Radiofrequency catheter ablation of ventricular arrhythmias in patients with hypertrophic cardiomyopathy.

BACKGROUND: Compared to other non-ischemic substrates, there is limited data on the role and outcome of catheter ablation in HCM. The objective of this study is to assess the safety and efficacy of catheter ablation for the treatment of VT in patients with HCM. METHODS: Fourteen patients with HCM and drug refractory VT who underwent catheter ablation at a single center were included in this study. The data was evaluated retrospectively. Acute success, procedure-related complications, and long-term outcomes were documented during follow up. RESULTS: Among the 14 patients (mean age 48.2 ± 8.2 years, 85.7% males, mean LVEF 42.6 ± 6.5%), 4 had an apical aneurysm. Eleven patients had evidence of scar-related VT and three patients had a bundle-branch re-entry VT. The most common sites for scar-related VT were the border-zones of the apical aneurysms, basal septum, and LV lateral wall. Patient either underwent an endocardial ablation or a combined endocardial and epicardial ablation. Acute success was achieved in all patients. In 6 patients VT was terminated during ablation. In two patients, non-clinical VTs were inducible at the end of the procedure. No major or minor complications were observed during and after the procedure in all patients. During long-term follow up, elimination of VTs reached 78%. CONCLUSION: Catheter ablation of VT in patients with HCM is safe and successful in eliminating VT. Combining endocardial and epicardial ablation techniques can potentially lead to better outcomes in these patients. Bundle branch re-entry should be considered as a potential mechanism of VT in patients with HCM.

Catheter ablation of ventricular tachycardia: strategies to improve outcomes.

Catheter ablation of ventricular arrhythmias has evolved considerably since it was first described more than 3 decades ago. Advancements in understanding the underlying substrate, utilizing pre-procedural imaging, and evolving ablation techniques have improved the outcomes of catheter ablation. Ensuring safety and efficacy during catheter ablation requires adequate planning, including analysis of the 12 lead ECG and appropriate pre-procedural imaging. Defining the underlying arrhythmogenic substrate and disease eitology allow for the developed of tailored ablation strategies, especially for patients with non-ischemic cardiomyopathies. During ablation, the type of anesthesia can affect VT induction, the quality of the electro-anatomic map, and the stability of the catheter during ablation. For high risk patients, appropriate selection of hemodynamic support can increase the success of VT ablation. For patients in whom VT is hemodynamically unstable or difficult to induce, substrate modification strategies can aid in safe and successful ablation. Recently, there has been an several advancements in substrate mapping strategies that can be used to identify and differentiate local late potentials. The incorporation of high-definition mapping and contact-sense technologies have both had incremental benefits on the success of ablation procedures. It is crucial to harness newer technology and ablation strategies with the highest level of peri-procedural safety to achieve optimal long-term outcomes in patients undergoing VT ablation.

Optimizing diastolic filling by pacing in nonobstructive hypertrophic cardiomyopathy.

BACKGROUND: Treatment options for symptomatic patients with nonobstructive hypertrophic cardiomyopathy (nHCM) are limited. OBJECTIVE: The purpose of this study was to determine the effect of sequential atrioventricular (AV) pacing, from different right ventricular (RV) sites with varying AV delays, on the diastolic function and functional capacity of patients with nHCM. METHODS: Twenty-one patients with symptomatic nHCM and normal left ventricular (LV) systolic function were prospectively enrolled. Inclusion criteria included PR interval >150 ms, E/e' ≥15, and an indication for implantable cardioverter-defibrillator (ICD) implantation. Doppler echocardiographic study was performed during dual-chamber pacing at various AV intervals. Pacing was performed at 3 RV sites: RV apex (RVA), RV midseptum (RVS), and RV outflow tract (RVO). The site and sensed AV delay (SAVD) at which optimal diastolic filling occurred were chosen based on diastolic filling period and E/e'. During ICD implantation, the RV lead was implanted at the site identified by the pacing study. Devices were programmed in DDD mode at the optimal SAVD. During follow-up, diastolic function and functional capacity were assessed. RESULTS: Among the 21 patients (age 47.8 ± 7.7 years; 81.0% male), baseline E/A and E/e' were 2.4 ± 0.6 and 17.2 ± 2.2, respectively. There was an improvement in diastolic function (E/e') in 18 patients (responders) when pacing from the RVA (12.9 ± 3.4; P <.001) than from the RVS (16.6 ± 2.3) and RVO (16.9 ± 2.2). Among responders, optimal diastolic filling occurred at SAVD of 130-160 ms with RVA pacing. Nonresponders had longer duration of symptoms (P = .006), lower LV ejection fraction (P = .037), and higher late gadolinium enhancement burden (P <.001). During 13.5 ± 1.5 months of follow-up, there was an improvement (Δ) in diastolic function (E/e' -4.1 ± 0.5), functional capacity (New York Heart Association functional class -1.5 ± 0.3), and reduction in N-terminal pro-brain natriuretic peptide level (-55.6 ± 12.3 pg/mL) compared to baseline. CONCLUSION: Pacing at an optimized AV delay from the RVA improves diastolic function and functional capacity in a subset of patients with nHCM.

Efficacy of SGLT2 Inhibitors in Patients With Diabetes and Nonobstructive Hypertrophic Cardiomyopathy.

The objective of this study was to evaluate the effects of sodium glucose co-transporter 2 inhibitors (SGLT2i) on functional capacity and diastolic function in patients with diabetes with nonobstructive hypertrophic cardiomyopathy (nHCM) and preserved left ventricular (LV) function. From January 2019 to October 2020, a prospective open-label study was performed on patients with type 2 diabetes mellitus and nHCM with New York Heart Association class II-III symptoms. Patients with a LV ejection fraction <50% were excluded. Patients were recruited from January 2019 to November 2019 to the SGLT2i arm and from November 2019 to October 2020 to the control arm. The primary composite end point was defined as achieving an improvement of at least 1.5 in E/e' and a reduction of ≥1 New York Heart Association functional class after 6 months of therapy. At baseline, there were no significant differences between the SGLT2i (n = 24) and control arms (n = 24). More patients in the SGLT2i arm achieved the primary end point than the patients in the control arm (70.8% vs 4.2%, p <0.001). After 6 months of therapy, patients in the SGLT2i arm showed a significant improvement in all diastolic function parameters (E/e' 16.3 ± 1.9 vs 13.3 ± 1.6, p <0.001; E/A 2.8 ± 0.1 vs 2.4 ± 0.1, p <0.001; left atrial volume 45.6 ± 5.2 vs 40.8 ± 4.9 ml/m2, p = 0.003). There was also an improvement in the 6-minute walk distance (295.1 ± 31.5 vs 343.0 ± 31.1 m, p <0.001) and N-terminal pro-B-type natriuretic peptide (481.4 ± 52.6 vs 440.9 ± 43.9 pg/ml, p <0.001) in patients who received SGLT2i. There was no significant change in the LV mass in the SGLT2i or control arm (-0.1 ± 0.3 vs 0.1 ± 0.5 g/m2, p = 0.319) after 6 months of therapy. A patient in the SGLT2i arm discontinued therapy because of a urinary tract infection. In conclusion, the use of SGLT2i improved diastolic function and functional capacity in patients with diabetes with nHCM and a preserved LV function.

Best Practices for the Catheter Ablation of Ventricular Arrhythmias.

Techniques for catheter ablation have evolved to effectively treat a range of ventricular arrhythmias. Pre-operative electrocardiographic and cardiac imaging data are very useful in understanding the arrhythmogenic substrate and can guide mapping and ablation. In this review, we focus on best practices for catheter ablation, with emphasis on tailoring ablation strategies, based on the presence or absence of structural heart disease, underlying clinical status, and hemodynamic stability of the ventricular arrhythmia. We discuss steps to make ablation safe and prevent complications, and techniques to improve the efficacy of ablation, including optimal use of electroanatomical mapping algorithms, energy delivery, intracardiac echocardiography, and selective use of mechanical circulatory support.

Catheter Ablation for Ventricular Arrhythmias in Hypertrophic Cardiomyopathy.

Implantable cardioverter-defibrillators are the mainstay of therapy for prevention of sudden cardiac death in high-risk patients with hypertrophic cardiomyopathy (HCM). Catheter ablation is a useful option for patients with recurrent, drug refractory monomorphic ventricular tachycardia (VT), and device therapy. Compared with other nonischemic substrates, there are limited data on the role and outcomes of catheter ablation in HCM. The challenges of VT ablation in HCM patients include deep intramural and epicardial substrates, suboptimal power delivery, and higher recurrence due to progression of disease. Patient selection, using cardiac MRI scar localization, and optimizing ablation techniques can improve outcomes in these patients.

Ventricular Tachycardia in Granulomatous Myocarditis: Role of Catheter Ablation.

Granulomatous myocarditis is an inflammatory disease of the myocardium, characterized by lymphocytic infiltration with characteristic granuloma formation. Although a host of disease processes can elicit myocardial granulomas, two common entities are cardiac sarcoidosis and cardiac tuberculosis. Cardiac arrhythmias in this condition are frequent and management of ventricular arrhythmias can be challenging, especially in those with drug-refractory ventricular tachycardia and electrical storm. In this review, we highlight the role of catheter ablation for ventricular tachycardia and optimal patient selection for catheter ablation, based on cardiac imaging.

His-bundle pacing versus cardiac resynchronisation therapy: Effect on ECG parameters of repolarization.

INTRODUCTION: Cardiac resynchronization therapy (CRT) by biventricular pacing (BiV) may worsen indices of ventricular repolarization. The impact of His bundle pacing (HBP) on repolarization is not well studied in patients with left ventricular systolic dysfunction. The aim of the study is to compare the repolarization parameters in ECG between these two pacing modalities. METHODS: Baseline and post implant parameters of 20 patients who had undergone HBP were compared with 18 patients who underwent CRT (BiV) implantation. Repolarization parameters were monitored before implantation, within 24  hours and after 6 weeks of implantation. Patients were followed up till 6 months with clinical and echocardiographic parameters. RESULT: Baseline clinical, electrocardiographic and echocardiographic parameters were similar in both groups. Significant differences were noted in QTc, Tp-e and Tp-e/QTc between HBP and CRT groups both on immediate post implant and after 6 weeks of implantation. Compared to pre-implantation,significant shortening of Tp-e and Tp-e/QTc was observed immediately (90.54 ± 24.35 vs 69.62 ± 12.92, p < 0.05 and 0.20 ± 0.05 vs 0.15 ± 0.03, p < 0.05) and after 6 weeks (90.54 ± 24.35 vs 66.08 ± 14.95, p < 0.05 and 0.20 ± 0.05 vs 0.15 ± 0.02, p < 0.05) in HBP implant (group A). However, these changes were not present in CRT cohort (group B). During a follow up of 6 months, NYHA class and LV function between two groups remain comparable. CONCLUSION: HBP is associated with significant reduction of Tp-e and Tp-e/QTc compared to CRT. Further evaluation is needed to determine whether this improvement in indices of repolarization is associated with reduction in clinical arrhythmic events or not.

High rate episodes in a dual chamber pacemaker: What is the mechanism?

Detection of high rate episodes can potentially result from oversensing of physiological or nonphysiological signals. Assessment of lead integrity, lead connection and analysis of noise characteristics on electrograms are decisive steps in the evaluation of oversensing. We report a case of high atrial and ventricular rate episodes due to minute ventilation oversensing in the presence of lead connector issues.

Putative role of prosthetic dental implants in the development of cardiac sarcoidosis: A case-control study.

BACKGROUND: Etiopathogenesis of cardiac sarcoidosis is poorly understood. The objective of this study is to examine a possible role of previous dental procedures on the development of cardiac sarcoidosis (CS). METHODS: Clinical details of 73 patients with CS from the Granulomatous Myocarditis Registry were extracted. Data regarding clinical presentation, comorbidities, baseline electrocardiogram, echocardiogram, and 18fluorodeoxyglucose(FDG) PET-CT was extracted from the registry database. A comprehensive history of dental procedures for all patients was recorded. The two control groups comprised of 79 patients with idiopathic ventricular tachycardia and/or complete heart block (with similar clinical presentation) and 145 healthy age and sex matched patients, respectively. RESULTS: Dental evaluation revealed that patients with CS had undergone a previous prosthetic dental implant(PI) (OR 12.4, 95% CI 4.0-38.1, p<0.001) or root canal treatment (RCT) (OR 2.43, 95% CI 1.12-5.26, p=0.025) more often than the healthy controls. The patients with CS and previous dental procedures had higher18FDG uptake in the LV myocardium (SUV max 8.6±3.3vs.5.5 ±1.8 (mean±SD), p<0.001) and mediastinal lymph nodes (9.3±4.6vs.5.4±1.7 (mean±SD), p<0.001) as compared to patients who did not undergo a dental procedure. The subset of CS patients with a previous PI or RCT had higher uptake levels in the myocardium (max SUV 9.4±3.1vs.6.7±2.0, p=0.011, number of abnormal LV Segments 10.3±3.1vs.6.5±2.8(mean±SD), p=0.008) and mediastinal lymph nodes(max SUV 10.5±4.8vs. 7.2±1.8,p=0.002) compared to those who underwent crowning or extraction. In addition, CS was diagnosed after a shorter latency period (47.3±21.0vs.81.6±25.3 months (mean±SD), p<0.001) following PI and RCT compared to other dental procedures. CONCLUSIONS: We observed a significant association between PI and RCT and the occurrence of CS. This group of patients also appear to have a more severe form of the disease.

CT-guided percutaneous epicardial access for ventricular tachycardia ablation: A proof-of-concept study.

INTRODUCTION: The objective of this study was to evaluate the safety and efficacy of preprocedural computed tomography (CT) to guide percutaneous epicardial puncture for catheter ablation of ventricular tachycardia. METHODS AND RESULTS: A preprocedural CT was used to plan the site, angle, and depth of needle insertion during epicardial access in 10 consecutive patients undergoing ventricular tachycardia (VT) ablation. Adjacent structures (right ventricle, diaphragm, liver, colon, internal mammary artery) were visualized and the course of the needle was planned avoiding these structures. During epicardial access, a protractor was used to guide the angle of needle entry into the subxiphoid space. Postprocedural CT was performed to calculate the deviation between the planned and executed access and to assess for any collateral damage. Percutaneous epicardial access was obtained successfully in all the patients using anterior (n = 4) and inferior (n = 6) approaches. The planned site and angle of puncture was more caudal (2.9 ± 0.9 vs. 3.7 ± 0.7 cm, p = .021) and acute (61.7 ± 5.8 vs. 49.0 ± 5.4°, p = .011) for an anterior approach compared to an inferior approach, respectively. Postprocedure CT revealed minimal deviation of the puncture site (5.4 ± 1.0 mm), angle (5.4 ± 1.2°), and length of needle insertion (0.5 ± 0.2 cm). With regard to the site of entry in the pericardial space, there was a deviation of 5.9 ± 1.1, 6.1 ± 1.1, and 5.8 ± 1.4 mm in the x, y, and z dimensions, respectively. In eight patients with minimal deviation between planned and executed access, there was no collateral injury to adjacent viscera or vessels. In two patients with increased deviation of angle and length of needle insertion, there was entry through the diaphragm during inferior access. CONCLUSIONS: Utilizing pre-procedural CT planning may aid in the success and safety of percutaneous epicardial access during VT ablation.

Refractory heart failure with LBBB - Pause before CRT.

In this report, we describe complete disappearance of LBBB with normalization of LV function in two patients with cardiac sarcoidosis (CS) after immunosuppressive therapy. Both of these patients were ideal Class IA candidates for CRT (Complete LBBB, QRS ≥ 150 ms, EF < 30%). If CS is identified early, immunosuppressive treatment can lead to not only improvement of left ventricular function but also disappearance of the left bundle branch block. Timely diagnosis and management of CS obviated the need of CRT in these patients. It may be reasonable to evaluate all non-ischemic cardiomyopathies for underlying reversible causes prior to CRT implantation.

PVCs with multiple exits and single site of origin in the outflow tract: What is the mechanism?

A 40 year old man with frequent PVCs with two different morphologies was referred for catheter ablation. Although initial mapping in the RVOT revealed fragmented potentials 20ms earlier than PVC2 onset with a good pace map score, ablation at this site was unsuccessful. Subsequent mapping in the LCC/NCC junction revealed that local ventricular activation preceded QRS onset by 30 and 28 ms for PVC1 and PVC2, respectively. Altering the pacing output at this site produced QRS morphologies similar to PVC1(low output,6mA) and PVC2(high output,15mA) with better pace map scores compared to RVOT. During high-output pacing, there was an increase in stim-QRS latency with decremental conduction. Ablation at this site was successful and suppressed both PVCs.

Pre-Treatment Myocardial 18FDG Uptake Predicts Response to Immunosuppression in Patients With Cardiac Sarcoidosis.

OBJECTIVES: This study identified predictors of clinical (CR) and echocardiographic response (ER) following immunosuppressive therapy (IST) in patients with cardiac sarcoidosis (CS). BACKGROUND: IST has been the cornerstone of treatment for patients with CS and active myocardial inflammation. However, there are little data to explain the variable response to IST in CS. METHODS: Data of 96 consecutive patients with CS from the Granulomatous Myocarditis Registry were analyzed. All patients underwent a 18fluorodeoxy glucose positron emission tomography-computed tomography (18FDG-PET-CT) before initiation of IST. Response was assessed after 4 to 6 months of therapy. CR was defined as an improvement in functional class (New York Heart Association functional class ≥I) and freedom from ventricular arrhythmias and heart failure hospitalizations. ER was defined as an improvement in left ventricular ejection fraction (LVEF) ≥10%. ER was assessed only in patients with a LVEF <50%. Complete responders had no residual myocardial FDG uptake and fulfilled both response criteria. Partial responders fulfilled only 1 response criteria or had residual FDG uptake. Nonresponders did not fulfill either CR or ER criteria. The uptake index (UI) was defined as the product of maximum standardized uptake value and the number of LV segments with abnormal uptake on 18FDG-PET-CT. RESULTS: Among 91 patients included in the final analysis, 54.9%, 20.9%, and 24.2% of patients were classified as complete and partial responders and nonresponders, respectively. Cox regression analysis (all responders vs. nonresponders) identified the following as independent predictors of response following immunosuppression: LVEF >40% (hazard ratio: 1.61; 95% confidence interval: 1.06 to 7.69; p = 0.031) and myocardial UI >30 (hazard ratio: 1.28; 95% confidence interval: 1.05 to 6.12; p = 0.010). The final model had a good discriminative power (area under the curve [AUC]: 0.85) and predictive accuracy (sensitivity: 85.5%; specificity: 86.4%). Pre-treatment myocardial UI had a strong positive correlation with change in LVEF following immunosuppression. CONCLUSIONS: Pre-treatment 18FDG myocardial uptake was a predictor of CR and ER response to immunosuppression in patients with CS.

Impact of interventricular delay on repolarization parameters in patients with biventricular pacing.

A 48-year-old man who was previously a responder to cardiac resynchronization therapy (CRT) presented with worsening of heart failure and reduction in the percentage biventricular (BiV) pacing. Device interrogation revealed T-wave oversensing that was eliminated by optimizing the interventricular (VV) delay. Compared to simultaneous BiV pacing, both sequential left ventricle-right ventricle (LV-RV) and univentricular LV pacing shortened the QTc, T peak-end intervals and reduced the T wave amplitude. Modification of VV delays can result in changes in wavefront of activation and thereby affect ventricular repolarization patterns.

Stroke in cardiac sarcoidosis: Need to worry?

OBJECTIVES: The occurrence of stroke in patients with cardiac sarcoidosis (CS) is an under-recognized entity. The objective of this study is to evaluate the clinical presentation, risk factors, etiology, temporal relationship and management of stroke in patients with CS. METHODS: The data of 111 patients with CS from the Granulomatous Myocarditis Registry was analyzed. Clinical data regarding the clinical presentation, risk factors for vascular disease, electrocardiogram, echocardiogram and 18 Fluorodeoxyglucose (FDG) PET-CT were extracted from the registry database. RESULTS: Among the 111 patients with CS, 8 patients (7.2%) had a history of ischemic stroke. Six of the eight patients with ischemic stroke were young (<50 years) without conventional risk factors for vascular disease. In five patients, stroke occurred prior to the diagnosis of CS. In all except one patient the ischemic stroke occurred in the anterior cerebral circulation. LV dysfunction was noted in all patients at the time of stroke, with the presence of an LV apical clot in four of the eight patients. Atrial fibrillation was documented in 2 patients. Two patients received thrombolysis and mechanical thrombectomy, while the others were treated with standard antiplatelets and statins. There was a significant improvement in the LV Ejection fraction (33.6 ± 15.2 to 49.1 ± 13.8%, p = 0.043) following immunosuppression. Two patients developed refractory HF and respiratory sepsis, respectively, and succumbed following prolonged ICU admissions. CONCLUSIONS: Ischemic stroke in patients with CS can be attributed to a cardioembolic phenomenon. A high index of clinical suspicion is needed for early diagnosis and management of these patients.

The prognostic value of dispersion of repolarization in stress cardiomyopathy.

INTRODUCTION: Although abnormalities of ventricular repolarization are a hallmark of SC, their clinical impact on management remains to be determined. This study sought to evaluate the prognostic value of dispersion of repolarization in stress cardiomyopathy (SC) with regards to major cardiac events (MCE), recovery time, and recurrence. METHODS: This study analyzed data from258 patients with SC, from January 2009 to January 2018. Standard 12 lead ECG recordings during the acute, subacute, and recovery phases were collected for each eligible patient. Logistic regression was used to identify independent predictors of MCE, a composite of 30 day all-cause mortality, cardiogenic shock, life-threatening ventricular arrhythmias, and stroke. RESULTS: Among the 101 eligible patients (80.2% females, mean age 45.8 ± 11.5 years) in the study cohort, MCE occurred in 16 patients (15.8%). Cox regression analysis identified two independent predictors of MCE: increased ΔQT dispersion ≥ 40 ms (HR 1.31, 95% CI 1.05-9.77, p = 0.029) and increased Δnegative T wave amplitude dispersion ≤ -2.0 mV (HR 1.25, 95% CI 1.11-11.93, p = 0.018) during the subacute phase. The final regression model had good accuracy (sensitivity 81.3%, specificity 96.5%) and discriminative power (AUC 0.89, 95% CI 0.83-0.95). Kaplan-Meier analysis revealed that there was increasing MCE in patients with zero, one, or two predictors (log rank p < 0.001). In addition, patients with increased dispersion also had a significantly longer time to achieve complete recovery (21.4 ± 6.8 vs. 8.5 ± 4.3 days, p = 0.012) and a higher incidence of recurrence (31.3% vs. 2.4%, p = 0.011) of SC. CONCLUSION: Evaluation of dynamic changes of dispersion of repolarization is a simple bed-side tool with high predictive accuracy for prognostication of short term adverse outcomes, delayed recovery, and recurrence in patients with SC.