Sequential Isolation of Persistent Left Superior Vena Cava and Right Superior Vena Cava Using Pulsed-field Ablation with a Pentaspline Catheter for Recurrent Persistent Atrial Fibrillation.

Pulsed-field ablation (PFA) is a novel technology for atrial fibrillation (AF) ablation that can deliver energy precisely with a lower risk of damage to the surrounding organs. Persistent left superior vena cava (PLSVC) is a congenital variant that can act as a driver of AF, and its isolation may be required in recurrent persistent AF. We describe a case where PFA was used for isolation of the right superior vena cava, PLSVC, and posterior wall of the left atrium.

Predictors of left atrial appendage emptying velocity: Derivation and validation of CHIRP3(M-1) score.

BACKGROUND: Atrial fibrillation (AF) leads to impaired left atrial appendage contractility, increasing the risk of thromboembolic stroke. The left atrial appendage emptying velocity (LAAev) measured on transesophageal echocardiogram (TEE) is a marker of increased thromboembolic risk. OBJECTIVES: To evaluate predictors of reduced LAAev for identifying individuals at increased risk of cardiogenic stroke. METHODS: This was a single-center retrospective review of TEEs and clinical charts. Predictors of LAAev <30 cm/s were identified using logistic regression. A risk prediction model was created using stepwise selection in a derivation set (n=695) and separately tested in a validated set (n=300). RESULTS: We included TEEs on 995 patients (age 71.3±12.7 years, female 38.1%, history of AF 82.1%, in AF at evaluation 27.7%, CHA2DS2-VASc score 4.1±1.9, LAAev 41.6±21.0 cm/s). Significant multivariable predictors of LAAev <30 cm/s in derivation set were used to create the CHIRP3M-1 score containing 8 variables: Coronary artery disease (1), congestive Heart failure (1), Increased left atrial volume index ≥42 mL/m2 (1), current Rhythm AF (1), Paroxysmal AF (2), Persistent AF (3), long standing Persistent/permanent AF (4), and >moderate Mitral regurgitation (-1). In the validation set, as compared to intermediate scores (3-4), those with a low scores (≤2) and high scores (≥5) had odds ratios for LAAev <30 cm/s of 0.41 (0.21, 0.78, p=0.007) and 2.58 (95% CI 1.45, 4.61, p=0.001) respectively. CONCLUSION: We developed and validated a novel risk stratification system to predict reduced LAAev using clinical and echocardiographic variables. This may help refine the stratification of cardiogenic stroke risk.

Evaluation of electrocardiographic criteria for predicting left ventricular hypertrophy and dilation in presence of left bundle branch block.

BACKGROUND: The utility of standard published electrocardiographic (ECG) criteria for left ventricular hypertrophy (LVH) in patients with left bundle branch block (LBBB) is not established. We have previously shown that in ECGs demonstrating LBBB, QRS duration outperforms vectorcardiographic X, Y, Z lead and root-mean-squared (3D) amplitudes and voltage-time-integrals in diagnosing LVH and dilation. We sought to evaluate diagnostic yields of published LVH criteria versus QRS duration for ECG based diagnosis of LVH and dilation in presence of LBBB. METHODS: We included adult patients with typical LBBB having ECG and transthoracic echocardiogram performed within 3 months of each other in 2010-2020. We obtained area under receiver-operator characteristic curve (AUC) for QRS duration and each of the published ECG LVH criteria to predict increased LV mass indexed (↑LVMi, women >95 g/m2, men >115 g/m2) and LV end diastolic volume indexed (↑LVEDVi, women >61 mL/m2, men >74 mL/m2). RESULTS: Among 413 adults (53 % women, age 73 ± 12 yr) with LBBB, the traditional LVH criteria performed poorly to detect ↑LVMi or ↑LVEDVi. Cornell voltage-duration product had the highest AUCs (↑LVMi 0.634, ↑LVEDVi 0.580). QRS duration had a higher AUC for diagnosing ↑LVMi (women 0.657, men 0.703) and ↑LVEDVi (women 0.668, men 0.699) compared to any other criteria. CONCLUSIONS: In patients with LBBB, prolonged QRS duration (women ≥150 ms, men ≥160 ms) is a superior predictor of LVH and dilation than traditional ECG-based LVH criteria.

Incidence and outcomes of cardiovascular implantable electronic device infections in patients with end-stage kidney disease.

BACKGROUND: End-stage kidney disease (ESKD) patients are prone to bloodstream infections that may result in a higher risk of cardiac implantable electronic device (CIED) infections. OBJECTIVE: The objective of this study was to assess the incidence, risk predictors, management strategies, and long-term outcomes of CIED infections in ESKD patients undergoing de novo CIED implantation. METHODS: This is a retrospective study using the United States Renal Data System. ESKD patients with de novo CIED implantation between January 1, 2006, and September 30, 2014, were included. Patients were observed until death, kidney transplantation, end of Medicare coverage, or September 30, 2015, to assess incidence of CIED infection. Management approach was determined from procedure codes for lead extraction within 60 days of CIED infection diagnosis. Patients with CIED infection were observed until December 31, 2019, to assess long-term outcomes. RESULTS: Of 15,515 ESKD patients undergoing de novo CIED implantation, incidence of CIED infection was 4.8% during a median follow-up of 1.3 years. The presence of a defibrillator (adjusted hazard ratio [aHR], 1.48), higher body mass index (aHR, 1.01), and younger age (aHR, 0.96) were independent risk factors for CIED infection. Lead extraction occurred in only 50.71% of patients by 60 days. After propensity score matching, the 3-year mortality was higher in those who did not undergo lead extraction compared with those who did (80.3% vs 72.3%) and time to mortality was shorter (0.3 vs 0.6 year). Only 13.8% of patients underwent reimplantation with a new CIED after lead extraction. CONCLUSION: CIED infections occur frequently in ESKD patients and are associated with a high mortality. Early lead extraction is not performed routinely but is associated with improved survival.

Artificial Intelligence Interpretation of the Electrocardiogram: A State-of-the-Art Review.

PURPOSE OF REVIEW: Artificial intelligence (AI) is transforming electrocardiography (ECG) interpretation. AI diagnostics can reach beyond human capabilities, facilitate automated access to nuanced ECG interpretation, and expand the scope of cardiovascular screening in the population. AI can be applied to the standard 12-lead resting ECG and single-lead ECGs in external monitors, implantable devices, and direct-to-consumer smart devices. We summarize the current state of the literature on AI-ECG. RECENT FINDINGS: Rhythm classification was the first application of AI-ECG. Subsequently, AI-ECG models have been developed for screening structural heart disease including hypertrophic cardiomyopathy, cardiac amyloidosis, aortic stenosis, pulmonary hypertension, and left ventricular systolic dysfunction. Further, AI models can predict future events like development of systolic heart failure and atrial fibrillation. AI-ECG exhibits potential in acute cardiac events and non-cardiac applications, including acute pulmonary embolism, electrolyte abnormalities, monitoring drugs therapy, sleep apnea, and predicting all-cause mortality. Many AI models in the domain of cardiac monitors and smart watches have received Food and Drug Administration (FDA) clearance for rhythm classification, while others for identification of cardiac amyloidosis, pulmonary hypertension and left ventricular dysfunction have received breakthrough device designation. As AI-ECG models continue to be developed, in addition to regulatory oversight and monetization challenges, thoughtful clinical implementation to streamline workflows, avoiding information overload and overwhelming of healthcare systems with false positive results is necessary. Research to demonstrate and validate improvement in healthcare efficiency and improved patient outcomes would be required before widespread adoption of any AI-ECG model.

Safety of catheter ablation in patients with recently implanted cardiac implantable electronic device: A 5-year experience.

INTRODUCTION: Catheter ablation (CA) can interfere with cardiac implantable electronic device (CIED) function. The safety of CA in the 1st year after CIED implantation/lead revision is uncertain. METHODS: This single center, retrospective cohort included patients who underwent CA between 2012 and 2017 and had a CIED implant/lead revision within the preceding year. We assessed the frequency of device/lead malfunctions in this population. RESULTS: We identified 1810 CAs in patients between 2012 and 2017, with 170 CAs in 163 patients within a year of a CIED implant/lead revision. Mean age 68 ± 12 years (68% men). Time between the CIED procedure and CA was 158 ± 99 days. The CA procedures included AF ablation (n = 57, 34%), AV node ablation (n = 40, 24%), SVT ablation (n = 37, 22%), and PVC/VT ablations (n = 36, 21%). The cumulative frequency of lead dislodgement, significant CIED dysfunction, and/or CIED-related infection following CA was (n = 1/170, 0.6%). There was a single atrial lead dislodgement (0.6%). There were no instances of power-on-reset or CIED-related infection. Following CA, there was no significant difference in RA or RV lead sensing (p = 0.52 and 0.84 respectively) or thresholds (p = 0.94 and 0.17 respectively). The RA impedance slightly decreased post-CA from 474 ± 80 Ohms to 460 ± 73 Ohms (p = 0.002), as did the RV impedance (from 515 ± 111 Ohms to 497 ± 98 Ohms, p < 0.0001). CONCLUSIONS: CA can be performed within 1 year following CIED implantation/lead revision with a low risk of CIED/lead malfunction or lead dislodgement. The ideal time to perform CA after a CIED remains uncertain.

Pilot study to evaluate left-to-right ventricular offset in biventricular pacing-comparison of electrocardiographic imaging and ECG.

INTRODUCTION: Biventricular pacing (BiVp) improves outcomes in systolic heart failure patients with electrical dyssynchrony. BiVp is delivered from epicardial left ventricular (LV) and endocardial right ventricular (RV) electrodes. Acute electrical activation changes with different LV-RV stimulation offsets can help guide individually optimized BiVp programming. We sought to study the BiVp ventricular activation with different LV-RV offsets and compare with 12-lead ECG. METHODS: In five patients with BiVp (63 ± 17-year-old, 80% male, LV ejection fraction 27 ± 6%), we evaluated acute ventricular epicardial activation, varying LV-RV offsets in 20 ms increments from -40 to 80 ms, using electrocardiographic imaging (ECGI) to obtain absolute ventricular electrical uncoupling (VEUabs, absolute difference in average LV and average RV activation time) and total activation time (TAT). For each patient, we calculated the correlation between ECGI and corresponding ECG (3D-QRS-area and QRS duration) with different LV-RV offsets. RESULTS: The LV-RV offset to attain minimum VEUabs in individual patients ranged 20-60 ms. In all patients, a larger LV-RV offset was required to achieve minimum VEUabs (36 ± 17 ms) or 3D-QRS-area (40 ± 14 ms) than that for minimum TAT (-4 ± 9 ms) or QRS duration (-8 ± 11 ms). In individual patients, 3D-QRS-area correlated with VEUabs (r 0.65 ± 0.24) and QRS duration correlated with TAT (r 0.95 ± 0.02). Minimum VEUabs and minimum 3D-QRS-area were obtained by LV-RV offset within 20 ms of each other in all five patients. CONCLUSIONS: LV-RV electrical uncoupling, as assessed by ECGI, can be minimized by optimizing LV-RV stimulation offset. 3D-QRS-area is a surrogate to identify LV-RV offset that minimizes LV-RV uncoupling.

Different methods of 3D QRS area calculation from vectorcardiographic X, Y, and Z Leads.

3DQRSarea is a strong marker for cardiac resynchronization therapy and can be obtained by taking the (i) summation or the (ii) difference of the areas subtended by positive and negative deflections in X, Y, Z vectorcardiographic electrocardiogram (ECG) leads. We correlated both methods with the instantaneous-absolute-3D-voltage-time-integral (VTIQRS-3D). 3DQRSarea consistently underestimated the VTIQRS -3D, but the summation method was a closer and more reliable approximation. The dissimilarity was less apparent in left bundle branch block (r2 summation .996 vs. difference .972) and biventricular paced ECGs (r2 .996 vs. .957) but was more apparent in normal ECGs (r2 .988 vs. .653).

Cardiac resynchronization therapy for pacing induced cardiomyopathy: Role of baseline right ventricular pacing burden.

BACKGROUND: Cardiac resynchronization therapy (CRT) is indicated for patients with heart failure with reduced left ventricular ejection fraction (LVEF) and chronic right ventricular (RV) pacing burden ≥40% (pacing-induced cardiomyopathy, PICM). It is uncertain whether baseline RV pacing burden impacts response to CRT. METHODS: We conducted a retrospective study of all CRT upgrades for PICM at our hospital from January 2017 to December 2018. Univariate and multivariable-adjusted changes in LVEF, and echocardiographic response (≥10% improvement in LVEF) at 3-12 months post-CRT upgrade were compared in those with RV pacing burden ≥90% versus <90%. RESULTS: We included 75 patients (age 74 ± 11 years, 71% male) who underwent CRT upgrade for PICM. The baseline RV pacing burden was ≥90% in 56 patients (median 99% [IQR 98%-99%]), and <90% in 19 patients (median 79% [IQR 73%-87%]). Improvement in LVEF was greater in those with baseline RV pacing burden ≥90% versus <90% (15.7 ± 9.3% vs. 7.5 ± 9.6%, p = .003). Baseline RV pacing burden ≥90% was a strong predictor of an improvement in LVEF ≥10% after CRT upgrade both in univariate and multivariate-adjusted models (p = .005 and .02, respectively). CONCLUSION: A higher baseline RV pacing burden predicts a greater improvement in LVEF after CRT upgrade for PICM.

Electrocardiographic Z-axis QRS-T voltage-time-integral in patients with typical right bundle branch block - Correlation with echocardiographic right ventricular size and function.

BACKGROUND: Right bundle branch block (RBBB) can be benign or associated with right ventricular (RV) functional and structural abnormalities. Our aim was to evaluate QRS-T voltage-time-integral (VTI) compared to QRS duration and lead V1 R' as markers for RV abnormalities. METHODS: We included adults with an ECG demonstrating RBBB and echocardiogram obtained within 3 months of each other, between 2010 and 2020. VTIQRS and VTIQRST were obtained for 12 standard ECG leads, reconstructed vectorcardiographic X, Y, Z leads and root-mean-squared (3D) ECG. Age, sex and BSA-adjusted linear regressions were used to assess associations of QRS duration, amplitudes, VTIs and lead V1 R' duration/VTI with echocardiographic tricuspid annular plane systolic excursion (TAPSE), RV tissue Doppler imaging S', basal and mid diameter, and systolic pressure (RVSP). RESULTS: Among 782 patients (33% women, age 71 ± 14 years) with RBBB, R' duration in lead V1 was modestly associated with RV S', RV diameters and RVSP (all p ≤ 0.03). QRS duration was more strongly associated with RV diameters (both p < 0.0001). AmplitudeQRS-Z was modestly correlated with all 5 RV echocardiographic variables (all p ≤ 0.02). VTIR'-V1 was more strongly associated with TAPSE, RV S' and RVSP (all p ≤ 0.0003). VTIQRS-Z and VTIQRST-Z were among the strongest correlates of the 5 RV variables (all p < 0.0001). VTIQRST-Z.√BSA cutoff of ≥62 µVsm had sensitivity 62.7% and specificity 65.7% for predicting ≥3 of 5 abnormal RV variables (AUC 0.66; men 0.71, women 0.60). CONCLUSION: In patients with RBBB, VTIQRST-Z is a stronger predictor of RV dysfunction and adverse remodeling than QRS duration and lead V1 R'.

Case of a misleading ECG.

An elderly man with severe chronic obstructive pulmonary disease and a history of complete heart block with pacemaker placement was found to have pacemaker lead infection and required device extraction. He had a standard dual chamber pacemaker in place, however the ECG obtained showed paced QRS complexes with presence of R wave in lead V1 and QS in lead I suggestive of left ventricular pacing. Additional imaging with CT scan obtained for confirmation revealed that the heart was displaced to the left posterior hemithorax secondary to pulmonary disease. Due to significant posterolateral rotation of the heart, a right ventricular paced rhythm can demonstrate Q/S waves in the lateral leads (I, aVL, V5-6) and R waves in the right precordial leads (V1-3). This can be misdiagnosed as a left ventricular paced rhythm.

Novel mutation in N-terminal fragment of ryanodine receptor 2 causing catecholaminergic polymorphic ventricular tachycardia.

CPVT is a rare inherited arrhythmogenic disorder characterized by bidirectional, polymorphic ventricular arrhythmias triggered by catecholamines released during exercise, stress, or sudden emotion in individuals with a normal resting electrocardiogram and structurally normal heart. Mutations in the ryanodine receptor 2 gene are the most common known etiology of this disorder. The c.1195A > G(p.Met399Val) variant in Exon 14 of RyR2 is currently classified as a Variant of Uncertain Significance. We present a case of CPVT caused by this novel disease-causing RyR2 variant and discuss its pathophysiology. The role of SSRIs in treating patients with CPVT unresponsive to mainstream therapies is also highlighted.

Electrocardiographic prediction of left ventricular hypertrophy in women and men with left bundle branch block - Comparison of QRS duration, amplitude and voltage-time-integral.

BACKGROUND: Standard ECG criteria for left ventricular (LV) hypertrophy rely on QRS amplitudes. However, in the setting of left bundle branch block (LBBB), ECG correlates of LV hypertrophy are not well established. We sought to evaluate quantitative ECG predictors of LV hypertrophy in the presence of LBBB. METHODS: We included adult patients with typical LBBB having ECG and transthoracic echocardiogram performed within 3 months of each other in 2010-2020. Orthogonal X, Y, Z leads were reconstructed from digital 12­lead ECGs using Kors's matrix. In addition to QRS duration, we evaluated QRS amplitudes and voltage-time-integrals (VTIs) from all 12 leads, X, Y, Z leads and 3D (root-mean-squared) ECG. We used age, sex and BSA-adjusted linear regressions to predict echocardiographic LV calculations (mass, end-diastolic and end-systolic volumes, ejection fraction) from ECG, and separately generated ROC curves for predicting echocardiographic abnormalities. RESULTS: We included 413 patients (53% women, age 73 ± 12 years). All 4 echocardiographic LV calculations were most strongly correlated with QRS duration (all p < 0.00001). In women, QRS duration ≥ 150 ms had sensitivity/specificity 56.3%/64.4% for increased LV mass and 62.7%/67.8% for increased LV end-diastolic volume. In men, QRS duration ≥ 160 ms had a sensitivity/specificity 63.1%/72.1% for increased LV mass and 58.3%/74.5% for increased LV end-diastolic volume. QRS duration was best able to discriminate eccentric hypertrophy (area under ROC curve 0.701) and increased LV end-diastolic volume (0.681). CONCLUSIONS: In patients with LBBB, QRS duration (≥ 150 in women and ≥ 160 in men) is a superior predictor of LV remodeling esp. eccentric hypertrophy and dilation.

Multicenter assessment of the outcomes of subcutaneous ICD implantation in patients with prior or future sternotomy.

BACKGROUND: The subcutaneous ICD (S-ICD) is a viable alternative to transvenous ICD and avoids intravascular complications in patients without a pacing indication. The outcomes of S-ICD implantation are uncertain in patients with prior sternotomy. OBJECTIVE: We aim to compare the implant techniques and outcomes with S-ICD implantation in patients with and without prior sternotomy. METHODS: Multicenter retrospective cohort study including adult patients with an S-ICD implanted between January 2014 and June 2020. Outcomes were compared between patients with and without prior sternotomy. RESULTS: Among the 212 patients (49 ± 15 years old, 43% women, BMI 30 ± 8 kg/m2 , 68% primary prevention, 30% ischemic cardiomyopathy, LVEF median 30% IQR 25%-45%) who underwent S-ICD implantation, 47 (22%) had a prior sternotomy. There was no difference in the sensing vector (57% vs. 53% primary, p = 0.55), laterality of the S-ICD lead to the sternum (94% vs. 96% leftward, p = 0.54), or the defibrillation threshold (65 ± 1.4 J vs. 65 ± 0.8 J, p = 0.76) with versus without prior sternotomy. The frequency of 30-day complications was similar with and without prior sternotomy (n = 3/47 vs. n = 15/165, 6% vs. 9%, p = 0.56). Over a median follow-up of 28 months (IQR 10-49 months), the frequency of inappropriate shocks was similar between those with and without prior sternotomy (n = 3/47 and n = 16/165, 6% vs. 10%, p = 0.58). CONCLUSION: Implantation of an S-ICD in patients with prior sternotomy is safe with a similar risk of 30-day complications and inappropriate ICD shocks as patients without prior sternotomy.

Narrow Complex Tachycardia With Intermittent 2:1 Atrioventricular Relationship.

Narrow QRS complex tachycardia has a broad differential diagnosis. We present a series of rhythm strips with representative onset, transition from 2:1 AV conduction to 1:1 AV conduction, and offset of tachycardia. By analyzing these rhythm strips, we can identify the electrophysiologic mechanism and diagnosis. (Level of Difficulty: Intermediate.).

UltraSound Axillary Vein Access (USAA): Learning curve and randomized comparison to traditional venous access for cardiac device implantation.

BACKGROUND: Many techniques exist for venous access (VA) during cardiac implantable electronic device (CIED) implantation. OBJECTIVE: We sought to evaluate the learning curve with ultrasound (US) guided axillary vein access (USAA). METHODS: Single-center prospective randomized controlled trial of patients undergoing CIED implantation. Patients were randomized in a 2:1 fashion to USAA versus conventional VA techniques. The primary outcomes were the success rates, VA times and 30-day complication rates. RESULTS: The study included 100 patients (age 68 ± 14 years, BMI 27 ± 4 kg/m2 ). USAA was successful in 66/70 implants (94%). Initial attempts at conventional VA included 47% axillary (n = 14), 30% (n = 9) cephalic, and 23% (n = 7) subclavian. The median access time was longer for USAA than conventional access (8.3 IQR 4.2-15.3 min vs. 5.2 IQR 3.4-8.6 min, p = .009). Among the five inexperienced USAA implanters, there was a significant improvement in median access time from first to last tertile of USAA implants (17.0 IQR 7.0-21.0 min to 8.6 IQR 4.5-10.8 min, p = .038). The experienced USAA implanter had similar access times with USAA compared with conventional access (4.0 IQR 3.3-4.7 min vs. 5.2 IQR 3.4-8.6 min, p = .15). Venograms were less common with USAA than conventional access (2% vs. 33%, p < .0001). The 30-day complication rate was similar with USAA (n = 4/70, 6%) versus conventional (n = 3/30, 10%, p = .44). CONCLUSION: Although the success rate with USAA was high, there was a significant learning curve. Once experienced with the USAA technique, there is the potential for reduced complications without adding to the procedure duration.