and non-selective His bundle pacing. We performed non-invasive epicardial electrical mapping to determine left and right ventricular activation times and patterns. Results In the primary analysis (n = 20, all patients), non-selective His bundle pacing did not prolong LVAT compared to select His bundle pacing by a pre-specified non-inferiority margin of 10ms (LVAT prolongation: -5.5ms, 95% confidence interval (CI): -0.6 to -10.4, non-inferiority p In patients with narrow intrinsic QRS (n = 6), non-selective His bundle pacing preserved left ventricular activation time (-2.9ms, 95%CI: -9.7 to 4.0, p = 0.331) but prolonged QRS duration (31.4ms, 95%CI: 22.0 to 40.7, p = 0.0003) and mean right ventricular activation time (16.8ms, 95%CI: -5.3 to 38.9, p = 0.108) compared to selective His bundle pacing. Activation pattern of the left ventricular surface was unchanged between selective and non-selective His bundle pacing. Non-selective His bundle pacing produced early basal right ventricular activation, which was not observed with selective His bundle pacing. Conclusions Compared to selective His bundle pacing, local myocardial capture during non-selective His bundle pacing produces right ventricular pre-excitation resulting in prolongation of QRS duration. However, non-selective His bundle pacing preserves the left ventricular activation time and pattern of selective His bundle pacing. When choosing between selective and non-selective His bundle pacing, left ventricular dyssynchrony is not an important factor. Abstract Figure: Selective vs Non-Selective HBP

Despite advances in the field of cardiac resynchronisation therapy (CRT), response rates and durability of therapy remain relatively static. Optimising device timing intervals may be the most common modifiable factor influencing CRT efficacy after implantation. This review addresses the concept of fusion pacing as a method for improving patient outcomes with CRT. Fusion pacing describes the delivery of CRT pacing with a programming strategy to preserve intrinsic atrioventricular (AV) conduction and ventricular activation via the right bundle branch. Several methods have been assessed to achieve fusion pacing. QRS complex duration (QRSd) shortening with CRT is associated with improved clinical response. Dynamic algorithm-based optimisation targeting narrowest QRSd in patients with intact AV conduction has shown promise in people with heart failure with left bundle branch block. Individualised dynamic programming achieving fusion may achieve the greatest magnitude of electrical synchrony, measured by QRSd narrowing.

Background His bundle pacing (HBP) can be affected by high thresholds and low sensing. Thus, in selected patients including a back-up lead is advisable. Objective Single-centre retrospective analysis of a large HBP experience, focusing on the back-up lead utilization over the years. Methods 677 pts (76±8 years; 433 males) were implanted with HBP from 2004 to 2019 July. The pts received S-HBP (67%) or NS-HBP by the 3830 lead. The pacing indications were AV block 54%, sinus node disease 17%, slow atrial fibrillation 23%, heart failure 6%. Ischemic cardiopathy was found in 26%; hypertension in 83%, diabetes in28% pts. Baseline QRS duration was 123±32 ms and EF 56±12%. Results 266 (39%) pts received the back-up lead. In sinus rhythm we implanted 3-chamber PM (His lead:LV port; VV delay 80 ms: His pulses and apical pacing during the refractory period). 30 pts (11%) received a particular type of 3-chamber PM which provides back-up pacing only if His capture fails, thus saving energy. In atrial fibrillation 2-chamber PM was implanted (His lead: atrial port, DVI). We recorded a significant decrease of back-up lead use over the years, strictly related to operators/centre experience (>70% during the first years, nearly 10% during the last year). The C315 fixed curve sheath, strongly contributed to the rapid reduction of back-up lead use thanks to better lead fixation and stability. Conclusion The back-up lead utilization is progressively decreasing. It is strictly related to the operator/centre experience. The presence of the back-up lead could strengthen the Hisian pacing reliability, potentially impacting pacing indication even in advanced conduction disturbances and saving device longevity. Funding Acknowledgement Type of funding source: None

Background The 12-lead electrocardiogram (ECG) is an essential tool for the diagnosis and management of heart failure (HF). There are few population-based studies on the prevalence and prognostic implications of ECG abnormalities in patients with HF. There are also no robust diagnostic criteria for HF. We explored these issues in a large administrative database. Methods The National Health Service Greater Glasgow and Clyde Health Board serves a population of ∼1.1 million. We obtained de-identified administrative data, including investigations, diagnosis and prescriptions, linked to hospital admissions and deaths, for anyone with a diagnosis of vascular disease or HF or prescribed loop diuretics (LD) or neuro-endocrine antagonists between 1st January 2012 and 1st April 2018. People were classified into 5 exclusive groups: a) prevalent HF; b) incident (or latent) HF with onset during follow-up; c) people taking LDs but with no diagnosis of HF at any time; d) new prescription of LDs during follow-up but with no diagnosis of HF at any time and d) people to whom none of the above applied. ECGs were classified according to heart rhythm (sinus, AF or flutter or pacemaker/CRT/ICD) and QRS duration 130ms. Follow-up for each group started on 1st of January 2012 (prior to the onset of the classifying event for incident groups). Results During the observation period, of 316,350 people included, 158,421 had a recorded ECG (mean of 3.2 per person with an ECG), including 8,768 prevalent and 13,195 incident cases of HF. Of those who never got a diagnosis of heart failure, 11,508 were receiving and a further 14,633 were newly prescribed LD during follow-up. There were 110,317 people who did not fall into the above groups, of whom 51,089 were aged ≥60 years. A higher proportion of those who were prescribed loop diuretics without a diagnosis of heart failure were women. A similar proportion of those with heart failure and those prescribed diuretics alone had, lung disease and renal dysfunction but patients with heart failure had more ischaemic heart disease, more often had a heart rhythm other than sinus and had longer QRS duration. By three years, 8,816 people (11%) had died, of whom 2,919 (33%) had a diagnosis of heart failure and 2,694 (31%) had been prescribed LD without a diagnosis of HF, together accounting for 64% of all deaths. Patients with a rhythm other than sinus had a worse prognosis in all 5 groups of patients. QRS duration >130ms was associated with a worse prognosis in patients with HF or taking LD. Conclusions Most people with cardiovascular disease who die will first develop HF or be prescribed a LD (indicating possible undiagnosed HF). Patient characteristics of those prescribed LD suggest that many might have HF with preserved left ventricular ejection fraction (HFpEF). Baseline characteristics and HR Funding Acknowledgement Type of funding source: None

Background/Introduction The majority of beta thalassemia major (β-TM) patients suffer from cardiac disorders, while a significant proportion of them die suddenly. Twelve-lead and signal-averaged electrocardiography are simple, inexpensive, readily available tools for identifying an unfavorable arrhythmiological substrate by detecting the presence of arrhythmias, conduction abnormalities and late potentials (LPs) in these patients. Methods 47 β-TM patients and 30 healthy controls were submitted to twelve-lead and signal-averaged electrocardiography. Basal rhythm, heart rate, PR interval duration, QRS complex duration and morphology, QTc interval duration and prevalence of LPs were recorded. Results β-TM patients demonstrated a more prolonged PR segment (167.74 msec vs. 147.07 msec) (p=0.043), a higher prevalence of PR prolongation (21.05% vs. 0%) (p=0.013) and a higher prevalence of LPs (18/47, 38.3% vs. 2/30, 6.7%) (p=0.002) compared with controls. In particular, every single SAECG parameter significantly differed among patients compared with controls. Among patients, left ventricular ejection fraction was marginally lower and QTc more prolonged among LPs positive subgroup compared with LPs negative subgroup. The prevalence of atrial fibrillation among b-TM patients was estimated at 10.64%. Conclusions β-TM patients have a higher prevalence of a prolonged PR segment, atrial fibrillation and LPs. Twelve-lead and SAECG performance was feasible in all subjects and constitutes a readily available tool for assessing myocardial electrophysiological alterations in this patient group, that could have significant impact on survival and quality of life with timely application of appropriate treatment. Funding Acknowledgement Type of funding source: None

Background Reliable quantitative predictors of response to cardiac resynchronization therapy (CRT) are needed. We compared the utility of pre-implantation R-wave and T-wave heterogeneity (RWH, TWH) to standard QRS complex duration for determination of mechanical super-response and mortality risk. Methods Of patients who received CRT devices between 2006 and 2018 at our institution, we retrospectively analyzed resting 12-lead ECG recordings from all 155 who met class I and IIA ACC/AHA/HRS guideline-based indications and had echocardiograms before and after implantation. Super-responders (n=35) (patients with ≥20% increase in LVEF and/or ≥20% decrease in LVESD) were compared to non super-responders (n=120), who did not. RWH and TWH, i.e., interlead splay, were measured by second central moment analysis. QRS complex duration was computed from the longest interval in a representative non-premature beat. Results Pre-implantation RWHV1–3 (p=0.01) and TWH in all lead sets tested (p=0.004 to 0.04) were significantly lower in super-responders than in non super-responders with corresponding significance for area under the curve (AUC) (p=0.002 to 0.03). Preimplantation QRS complex duration did not differ between super-responders and non super-responders (166±3 vs. 167±2 ms, p=0.8); the AUC for QRS complex duration (0.48, p=0.74) was not significant. RWHV1–3LILII at >420 μV predicted 3-year all-cause mortality (p=0.037) with a hazard ratio of 7.440 (95% CI: 1.015–54.527, p=0.048) but QRS complex duration >150 ms did not predict mortality (p=0.27). Conclusion Pre-implantation interlead EKG heterogeneity is superior to QRS complex duration in predicting mechanical super-response to CRT and survival. Bortolotto ESC graph Funding Acknowledgement Type of funding source: None

Background Most recent consensus conference report recommends Brugada syndrome (BrS) is diagnosed in patients with ST segment elevation with spontaneous, drug-induced or fever-induced type 1 morphology. Prognosis in patients with type 2 or 3 ECG without drug-induced or fever-induced type 1 ECG is still unknown. Purpose To evaluate a long-term prognosis in patients with non-type 1 Brugada ECG in a large Japanese cohort of BrS (The Japan Idiopathic Ventricular Fibrillation Study [J-IVFS]). Methods From 528 patients in J-IVFS, a total of 28 consecutive non-type 1 patients (54±14 years, all male, previous sustained ventricular tachyarrhythmias (VTs) 1, syncope 11, asymptomatic 16) were enrolled. Cardiac events (CI: sudden cardiac death or VTs) during the follow-up period were evaluated, and risk factors for the cardiac events were assessed. Results During a mean follow-up period of 111±91 months (median 134 months), 4 patients experienced cardiac events (1.5%/yr), who all had received implantable cardioverter defibrillator implantation. There was no statistically significant clinical risk factor for cardiac events. However, the incidences of cardiac events tended to be higher in symptomatic patients (CI: 25.0, non-CI: 6.3%, p=0.17), those with wide QRS duration >90 msec in lead V2 (CI: 30.0, non-CI: 6.3%, p=0.11), and those with inducible VTs (CI: 21.1, non-CI: 0%, p=0.20), as determined by the Kaplan-Meier method. The annual incidences of cardiac events in patients with symptom, wide QRS duration >90msec in lead V2, or inducible VTs were 2.8, 3.5, and 2.0%/yr, respectively. The incidences of cardiac events were significantly higher in patients with all these 3 factors (9.9%/yr) than those without (p=0.01). Conclusions Our large-scaled multicentre study revealed long-term prognosis in patients with non-type 1 Brugada ECG. The combination of symptom, wide QRS duration in lead V2, and inducible VTs may be useful to evaluate risk for cardiac events. The patients with all these parameters showed high risk for cardiac events and need to be carefully followed. Funding Acknowledgement Type of funding source: None

Background Due to compactness and cheapness, smartphone ECG (sECG) could be very useful to equine practitioners. However, previous studies have evaluated the accuracy of sECG in hospitalised horses only. Different conditions in the field could influence the accuracy of the device. The aim of this study is to compare the accuracy of sECG in field and in hospital conditions. Methods This is a prospective study. Paired standard base-apex ECG (stECG) and sECG were recorded in hospitalised horses and in subjects examined in field conditions. ECGs were analysed for heart rate and rhythm, presence/type of arrhythmias, presence/duration of artefacts, electrocardiographic waves and interval parameters by a blinded clinician. Statistical analysis evaluated the agreement between stECG and sECG and the differences in the prevalence of artefact in field and hospital conditions. Results Nineteen (hospital) and 40 (field) paired ECGs were analysed. Agreement between stECG and sECG was found for heart rate and rhythm, evaluation of atrioventricular block and premature complexes, P wave and PQ interval duration, and QRS complex duration and polarity. No differences were found between artefacts recorded in hospital and in field conditions. Conclusion sECG is a feasible tool for evaluation of rhythm in horses and is as accurate in field as in ambulatory conditions.

Introduction The sudden cardiac death risk in Brugada Syndrome (BrS) is higher in patients with spontaneous type 1 pattern. Brugada diagnosis is also established in patients with induced type 1 morphology after provocative test with intravenous administration with a sodium blocker channel. Nevertheless, this group of patients is known to be at a lower risk of SCD, and their risk stratification is still a matter of discussion. Late potentials (LP) detected on signal-averaged ECG (SAECG) on the RVOT have been previously proposed as a predictor factor for BrS, even though data is lacking on its value. Purpose To evaluate the association between positive LP (LMS40> 38ms) on SAECG with modified Brugada leads and a positive flecainide test in patients with non-type 1 BrS. Methods Retrospective single-center study of non-type 1 BrS patients referred for the performance of a flecainide provocative test. Patients presenting with spontaneous type 1 morphology were excluded from the study. Study of LP on SAECG with modified leads for Brugada were evaluated before administration of flecainide [2mg/kg (maximum150mg), for 10minutes] with determination of filtered QRS duration (fQRS), root mean square voltage of the last 40ms of the QRS complex (RMS40) and duration of low amplitude signals Results 126 patients (47.3 ± 14.1 years, 61.9% males) underwent study with LP SAECG and flecainide test. Among these patients, 7.9% were symptomatic and 16.7% had familiar history of BrS. Flecainide test was positive in 46.8% of patients. In patients with a positive flecainide test, 64.4% presented LMS40 > 38ms whereas LMS40 > 38ms was present in only 46% of those with a negative flecainide test (p = 0.031). The presence of positive LMS40 was a positive predictor for a positive flecainide test, associated with a two-fold increase likelihood in the induction of a Brugada pattern (OR: 2,12; IC95% 1,025-4,392; P = 0,043). There was no association between fQRS or RMS40 and a positive flecainide test (p = NS). fQRS > 114ms and RMS40 Conclusion In patient with non-type 1 Brugada syndrome, LMS40 > 38ms in SAECG was a predictor for a positive flecainide test, suggesting that this finding could be helpful on the risk stratification of patients undergoing diagnostic study for Brugada syndrome. Abstract Figure. Effect of LMS 40 in flecainide test

Physiological data in healthy subjects show that QRS duration is shorter in females compared to males. QRS duration is also shorter in subjects of African origin compared to Caucasians. The same sex difference is present in both race strata, thus QRS duration progressively increases from African females to Caucasian females, to African men, and to Caucasian men. This chapter shows data of 523 healthy subjects. These data also show that the QRS durations are heart rate dependent in a nonuniform fashion. While heart rate increases lead to the increases in QRS duration in approximately 40% of the healthy population, in the remaining 60% of the population, heart rate increases led to QRS complex shortening. This might have importance for the implementation of the guidelines for cardiac resynchronization therapy initiation.

40 year old man admitted to hospital due to tachycardia episode. His normal ECG was consistent with RBBB with a QRS duration of 200msec. He had undergone a VSD operation when he was 6. He had a 3/6 systolic murmor . On TTE, there was a VSD patch and a residual tiny VSD with a L-R shunt. The maximum systolic gradient of VSD shunt was measured as 92mmHg .There was also moderate tricuspid regurgitation (TR) with a peak velocity of 5.1m/sec and estimated sPAP of 103mmHg. Considering the measured sPAP and the VSD shunt gradients, his systolic blood pressure (SBP)should approximately be equal to sum of those two ( 103+ 92 = 195mmHg). However his BP was 140/90mmHg.When we examined his heart for a possible explanation for this inconsistency, we noticed a systolic aliasing inside the RV with a maximum velocity of 3.1m/sec and systolic gradient of 38mmHg. However the chamber with lower pressure (P) was the one to which the VSD shunt was directed, and this chamber was in direct continuity with pulmonary artery. So to confirm the P in this chamber we also used pulmonary regurgitation flow and measured a peak diastolic velocity of 3.8m/sec, meaning a mean PAP of 60mmHg .Cardiac catheterization also confirmed a sPAP of 116mmHg and mPAP of 65mmHg. The systolic aortic P was 145mmHg and systolic LV P was 152mmHg. So the unexpectedly high gradient of VSD shunt was still a mystery for us. While searching the literature to explain this , we noticed that the patients’ heart was resembling the reptilian heart model. The reptilian heart has two atria and one ventricle with 3 segments seperated via muscular ridges. In our patients’ heart ,the small chamber with high P in the RV was the cavum venosum, the larger chamber of RV with VSD was the cavum pulmonale, and the left ventricle was the cavum arteriosum. (Fig) The reptilian hearts typically have noncompacted myocardium which was actually the case in our patient. The reptilian hearts also have unique conduction system with no AV node and His bundle, and slow depolarization of ventricle from left to right. When we performed EPS, we found that the patient had no AV node and His bundle. Bringing together all these findings, we conclude that the patient has a reptilian heart with all anatomical, electrical and physiological features. And the answer to the mystery of inconsistent P recordings was hidden in ECG. The RBBB with very long QRS duration causes a delay between contraction of ventricles resulting in a dynamic P gradient between ventricles. We demonstrated this dinamic bidirectional shunt on CW recording when we obtained a more optimal recording of the shunt flow.This case demonstrates us one more evidence of human evolution; arising from single cell and developing to fish, to reptiles and to mammals. The evolution takes place again and again during neonatal life. If there is an embryological arrest, as occured in our patient, we can easily see the clues of this amazing human evolution. Abstract P1500 Figure

Background Pediatric dilated cardiomyopathy (DCM) affects left ventricular (LV) function and carries a high risk of death or heart transplantation. However, the relation of LV regional function and inefficiency to clinical outcomes is underexplored. Purpose The aim of this study was to understand the relationship of regional LV mechanics, global LV function and clinical characteristics to the outcomes of death or heart transplant in children with DCM; through the integration of a vast amount of information enabled by unsupervised machine learning techniques. Methods DCM was defined by a LV end-diastolic dimension z-score > 2 and LV ejection fraction (EF) Results 50 children with DCM (age 0 to 18 years) were analyzed. Clustering on the two first dimensions of the low-dimensional space resulted in three clusters (Figure A), with significantly different proportions of the composite outcome of death or heart transplant (Cl1 = 79%, Cl2 = 50%, Cl3 = 20%; p = 0.01). The group with the highest proportion of death or transplant (cluster 1) comprised the oldest and most frequently medicated subjects, with impaired LVEF and GLS, and with the widest QRS duration (p Conclusion Our results serve as a proof-of-concept that machine-learning based approaches can be useful to explore and understand which regional and global echo parameters in combination with clinical parameters are associated with a higher risk of death or transplant in pediatric DCM. Abstract 546 Figure

Background The exact mechanism for Brugada Syndrome (BrS) is still not clear. There are two main physiologic hypotheses that have been suggested: the repolarization and the depolarization disorder models. Right ventricular (RV) activation delay was verified by echocardiography, conduction time in an explanted heart or in computer simulation. Verification of prolonged longitudinal activation time in human RV of only 5 patients of type-1 BrS and 5 controls was reported in 2008. Methods Bidirectional longitudinal activation times were assessed between RV outflow tract (RVot) and RV-apex (RVa) by stimulating and mapping RV endocardium in BrS patients. Conduction velocity was calculated considering ventricle size and distance between catheters. Results The studies were performed in controls (n = 18) and BrS patients (n = 6). There was no statistical difference in RP interval and QRS duration (PR 146 ± 21.7 vs 167 ± 45.2 ms, p = 0.325; QRS 102 ± 28.2 vs 122 ± 32.2 ms, p = 0.163). There was no difference of longitudinal activation time on stimulation at 500 ms (RVa to RVot: 63 ± 14.3 versus 80 ± 34.2 ms, p = 0.290; RVot to RVa: 50 ± 12.2 versus 76 ± 35.1 ms, p = 0.122). The BrS patients had longer longitudinal activation time on stimulation at 400 ms (RVa to RVot: 61 ± 15.2 versus 87 ± 28.7 ms, p = 0.009; RVot to RVa: 52 ± 11.1 versus 76 ± 35.3 ms, p = 0.029). The difference was not significant when isoproterenol was infused. Conclusions BrS patients display bidirectional longitudinal conduction delay when rapid stimulation. These findings support that BrS might be partly attributable to depolarization abnormality.

A 69-year-old man with history of non-insulin-treated type 2 diabetes mellitus, arterial hypertension and mixed dyslipidemia presented to the emergency department with chest pain lasting for four days. Immediate twelve-lead electrocardiogram unveiled an inferior ST-segment elevation myocardial infarction (STEMI), prompting emergent coronary angiography, which, in turn, revealed two-vessel disease, specifically proximal ramus intermedius 60-70% stenosis and proximal right coronary artery acute occlusion. Culprit lesion was successfully managed with balloon angioplasty and a single drug-eluting stent implantation. Still, clinical course was noticeable for deterioration, under the form of cardiogenic shock, which required invasive ventilation and intravenous vasopressor support with norepinephrine. Despite biventricular systolic function relative preservation, transthoracic echocardiography disclosed inferior akinesis, right ventricle dilation, mild circumferential pericardial effusion and, particularly, a 2.3cm posteroinferior ventricular septal defect (VSD), in the setting of a 4.4cm2 pseudoaneurism, resulting in left-to-right shunting, quantified through maximal/mean trans-VSD pressure gradients of 84/44mmHg. Further imaging with transesophageal echocardiography and cardiac computed tomography angiography allowing the conception of a 3D-printed model was performed. Surgical correction of the defect followed, achieving partial anatomic success, namely with residual shunting, as of a left ventricular systolic pressure of 80mmHg and a right ventricular systolic pressure of 25mmHg. Patient survived, recovered and got discharged three weeks later. At one-year follow-up, he was hospitalized for acute decompensated heart failure (hemodynamic profile C) twice, with medication non-adherence reported as the main precipitating factor. In addition to a significant remaining left-to-right shunt (maximal velocity 3m/s), adverse cardiac remodeling was recognized, featuring left ventricular ejection fraction of 30-35%, severe functional mitral regurgitation, severe postcapillary pulmonary hypertension and de novo left bundle branch block (QRS duration of 197ms). Having been deemed clinically unsuitable for another surgical correction, patient underwent percutaneous VSD closure with both AmplatzerTM septal and muscular VSD occluders, with a suboptimal result. He is now on New York Heart Association class III heart failure and on the waiting list for both MitraClip and cardiac resynchronization therapy implantation. Reflecting numerous breakthroughs in the management of acute myocardial infarction, incidence of mechanical complications is on the decline. Nevertheless, when they occur, morbidity and mortality remain high. Acquired ventricular septal defects are no exception, demanding the best care from a tertiary hospital heart team. Abstract P714 Figure.

Background Pacing from RV mid septum and outflow tract septum has been proposed as a more physiological site of pacing and narrower paced QRS complex duration. The paced QRS morphology and duration in different RV pacing sites is under continued discussion. Hence, this study was designed to address the correlation of pacing sites in right ventricle with paced QRS complex duration. Methods Two hundred fifty-two consecutive patients who underwent pacemaker implantation were enrolled. Baseline clinical characteristics were recorded for each patient. All patient underwent fluoroscopy, electrocardiogram and echocardiography post pacemaker implantation. Paced QRS duration was calculated from the leads with maximum QRS duration. Results Mean paced QRS (pQRS) duration was significantly higher in apical septum group with a mean of 148.9 ± 14.8 m s compared to mid septum (139.6 ± 19.9 m s; p-value 0.003) and RVOT septum (139.6 ± 14.8 m s; p-value 0.002) groups, respectively. There was no significant difference between mid-septal and RVOT septal pQRS duration. On multivariate analysis, female gender, baseline QRS duration and RVOT septal pacing were the only predictors for narrow pQRS duration ( Conclusion RV mid-septal and RVOT septal pacing were associated with significantly lower pQRS duration as compared with apical pacing. Based on multivariate analysis RVOT septal pacing appears to be preferred and more physiological pacing site.

Aims To evaluate the impact of the interaction of QRS duration and morphology on left ventricular (LV) reverse remodelling and LV functional improvement in heart failure (HF) patients treated with cardiac resynchronization therapy (CRT). Methods and results From an ongoing registry of HF patients treated with CRT according to contemporary guidelines, demographic, clinical, electrocardiographic (ECG) and echocardiographic characteristics were analysed. Patients were divided according to QRS duration and morphology

Background In patients with dilated cardiomyopathy and left bundle branch block (LBBB), different regions of the left ventricle (LV) have been shown to perform different amounts of work. In this study, we investigate the acute impact of cardiac resynchronization therapy (CRT) on regional LV work distribution and its relation to long-term reverse-remodelling. Methods We recruited 130 heart failure patients, referred for CRT. Regional myocardial work was calculated from non-invasive echocardiographic segmental stress-strain-loop-area before and immediately after CRT. The magnitude of volumetric reverse-remodelling was determined from the change in LV end-systolic volume (ESV), 11±2 months after implantation. Characteristics of patients with the lowest and highest quartile of LV ESV reverse remodelling (ΔLV ESV −48%) were compared. Results Before CRT, myocardial work showed significant differences among the walls of the LV (Figure 1A). CRT caused an acute re-distribution of myocardial work, on average with most increase in the septum and most decrease laterally (all walls p Figure 1 Conclusions The acute re-distribution of regional myocardial work between the septal and lateral wall of the left ventricle is the main determinant of long term reverse-remodelling after CRT-implantation. Our data suggest that modification of regional loading is the mode of action of CRT treatment.

Introduction Cardiac resynchronization therapy (CRT) has evolved as an important treatment in patients with symptomatic heart failure, reduced left ventricular (LV) ejection fraction and wide QRS. However, as one third of patients do not benefit from the therapy, there is need for better selection criteria. Previous studies have shown an association between recovery of septal function and response to CRT. Purpose To test the hypothesis that septal dysfunction in the absence of scar predicts response to CRT. Methods In 121 patients undergoing CRT implantation according to current European Society of Cardiology guidelines, we performed speckle-tracking echocardiography and estimated LV pressure non-invasively based on a method recently innovated in our lab. Pressure-strain analysis was used to calculate myocardial work. Septal dysfunction with asymmetric LV workload was calculated as the difference between LV lateral wall and septal work. Late gadolinium enhancement cardiac magnetic resonance imaging (LGE-CMR) was performed to assess septal scar. CRT response was defined as ≥15% reduction of LV end systolic volume by echocardiography at 6 months follow-up. Results Eighty-eight patients (73%) responded to CRT at 6 months follow-up. Multivariate logistic regression analysis including lateral-to-septal work difference, septal scar, QRS duration and QRS morphology found that only lateral-to-septal work difference and septal scar were significant predictors of CRT response (both p Conclusions A multimodality approach with strain echocardiography and LGE-CMR was able to detect CRT responders with high accuracy, also in the subset of patients with intermediate QRS duration. A dysfunctional but viable septum appears to be an ideal target for CRT.

A eletrocardiografia computadorizada é mais precisa e prática quando comparada à convencional e por essa razão vem ganhando espaço na rotina clínica. No entanto os valores de referência devem diferir para os dois métodos. O objetivo desse trabalho foi analisar e comparar o exame eletrocardiográfico computadorizado com o exame obtido pelo método convencional em equinos. O estudo demonstrou diferenças na amplitude da onda P (P

Wide complex tachycardia is defined as a cardiac rhythm with a rate greater than 100 beats/min (bpm) and a QRS complex duration greater than 0.10 to 0.12seconds (s) in the adult patient; wide complex tachycardia (WCT) in children is defined according to age-related metrics. The differential diagnosis of the WCT includes ventricular tachycardia and supraventricular tachycardia with aberrant intraventricular conduction, including both relatively benign and life-threatening dysrhythmias. This review focuses on the differential diagnosis of WCT with a discussion of strategies useful in making the appropriate diagnosis, when possible.

Background An accurate and universal method for diagnosis of biventricular (BiV) capture using a standard 12-lead electrocardiogram (ECG) would be useful for assessment of cardiac resynchronization therapy (CRT) patients. Our objective was to develop and validate such an ECG method for BiV capture diagnosis that would be independent of pacing lead positions—a major confounder that significantly influences the morphologies of paced QRS complexes. Methods On the basis of an evaluation of 789 ECGs of 443 patients with heart failure and various right ventricular (RV) and left ventricular (LV) lead positions, the following algorithm was constructed and validated. BiV capture was diagnosed if the QRS in lead I was predominantly negative and either V1 QRS was predominantly positive or V6 QRS was of negative onset and predominantly negative (step 1), or if QRS complex duration was

Aim. To assess the prevalence and clinical value of various types of left ventricular (LV) myocardial dyssynchrony in patients with systolic chronic heart failure (CHF). Material and methods. In total, 71 patients with Functional Class (FC) II–IV CHF (LV ejection fraction (EF)

Cardiac resynchronization therapy (CRT) is one of the important advances in the treatment of ventricular systolic heart failure (HF) in recent years. It can reduce the mortality and improve the quality of life of patients. Patients who had response to CRT were often accompanied with a reversal of

ECG Challenge: A 65-year-old man with a history of hypertension being treated with a β-blocker presents to his physician for a routine physical examination. His pulse is noted to be slower than usual; hence, an ECG is obtained. There is a regular rhythm at a rate of 48 bpm. The QRS complex duration is normal (0.08 second), and there is a normal morphology, as well as an axis between 0° and 90° (positive QRS complex in leads I and aVF). The QT/QTc intervals are normal (440/390 milliseconds). P waves …