QRS Axis Research Articles

Combined Effects of Age and Comorbidities on Electrocardiographic Parameters in a Large Non-Selected Population.

Background: Previous studies have evaluated average electrocardiographic (ECG) values in healthy subjects or specific subpopulations. However, none have evaluated ECG average values in not selected populations, so we examined ECG changes with respect to age and sex in a large primary population. Methods: From digitized ECG stored from 2008 to 2021 in the Modena province, 130,471 patients were enrolled. Heart rate, P, QRS and T wave axis, P, QRS and T wave duration, PR interval, QTc, and frontal QRS-T angle were evaluated. Results: All ECG parameters showed a dependence on age, but only some of them with a straight-line correlation: QRS axis (p < 0.001, R2 = 0.991, r = 0.996), PR interval (p < 0.001, R2 = 0.978, r = 0.989), QTc (p < 0.001, R2 = 0.935, r = 0.967), and, in over 51.5 years old, QRS-T angle (p < 0.001, R2 = 0.979, r = 0.956). Differences between females and males and in different clinical settings were observed. Conclusions: ECG changes with ageing are explainable by intrinsic modifications of the heart and thorax and with the appearance of cardiovascular diseases and comorbidities. Age-related reference values were computed and applicable in clinical practice. Significant deviations from mean values and from Z-scores should be investigated.

Left bundle branch pacing with normal paced QRS axis produce more physiological left ventricular lateral wall depolarization than its pacing resulting in heart axis deviation

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministry of Health of the Czech Republic Background Left bundle branch pacing is defined as the pacing of the trunk or its proximal fascicles, usually with septal myocardial pacing at low output. It preserves physiological left ventricular activation; however, it is unknown if there is a difference between captures with normal or deviated axes and pacing in proximal vs. distal locations. Objective To study ventricular activation during nonselective LBB pacing (nsLBBp) resulting in different paced QRS axes and proximal vs. distal pacing positions using ultra-high-frequency ECG (UHF-ECG). Methods This was a retrospective analysis of patients with bradycardia in which nsLBBp was archived during an implant procedure, and UHF-ECG analysis of ventricular activation was performed. nsLBBp captures were classified according to paced QRS axis as with superior (-30°;-90°), normal (-29°;60°), or inferior (61°;120°) axis deviation and proximal (LBbpo to ventricular EGM signal distance ≥ 26 ms) vs. distal (LBBpo to ventricular EGM signal distance &amp;lt; 26 ms). UHF-ECG electrical dyssynchrony parameters – e-DYS (difference between the first and last ventricular activation), local depolarization durations in precordial leads (V1-V8d), and their mean value (Vdmean) were calculated. Results We have studied 79 nsLBBp, of which 35 had superior, 28 normal, and 16 had inferior paced QRS axes. There was no difference in LBBpo to V distance, QRSduration, V5 RWPT, or e-DYS (-27 ms vs. – 22 ms vs. -25 ms for superior vs. normal vs. inferior axes; p = NS) between them. However, nsLBBp with normal paced QRS axis had shorter Vdmean (43 ±6 ms) compared to captures with superior (48 ± 7 ms) and inferior axis deviation (48 ± 6 ms); p &amp;lt; 0.05. It was mainly due to shorter V7-8d during nsLBBp with normal axis (mean difference of - 10 ms; p &amp;lt; 0.05) than in captures with superior or inferior axes. No difference in any of the studied parameters was noted when comparing proximal vs. distal pacing locations. Conclusion Nonselective capture of the left bundle branch resulting in normal paced QRS axis produces more physiological LV activation compared to captures with superior or inferior axes deviations.

A new method for right ventricular lead implantation into the intraventricular septum

Abstract Funding Acknowledgements Type of funding sources: None. Background Right ventricular (RV) lead placement into the interventricular septum is only accurate in 16–48% of cases under conventional fluoroscopic guidance. A previous report showed the importance of individualized left anterior oblique (LAO) projection to improve the success rate of RV lead placement into the interventricular septum. However, this procedure is complicated. We sought to investigate the preprocedural predictors of individualized LAO projection. Methods We assessed the relationship between preoperative electrocardiographic parameters and the angle of the interventricular septum obtained using thoracic computed tomography (CT). Results In the retrospective derivation cohort group (n=39), the mean angle of individualized LAO assessed by thoracic CT was 53.1±8.9°, and the preoperative electrocardiogram QRS axis was strongly correlated with the interventricular septum axis detected by thoracic CT (R2 = 0.490). In contrast, the preoperative electrocardiographic transitional zone was not associated with the interventricular septum axis (R2 = 0.041, P = 0.78). Using individual LAO projection derived from the preoperative electrocardiogram QRS axis, it was confirmed that the RV lead was placed in the interventricular septum during the pacemaker procedure in the prospective internal validation group (n=30). The success rate for placing the RV lead into the interventricular septum was significantly improved in the internal validation cohort group (93% vs. 64%, P &amp;lt; 0.05). In addition, the N-terminal pro-brain natriuretic peptide level decreased significantly after surgery in the interventricular septal indwelling group. Conclusions Individualized LAO angle derived from the preoperative electrocardiogram QRS axis is a new useful and simple method for RV lead implantation into the interventricular septum.

Left bundle branch area pacing in patients with heart failure and right bundle branch block: Results from International LBBAP Collaborative-Study Group.

BackgroundCardiac resynchronization therapy (CRT) using biventricular pacing has limited efficacy in patients with heart failure (HF) and right bundle branch block (RBBB). Left bundle branch area pacing (LBBAP) is a novel physiologic pacing option.ObjectiveThe aim of the study was to assess the feasibility and outcomes of LBBAP in HF patients with RBBB and reduced left ventricular systolic function, and indication for CRT or ventricular pacing.MethodsLBBAP was attempted in patients with left ventricular ejection fraction (LVEF) <50%, RBBB, HF, and indications for CRT or ventricular pacing. Procedural, pacing, and electrocardiographic parameters; clinical response (no HF hospitalization and improvement in NYHA class); and echocardiographic response (≥5% increase in ejection fraction) to LBBAP were assessed.ResultsLBBAP was attempted in 121 patients and successful in 107 (88%). Patient characteristics included age 74 ± 12 years, female 25%, ischemic cardiomyopathy 49%, and ejection fraction 35% ± 9%. QRS axis at baseline was normal in 24%, left axis 63%, right axis 13%. LBBAP threshold and R-wave amplitudes were 0.8 ± 0.3 V @ 0.5 ms and 10 ± 9 mV at implant and remained stable during mean follow-up of 13 ± 8 months. LBBAP resulted in narrowing of QRS duration (156 ± 20 ms to 150 ± 24 ms (P = .01) with R-wave peak times in V6 of 85 ± 16 ms. LVEF improved from 35% ± 9% to 43% ± 12% (P < .01). Clinical and echocardiographic response was observed in 60% and 61% of patients, respectively. Female sex and reduction in QRS duration with LBBAP were predictive of echocardiographic response and super-response.ConclusionLBBAP is a feasible alternative to deliver CRT or physiologic ventricular pacing in patients with RBBB, HF, and LV dysfunction.

Czy wraz z nastolatkiem rośnie jego elektrokardiogram? — badanie na podstawie 3-letniej obserwacji

Background: Human heart’s growth and development are followed by gradual changes on the electrocardiogram. The study was conducted to analyse changes in the resting electrocardiogram of 10-year-olds in relation to their somatic growth. Methods: 120 students (62 male) aged 10.8 (+/-0.49) years were examined. The study consisted of a resting electrocardiogram and anthropometric measurements repeated in 3-year interval. Statistical analysis of changes in electrocardiographic parameters (PR, QRS, QTc, QRS axis, wave amplitudes) and corresponding changes in height, weight and BMI was conducted. Results: Through time, a substantial elongation of PR (p < 0.001), ORS (p < 0.001) and QT (p < 0.001) lengths was observed while the QRS axis and corrected QT time remained stable (p=0.320 and 0.857 respectively). In girls PR elongation correlated with an increase in BMI (r=0.33). Right axis deviation corresponded with height gain in boys (r=0.45). R and S amplitudes in limb leads did not change significantly except for lead I. There was a considerable decline in R and S wave voltages in precordial leads in adolescent girls that corresponded with weight and BMI increase. In boys the increase in BMI was related to greater R waves in left precordial leads. Conclusion: Adolescent growth has an influence on some electrocardiographic variables. There are significant differences between boys’ and girls’ electrocardiograms regarding QRS amplitudes.

Electrocardiographic variables associated with underlying Brugada syndrome or drug-induced Type 1 Brugada pattern in patients with slow/fast atrioventricular nodal reentrant tachycardia.

BackgroundThe coexistence of clinical atrioventricular nodal reentrant tachycardia (AVNRT) and drug‐induced type 1 Brugada pattern (DI‐Type 1 BrP) has been previously reported. The present study was designed to determine the 12‐lead ECG characteristics at baseline and during AVNRT and to identify a subset of 12‐lead ECG variables of benefit associated with underlying Brugada syndrome (BrS)/DI‐Type 1 BrP among patients with slow/fast AVNRT.MethodsA total of 40 (11 numerical/29 categorical) 12‐lead ECG parameters were analyzed and compared between patients with (n = 69) and without (n = 104) BrS/DI‐Type1‐BrP matched for age, female gender, body mass index, left ventricular ejection fraction and comorbid conditions. Five distinct types of ECG pattern (Type A/B/C/D/E) in V1–V2 leads during AVNRT were defined.ResultsA total of nine electrocardiographic variables, four at baseline, and five during AVNRT were identified. At baseline, patients with BrS/DI‐Type 1 BrP had higher prevalence of interatrial block, leftward shift of frontal plane QRS axis, the absence of normal QRS pattern (the presence of rSr’ pattern or type 2/3 Brugada pattern) in V1–V2 and QRS fragmentation in inferior leads compared to patients without BrS/DI‐Type 1 BrP. During AVNRT, patients with BrS/DI‐Type 1 BrP had higher prevalence of Type A ECG pattern (“coved‐type” ST‐segment elevation) in V1–V2, Type C ECG pattern (pseudo‐r’ deflection in V1 and “RBBB‐like” pattern in V2), pseudo‐r’ deflection in V1, QRS fragmentation in inferior leads and “isolated” QRS fragmentation/notching/slurring in aVL compared to patients without BrS/DI‐Type 1 BrP.ConclusionsWe identify several electrocardiographic variables that point to an underlying type 1 BrP among patients with slow/fast AVNRT.

The prognostic significance of the electrical QRS axis on long-term mortality in acute coronary syndrome patients - The TACOS study

IntroductionThere are several potential causes of QRS-axis deviation in the ECG, but there is limited data on the prognostic significance of QRS-axis deviation in ACS patients. Subjects and methodsWe evaluated the long-term prognostic significance of acute phase frontal plane QRS-axis deviation and its shift during hospital stay in ACS patients. A total of 1026 patients who met the inclusion criteria were divided into three categories: normal (n = 823), left (n = 166) and right/extreme axis (n = 37). ResultsThe median survival time was 9.0 years (95% CI 7.9—10.0) in the normal, 3.6 years (95% CI 2.4—4.7) in the left and 1.3 years (95% CI 0.2—2.4) in the right/extreme axis category. Both short and long-term all-cause mortality was lowest in the normal axis category and highest in the right/extreme axis category. Compared to normal axis, both admission phase QRS-axis deviation groups were independently associated with a higher risk of all-cause mortality. When including left ventricular hypertrophy in the ECG, only the right/extreme axis retained its statistical significance (aHR 1.76; 95% CI 1.16—2.66, p = 0.007). Axis shift to another axis category had no effect on mortality. ConclusionIn ACS patients, acute phase QRS-axis deviation was associated with higher risk of all-cause mortality. Among the axis deviation groups, right/extreme QRS-axis deviation was the strongest predictor of mortality in the multivariable analysis. Further studies are required to investigate to what extent this association is caused by pre-existing or by ACS-induced axis deviations. QRS-axis shift during hospital stay had no effect on all-cause mortality.

PO-618-08 IMPACT OF LEFT BUNDLE AREA PACING ON QRS DURATION IN PATIENTS WITH PREEXISTING RIGHT BUNDLE BRANCH BLOCK: INSIGHT INTO MECHANISM OF QRS SHORTENING

Conduction system pacing is increasingly used for cardiac resynchronization. Given the limitations of His bundle pacing, left bundle area pacing (LBAP) is becoming more common. LBAP is proven to shorten QRS duration in patients (pts) with LBBB or RV pacing, but the impact of LBAP in pts with preexisting RBBB is not well reported. To better understand the effect of LBAP on QRS duration (QRSd) in pts with preexisting RBBB. Retrospective review of ECGs from pts (selected from a conduction system pacing database) with preexisting RBBB who underwent LBAP between Jan 2020 and Dec 2021. Baseline characteristics, intra-operative data, and ECGs were analyzed using STATA and Wilcoxon signed-rank tests were performed. A total of 14 pts with preexisting RBBB had attempted LBAP, of whom 12 (86%) were successful; data reported on these 12 pts (Table). Mean age=76 yrs. 10 of 14 (71%) were male. Indications for LBAP were AV block (93%) and CRT (7%). Mean R wave = 10.8 mV, mean impedance = 623 Ohms, and mean threshold was 0.54 V at 0.77 ms. Four of 12 (25%) pts had baseline RBBB and 8 (75%) had baseline bifascicular block (RBBB + LAFB). LBAP resulted in significant shortening of the QRSd compared to baseline (129.9±13.0 vs 150.1±15.7 ms, mean difference -20.2±10.3 ms, p=0.002, Figure). Frontal QRS axis showed a non-significant rightward shift (mean difference of 14.6⁰). LV activation time (LVAT) was not significantly different between baseline and paced QRS complexes (43.7±11.0 ms vs 53.8±13.8 ms, p=0.06). The duration of the terminal positive deflection (r') in lead V1 decreased from 68.3±11.1 ms to 45.8±21.1 ms, P=0.002. LBAP shortened QRSd in all pts with preexisting RBBB (with or without LAFB) and this effect was statistically significant. The lack of change in LVAT and narrowing of the r' in lead V1 both suggest that right sided recruitment, and not improved propagation in the diseased LBB, explain the QRS shortening. Right sided recruitment may result from non-selective capture of the RBB or interventricular muscle via a large, virtual electrode. Larger studies are need to determine the clinical impacts of LBAP on patients with RBBB.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

A community-based study on electrocardiographic abnormalities of adult population from South India - Findings from a cross sectional survey

BackgroundThere are no data on electrocardiographic (ECG) findings from general population of Indian subcontinent. We analyzed ECG abnormalities of in adults as part of a community survey of prevalence of coronary artery disease and risk factors from South India. Methods and resultsIn this cross-sectional study of men and women between the ages 20 to 79 years, ECGs recorded digitally were analyzed using the Minnesota code. Electrocardiograms were analyzed for abnormalities in 4630 participants (women 59.6%). The overall prevalence of ECG abnormalities (39.9%) was higher in men (47.24% vs. 34.9% p <0.0001). QRS axis deviation, first degree AV block, fascicular blocks, incomplete right bundle branch block, sinus bradycardia and ST elevation in the anterior chest leads were markedly higher in men. Sinus tachycardia and low voltage QRS occurred more often in women. The overall prevalence of atrial fibrillation was 0.32% which was markedly lower than the western data. Brugada and early repolarisation patterns occurred in 1.06% and 1.56% respectively, equal in both age groups, but markedly higher in men. Brugada pattern occurred more often than in the west, but much less than the Far East population. Early repolarisation pattern was similar to rest of Asian population, but significantly less than the Caucasian population ConclusionIn this community-based study, prevalence of major electrocardiographic abnormalities was high. Overall, men had significantly higher ECG abnormalities.

Longitudinal change, gender difference and hemodynamic implications of aortoseptal angle in adults without structural heart diseases

This is an era of function evaluation for heart, but still there are some structural changes remains to be recognized. Aorto-septal angle (AoSA) is a morphologic description of the heart and adjacent major vessel. Previous studies have shown its potential hemodynamic significance, however, these are conducted in patients with structural heart diseases. The present study investigated its longitudinal change in 140 adults without structural heart disease from 20 to 90 years old and its independent clinical correlates. The findings included: 1. Advanced age, male and presence of sigmoid IVS were independent predictors of a steep AoSA. 2. Females tend to have a wider AoSA compared to age-matched males before 70 years old but they undergo more dramatic decrease with aging so that no gender difference was found beyond 70 years old. 3. Electrocardiographic QRS axis left deviation tends to be correlated with a steeper AoSA. 4. In adults without structural heart disease, no clinically significant association between AoSA and aortic velocity was found. Further prospective study from multi-centers is needed to verify these findings.

Electrocardiographic QRS axis shift, rotation and COVİD-19.

In patients with coronavirus disease-2019 (COVID-19), severe dyspnea is the most dramatic complication. Severe respiratory difficulties may include electrocardiographic frontal QRS axis rightward shift (Rws) and clockwise rotation (Cwr). This study investigated the predictability of advanced lung tomography findings with QRS axis shift and rotation. This was a retrospective analysis of 160 patients. Patients were divided into the following two groups: normal (n = 80) and low (n = 80) oxygen saturation. These groups were further divided into four groups according to the rightward and leftward axis shift (Lws) on the electrocardiographic follow-up findings. These groups were compared in terms of electrocardiographic rotation (Cwr, counterclockwise rotation, or normal transition), tomographic stage (CO-RADS5(advanced)/CO-RADS1-4), electrocardiographic intervals, and laboratory findings. In patients with low oxygen saturation, the amount of QRS axis shift, Cwr, and tomographic stage were significantly higher in the Rws group than in the Lws group. There were no differences in the above parameters between the Rws and Lws groups in patients with normal oxygen saturation. Logistic regression analysis revealed that the presence of Cwr and Rws independently increased the risk of CO-RADS5 by 18.9 and 4.6 fold, respectively, in patients with low oxygen saturation. In COVID-19 patients who have dyspnea with low oxygen saturation, electrocardiographically clockwise rotation with a rightward axis shift demonstrated good sensitivity (80% [0.657-0.943]) and specificity (80% [0.552->1]) for predicting advanced lung tomographic findings. NCT04698083.

A Comparative Study of ECG and Blood Pressure among Smokers and Non-Smokers

Background: Smoking is one of the most significant risk factors for a wide range of illnesses, including lung and heart disease, cancer, and many others. There are currently 1.2 billion smokers around the globe, and that figure is expected to climb by 1.6 billion by the year 2020. Tobacco use kills about 3.5 to 4 million people worldwide every year, and this number is expected to rise to 10 million by 2020. Mostly, the acute consequences of smoking are well-documented. These contain an increase in heart rate and blood pressure, as well as a decrease in cardiac output and vasoconstriction. Smoking is the subject of the current investigation. Smokers vs non-smokers on ECG and blood pressure. Objectives: To examine the differences in blood pressure between people who smoke and those who don't and to examine the differences in ECG waveforms between smokers and nonsmokers Methods: May 2020 through April 2021 was when the research was carried out at PUMHS, There were fifty smokers and fifty non-smokers aged 20 to 35 years old in each group. After a thorough description of the study's goals and objectives, only those individuals who agreed to take part were included. Participants who met certain criteria were discarded. Blood pressure (sitting position) and an electrocardiogram (supine posture) were got while the individuals were in a resting condition. Results: The research had 100 participants, 50 of them were smokers and the other 50 were non-smokers. Nonsmokers and smokers had similar age distributions, and the disparity was not statistically significant (p-value- 0.97). In Lead III, 54% had an inverted wave compared to 40% normal and this difference found to be statistically significant, i.e. highest percentage of flat and inverted waves found in smokers. The difference in presence of abnormal waves among smokers and non-smokers in Lead V1 to V4 was found to be statistically significant. When a comparison of vitals and ECG between smokers based on pack-years (1- 3 pack-year, 4-6pack year, and 7-9pack year) was done there was no statistical significance attributed to various other parameters like pulse, heart rate, respiratory rate, systolic BP, diastolic BP, P wave amplitude, P wave duration, PR interval, QRS duration, QT interval, and QRS axis, except QTc. Conclusion: Researchers found that in smokers, there were a variety of ECG alterations and an increase in blood pressure despite the lack of any heart disease. Keywords: Smokers; Non-smokers; Blood Pressure; ECG.

Modern mapping and ablation of idiopathic outflow tract ventricular arrhythmias.

Outflow tract (OT) premature ventricular complexes (PVCs) are being recognized as a common and often troubling, clinical electrocardiographic finding. The OT areas consist of the Right Ventricular Outflow Tract (RVOT), the Left Ventricular Outflow Tract (LVOT), the Aortomitral Continuity (AMC), the aortic cusps and the Left Ventricular (LV) summit. By definition, all OT PVCs will exhibit an inferior QRS axis, defined as positive net forces in leads II, III and aVF. Activation mapping using the contemporary 3D mapping systems followed by pace mapping is the cornerstone strategy of every ablation procedure in these patients. In this mini review we discuss in brief all the modern mapping and ablation modalities for successful elimination of OT PVCs, along with the potential advantages and disadvantages of each ablation technique.

Evaluation of the 2021 European Society of Cardiology guidelines in pre-existing right bundle branch block patients undergoing transcatheter aortic valve implantation with a balloon-expandable valve.

AimsThe 2021 European Society of Cardiology guidelines recommend early pacemaker implantation in pre-existing right bundle branch block (RBBB) patients who develop PR prolongation or QRS axis change after transcatheter aortic valve implantation (TAVI). We aimed to evaluate this recommendation in TAVI recipients with a balloon-expandable valve (BEV).Methods and resultsWe retrospectively reviewed 188 pre-existing RBBB patients without pre-existing permanent pacemaker (PPM) who underwent TAVI with a BEV at our institution in 2015–19. Patients who developed high-degree atrioventricular block (HAVB) during TAVI or within 24 h post-TAVI were excluded. Eligible patients were divided according to the guideline-directed criteria (ΔPR interval ≥20 ms and/or QRS axis change). Patients who met the criteria (n = 102, 54.3%), compared with those who did not (n = 86), had a higher prevalence of baseline right axis deviation and were more likely to have received a larger valve with greater oversizing. The 30-day delayed HAVB rate did not differ significantly between the groups (3.9% vs. 4.7%, P = 1.00; odds ratio = 0.84, 95% confidence interval = 0.20–3.45). There was also no significant difference in terms of death (5.0% vs. 8.4% at 1 year; overall log-rank P = 0.94) or a composite of death or PPM implantation (14.8% vs. 16.6% at 1 year; overall log-rank P = 0.94) during follow-up post-TAVI. The majority of PR prolongations (79.4%) and QRS axis changes (52.0%) regressed within the following 24 h.ConclusionThe present data did not demonstrate an association of significant changes in PR interval or QRS axis with heightened delayed HAVB risk in BEV recipients with pre-existing RBBB. Prospective studies are warranted to confirm these findings.

Resting electrocardiogram and blood pressure in young athletes and nonathletes: A 4-year follow-up.

A follow-up data on electrocardiogram (ECG) and blood pressure (BP) changes in adolescent athletes are scarce. We compared ECG and BP between adolescent athletes and nonathletes in a 4-year follow-up. A total of 154 youth sports clubs (SC) in Finland and 100 secondary schools for comparison data participated in this observational follow-up study. Those who maintained or adopted SC participation are referred to as 'Always athletes' (n = 137), those who never participated in SC as 'Never athletes' (n = 108) and those who dropped out ofSC during the follow-up as 'Changers' (n = 116). The mean age of the participants was 15.5 (0.6) years in all study groups at baseline. Resting ECG including heart rate, PR interval, QRS duration, QRS axis, QRS amplitude, T axisand QT interval and BP were measured from all participants at baseline and after follow-up. 'Always athletes' had lower resting heart rate, more negative T-wave axis and higher QRS amplitude than 'Never athletes' at baseline and at 4 years (p < 0.05). 'Changers' had lower resting heart rate, more negative T-wave axis and higher QRS amplitude, systolic BP and pulse pressure than 'Never athletes' at baseline (p < 0.05). None of the observed differences at baseline, were visible at 4 years (p > 0.05) except the difference in T-wave axis (p = 0.028). The significant group × time interaction between 'Changers' and 'Never athletes' was found for QRS amplitude (p = 0.017). Adolescent athletes have several training-induced cardiovascular adaptations, which return towards the levels of nonathletes after cessation of regular training.

Pediatric T-wave memory after accessory pathway ablation in Wolff-Parkinson-White syndrome.

Altered ventricular depolarization due to manifest accessory pathway conduction (ie, Wolff-Parkinson-White syndrome) leads to repolarization abnormalities that persist after pathway ablation. The term T-wave memory (TWM) has been applied to these changes, as the postablation T-wave vector "remembers" the pre-excited QRS vector. In adults, these abnormalities can be misinterpreted as ischemia leading to unnecessary interventions. To date, no comprehensive studies have evaluated this phenomenon in the pediatric population. The purpose of this study was to define TWM in the pediatric population, identify preablation risk factors, and delineate the timeline of recovery. Pre- and postablation electrocardiograms (ECGs) in patients ≤25 years were analyzed over a 5-year period. Frontal plane QTc interval, T-wave axis, QRST angle, and T-wave inversions were used to identify patients with TWM. Univariate analysis was performed to determine the association of preablation ECG features with the outcome of TWM. TWM was present in 42% of pediatric patients, with resolution occurring within 3 months of ablation. Preablation QRS axis <0° was a strong predictor of TWM (odds ratio [OR] 15.2; 95% confidence interval [CI] 5.7-40), followed by posteroseptal pathway location (right posteroseptal-OR 8.9; 95% CI 4.2-18.8; left posteroseptal-OR 6.1; 95% CI 1.7-22.3). The degree of pre-excitation had a modest association with the development of TWM. No adverse events were observed. TWM is less common in children compared to adults, and normalization occurred within 3 months postablation. The most predictive features for the development of TWM include a leftward pre-excited QRS axis and posteroseptal pathway location.

RELATIONSHIP OF ELECTROCARDIOGRAM VARIABLES WITH BLOOD PRESSURE IN UNDERGRADUATE MEDICAL STUDENTS.

INTRODUCTION: Across the world the prevalence of hypertension and other cardiovascular diseases are increasing at an alarming rate. These diseases also affect the young age and medical students are no exception. In this study, ECG variables like R-R interval, QRS Axis of the medical students along with their Blood pressure were recorded and the relationship between ECG variables and Blood pressure was studied. MATERIALS AND METHODS: The study was done in Dept. of Physiology, Jorhat Medical College .Sample size was calculated as 160 using EpiTools Software. Recording of Electrocardiogram and Blood pressure of 160 students were done and saved for further analysis. P values were calculated by Anova test in case of more than two variables,. Scatter diagrams were used to see the relationship between study variables. The P value &lt;0.05 was considered as signicant. RESULTS: Comparison of ECG Variables between hypotensive, normotensive and hypertensive students showed that R-R Interval decreased signicantly from 21.37±4.24 in hypotensives to 19.74±3.39 in normotensives and 18.27±4.07 in hypertensive students. QRS Axis decreased from 75.35±10.99 degrees in hypotensives to 54.80±34.94 degrees in normotensives and 50.43±25.59 degrees in hypertensive students. CONCLUSION: Changing of life style that includes reduced consumption of fat rich diets, fast foods, red meat and salt, performing regular physical exercises, and regular health check up in the form of Blood pressure and Electrocardiogram recording could be benecial for the students to identify and take preventive measures against any cardiovascular ailments.

Predictions of arrhythmic, heart failure and mortality outcomes in pericarditis using automatic electrocardiogram analysis: a retrospective cohort study

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Pericarditis is a relatively rare disease with a global burden. Despite its strong association with adverse cardiovascular outcomes, identification of patients at risk of future heart failure or arrhythmic events is difficult. In the following study, automated electrocardiogram (ECG) variables were used to predict new onset ventricular tachycardia/fibrillation (VT/VF), atrial fibrillation (AF) and heart failure with reduced ejection fraction (HF) in an Asian cohort of pericarditis patients. Purpose Assessing the use of automated ECG parameters to predict prognosis in pericarditis patients. Methods Consecutive patients admitted to a single tertiary center in China, for a diagnosis of pericarditis between 1st January 2005 and 31st December 2019, were included. Patients with existing AF or HF were excluded. The follow-up period was until the 31st December 2020, or death. Cox regression was applied to identify significant predictors of the incident VT/VF, AF or HFrEF. Results A total of 874 patients were included. The cohort was 57% male and had a median age of 59 (IQR: 50-70) years old. During follow-up, 57 patients (6.5%), 156 (17.8%) and 168 (19.2%) suffered from VT/VF, AF and HF, respectively. Cox regression identified baseline VT/VF, terminal angle of the QRS vector in the transverse plane, mean QRS duration and mean QTc intervals as significant predictors of incident VT/VF events, with only the foremost maintaining significance in multivariate analysis. In contrast, baseline age, prior diagnoses of hypertension, malignancy and atrial flutter, initial angle and magnitude of the QRS vector in the transverse plane, P-wave and QRS axis in the frontal plane, ST segment axis in the frontal and horizontal planes, mean PT interval, mean PR segment duration and QTc intervals were all univariate predictors of incident AF, albeit only baseline age and initial angle of the QRS vector in the transverse plane retained significance after multivariate adjustment. As it pertains to new-onset HFrEF, several clinical and electrocardiographic parameters demonstrated an association in univariate analysis, with history of hypertension, history of sudden cardiac death (SCD), initial QRS angle in transverse plane, initial 40ms QRS complex axis, ST-segment axis in the horizontal plane, T-wave frontal axis and atrial rate all showcasing significant relationships in multivariate analysis. Conclusions AF and HFrEF are relatively common complications, whilst VT/VF occurs less frequently in the context of pericarditis. Different clinical and ECG predictors of these outcomes were identified. Future studies are still needed to evaluate their use for risk stratification in the clinical setting.

Comparison of sites of wall thickening and abnormal late enhancement on cardiac CT and magnetic resonance imaging with electrocardiography findings in patients with confirmed cardiac amyloidosis

Abstract Funding Acknowledgements Type of funding sources: None. Background Left ventricular (LV) wall thickening and diastolic dysfunction on a transthoracic echocardiogram (TTE) without a high voltage R wave on V5 leads on an ECG leads to a diagnosis of cardiac amyloidosis. A final diagnosis is made by endomyocardial biopsy. However, amyloid sometimes invades the right ventricle (RV), and left (LA) and right (RA) atria, causing ECG changes such as sick sinus syndrome (SSS), arrhythmia, and QRS wave axis deviation. Purpose To elucidate the relationship between sites of wall thickening and abnormal late enhancement (LE) on cardiac computed tomography (CT) and magnetic resonance imaging (MRI), suggesting amyloid invasion, with ECG findings in patients with cardiac amyloidosis confirmed by biopsy. Methods A total of 26 patients (11 females) with suspected cardiac amyloidosis, who had LV wall thickening by TTE without a high voltage R wave in V5 leads on ECG, underwent cardiac CT. LV wall thickening observed on CT in the early phase led to a late phase acquisition. Five patients (3 females, mean age 73 years) were diagnosed with cardiac amyloidosis: complicated multiple myeloma, 2; senile ATTR (transthyretin) amyloidosis, 1; immunoglobulin light chain (AL) amyloidosis, 1; and transthyretin mutation, 1. Four patients underwent cardiac MRI. Results Case 1 had wall thickening in the basal interventricular septum (IVS), LV inferior-posterior wall, LA on CT, abnormal LE in the endocardium in whole LV, RV, and RA on CT, and LE in the endocardium in whole LV, RV, LA, and IVS on MRI. ECG showed SSS (junctional rhythm), left axis QRS wave deviation, no low voltage R wave in limb leads, and a mild LA load. Case 2 had wall thickening in whole LV, RV, LA, and IVS on CT, and unclear (CT) or no (MRI) abnormal LE. ECG revealed SSS (junctional rhythm), a normal QRS axis, no low voltage R wave in limb leads, and no LA load. Case 3 had wall thickening in the LA and basal IVS on CT, abnormal LE in the LA and basal IVS on CT, and LE in the LA only on MRI. ECG revealed atrial tachycardia, a normal QRS axis with low voltage R wave in limb leads, and no LA load. Case 4 had wall thickening in the LA, an RV moderator band on CT, an unclear LE on CT, and LE in whole LV, endocardium in the RV, and whole IVS on MRI. ECG showed a normal sinus rhythm, left axis QRS wave deviation, with low voltage R wave in limb leads, and no LA load. Case 5 had wall thickening in the IVS, LV lateral wall, LV anterior wall, RA, RV outflow tract, and RA appendage, and no abnormal LE on CT (MRI not performed). ECG revealed a normal sinus rhythm, right axis QRS wave deviation, with low voltage R wave in limb leads, and a mild LA load. Conclusions In this pilot study of a small number of patients with cardiac amyloidosis, few relationships between sites of wall thickening and abnormal LE on ECG were found. However, a long-term follow-up study with more patients may reveal relationships between such parameters using this methodology. Abstract Figure. Classification by wall thickening on CT

Effect and Significance of Electrocardiographic Changes on Standing and Hyperventilation Prior to Exercise Electrocardiographic Testing

Electrocardiographic changes on standing from supine position and subsequent hyperventilation were studied in 100 persons. Changes were correlated with any evidence of myocardial ischemia during stress and/or recovery phase of treadmill stress testing. 15 individuals showed electrocardiographic changes on standing from supine position. Increase in heart rate of more than 30 beats per minute without a fall of more than 20 mm Hg in systolic blood pressure was seen in three cases. Two of them developed ischemic changes during exercise. Decrease in R wave amplitude in leads V2 to V6 was seen in one individual who developed ischemic changes during exercise. New inversion of T waves in leads V2 to V4 in a case with pre-existing RBBB and inverted T wave becoming positive in lead V2 were also associated with electrocardiographic evidence of myocardial ischemia during exercise testing. Mild change in QRS axis, decrease in R wave amplitude in leads II, III, aVF and/or V3 to V5 , ST segment depression of less than 1 mm and decrease in amplitude or inversion of T waves in leads II, III, aVF and V1 to V6 did not have any correlation with evidence of myocardial ischemia during exercise. Fourteen persons showed new electrocardiographic changes during hyperventilation after standing. Three cases had decrease in heart rate. All the three had evidence of myocardial ischemia during treadmill testing. Increase in amplitude of R wave in lead V4, normalization of pre-excitation with unmasking of old myocardial infarction and ST segment depression of more than 2 mm in inferior and lateral precordial leads with ST segment elevation in lead aVR were also associated with development of ECG evidence of myocardial ischemia during treadmill testing. Decrease in R wave amplitude in leads II, III, aVF and/or V4 - V6 , ST segment depression of less than 1mm in inferior or lateral precordial leads and inversion of T waves did not have any significant correlation with development of electrocardiographic signs of myocardial ischemia during treadmill stress test.