Rhythm vs Rate Control Strategy for Atrial Fibrillation: A Meta-Analysis of Randomized Controlled Trials.

BACKGROUND: Rhythm control, either with antiarrhythmic drugs or catheter ablation, and rate control strategies are the cornerstones of atrial fibrillation (AF) management. Despite the increasing role of rhythm control over the past few years, it remains inconclusive which strategy is superior in improving clinical outcomes. OBJECTIVES: This study summarizes the total and time-varying evidence regarding the efficacy of rhythm- vs rate-control strategies in the management of AF. METHODS: We systematically perused the MEDLINE, CENTRAL (Cochrane Central Register of Controlled Trials), and Web of Science databases for randomized controlled trials from inception to November 2023. We included studies that compared the efficacy of rhythm control (ie, antiarrhythmic drugs classes Ia, Ic, or III, AF catheter ablation, and electrical cardioversion) and rate control (ie, beta-blocker, digitalis, or calcium antagonist) strategies among patients with nonvalvular AF. The primary outcome was cardiovascular (CV) death, whereas secondary outcomes included all-cause death, stroke, hospitalization for heart failure (HF), sinus rhythm at the end of the follow-up, and rhythm control-related adverse events. A cumulative meta-analysis to assess temporal trends and a meta-regression analysis using the percentage of ablation use was performed. RESULTS: We identified 18 studies with a total of 17,536 patients (mean age: 68.6 ± 9.7 years, 37.9% females) and a mean follow-up of 28.5 months. Of those, 31.9% had paroxysmal AF. A rhythm control strategy reduced CV death (HR: 0.78; 95% CI: 0.62-0.96), stroke (HR: 0.801; 95% CI: 0.643-0.998), and hospitalization for HF (HR: 0.80; 95% CI: 0.69-0.94) but not all-cause death (HR: 0.86; 95% CI: 0.73-1.02) compared with a rate control strategy. This benefit was driven by contemporary studies, whereas more ablation use within the rhythm control arm was associated with improved outcomes, except stroke. CONCLUSIONS: In patients with AF, a contemporary rhythm control strategy leads to reduced CV mortality, HF events, and stroke compared with a rate control strategy.

Clinical Significance of Supraventricular Tachycardia During Pregnancy in Healthy Women.

BACKGROUND: Supraventricular tachycardias (SVT) are the most frequently encountered arrhythmias in pregnancy with unclear clinical significance. OBJECTIVES: This study sought to report the prevalence, describe the management, and explore the association between SVT and adverse obstetric outcomes. METHODS: Cohort study of primiparous and multiparous women without history of Cesarean section (CS), and with structurally normal hearts admitted in labor. The study group consisted of women with at least 1 SVT episode during pregnancy, and the control group was randomly selected in a 4:1 ratio. RESULTS: Of 141,769 women meeting the inclusion criteria, SVT diagnosis was confirmed in 122. A total of 76 (age 33.2 ± 4.8 years) had at least 1 symptomatic and documented episode during pregnancy. In women with a known SVT diagnosis before pregnancy, medical therapy was not associated with a lower risk of SVT recurrence (OR: 1.07; 95% CI: 0.41-2.80). However, catheter ablation before pregnancy was associated with significantly lower risk of SVT recurrence (OR: 0.09; 95% CI: 0.04-0.23). Women with SVT during pregnancy had higher incidence of CS (39.5% vs 27.0%; P = 0.03), and preterm labor (PTL) (30.3% vs 8.6%; P < 0.001). Adjusting for age and parity, SVT during pregnancy was an independent predictor of CS (OR: 1.80; 95% CI: 1.03-3.10), particularly planned CS (OR: 2.89; 95% CI: 1.06-7.89) and PTL (OR: 4.37; 95% CI: 2.30-8.31). CONCLUSIONS: SVT during pregnancy is associated with increased risk for CS and PTL in healthy women. History of SVT should be sought as early as preconception counseling, and a multidisciplinary approach is warranted for both prevention and management of SVT occurrence.

Anatomically Based Ablation of Left Ventricular Summit Premature Ventricular Complexes Guided by Intracardiac Echocardiography.

Catheter ablation of premature ventricular contractions (PVCs) arising from the left ventricular summit (LVS) presents technical challenges due to the regional anatomy and frequent intramural site of origin (SOO). Intracardiac echocardiography (ICE) and the CARTOSOUND® (Biosense Webster, Diamond Bar, CA, USA) module allow the operator to directly reconstruct and visualize the dimensions and orientation of the LVS live and present it in relation to neighboring structures. We retrospectively reviewed consecutive cases between January 2021 and December 2022 of patients undergoing PVC ablation for a presumed LVS origin. The LVS was reconstructed by creating a three-dimensional representation of the left ventricular septum, using two-dimensional ICE sections. The earliest site in each chamber was tagged on the reconstructed LVS, and the presumed SOO was localized using a geometrical center point from all sites. Ablation was first delivered to the earliest site, except when the presence of coronary branches precluded radiofrequency delivery within the great cardiac vein. Of 20 patients (8 women, 62.4 ± 7.1 years old) with a presumed LVS origin, 12 had PVC recurrence within the monitoring period after the initial ablation for 192.5 ± 37.2 s at the earliest site. Among them, earliest activation was seen at the sinus of Valsalva (SoV), coronary venous system (CVS), and left ventricular endocardium (LVE) in four, six, and two patients, respectively. Using the reconstructed LVS, the anatomically closest site to the SOO was identified in the SoV, CVS, and LVE in four, two, and six cases, respectively. Throughout the study period (14.5 months; range, 9.3-19.7 months), 17 patients (85%) had complete elimination of PVCs as evaluated by 24-h event monitors at the 12-month visit. In 50% of cases, among patients in whom ablation at the earliest signal was unsuccessful, the site of successful ablation did not correlate with the second earliest signal or had no identifiable signal during initial activation mapping. The reconstructed LVS not only guided activation mapping but also identified sites proximal to the center point that had either a late activation signal, a low-amplitude signal, or no signal at all.

Clinical significance of unexplained persistent sinus tachycardia in women with structurally normal heart during the peripartum period.

BACKGROUND: Persistent sinus tachycardia (ST) is frequently encountered during pregnancy and peripartum period and its etiology often remains elusive. We sought to examine the possible association between unexplained persistent ST and obstetric outcomes. METHODS: A case control study was conducted using chart review of women admitted in labor to one of 7 hospitals of Northwell Health between January 2015 to June 2021. After excluding women with structurally abnormal hearts, we identified patients with persistent ST during the peripartum period, defined as a heart rate of more than 100 bpm for more than 48 h. A control group was created by randomly subsampling those who did not meet the inclusion criteria for sinus tachycardia. Obstetric outcomes were measured as mother's length of stay (LOS), pre-term labor (PTL), admission to the neonatal ICU (NICU), and whether she received cesarean-section (CS). RESULTS: Seventy-eight patients with persistent ST were identified, out of 141,769 women admitted for labor throughout the Northwell Health system. 23 patients with ST attributable to infection or hypovolemia from anemia requiring transfusion and 55 with unclear etiology were identified. After adjusting for age and parity, pregnant mothers with ST were 2.35 times more likely to have a CS than those without (95% CI: 1.46-3.81, p = 0.0005) and had 1.38 times the LOS (1.21- 1.56, p < 0.0001). Among mothers with ST, those with unexplained ST were 2.14 times more likely to have a CS (1.22-3.75, p = 0.008). CONCLUSION: Among pregnant patients, patients with ST have higher rates of CS.This association is unclear, however potential mechanisms include catecholamine surge, indolent infection, hormonal fluctuations, and medications. More studies are needed to explore the mechanism of ST in pregnant woman to determine the clinical significance and appropriate management.

Leveraging electronic health record query to streamline adverse event reporting and protocol compliance.

Electronic medical records are increasingly being leveraged to improve the efficiency and effectiveness of clinical trials. Reporting safety data and adhering to follow-up schedules are two challenges faced by study centers conducting a large number of clinical trials led by a single principal investigator. The Lenox Hill Electrophysiology Research Department collaborated with Northwell Health's informatics department to develop a live query accessing both inpatient and outpatient data. To demonstrate the efficacy of this approach we compared the compliance rate of adverse event reporting and patient follow-up visits between a clinical trial run using this approach and a clinical trial conducted prior to use. We compared the number of out of window visits, missed visits, missed assessments, subject drop out and number of late reported adverse events between both studies. The trial run using the described query method had a marked reduction in these categories. Leveraging available informatics resources have allowed for improved efficiency, accurate adverse even reporting and improved follow-up scheduling.

Delayed cardiac repolarisation as a predictor of in-hospital mortality in patients with COVID-19.

OBJECTIVE: With the rapid influx of COVID-19 admissions during the first wave of the pandemic, there was an obvious need for an efficient and streamlined risk stratification tool to aid in triaging. To this date, no clinical prediction tool exists for patients presenting to the hospital with COVID-19 infection. METHODS: This is a retrospective cohort study of patients admitted in one of 13 Northwell Health Hospitals, located in the wider New York Metropolitan area between 1 March 2020 and 27 April 2020. Inclusion criteria were a positive SARS-CoV-2 nasal swab, a 12-lead ECG within 48 hours, and a complete basic metabolic panel within 96 hours of presentation. RESULTS: All-cause, in-hospital mortality was 27.1% among 7098 patients. Independent predictors of mortality included demographic characteristics (male gender, race and increased age), presenting vitals (oxygen saturation <92% and heart rate >120 bpm), metabolic panel values (serum lactate >2.0 mmol/L, sodium >145, mmol/L, blood urea nitrogen >40 mmol/L, aspartate aminotransferase >40 U/L, Creatinine >1.3 mg/dL and glycose >100 mg/L) and comorbidities (congestive heart failure, chronic obstructive pulmonary disease and coronary artery disease). In addition to those, our analysis showed that delayed cardiac repolarisation (QT corrected for heart rate (QTc) >500 ms) was independently associated with mortality (OR 1.41, 95% CI 1.05 to 1.90). Previously mentioned parameters were incorporated into a risk score that accurately predicted in-hospital mortality (AUC 0.78). CONCLUSION: In the largest cohort of COVID-19 patients with complete ECG data on presentation, we found that in addition to demographics, presenting vitals, clinical history and basic metabolic panel values, QTc >500 ms is an independent risk factor for in-hospital mortality.

Increased Inpatient Mortality for Cardiovascular Patients During the First Wave of the COVID-19 Epidemic in New York.

Background The acuity and magnitude of the first wave of the COVID-19 epidemic in New York mandated a drastic change in healthcare access and delivery of care. Methods and Results We retrospectively studied patients admitted with an acute cardiovascular syndrome as their principal diagnosis to 13 hospitals across Northwell Health during March 11 through May 26, 2020 (first COVID-19 epidemic wave) and the same period in 2019. Three thousand sixteen patients (242 COVID-19 positive) were admitted for an acute cardiovascular syndrome during the first COVID-19 wave compared with 9422 patients 1 year prior (decrease of 68.0%, P<0.001). During this time, patients with cardiovascular disease presented later to the hospital (360 versus 120 minutes for acute myocardial infarction), underwent fewer procedures (34.6% versus 45.6%, P<0.001), were less likely to be treated in an intensive care unit setting (8.7% versus 10.8%, P<0.001), and had a longer hospital stay (2.91 [1.71-6.05] versus 2.87 [1.82-4.95] days, P=0.033). Inpatient cardiovascular mortality during the first epidemic outbreak increased by 111.1% (3.8 versus 1.8, P<0.001) and was not related to COVID-19-related admissions, all cause in-hospital mortality, or incidence of out-of-hospital cardiac deaths in New York. Admission during the first COVID-19 surge along with age and positive COVID-19 test independently predicted mortality for cardiovascular admissions (odds ratios, 1.30, 1.05, and 5.09, respectively, P<0.0001). Conclusions A lower rate and later presentation of patients with cardiovascular pathology, coupled with deviation from common clinical practice mandated by the first wave of the COVID-19 pandemic, might have accounted for higher in-hospital cardiovascular mortality during that period.

Clinical predictors of heart block during atrioventricular nodal reentrant tachycardia ablation: A multicenter 18-year experience.

BACKGROUND: Catheter ablation is considered the first-line treatment of symptomatic atrioventricular nodal reentrant tachycardia (AVNRT). It has been associated with a risk of heart block (HB) requiring a pacemaker. This study aims to determine potential clinical predictors of complete heart block as a result AVNRT ablation. METHODS: Consecutive patients undergoing catheter ablation for AVNRT from January 2001 to June 2019 at two tertiary hospitals were included. We defined ablation-related HB as the unscheduled implantation of pacemaker within a month of the index procedure. Use of electroanatomic mapping (EAM), operator experience, inpatient status, age, sex, fluoroscopy time, baseline PR interval, and baseline HV interval was included in univariate and multivariate models to predict HB post ablation. RESULTS: In 1708 patients (56.4 ± 17.0 years, 61% females), acute procedural success was 97.1%. The overall incidence of HB was 1.3%. Multivariate analysis showed that age more than 70 (odds ratio [OR] 7.907, p ≤ .001, confidence interval [CI] 2.759-22.666), baseline PR ≥ 190 ms (OR 2.867, p = .026, CI 1.135-7.239) and no use of EAM (OR 0.306, p = .037, CI 0.101-0.032) were independent predictors of HB. CONCLUSION: Although the incidence of HB post AVNRT ablation is generally low, patients can be further stratified using three simple predictors.

Association between regional distributions of SARS-CoV-2 seroconversion and out-of-hospital sudden death during the first epidemic outbreak in New York.

BACKGROUND: Increased incidence of out-of-hospital sudden death (OHSD) has been reported during the coronavirus 2019 (COVID-19) pandemic. New York City (NYC) represents a unique opportunity to examine the epidemiologic association between the two given the variable regional distribution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in its highly diverse neighborhoods. OBJECTIVE: The purpose of this study was to examine the association between OHSD and SARS-CoV-2 epidemiologic burden during the first COVID-19 pandemic across the highly diverse neighborhoods of NYC. METHODS: The incidences of OHSD between March 20 and April 22, 2019, and between March 20 and April 22, 2020, as reported by the Fire Department of New York were obtained. As a surrogate for viral epidemiologic burden, we used percentage of positive SARS-CoV-2 antibody tests performed between March 3 and August 20, 2020. Data were reported separately for the 176 zip codes of NYC. Correlation analysis and regression analysis were performed between the 2 measures to examine association. RESULTS: Incidence of OHSD per 10,000 inhabitants and percentage of SARS-CoV-2 seroconversion were highly variable across NYC neighborhoods, varying from 0.0 to 22.9 and 12.4% to 50.9%, respectively. Correlation analysis showed a moderate positive correlation between neighborhood data on OHSD and percentage of positive antibody tests to SARS-CoV-2 (Spearman ρ 0.506; P <.001). Regression analysis showed that seroconversion to SARS-CoV-2 and OHSD in 2019 were independent predictors for OHSD during the first epidemic surge in NYC (R2 = 0.645). CONCLUSION: The association in geographic distribution between OHSD and SARS-CoV-2 epidemiologic burden suggests either a causality between the 2 syndromes or the presence of local determinants affecting both measures in a similar fashion.

Surface unipolar electrogram characteristics to predict site of origin of outflow tract arrhythmias using noninvasive mapping.

BACKGROUND: Noninvasive electroanatomic mapping (NIEAM) demonstrate patterns of depolarization that are useful in identifying the chamber of origin (COO) in outflow tract ventricular arrhythmias (OTVA). However, its use in predicting exact site of origin (SOO) has not yet been validated. METHODS: NIEAMs (CardioInsight, Medtronic) from 40 patients (age 62.5 ± 2.6) undergoing ablation for OTVA were reviewed for diagnostic accuracy in predicting the SOO. Earliest arrhythmia breakout and directionality of earliest instantaneous unipolar electrograms (uEGMs) on NIEAMs were evaluated subjectively by two observers for quality and amplitude. Sites with most negative earliest uEGMs on right and left ventricular outflow tracts, as well as epicardial surface were manually identified. Using NIEAM-based activation timing of the lateral mitral annulus and basal septum COO was identified for each OTVA. Predictions of SOO using NIEAMs was compared with true SOO from invasive study. NIEAMs SOO predictions were compared with subjective 12 lead electrocardiogram (ECG) review by two observers. RESULTS: Review of arrhythmia breakout and signal directionality had poor diagnostic value in predicting SOO in OTVA (50.6% and 49.4%, 56.6% and 43.4%, respectively) and underperformed compared with ECG interpretation (59.1% and 80.5%). After excluding uEGMs with poor characteristics, the uEGM with most negative amplitude at the COO was predictive of the true SOO with 96.4% sensitivity and specificity. CONCLUSION: We propose a stepwise approach when interpreting NIEAMs for OTVA where patterns of activation are evaluated first to determine the COO, followed by identification of the site with most negative amplitude instantaneous uEGM to determine SOO.

Non-invasive electroanatomic mapping to reduce mapping time during catheter ablation of outflow tract ventricular premature depolarizations.

PURPOSE: Ventricular premature depolarizations (VPD) commonly arise from the septal anterior right ventricular outflow tract (sRVOT), the left coronary cusp (LCC), and the distal great cardiac vein (dGCV), and share common ECG characteristics. To assess the diagnostic accuracy of non-invasive electroanatomic mapping (NIEAM) in differentiating VPD origin between sRVOT, LCC and dGCV and quantify its clinical utility in eliminating unnecessary mapping and ablation. METHODS: ECGs and NIEAMs (CardioInsight, Medtronic) from 32 patients (56.3 ± 15.2 years) undergoing ablation for VPDs originating from sRVOT, LCC, or dGCV were blindly reviewed for their diagnostic accuracy in predicting the SOO. A 2-step algorithm using NIEAM-based activation timing of the superior basal septum of < 22.5 ms and lateral mitral annulus of > 60.5 ms was compared with subjective ECG evaluation, the maximum deflection index (MDI), and the V2 transitional ratio in predicting SOO. We calculated the mapping and ablation time that could have been avoided had the operators relied on activation timing by NIEAM in designing their mapping and ablation strategy. RESULTS: NIEAM was superior to subjective ECG evaluation, MDI, and V2 transition ratio in predicting the SOO yielding a sensitivity and specificity of 96.9% and 98.4% respectively. Using NIEAM in determining the SOO would have obviated 22 ± 4.5 min of mapping in the wrong chamber and prevented unnecessary ablation of 4.5 ± 1.8 min. CONCLUSION: NIEAM has high diagnostic accuracy in differentiating between sRVOT, LCC, and dGCV VPDs, and can significantly reduce mapping time, obviating the need for unnecessary access and ablation.

Anatomic predictors of recurrence after cryoablation for atrial fibrillation: a computed tomography based composite score.

BACKGROUND: Effective pulmonary vein isolation (PVI) with cryoablation depends on adequate occlusion of pulmonary veins (PV) by the cryoballoon and is therefore likely to be affected by PV and left atrial (LA) anatomical characteristics and variants. Thus, the objective of this study was to investigate the effect of LA and PV anatomy, evaluated by computed tomography (CT), on acute and long-term outcomes of cryoablation for atrial fibrillation (AF). METHODS: Fifty-eight patients (64.72 + 9.44 years, 60.3% male) undergoing cryoablation for paroxysmal or early persistent AF were included. Pre-procedural CT images were analyzed to evaluate LA dimensions and PV anatomical characteristics. Predictors of recurrence were identified using regression analysis. RESULTS: 60.3% of patients had two PVs on each side with separate ostia, whereas 29.3% and 10.3% had right middle and left common PVs, respectively. The following anatomic characteristics were found to be independent predictors of recurrence: right superior PV ostial max:min diameter ratio > 1.32, left superior PV ostial max:min diameter ratio > 1.2, right superior PV antral circumference > 69.1 mm, right inferior PV antral circumference > 61.38 mm, right superior PV angle > 22.7°. Using these factors, LA diameter and right middle PV, a scoring model was created for prediction of "unfavorable" LA-PV anatomy (AUC = 0.867, p = 0.000009, score range = 0-7). Score of ≥ 4 predicted need for longer cryoenergy ablation (p = 0.039) and more frequent switch to radiofrequency energy (p = 0.066) to achieve PVI, and had a sensitivity of 83.3% and specificity of 82.5% to predict clinical recurrence. CONCLUSION: CT-based scoring system is useful to identify "unfavorable" anatomy prior to cryo-PVI, which can result in procedural difficulty and poor outcomes.

Intracardiac echocardiography guided nonocclusive balloon cryothermal applications to achieve antral isolation during pulmonary vein isolation.

OBJECTIVE: Ablation for atrial fibrillation (AF) requires electrical isolation of the pulmonary veins (PV) by wide-area circumferential PV antral isolation (PVAI). Cryoballoon ablation delivers cryoenergy circumferentially after occlusion of the PV by the cryoballoon; thus, it is likely that the level of isolation, determined by adequate balloon-tissue contact, depends on PV anatomy. We sought to examine the need for nonocclusive segmental cryoballoon ablation in achieving antral isolation, describe methods of accurate visualization of the cryoballoon using intracardiac echocardiography (ICE), and provide data on biophysical characteristics of an effective nonocclusive cryothermal lesion. METHODS: Forty consecutive patients undergoing catheter ablation with a second-generation 28-mm cryoballoon and electroanatomic mapping (EAM) were included. Balloon was visualized with ICE, and its location was registered in EAM using available technology (CARTOSOUND, Biosense Webster). Need for delivery of nonocclusive lesions was based on level of isolation post occlusive lesions. RESULTS: Nonocclusive lesions to PVAI was required in 26 of 40 patients (65%) or 46 out of 148 veins (31%). Left PVs > 19.4 ± 2.9 mm, right superior PV > 20.2 ± 4.7mm, funnel-shaped PVs, and right PVs not converging to a carina were more likely to require nonocclusive lesions to achieve an antral level of isolation. Projection of balloon contour on EAM using CARTOSOUND successfully predicted level of isolation by voltage mapping. CONCLUSION: Nonocclusive cryoballoon applications are commonly required to achieve antral isolation. Use of ICE can be helpful in determining the accurate location of the balloon and in predicting the level of isolation by voltage map.

Early recurrence of atrial fibrillation after pulmonary vein isolation: a comparative analysis between cryogenic and contact force radiofrequency ablation.

BACKGROUND: Early recurrence (ER) of atrial fibrillation (AF) within 90 days post-ablation is observed in up to 50% of patients and has been attributed to transient inflammation. The importance of ER in current era of pulmonary vein isolation (PVI) with cryoballoon ablation (CBA) and contact-force catheter radiofrequency ablation (cfRFA) has not been clearly reported. In addition, it is not known whether there are differences between types of ablation energy used during PVI. METHODS: Study population was drawn from a prospective multicenter database of AF ablation. Consecutive patients undergoing first-time ablation with PVI alone, using either second-generation CBA or cfRFA catheters were included. Patients were followed at 0.5, 3, 6, and 12 months to assess recurrence. Predictors of late recurrence (LR), defined as recurrence outside the blanking period, were assessed by Cox proportional hazards regression models. Freedom from LR was calculated and compared between two groups using the Kaplan-Meier method and log-rank test. RESULTS: Study cohort included 300 patients (1:1 CBA:RFA, age 63.6 ± 10.3 years, 67% male). There were no baseline characteristic differences between the CBA and cfRFA groups. ER occurred in 23.3% and 16.7% of patients in the CBA and cfRFA groups, respectively (p = 0.149). One-year freedom from LR was similar for both groups (72.7% CBA vs. 78% cfRFA, p = 0.287). Fifty-two patients (25 CBA and 27 cfRFA) underwent repeat ablation and no difference in durability of PVI was found. ER was the only common independent predictor of LR for either group and for the entire cohort (HR 2.3). CONCLUSIONS: In our series of AF ablation using second-generation cryoballoon and contact-force RFA catheters, recurrence in the "blanking period" is seen in 20% and remains predictive of late recurrence irrespective of the energy used.

Conduction patterns of idiopathic arrhythmias from the endocardium and epicardium of outflow tracts: New insights with noninvasive electroanatomic mapping.

BACKGROUND: Idiopathic arrhythmias commonly arise from the septal right ventricular outflow tract (RVOT), sinuses of Valsalva (SoV), and great cardiac vein (GCV). Predicting the exact site of origin is important for preparation for catheter ablation. OBJECTIVE: The purpose of this study was to examine the diagnostic value of noninvasive electroanatomic mapping (NIEAM) to differentiate between septal RVOT, SoV, and GCV origin and compare it to that of 12-lead electrocardiography (ECG). METHODS: NIEAM maps (CardioInsight, Medtronic) were generated during spontaneous ventricular premature depolarizations (VPDs) and threshold pacing from septal RVOT, SoV, and GCV. Origin prediction using NIEAM was compared to algorithmic ECG criteria (maximal deflection index; V2 transition ratio) and subjective ECG evaluation. RESULTS: Sixty NIEAMs (18 spontaneous VPDs and 42 pace-maps) from 31 patients (age 56 ± 16 years) were analyzed. NIEAM showed distinct conduction patterns, best visualized at the base of the heart: septal RVOT VPDs propagate toward the tricuspid annulus, depolarizing the septum from inferior to superior; SoV VPDs engage the superior septum early; and GCV VPDs move laterally along the mitral annulus, depolarizing the heart from left to right. Activation of the lateral mitral annulus >60.50 ms and the superior basal septum <22.5 ms from onset predicts RVOT and SoV origin, respectively, in 100% of cases. NIEAM was superior to maximum deflection index in predicting GCV origin (100% vs 42.2% accuracy) and superior to V2 transition ratio in predicting SoV origin (100% vs 75.9% accuracy). CONCLUSION: Arrhythmias arising from the outflow tracts follow distinct propagation patterns depending on the origin. A 2-step algorithm using activation timing by NIEAM yields 100% diagnostic accuracy in predicting origin.