Sinus Rhythm Electrocardiographic Abnormalities, Sites of Origin, and Ablation Outcomes of Ventricular Premature Depolarizations Initiating Ventricular Fibrillation

BACKGROUND

Ventricular fibrillation (VF) can be initiated by ventricular premature depolarizations (VPDs) in the absence of obvious structural abnormalities.

OBJECTIVE

To determine the prevalence of 12-lead ECG sinus rhythm reduced QRS amplitude, QRS fractionation (QRSf) and early repolarization (ER) pattern, and the outcome of catheter ablation and VPD anatomic distribution in patients with VPDs initiating VF.

METHODS

We compared a cohort with no apparent structural heart disease and VPDs initiating VF (Group 1, n=42) to a reference cohort (Group 2, n=61) of patients with no structural heart disease and symptomatic unifocal VPDs.

RESULTS

A reduced QRS amplitude (<.55 mV) in aVF (59 % vs 10%, p<0.001), QRSf in ≥2 contiguous leads (50% vs 16%, p<0.001) and early repolarization pattern (21.4% vs 1.6%, p=0.01) were more common in Group 1 vs Group 2. At least one abnormal ECG finding was present in 34 (81%) Group 1 vs 17 (28%) Group 2 patients, (p<0.001). VPD origin included RV and LV distal Purkinje system and moderator band/ papillary muscles, in 83% Group 1 vs 18% Group 2 patients, p<0.001. VF was eliminated with single ablation procedure in 77% of Group 1 patients with at least 2 years of follow-up.

CONCLUSIONS

A reduced QRS amplitude (<.55 mV) in aVF, QRS fractionation in ≥2 contiguous leads and/or an early repolarization pattern are frequently observed in patients with VPDs initiating VF. VPDs initiating VF typically originate from the distal Purkinje system and papillary muscles and can be successfully eliminated with catheter ablation.

Racial, Ethnic, and Socioeconomic Inequities in Access to Left Atrial Appendage Occlusion

Background Inequitable access to high-technology therapeutics may perpetuate inequities in care. We examined the characteristics of US hospitals that did and did not establish left atrial appendage occlusion (LAAO) programs, the patient populations those hospitals served, and the associations between zip code-level racial, ethnic, and socioeconomic composition and rates of LAAO among Medicare beneficiaries living within large metropolitan areas with LAAO programs. Methods and Results We conducted cross-sectional analyses of Medicare fee-for-service claims for beneficiaries aged 66 years or older between 2016 and 2019. We identified hospitals establishing LAAO programs during the study period. We used generalized linear mixed models to measure the association between zip code-level racial, ethnic, and socioeconomic composition and age-adjusted rates of LAAO in the most populous 25 metropolitan areas with LAAO sites. During the study period, 507 candidate hospitals started LAAO programs, and 745 candidate hospitals did not. Most new LAAO programs opened in metropolitan areas (97.4%). Compared with non-LAAO centers, LAAO centers treated patients with higher median household incomes (difference of $913 [95% CI, $197-$1629], P=0.01). Zip code-level rates of LAAO procedures per 100 000 Medicare beneficiaries in large metropolitan areas were 0.34% (95% CI, 0.33%-0.35%) lower for each $1000 zip code-level decrease in median household income. After adjustment for socioeconomic markers, age, and clinical comorbidities, LAAO rates were lower in zip codes with higher proportions of Black or Hispanic patients. Conclusions Growth in LAAO programs in the United States had been concentrated in metropolitan areas. LAAO centers treated wealthier patient populations in hospitals without LAAO programs. Within major metropolitan areas with LAAO programs, zip codes with higher proportions of Black and Hispanic patients and more patients experiencing socioeconomic disadvantage had lower age-adjusted rates of LAAO. Thus, geographic proximity alone may not ensure equitable access to LAAO. Unequal access to LAAO may reflect disparities in referral patterns, rates of diagnosis, and preferences for using novel therapies experienced by racial and ethnic minority groups and patients experiencing socioeconomic disadvantage.

Very low-calorie ketogenic diet (VLCKD): an antihypertensive nutritional approach

BACKGROUND

Obesity is accompanied by hormonal, inflammatory and endothelial alterations. These alterations induce a stimulation of several other mechanisms that contribute to the hypertensive state and to increase the cardiovascular morbidity. This pilot, open - label, single- center, prospective clinical trial aimed to evaluate the effect of very low- calorie ketogenic diet (VLCKD) on blood pressure (BP) in women with of obesity and hypertension.

METHODS

A total of 137 women, who met the inclusion criteria and accepted to adhere to VLCKD, were consecutively enrolled. Assessment of anthropometric parameters (weight, height, and waist circumference), body composition (through bioelectrical impedance analysis), systolic (SBP) and diastolic blood pressure (DBP) and blood sample collection were carried out at baseline and after 45 days of the active phase of VLCKD.

RESULTS

After VLCKD all the women experienced a significant reduction in body weight and an overall improvement of body composition parameters. In addition, high sensitivity C reactive protein (hs- CRP) levels were significantly diminished (p < 0.001), while phase angle (PhA) increased by almost 9% (p < 0.001). Interestingly, both SBP and DBP were significantly improved (-12.89% and - 10.77%, respectively; p < 0.001). At baseline, SBP and DBP showed statistically significant correlations with body mass index (BMI), waist circumference, hs-CRP levels, PhA, total body water (TBW), extracellular water (ECW), Na / K ratio, and fat mass. Even after VLCKD, all correlations among SBP and DBP with the study variables were statistically significant, except for the association between DBP and Na / K ratio. Changes (%) in both SBP and DBP were associated with ∆BMI%, ∆PhA% and ∆hs- CRP levels (p < 0.001). In addition, only ∆SBP% was associated with ∆waist circumference (p = 0.017), ∆TBW (p = 0.017), and ∆fat mass (p < 0.001); while only ∆DBP% was associated with ∆ECW (p = 0.018), and ∆Na / K ratio (p = 0.048). After adjusting for ∆BMI, ∆WC, ∆PhA, ∆TBW, and ∆fat mass, the correlation between changes in ∆SBP and ∆hs -CRP levels remained statistically significant (p < 0.001). Similarly, the correlation between ∆DBP and ∆hs- CRP levels also remained statistically significant after adjustment for ∆BMI, ∆PhA, ∆Na / K ratio, and ∆ECW (p < 0.001). From multiple regression analysis ∆hs- CRP levels seemed to be the main predictor of changes of BP (p < 0.001).

CONCLUSION

VLCKD reduces BP in women with of obesity and hypertension in a safely manner.

The value of functional substrate mapping in ventricular tachycardia ablation

In the setting of structural heart disease, ventricular tachycardia (VT) is typically associated with a re-entrant mechanism. In patients with hemodynamically tolerated VTs, activation and entrainment mapping remain the gold standard for the identification of the critical parts of the circuit. However, this is rarely accomplished, as most VTs are not hemodynamically tolerated to permit mapping during tachycardia. Other limitations include noninducibility of arrhythmia or nonsustained VT. This has led to the development of substrate mapping techniques during sinus rhythm, eliminating the need for prolonged periods of mapping during tachycardia. Recurrence rates following VT ablation are high; therefore, new mapping techniques for substrate characterization are required. Advances in catheter technology and especially multielectrode mapping of abnormal electrograms has increased the ability to identify the mechanism of scar-related VT. Several substrate-guided approaches have been developed to overcome this, including scar homogenization and late potential mapping. Dynamic substrate changes are mainly identified within regions of myocardial scar and can be identified as local abnormal ventricular activities. Furthermore, mapping strategies incorporating ventricular extrastimulation, including from different directions and coupling intervals, have been shown to increase the accuracy of substrate mapping. The implementation of extrastimulus substrate mapping and automated annotation require less extensive ablation and would make VT ablation procedures less cumbersome and accessible to more patients.

A systematic review and meta-analysis comparing radiofrequency catheter ablation with medical therapy for ventricular tachycardia in patients with ischemic and non-ischemic cardiomyopathies

BACKGROUND

In patients with cardiomyopathy, radiofrequency catheter ablation (CA) for ventricular tachycardia (VT) is an adjunctive and alternative treatment option to long-term anti-arrhythmic drug therapy. We sought to compare CA with medical therapy for the management of VT in patients with ischemic and non-ischemic cardiomyopathies.

METHODS

MEDLINE, Cochrane, and ClinicalTrials.gov databases were evaluated for relevant studies.

RESULTS

Eleven studies with 2126 adult patients were included (711 in CA, 1415 in medical therapy). In the randomized controlled trial (RCT) analysis, CA reduced risk of recurrent VT (risk ratio (RR) 0.79 [95% CI 0.67 to 0.93], p = 0.005), ICD shocks (RR 0.64 [95% CI 0.45 to 0.89] p = 0.008), and cardiac hospitalizations (RR 0.76 [95% CI 0.63 to 0.92] p = 0.005). There was no difference in all-cause mortality (RR 0.94, p = 0.71). In combined RCT and observational study analysis, there was a trend for reduction in all-cause mortality (RR 0.75 [95% CI 0.55 to 1.02] p = 0.07). In subgroup analysis of studies with mean left ventricular ejection fraction (LVEF) < 35%, CA demonstrated reduction in mortality (RR 0.71, p = 0.004), ICD shocks (RR 0.63, p = 0.03), VT recurrence (RR 0.76, p = 0.004), and cardiac hospitalizations (RR 0.75, p = 0.02). The subgroup of early CA prior to ICD shocks demonstrated reduction in ICD shocks (RR 0.57, p < 0.001) and VT recurrence (RR 0.74, p = 0.01).

CONCLUSIONS

CA for VT demonstrated a lower risk of VT recurrence, ICD shocks, and hospitalization in comparison to medical therapy. The subgroups of early CA and LVEF < 35% demonstrated better outcomes.

Predictors of Atrial Fibrillation in Patients With Stroke Attributed to Large- or Small-Vessel Disease: A Prespecified Secondary Analysis of the STROKE AF Randomized Clinical Trial

Importance

The Stroke of Known Cause and Underlying Atrial Fibrillation (STROKE AF) trial found that approximately 1 in 8 patients with recent ischemic stroke attributed to large- or small-vessel disease had poststroke atrial fibrillation (AF) detected by an insertable cardiac monitor (ICM) at 12 months. Identifying predictors of AF could be useful when considering an ICM in routine poststroke clinical care.

Objective

To determine the association between commonly assessed risk factors and poststroke detection of new AF in the STROKE AF cohort monitored by ICM.

Design, Setting, and Participants

This was a prespecified analysis of a randomized (1:1) clinical trial that enrolled patients between April 1, 2016, and July 12, 2019, with primary follow-up through 2020 and mean (SD) duration of 11.0 (3.0) months. Eligible patients were selected from 33 clinical research sites in the US. Patients had an index stroke attributed to large- or small-vessel disease and were 60 years or older or aged 50 to 59 years with at least 1 additional stroke risk factor. A total of 496 patients were enrolled, and 492 were randomly assigned to study groups (3 did not meet inclusion criteria, and 1 withdrew consent). Patients in the ICM group had the index stroke within 10 days before insertion. Data were analyzed from October 8, 2021, to January 28, 2022.

Interventions

ICM monitoring vs site-specific usual care (short-duration external cardiac monitoring).

Main Outcomes and Measures

The ICM device automatically detects AF episodes 2 or more minutes in length; episodes were adjudicated by an expert committee. Cox regression multivariable modeling included all parameters identified in the univariate analysis having P values <.10. AF detection rates were calculated using Kaplan-Meier survival estimates.

Results

The analysis included the 242 participants randomly assigned to the ICM group in the STROKE AF study. Among 242 patients monitored with ICM, 27 developed AF (mean [SD] age, 66.6 [9.3] years; 144 men [60.0%]; 96 [40.0%] women). Two patients had missing baseline data and exited the study early. Univariate predictors of AF detection included age (per 1-year increments: hazard ratio [HR], 1.05; 95% CI, 1.01-1.09; P = .02), CHA2DS2-VASc score (per point: HR, 1.54; 95% CI, 1.15-2.06; P = .004), chronic obstructive pulmonary disease (HR, 2.49; 95% CI, 0.86-7.20; P = .09), congestive heart failure (CHF; with preserved or reduced ejection fraction: HR, 6.64; 95% CI, 2.29-19.24; P < .001), left atrial enlargement (LAE; HR, 3.63; 95% CI, 1.55-8.47; P = .003), QRS duration (HR, 1.02; 95% CI, 1.00-1.04; P = .04), and kidney dysfunction (HR, 3.58; 95% CI, 1.35-9.46; P = .01). In multivariable modeling (n = 197), only CHF (HR, 5.06; 95% CI, 1.45-17.64; P = .05) and LAE (HR, 3.32; 1.34-8.19; P = .009) remained significant predictors of AF. At 12 months, patients with CHF and/or LAE (40 of 142 patients) had an AF detection rate of 23.4% vs 5.0% for patients with neither (HR, 5.1; 95% CI, 2.0-12.8; P < .001).

Conclusions and Relevance

Among patients with ischemic stroke attributed to large- or small-vessel disease, CHF and LAE were associated with a significantly increased risk of poststroke AF detection. These patients may benefit most from the use of ICMs as part of a secondary stroke prevention strategy. However, the study was not powered for clinical predictors of AF, and therefore, other clinical characteristics may not have reached statistical significance.

Trial Registration

ClinicalTrials.gov Identifier: NCT02700945.

Epicardial access facilitated by carbon dioxide insufflation via intentional coronary vein exit: step-by-step description of the technique and review of the literature

Pericardial access from a subxiphoid approach is often necessary to gain access to a critical epicardial substrate that is inaccessible from the endocardium. Although relatively safe, a rate of up to 5% of acute and 2% delayed complications has been reported. Intentional perforation of a distal coronary vein branch with pericardial insufflation of CO₂ to create a negative contrast space anterior to the right ventricle is an emerging approach to facilitate pericardial access. In this report, we describe the technique of intentional coronary vein exit with CO₂ insufflation to perform epicardial mapping and ablation of ventricular tachycardia (VT) in a step-by-step approach and review the published literature on this topic.

Mechanisms of Ventricular Arrhythmias and Implications for Catheter Ablation

Ventricular arrhythmias present with a wide spectrum of clinical manifestations, from mildly symptomatic frequent premature ventricular contractions to life-threatening events. Pathophysiologically, idiopathic ventricular arrhythmias occur in the absence of structural heart disease or ion channelopathies. Ventricular arrhythmias in the context of structural heart disease are usually determined by scar-related reentry and are associated with increased mortality. Catheter ablation is safe and highly effective in treating ventricular arrhythmias. The proper characterization of the arrhythmogenic substrate is essential for accurate procedural planning. We provide an overview on the main mechanisms of ventricular arrhythmias and their implications for catheter ablation.

Safety of Pill-in-the-Pocket Class 1C Antiarrhythmic Drugs for Atrial Fibrillation

BACKGROUND

Guidelines recommend that initial trial of a "pill-in-the-pocket" (PIP) Class 1C antiarrhythmic drug (AAD) for cardioversion of atrial fibrillation (AF) be performed in a monitored setting because of the potential for adverse reactions.

OBJECTIVES

This study sought to characterize real-world, contemporary use of the PIP approach, including the setting of initiation and incidence of adverse events.

METHODS

This retrospective cohort study included all patients at the Hospital of the University of Pennsylvania treated with a PIP approach for AF between 2007 and 2020.

RESULTS

A total of 273 patients (age 56 ± 13 years; 182 [67%] male; CHA₂DS₂VASc score 1.1 ± 1.2) took a first dose of PIP AAD. Flecainide was used in 151 (55%) and propafenone in 122 (45%). The first dose of PIP AAD was taken in a monitored setting in 167 (62%). Significant adverse events occurred in 7 patients (3%), 2 of whom had taken the dose in a monitored setting. Significant adverse events included unexplained syncope (1 of 7), symptomatic bradycardia/hypotension (4 of 7), and 1:1 atrial flutter (2 of 7). All occurred in patients taking 300 mg of flecainide (n = 4) or 600 mg of propafenone (n = 3). Electrical cardioversion was performed in 29 (11%) patients because of failure of the AAD to terminate AF. One patient required intravenous fluids and vasopressors for 2 hours because of persistent hypotension and bradycardia. Two patients required permanent pacemakers for bradycardia. The remaining patients required no intervention.

CONCLUSIONS

Our data support the current recommendation to initiate PIP AAD in a monitored setting because of rare significant adverse reactions that can require urgent intervention.

Impact of Left Ventricular Papillary Muscle Ventricular Arrhythmia Ablation on Mitral Valve Function

BACKGROUND

Although efficacious, catheter ablation (CA) of ventricular arrhythmias (VAs) originating from left ventricular (LV) papillary muscles (PAPs) has the potential to affect mitral valve (MV) function.

OBJECTIVES

The aim of this study was to determine whether lesions delivered during CA of VAs from LV PAPs affected MV function.

METHODS

Consecutive patients undergoing CA of LV PAP VAs from January 2015 to December 2020 in whom both preprocedural and postprocedural transthoracic echocardiography was performed were included. Radiofrequency ablation was performed with an irrigated-tip catheter with or without contact force sensing and intracardiac echocardiographic guidance. The PAPs were delineated into segments: tip, body, and base. Pre- and post-CA transthoracic echocardiograms were reviewed to assess MV regurgitation, which was graded 0 (none), 1 (mild), 2 (moderate), or 3 (severe). A change of ≥2 grades from baseline was considered significant.

RESULTS

A total of 103 patients (mean age 63 ± 15 years, 78% men) were included. VAs were ablated from the anterolateral PAP in 35% (n = 36), posteromedial PAP in 55% (n = 57), and both PAPs in 10% (n = 10). Lesion distribution was as follows: PAP tip in 52 (50%), PAP base in 34 (33%), PAP body in 13 (13%), and entire PAP in 4 (4%). The mean number of lesions delivered was 16 ± 13 (median 14). Of 103 patients, 102 (99%) showed no change in MV function.

CONCLUSIONS

Using intracardiac echocardiographic guidance, lesions can be safely delivered on various aspects of this structure without adverse impact on MV function.

Esophageal image segmentation for guidance of posterior wall lesions during atrial fibrillation ablation

BACKGROUND

Despite luminal esophageal temperature (LET) monitoring, esophageal injury remains a risk which impacts decision making during atrial fibrillation (AF) ablation. We sought to compare procedural characteristics including radiofrequency (RF) power, duration, and LET, among ablation procedures with and without image segmentation for esophageal visualization (EV).

METHODS

The retrospective cohort included 73 patients (mean age 65.2 ± 8.6 years, 36% female, 55% paroxysmal AF) who underwent pre-procedural cardiac magnetic resonance or computed tomography and LET monitoring. Of all patients, 35 were historical patients that underwent standard AF ablation without EV, and 38 were contemporary patients, 28 of whom underwent AF ablation with EV and 10 that underwent AF ablation without EV.

RESULTS

Total RF time was similar between the groups. The distribution of ablation power delivery was skewed toward higher power in the contemporary patients. However, among patients in the contemporary group, the proportion of > 35 Watts lesions was lower with EV (P < 0.001). There was no difference between the max or mean LET. The standard deviation of LET change within patient during posterior wall ablation was lower in those with esophageal visualization compared to historical controls, but no change was seen compared to a smaller group of contemporary controls. No long-term clinical esophageal injury was observed.

CONCLUSIONS

In a retrospective analysis, EV was successfully performed in 28 patients. EV impacted RF power delivery decisions but was unassociated with RF time, changes in LET, or long-term safety.

Prognostic value of right ventricular refractory period heterogeneity in Type-1 Brugada electrocardiographic pattern

AIMS

To investigate the prognostic significance of heterogeneity in the refractoriness of right ventricular (RV) outflow tract (RVOT) and RV apex at the electrophysiological study (EPS) in Brugada syndrome (BrS).

METHODS AND RESULTS

A cohort of BrS patients (primary prevention) from five Italian centres was retrospectively analysed. Patients with spontaneous or drug-induced Type-1 electrocardiogram (ECG) + symptoms were offered an EPS for prognostic stratification. The primary endpoint was a composite of sudden cardiac death (SCD), resuscitated cardiac arrest, or appropriate intervention by the implantable cardioverter-defibrillator (ICD). Three hundred and seventy-two patients with BrS were evaluated (44 ± 15 years, 69% males, 23% with ICD): 4 SCDs and 17 ICD interventions occurred at follow-up (median 48, interquartile range: 36-60 months). Family history of SCD, syncope, and a spontaneous Type-1 ECG pattern were univariate predictors of the primary endpoint in the whole population. In patients undergoing EPS (n = 198, 53%, 44 ± 12 years, 71% males, 39% with ICD), 3 SCD and 15 ICD interventions occurred at follow-up. In this subset, the primary endpoint was not only predicted by ventricular tachycardia/fibrillation inducibility but also by a difference in the refractory period between RVOT and RV apex (ΔRPRVOT-apex) >60 ms. ΔRPRVOT-apex > 60 ms remained an independent predictor of SCD/ICD shock at bivariate analysis, even when adjusted for the other univariate predictors, showing the highest predictive power at C-statistic analysis (0.75, 95% confidence interval 0.63-0.86).

CONCLUSIONS

Heterogeneity of RV refractory periods is a strong, independent predictor of life-threatening arrhythmias in BrS patients, beyond VT/VF inducibility at EPS and common clinical predictors.

Lipomatous Metaplasia Enables Ventricular Tachycardia by Reducing Current Loss Within the Protected Corridor

BACKGROUND

Post-myocardial infarction ventricular tachycardia (VT) is due to re-entry through surviving conductive myocardial corridors across infarcted tissue. However, not all conductive corridors participate in re-entry.

OBJECTIVES

This study sought to test the hypothesis that critical VT corridors are more likely to traverse near lipomatous metaplasia (LM) and that current loss is reduced during impulse propagation through such corridors.

METHODS

Among 30 patients in the Prospective 2-center INFINITY (Intra-Myocardial Fat Deposition and Ventricular Tachycardia in Cardiomyopathy) study, potential VT-viable corridors within myocardial scar or LM were computed from late gadolinium enhancement cardiac magnetic resonance images. Because late gadolinium enhancement highlights both scar and LM, LM was distinguished from scar by using computed tomography. The SD of the current along each corridor was measured.

RESULTS

Scar exhibited lower impedance than LM (median Z-score -0.22 [IQR: -0.84 to 0.35] vs -0.07 [IQR: -0.67 to 0.54]; P < 0.001). Among all 381 corridors, 84 were proven to participate in VT re-entry circuits, 83 (99%) of which traversed or were adjacent to LM. In comparison, only 13 (4%) non-VT corridors were adjacent to LM. Critical corridors adjacent to LM displayed lower SD of current compared with noncritical corridors through scar but distant from LM (2.0 [IQR: 1.0 to 3.4] μA vs 8.4 [IQR: 5.5 to 12.8] μA; P < 0.001).

CONCLUSIONS

Corridors critical to VT circuitry traverse infarcted tissue through or near LM. This association is likely mediated by increased regional resistance and reduced current loss as impulses traverse corridors adjacent to LM.