Lead V1 Research Articles

Electrocardiogram Parameters That Affect the Success Rate of Radiofrequency Ablation in Patients with Outflow Tract Ventricular Premature Complexes.

Objectives The objectives of this study are to assess the efficacy of radiofrequency catheter ablation (RFCA) in patients with outflow tract (OT) ventricular premature complexes (VPCs) and to explore the electrocardiographic (ECG) features of initially successful procedures. Methods Based on the outcome of ablation, 154 consecutive patients with OT-VPCs who underwent RFCA from January 2017 to December 2019 were divided into two groups. The rate of successful procedures and the ECG features were analyzed and compared between the two groups. Results The highest success rate was found in patients with VPCs from the right ventricular outflow tract (RVOT), and the lowest success rate was evident among patients with complexes from both the RVOT and the left ventricular OT (LVOT). The patients with successful procedures (136) reflected a lower pseudo delta wave ratio (16.2% vs. 44.4%, P < 0.01), a smaller R-wave amplitude in lead V1 (V1) (0.23 ± 0.24 mV vs. 0.35 ± 0.44 mV, P < 0.05), shorter intrinsicoid deflection time in lead V2 (V2) (44.00 ± 18.33 ms vs. 57.41 ± 20.67 ms, P < 0.01), a shorter RS duration in V2 (93.67 ± 21.33 ms vs. 106.93 ± 18.76 ms, P < 0.01), and smaller R/S-waveratios in V2. Furthermore, multivariate analysis demonstrated that RS duration in V2 was above 109.17 ms and R/S ratio in V2 was above 0.28, forecasting a failed procedure. Conclusions The ECG predictors of failed ablation were characterized by RS duration and R/S ratio in V2.

Prognostic role of serial electrocardiographic changes in patients with acute pulmonary embolism. Data from the Italian Pulmonary Embolism Registry

BackgroundThe prognostic role of serial electrocardiographic modifications in patients with acute pulmonary embolism (PE) have been poorly investigated. We evaluate the electrocardiographic changes in PE patients during their hospitalization and the prognostic role of such ECG modifications in respect to 30-day mortality in patients enrolled in the Italian Pulmonary Embolism Registry (IPER). MethodsSubjects enrolled into the IPER (September 2006–August 2010) were stratified according to their hemodynamic status, as high- (hemodynamically unstable) and non-high-risk (hemodynamically stable) patients. ECG features were analysed at three fixed time points: at presentation, on day 3 and at discharge. ResultsOverall, 687 patients (286 males, mean age 69.0 ± 15.5 years) were included in the study. Among these, 71 (10.3 %) were at high-risk. In these patients, multivariate analysis revealed that the persistence of right ventricular strain (RVS) after three days from hospitalization was a predictor of 30-day mortality [HRa: 2.78 (95 % CI: 1.05–7.31, p = 0.003)]. Moreover, the persistence of right bundle branch block (RBBB) [HRa: 2. 48 (95 % CI: 1.03–5.09, p = 0.002)], negative T waves in V1-V4 (NTWs) [HRa: 1.63 (95 % CI: 1.04–2.55), p < 0.0001] and qR complex in lead V1 [HRa: HR: 5.44, (95 % CI: 3.22–9.44, p < 0.0001)] were associated with an increased risk of 30-day mortality. When RBBB, NTWs and qR complex in V1 lead were present concomitantly, the 30-day risk of death resulted significantly higher [HR: 12.5 (95 % CI: 3.39–46.4,) p < 0.0001]. ConclusionsPersistence of RBBB, NTWs, and qR pattern in V1 lead at day 3 of hospitalization are independent prognostic factors of death within 30 days in high-risk acute PE patients. The prognostic power of any single ECG abnormality is lower compared to the combination of the three ECG variables.

Clinical and electrocardiographic characteristics in patients with fulminant myocarditis.

BackgroundThe purpose of this study was to evaluate clinical and electrocardiographic characteristics in patients with fulminant myocarditis.MethodsA total of 72 patients were divided into three groups: pericarditis (control: n = 25), acute myocarditis (n = 27), and fulminant myocarditis (n = 20). Patients' characteristics and electrocardiograms on admission were retrospectively analyzed in the three groups.ResultsBNP levels in the fulminant group were significantly higher than those in the other two groups. ST elevation was observed at lead aVR in the fulminant myocarditis group, whereas ST depression was observed at lead aVR in the other groups (p = .001). The maximum degree of ST elevation among the three groups was similar. However, the number of ST‐elevation leads in the fulminant myocarditis group was significantly lower than that in the other groups (p = .004). The voltage of R wave in lead V5 in the fulminant myocarditis group was significantly lower than that in the other groups (p = .005). Moreover, in the Cabrera sequence, the prevalence of ST elevation in the inferior leads, aVR, and V3–V6 in the fulminant myocarditis group was significantly or nearly significantly lower than that in the other groups.ConclusionsIn fulminant myocarditis, ST‐segment elevation was observed in lead aVR, and contrarily, the number and extent of ST‐segment elevation and R wave voltage were smaller than those in the other groups. These results suggest that the number of myocytes with maintained action potential may be reduced following progressive myocardial damage and interstitial edema due to severe inflammation.

Minor ST-T changes on electrocardiograms are associated with reduced constructive myocardial work in hypertensive patients with a preserved ejection fraction.

Minor ST-T changes on electrocardiograms are observed in patients with hypertensive heart disease with a preserved left ventricular ejection fraction (LVEF); however, the relationship between minor ST-T changes and global myocardial work on echocardiograms remains unclear. We evaluated the global longitudinal strain (GLS), global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE) in 186 hypertensive patients with preserved LVEF (>50%) using an offline analysis system (View Pal, GE). Minor ST-T changes as well as major ST-T changes (depression in ST in lead V5 > 1 mV) were also evaluated by electrocardiography. The mean age was 79.4 ± 8.2 years (men 37.6%). Patients with minor and major ST-changes had a smaller absolute GLS (-20.3 ± 3.1, -18.2 ± 3.7, and -15.2 ± 5.0%, P < 0.001) and a smaller constructive workload [GWI (2148 ± 486, 1938 ± 462, and 1685 ± 701 mmHg%, P = 0.002) and GCW (2419 ± 510, 2185 ± 466, and 1865 ± 702 mmHg%, P < 0.001)] than those with no ST-T changes. Additionally, patients with minor and major ST-T changes had increased wasted myocardial work [GWW (87 ± 61, 105 ± 56, and 127 ± 75 mmHg%, P = 0.045)], which resulted in reductions in the myocardial work efficiency [GWE (95 ± 4, 94 ± 3, and 89 ± 12%, P < 0.001)]. Even after adjustments for confounding factors, including EF, diastolic function parameters, LV hypertrophy, history of heart failure and atrial fibrillation, patients with minor ST-T changes had significantly smaller LV global constructive work in comparison to those without [GWI (2260 ± 33 vs. 2025 ± 76 mmHg%, P = 0.007) and GCW (2501 ± 45 vs. 2210 ± 105 mmHg%, P = 0.003)]. In conclusion, in hypertensive patients with preserved LVEF, minor ST-T changes on electrocardiograms were associated with reduced constructive work in the LV.

Early ischemic ST-segment and T-wave changes during balloon angioplasty

BackgroundAcute coronary occlusion results in increased T-wave amplitude and ST-segment elevation in the ECG leads facing the ischemic region. Material and methodsWe performed continuous ECG recording in 34 patients during balloon occlusion of the left anterior descending (LAD), left circumflex (LCx) and right coronary artery (RCA). Delta (Δ) ST and ΔT amplitudes were calculated by subtracting the preinflation values from the values measured during balloon inflation. ResultsOcclusion of the LAD resulted in greater increase in the amplitude of the T wave than of the ST segment in lead V2 (ΔT +3.4 mm, inter-quartile range [IQR] 1—6 mm; ΔST +1.4 mm, 0.5—3 mm). During RCA occlusion, ΔST and ΔT didn't differ significantly. LCx occlusion resulted in significant differences between ΔST and ΔT in all leads, except aVF and V3-V4. In two patients (LCx), we observed a biphasic ST-T response: an initial negative change of the T-wave amplitude was followed by a positive change in leads V1-V2. In leads II, III, aVF and V4-V6, there was an initial positive change, followed by a final negative change towards the end of the occlusion. ConclusionContinuous 12‑lead ECG recording during balloon occlusion of the LCx resulted in significant differences between the ΔST and ΔT values in all leads except aVF and V3-V4. LAD and RCA occlusion resulted in less evident differences between the ST-segment and T-wave changes. A change in polarity of T-wave changes during balloon occlusion (initial negative and final positive change, or vice versa) proved to be a rare finding.

The value of QRS onset of the outflow tract PVC in V1 and V2 leads recorded in fourth, third, and second intercostal spaces to differentiate main origins of premature ventricular contraction-Aprospective cohort study.

BackgroundElectrocardiography (ECG) is now proposed as a simple and cost‐effective tool to determine the location of arrhythmias before ablation. We aimed to examine the value of the QRS onset of outflow tract PVC in V1 and V2 leads recorded in fourth, third, and second intercostal spaces to differentiate two main origins for premature ventricular contraction (PVC) including right ventricular outflow tract (RVOT) and left ventricular outflow tract (LVOT).MethodsIn this prospective cohort study, a total of 58 patients were studied, from whom a surface ECG was obtained using V1 and V2 leads in the fourth, third, and second intercostal spaces. ECG and Electrophysiology studie (EPS) data were then recorded and compared to determine the sensitivity and specificity of QRS onset in locating arrhythmias. The reciever operating characterictic (ROC) curve analysis was applied to test diagnostic performance.ResultsBased on the time of PVC initiation in each of the V1 and V2 leads in the fourth intercostal space, if PVC is recorded earlier in the V1 lead, its source in 95.8% of the patients is RVOT and if PVC preceded the V2 lead, 70.59% of the patients had PVC from LVOT. Comparing of QRS onset in V1 and V2 leadsrecorded from third% and and second intercostal spaces had considerable sensitivity and specificity to determine the origin of the outflow tract PVC (81.82 and 94.12%, respectively)ConclusionSimultaneous recording of outflow tract PVCs from second third and fourth intercostal spaces and comparing their onset can determine the left and right outflow tract PVCs with high sensitivity and specificity.

Methadone Blockade of Cardiac Inward Rectifier K+ Current Augments Membrane Instability and Amplifies U Waves on Surface ECGs: A Translational Study.

BackgroundMethadone is associated with a disproportionate risk of sudden death and ventricular tachyarrhythmia despite only modest inhibition of delayed rectifier K+ current (I Kr), the principal mechanism of drug‐associated arrhythmia. Congenital defects of inward rectifier K+ current (I K1) have been linked to increased U‐wave amplitude on ECG and fatal arrhythmia. We hypothesized that methadone may also be a potent inhibitor of I K1, contributing to delayed repolarization and manifesting on surface ECGs as augmented U‐wave integrals.Methods and ResultsUsing a whole‐cell voltage clamp, methadone inhibited both recombinant and native I K1 with a half‐maximal inhibitory concentration IC50) of 1.5 μmol/L, similar to that observed for I Kr block (half‐maximal inhibitory concentration of 2.9 μmol/L). Methadone modestly increased the action potential duration at 90% repolarization and slowed terminal repolarization at low concentrations. At higher concentrations, action potential duration at 90% repolarization lengthening was abolished, but its effect on terminal repolarization rose steadily and correlated with increased fluctuations of diastolic membrane potential. In parallel, patient ECGs were analyzed before and after methadone initiation, with 68% of patients having a markedly increased U‐wave integral compared with premethadone (lead V3; mean +38%±15%, P=0.016), along with increased QT and TPeak to TEnd intervals, likely reflective of I Kr block.ConclusionsMethadone is a potent I K1 inhibitor that causes augmentation of U waves on surface ECG. We propose that increased membrane instability resulting from I K1 block may better explain methadone’s arrhythmia risk beyond I Kr inhibition alone. Drug‐induced augmentation of U waves may represent evidence of blockade of multiple repolarizing ion channels, and evaluation of the effect of that agent on I K1 may be warranted.

DISSOCIATION BETWEEN LEFT ATRIAL AND LEFT VENTRICULAR CHANGES IN HYPERTENSIVE PATIENTS WITH ATRIAL CARDIOMYOPATHY

Objective: Arterial hypertension (AH) is most important cardiovascular risk factor, associated with adverse left ventricular (LV) remodeling. In according to concept of atrial cardiomyopathy (ACMP) left atrium (LA) may be a more sensitive to pressure and volume overload than LV. We tried to delineate atrial and ventricular remodeling in hypertensive patients (pts) with and without ACMP. Design and method: Conventional and speckle tracking echocardiography was performed on 426 hypertensive patients [mean age 63 yrs, 51% men] with LV ejection fraction &gt; 45%. Global peak LA longitudinal strain (PALS) and strain rate (PALSR) in the reservoir © and contractile © phase were assessed. ACMP was defined as P-wave terminal force in lead V1 &gt; 4000 V × ms and/or LA size &gt; 4,3 sm for women and &gt; 4,7 sm for men. Results: Pts with ACMP (n = 214) were significantly younger to compare with non-ACMP pts (n = 212) [60 (51; 69) vs 66 (61; 73) yrs, p &lt; 0,001] and were less likely to have CAD [87 (41%) vs 174 (82%) pts, p &lt; 0,001], type 2 diabetes mellitus [18 (8%) vs 47 (22%) pts, p = 0,001]. Frequency of atrial fibrillation and anamnesis of previous heart failure hospitalization did not differ between comparing groups. Pts with ACMP had significantly higher LA diameter [3,9 (3,6; 4,5) vs 3,8 (3,5; 4,0) sm, p &lt; 0,001], LA volume index [34 (27; 42) vs 28 (22; 34) ml/m2, p &lt; 0,001] and lower PALSr [11,7 (10,4; 14,3) vs 14,7 (11,9; 16,4) %, p = 0,003], PALSc [-12,5 (-14,9; -9,5) vs -13,9 (-15,5; -11,2) %, p = 0,04] as well as PALSRr [1,85 (1,45; 1,95) vs 2,15 (1,78; 2,31) 1/s, p = 0,01] and PALSRc [-1,75 (-2,00; -1,38) vs -1,96 (-2,20; -1,81) 1/s, p = 0,009] than non-ACMP pts. Along with that pts with ACMP had significantly lower LV end-diastolic diameter [4,8 (4,5; 5,2) vs 4,9 (4,5; 5,4) sm, p = 0,006], A [0,60 (0,53; 0,70) vs 0,62 (0,55; 0,77) m/s, p = 0,04], E/É [6,6 (5,3; 9,6) vs 7,2 (6,2; 10,5), p = 0,01] and greater LV ejection fraction [62 (58; 67) vs 58 (51; 62), p &lt; 0,001]. Conclusions: In hypertensive pts with ACMP more prominent LA changes were accompanied by less obvious LV abnormalities.

Poor R-wave progression as a predictor of sudden cardiac death in the general population and subjects with coronary artery disease

Poor R-wave progression (PRWP) is a common clinical finding on the standard 12-lead electrocardiogram (ECG), but its prognostic significance is unclear. The purpose of this study was to examine the prognosis associated with PRWP in terms of sudden cardiac death (SCD), cardiac death, and all-cause mortality in general population subjects with and without coronary artery disease (CAD). Data and 12-lead ECGs were collected from a Finnish general population health examination survey conducted during 1978-1980 with follow-up until 2011. The study population consisted of 6854 subjects. Main end points were SCD, cardiac death, and all-cause mortality. PRWP was defined as R-wave amplitude ≤ 0.3 mV in lead V3 and R-wave amplitude in lead V2 ≤ R-wave amplitude in lead V3. PRWP occurred in 213 subjects (3.1%). During the follow-up period of 24.3 ± 10.4 years, 3723 subjects (54.3%) died. PRWP was associated with older age, higher prevalence of heart failure and CAD, and β-blocker medication. In multivariate analyses, PRWP was associated with SCD (hazard ratio [HR] 2.13; 95% confidence interval [CI] 1.34-3.39), cardiac death (HR 1.75; 95% CI 1.35-2.15), and all-cause mortality (HR 1.29; 95% CI 1.08-1.54). In the subgroup with CAD, PRWP had a stronger association with cardiac mortality (HR 1.71; 95% CI 1.19-2.46) than in the subgroup without CAD, while the association with SCD was significant only in the subgroup with CAD (HR 2.62; 95% CI 1.38-4.98). PRWP was associated with adverse prognosis in the general population and with SCD in subjects with CAD.

P wave peak time and P wave dispersion in severe COVID-19 infection.

With this study, we aimed at evaluating the association between electrocardiographic P wave indices and the severity of COVID-19 infection indicated as intensive care unit (ICU) admission. We included 247 patients who were hospitalized with a diagnosis of COVID-19 infection and underwent 12 lead standard Electrocardiography (ECG). P wave indices, P wave dispersion (Pdis), P wave peak time in V1 lead (PWPTV1), and D2 lead (PWPTD2) were measured using admission ECG. Comparisons were performed between ICU admitting and non-ICU admitting patients. 160 patients were hospitalized in normal wards, and 87 patients were admitted to ICU. Pdis, PWPTV1, and PWPTD2 were prolonged in ICU admitted patients compared with the normal ward admitted patients [40 (30-50) ms vs. 50 (40-55) ms; p<0.001, 61±9 ms vs. 68±9 ms; p<0.001, and 55±7 ms vs. 64±7 ms; p<0.001, respectively]. In multiple logistic regression analysis, PWPTV1 and PWPTD2 were independent predictors of ICU admission. A cut-off point of 67.5 ms PWPTv1 has a sensitivity of 62.1% and a specificity of 69.4% (AUC=0.710, 95% CI: 0.642-0.777, p<0.001) and a cut-off point of 62.5 ms PWPTD2 has a sensitivity of 60.9% and a specificity of 83.6% (AUC=0.819, 95% CI: 0.777-0.871, p<0.001). Admission ECG atrial indices Pdis and PWPT were associated with intensive care unit admission in newly diagnosed COVID-19 patients.

Derivation and Validation of a Screening Model for Hypertrophic Cardiomyopathy Based on Electrocardiogram Features.

BackgroundHypertrophic cardiomyopathy (HCM) is a widely distributed, but clinically heterogeneous genetic heart disease, affects approximately 20 million people worldwide. Nowadays, HCM is treatable with the advancement of medical interventions. However, due to occult clinical presentations and a lack of easy, inexpensive, and widely popularized screening approaches in the general population, 80–90% HCM patients are not clinically identifiable, which brings certain safety hazards could have been prevented. The majority HCM patients showed abnormal and diverse electrocardiogram (ECG) presentations, it is unclear which ECG parameters are the most efficient for HCM screening.ObjectiveWe aimed to develop a pragmatic prediction model based on the most common ECG features to screen for HCM.MethodsBetween April 1st and September 30th, 2020, 423 consecutive subjects from the International Cooperation Center for Hypertrophic Cardiomyopathy of Xijing Hospital [172 HCM patients, 251 participants without left ventricular hypertrophy (non-HCM)] were prospectively included in the training cohort. Between January 4th and February 30th, 2021, 163 participants from the same center were included in the temporal internal validation cohort (62 HCM patients, 101 non-HCM participants). External validation was performed using retrospectively collected ECG data from Xijing Hospital (3,232 HCM ECG samples from January 1st, 2000, to March 31st, 2020; 95,184 non-HCM ECG samples from January 1st to December 31st, 2020). The C-statistic was used to measure the discriminative ability of the model.ResultsAmong 30 ECG features examined, all except abnormal Q wave significantly differed between the HCM patients and non-HCM comparators. After several independent feature selection approaches and model evaluation, we included only two ECG features, T wave inversion (TWI) and the amplitude of S wave in lead V1 (SV1), in the HCM prediction model. The model showed a clearly useful discriminative performance (C-statistic > 0.75) in the training [C-statistic 0.857 (0.818–0.896)], and temporal validation cohorts [C-statistic 0.871 (0.812–0.930)]. In the external validation cohort, the C-statistic of the model was 0.833 [0.825–0.841]. A browser-based calculator was generated accordingly.ConclusionThe pragmatic model established using only TWI and SV1 may be helpful for predicting the probability of HCM and shows promise for use in population-based HCM screening.

Can 12 lead ECG predit the level of conduction system disease?

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Permanent His bundle pacing (p-HBP) could be an alternative for cardiac resynchronization therapy (CRT), but an important limitation is that p-HBP cannot always correct the left bundle branch block (LBBB). The aim is to assess electrocardiographic (ECG) patterns of LBBB that can predict ECG response (QRS narrowing) to p-HBP. Methods Prospective descriptive study of patients with LBBB and CRT indication proposed for CRT by p-HBP. We analyzed the correlation between the different ECG patterns and the correction of LBBB. Results We included 70 patients. Once located His bundle electrogram, pacing at this level narrowed the QRS in 81.4% (n=57). We distinguished two ECG patterns in lead V1: QS or rS. Thirty-four patients (51.4%) presented QS pattern in lead V1 (Fig 1A), and in 94.1% of these correction of the LBBB was achieved (Fig 1B). The rS pattern was present in 36 patients and in 69.4% of these the correction of the LBBB was achieved. Differences between both groups were statistically significant (p=.008). The presence of QS pattern in V1 had a sensitivity of 56%, a specificity of 84.6% and a positive predictive value of 94.1% to predict LBBB correction. The AUC by a receiver operating characteristic analysis was .70±. In patients with rS pattern in lead V1, we analyzed the ratio between the descending and the ascending S wave component duration; the difference between patients in whom LBBB was corrected (ratio 0.742±0.124) and patients in whom it was not corrected (0.476±0.124) were statistically significant (p=.001). The AUC by a receiver operating characteristic analysis was .968 (very good predictor of LBBB correction). In this case, a ratio between the descending and the ascending S wave component duration≥0.64 (Fig 2C-D) showed a sensitivity of 92%, a specificity and a PPV of 100%, and a negative predictive value (NPV) of 83.3%. Related to the ratio between the ascending S wave component duration and the total QRS duration, it was 0.513±0.043 in patients with LBBB correction vs 0.60 ± 0.046 in those in whom it did not correct (P=.001). The AUC by a receiver operating characteristics analysis was .896 (good test to predict LBBB correction in patients with rS pattern in lead V1). We analyzed the ratio between the descending and the ascending S wave component duration in the global of patients, including those with QS pattern. Patients in whom it corrected the LBBB presented a ratio of 0.754±0.13 vs 0.459±0.081 in whom it did not correct (P&amp;lt;.001) (AUC .977). The ratio between the ascending S wave component duration and the total QRS duration in patients with LBBB correction was 0.542±0.003 vs 0.623±0.063 in whom it did not correct (P&amp;lt;.001) (AUC .84). Conclusions In patients with LBBB and CRT indication, the QS pattern in lead V1 predicts the correction of the QRS with HBP. In the case of rS pattern in lead V1, the ratio descending/ascending S wave component duration has a strong correlation with the LBBB correction.

Development and validation of a new ECG algorithm based on the analysis of lead V3 to determine the origin of outflow tract ventricular arrhythmias

Abstract Funding Acknowledgements Type of funding sources: None. Introduction (Aim) To preoperatively differentiate the site of origin outflow tract ventricular arrhythmias (OT-VA) it is of utmost importance for procedure planning yet challenging for those with a precordial transition (PT) at lead V3: close-proximity anatomical structures produce similar VA morphologies, thus leading to possible misdiagnosis. We sought to create an ECG algorithm that could be accurate and useful in overcoming this problem. Methods and Results 74 consecutive patients (Pts) with OT-VA who underwent successful radio-frequency catheter ablation (V3 PT 60.8%) were enrolled. The ECG characteristics of the first 30 Pts were analyzed (retrospective cohort); those with a PT at lead V3 underwent activation-mapping of both OT to ensure a correct diagnosis. LV-OT and RV-OT groups shared similar characteristics, including BMI and BSA. Above all ECG measurements, the V3 duration index (DI) and amplitude percentage, both calculated with the formula [R\(R+S)]*100 (computing duration and amplitude measurements respectively), showed the greatest AUC. A V3 DI &amp;lt; 50% established a certain diagnosis of origin at RV-OT (sensitivity 86.7%, specificity 100%, PPV 100%, NPV 88.2%; AUC 0.931). If the V3 DI was ≥ 50%, a V3 R wave percentage ≥ 50% established a certain diagnosis of origin at LV-OT (sensitivity 86.7%, specificity 100%, PPV 100%, NPV 88.2%, AUC 0.951). While a direct study of the RV-OT or LV-OT is suggested in these first two cases, few classification errors occurred only in the rare event of a V3 DI ≥ 50% with a V3 R wave percentage &amp;lt; 50% (Figure 1). In the prospective cohort, the two indices were confirmed to have the two best AUCs (0.992 and 0.986, respectively), and the algorithm showed an accuracy of 95.45%. Since the aortic cusps are structures posterior to RV-OT, therefore further away from V2, these foci more frequently show a QRS onset at ≥ V3; a characteristic which in our series was associated with an odds ratio for LV-OT origin of 4.1 [95% CI 1.47 – 11.39], p = 0.007. Using the transition ratio, we found a statistical significance only in lead V3, with a cut-off of ≥ 1 for predicting an LV-OT origin (LV-OT vs. RV-OT: 7.70 ± 12.75 vs. 0.70 ± 0.55, p &amp;lt; 0.001; AUC 0.898). Analyzing the overall case series, we can generalize the following: duration and amplitude indices showed an increasing AUC passing from lead V1 to V3 (Figure 2). The indices based on the complete measurement of the wave R compared to the QRS showed better AUCs than those on partial measures in V2 and V3: the duration index was better than the deflection index, as well as the amplitude percentage was better than the amplitude ratio. Conclusions The usefulness of the algorithm lies in providing preoperatively two assured outcomes in most cases (86.36%), allowing to limit the procedure to one OT directly - even in the event of a V3 PT - while it can select a small subgroup of complex Pts in which a study of both OT is recommended.

Machine-learned physiological signatures from the ECG predict sudden death in ischemic cardiomyopathy

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Institute of Health (NIH) Background Low left ventricular ejection fraction (LVEF) is an imperfect predictor of sudden cardiac death (SCD) in patients with ischemic cardiomyopathy. Novel features from the ECG might provide a readily available tool to better predict risk. Purpose We hypothesized that machine learning (ML) of the ECG can be used to predict SCD, and the ML-learned ECG features could be referenced to interpretable intracardiac signals (monophasic action potentials: MAP) to provide mechanistic insights. Methods We studied 5603 ECG Lead V1 beats in 41 patients (64±10 Y) with coronary disease and LVEF≤40% in steady-state pacing. Patients were randomly allocated to independent training and test cohorts in a 70:30 ratio, repeated K=10-fold. Support vector machines were trained to predict mortality at 3Y from the top 20 features derived from these beats. Patient-level predictions were made by computing an ECG score that indicates the proportion of test set beats in that patient computed by the beat-level model to predict death. Explainability analysis was performed using the arithmetic mean of MAP and ECG beats that predicted SCD versus those that predicted survival. Results Fig 1A. shows ECG lead V1 and MAP in a 79 Y man with LVEF 29%. Fig 1B shows the dataflow in the study. Predictive accuracies of ML models were 78 and 70% and optimal with 20 features for both ECG and MAP models respectively (Fig. 1C). Beat-level predictions in the validation (n=1678 Lead I beats) cohorts yielded c-statistics of 0.78 with the ECG (95% CI, 0.62–0.91) and 0.75 with MAPs (95% CI, 0.75-0.76) (data not shown). In multivariable patient-level models, c-statistic was 0.87 with ECGs (95% CI, 0.76-0.98) (Fig 1D) and 0.82 with MAPs. On explainability analysis, ECG beats that predicted SCD (Fig 2; red) had lower amplitude and more notched T-waves in lead V1 than beats that predicted no SCD (Fig 2; blue). MAP that predicted SCD had higher repolarization current at the same time points. Both QT duration (ECG) and action potential duration (MAP) did not differ (Fig 2). Conclusions Machine learning of the ECG reveals novel predictors of SCD risk in patients with ischemic cardiomyopathy analogous to those identified in intracardiac signals. This approach can be used as a point-of-care ECG risk tool to improve risk stratification and allocation for ICD therapy beyond LVEF alone and may shed insights into the pathophysiology of ventricular arrhythmias.

Digitalised ECG measure of p-wave duration predicts incident heart failure

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): Uppsala University Hospital Background and purpose Early identification of patients at risk of congestive heart failure (HF) may potentially alter their poor prognosis. The aim was therefore to test whether the P-wave and PR-interval, simple non-invasive ECG measures reflecting systolic and diastolic atrial function, could predict incident HF. Methods The PIVUS (Prospective Investigation of the Vasculature in Seniors) study including all individuals aged 70 years (1016 individuals, 50% women) was used to identify predictors of HF. Subjects with prevalent HF, QRS duration ≥ 130 msec or atrial arrhythmias on baseline ECG were excluded. Cox proportional hazard analysis was used to relate P-wave duration (Pdur), amplitude (Pamp) and PR interval in lead V1, to incident HF. Adjustment was performed for gender, RR-interval, beta-blocking agents, systolic blood pressure, body mass index and smoking. Results A total of 107 of 836 (12,8%) subjects at risk, developed HF during 15 years follow-up. The multivariate analysis, showed a strong U-shaped correlation between Pdur and incident HF (p=0.0001), which was significant for a Pdur&amp;lt; 60 msec [HR 2.75 (95% CI 1.87-4.06) at Pdur 40 msec]. There was no significant relationship between incident HF and the PR-interval, or the Pamp. A Pdur&amp;lt;60 msec improved discrimination by 3.7% when added to the confounders described above (p=0.048). Conclusions A short P-duration, a simple and easy ECG measure, may potentially be a useful predictor of developing HF, enabling early detection and treatment of HF.

Longer left ventricular activation time is associated with lower mortality and risk of heart failure hospitalization in CRT recipients

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): ALF Governmental Funding within the Swedish health care system Introduction Cardiac resynchronization therapy (CRT) is an established treatment for heart failure in selected patients. Longer QRS duration has been showed to correlate to clinical outcome, but measures global activation time, rather than the left ventricular dyssynchrony that CRT aims to correct. This study therefore evaluated the incremental value of using Left Ventricular Activation Time (LVAT) for prediction of outcome after CRT. Methods Medical records of 445 patients receiving CRT implants at a large-volume tertiary care center were retrospectively evaluated. Digital electrocardiograms (ECG) before and after CRT implantation were collected and ECG parameters were analysed in relation to a primary composite endpoint of time to heart failure hospitalisation or death from any cause. LVAT was defined as time from QRS onset to maximum positive deflection in lead V6 (Figure 1). Results Patients were followed for up to 6 years (median 2.7), during which 147 patients (33%) reached the primary endpoint (93 deaths and 103 heart failure hospitalisations). LVAT was measured pre-implant (median 71ms [58-88]) and post-implant (median 74ms [57-96]). There was no CRT-mediated reduction in LVAT (delta -2.3ms +/-31ms, p=0.27). When divided into quartiles, preoperative LVAT had a significant association with clinical outcome (HR 0.76 [0.64-0.90] per increasing quartile, p=0.001), also shown in a median-split Kaplan Meier curve (Figure 2, log rank p=0.001). Multivariate hazard ratio (adjusted for relevant clinical variables) was 0.83; [0.69-0.99]; p=0.047). There was an interaction between LVAT and ECG morphology (p=0.033), and when ECG groups were analysed separately, there was only a significant result for those with native left bundle branch block morphology. Post-implant LVAT, or change in LVAT, did not correlate with the primary endpoint (p=0.25 and p=0.38 respectively. Conclusion In CRT recipients, longer pre-implant LVAT was associated with lower risk of heart failure hospitalisation and death during a follow-up of up to 6 years. This association was mainly seen in patients with native LBBB prior to implant. No association was seen with post-CRT LVAT and clinical outcome. If confirmed in prospective trials, evaluation of preoperative LVAT may help optimise patient selection for CRT.

Early experience with the second generation of leadless pacemakers and correlation with ecg parameters

Abstract Funding Acknowledgements Type of funding sources: None. Background Leadless pacing has evolved as a safe and effective treatment option in selected patients. With the updated generation that allows sensing of atrial contraction, atrioventricular synchronized pacing is now possible in a VDD mode. Previous retrospective analyses have demonstrated that echocardiographic parameters may be helpful in selecting patients with a higher chance of good atrioventricular synchronous pacing behaviour. Purpose Analysis of the early experience with the second generation of leadless pacemaker and the role of ECG parameters to predict a good atrial contraction signal (so-called A4 amplitude) in patients who underwent leadless pacemaker implantation in four tertiary centres. Methods and Results In this retrospective analysis, a total of 136 patients were included. Mean age was 78.0 (64.7 - 84.2 years) years with 48.9 % being male. Coronary artery disease was the leading underlying heart disease with 27.1 % affected patients. 61.7 % of the population suffered from sinus rhythm with complete or intermittent atrioventricular block. The majority of devices were implanted at the mid-septal (61.2 %) or high-septal (25.6 %) right ventricle, respectively. Electrical parameters were optimal at implant (Table 1) and remained stable over time (Table 1). In addition, A4 signal amplitude remained stable too during follow-up compared to the value early after implantation (Table 1). From this entire cohort, patients with an ECG available at implant and those in which the device was working predominantly in the VDD mode were selected for further analyses (62 patients). PR interval measured from the ECG prior to implantation did not correlate with the A4 signal amplitude (Figure 1A; P = NS). Next, P wave amplitudes were measured in all 12 ECG leads. There was a correlation between P wave amplitude from lead V2 with the A4 amplitude (Figure 1B; P = 0.034, R2 = 0.09), whereas the other right-sided ECG leads (V1/aVR), either alone or in combination, did not correlate with the A4 signal amplitude (P = NS). Conclusions In our cohort of patients with the second generation of leadless pacemakers, offering VDD pacing, good electrical parameters can be achieved as it has been observed with the first generation. Also the A4 signal amplitude as a marker for atrial contraction remains stable over time. In regard to ECG parameters measured prior to device implantation, only the P wave amplitude in lead V2 correlated with a amplitude of the A4 signal.

Association between complete right bundle branch block and atrial fibrillation development.

BackgroundComplete right bundle branch block (CRBBB) is an important predictor of atrial fibrillation (AF) recurrence after pulmonary vein isolation. However, the association between CRBBB and AF development remains unclear.MethodsWe performed a retrospective study of 2639 patients (male, n = 1549; female, n = 1090; mean age, 58 ± 13 years). CRBBB was defined as a late R (R′) wave in lead V1 or V2 with a slurred S wave in lead I and/or lead V6 with a prolonged QRS duration (≥120 ms).ResultsAmong the 2639 patients, CRBBB was detected in 40 patients (1.5%), and the prevalence of AF was 7.4% (196/2639). The proportion of patients with AF and CRBBB was higher than the proportion of patients with AF without CRBBB (22.5% vs. 7.2%; p = 0.001). In the forward multivariate logistic analysis, CRBBB (odds ratio [OR], 3.329; 95% confidence interval [CI], 1.350–8.211; p = 0.009), complete left bundle branch block (OR, 2.209; 95% CI, 1.238–3.940; p = 0.007), age (OR, 1.020; 95% CI, 1.005–1.035; p = 0.009), valvular heart disease (OR, 2.332; 95% CI, 1.531–3.552; p < 0.001), left atrial diameter (OR, 1.133; 95% CI, 1.104–1.163; p < 0.001), left ventricular ejection fraction (OR, 1.023; 95% CI, 1.006–1.041; p = 0.007), and class I or III anti‐arrhythmic drug use (OR, 10.534; 95% CI, 7.090–15.651; p < 0.001) were associated with AF.ConclusionComplete right bundle branch block was significantly associated with AF development in hospitalized patients with cardiovascular diseases.

Prevalence of exercise-induced arrhythmias in young athletes with fragmented QRS pattern in lead V1

Abstract Funding Acknowledgements Type of funding sources: None. Background Resting 12-lead electrocardiogram (ECG) in apparently health athletes has specific pattern, typically associate to heart remodelling in response to regular exercise. (1,2) Moreover, these adaptations were correlated to typical ventricular arrhythmias, not associated with underlying cardiac abnormalities.(3) Recently, also fragmented QRS complex in lead V1 (fQRSV1), representing right ventricular (RV) activation, seems related to training-induced RV remodelling in athletes, where its prevalence is greater.(4) Purpose Evaluate presence of fQRSV1pattern at resting ECG in a population of young athletes and its relationship with training-associated structural heart adaptations and exercise-induced ventricular arrhythmias. Methods This study retrospectively enrolled subjects who consecutively undergo to annual pre-participation screening and also to transthoracic echocardiography assessment, from January 2015 to September 2020. For each participant, medical history, physical examination, resting ECG, maximal standardized exercise test and echocardiographic evaluation were collected. All ECG were reviewed by two independent physicians to evaluate fQRSV1 pattern. Results 684 young athletes (mean age 14.87±1.96 years, 36% female) were included and the overall prevalence of fQRSV1was 27%. Figure 1 shows an example of fQRSV1 pattern. Principal subject characteristics and evaluations data are shown in Table 1. fQRSV1 subjects presented a significantly wider QRS interval (p=0.004) and lower heart rate at rest (p=0.001). Exercise workload expressed in METs and exercise duration were higher in subjects with fQRSV1 (p=0.002 and p=0.023, respectively). Echocardiographic data showed that subjects with fQRSV1differ in morphological and functional right ventricular (RV) characteristics, especially had a higher indexed RV end diastolic diameter (p=0.019) and higher TAPSE (p=0.013). Patients with fQRSV1did not show an increased occurrence of supraventricular or ventricular arrhythmias, regardless of morphology, neither for isolated nor for repetitive events. Conclusion Overall prevalence of fQRSV1 pattern in young athletes is comparable with the one studied in other population of adult athletes in previous studies. Adolescent athletes with fQRSV1 present structural heart characteristic that differ from subjects without this ECG pattern, especially in RV feature. No differences in prevalence of any type of exercise-induced arrhythmias was shown, especially in common ventricular arrhythmias consistent with origin from the right ventricular outflow tract, previously described in healthy athletes.

Evaluation of the shortening of the stimulus-to-peak left ventricular activation time at continuous low output to confirm left bundle branch capture.

BackgroundLeft bundle branch area pacing (LBBAP) is a physiological pacing method for treatment of atrioventricular block. However, there is a need for a new convenient and safe method for performing left bundle branch pacing (LBBP) and to confirm left conduction system capture.ObjectiveThis study aimed to explore a new convenient and safe method for performing selective LBBP.MethodsA total of 28 patients who had indications for pacing therapy and received LBBAP were recruited retrospectively. Demographic and baseline patient characteristics, electrocardiograms, pacing parameters, and intracardiac electrogram pattern were evaluated. Continuous unipolar pacing at low output (2 V / 0.5 ms) was performed during the whole period of LBBP lead implantation. Successful left bundle branch (LBB) capture was defined as the abrupt change of the pacing stimulus to the peak of R wave in lead V5 during continuous pacing at low output (2 V / 0.5 ms).ResultsThe parameters of the 2 shortenings (stimulus-to-peak left ventricular activation time [S-peak LVAT] before shortening, S-peak LVAT after shortening, and the duration of shortening) all showed a significant positive correlation (Pearson product-moment correlation coefficient [PCC] = 0.915, P < .001; PCC = 0.897, P < 0.001; PCCs = 0.765, P < 0.001). Shortening of the S-peak LVAT with continuous low output had a 100% sensitivity and 33.3% specificity for predicting stimulus-ventricular potential interval (S-V interval).ConclusionAbrupt shortening of the S-peak LVAT at continuous low output was associated with abrupt shortening of the S-peak LVAT at low and high output. High rate of selective LBB capture can be achieved with the method of continuous low output, shortening the S-peak LVAT.