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.

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.

Prevalence, clinical profile, and stroke risk of atrial fibrillation in rural Andhra Pradesh, India (the AP-AF study).

The burden of atrial fibrillation (AF) is increasing worldwide. It is often asymptomatic, with stroke being the first manifestation in some. AF burden in the community and the practice of stroke prophylaxis has not been studied in India. The problem might be higher in rural regions due to poor health awareness and challenges to healthcare access. This study aimed to estimate the prevalence of AF, clinical profile and stroke risk in rural India. METHODS: This is a community-based cross-sectional study done in rural Andhra Pradesh (AP). Adults from 40 villages formed the study population. We did a door-to door survey to collect information on demographics, and medical history. Electrocardiogram was recorded using a smart phone based Alivecor device. Participants diagnosed with AF underwent echocardiogram. Study cardiologists assessed the cardiovascular risk profile and collected detailed medical history. RESULTS: Fourteen of the 4281 individuals screened had AF (0.3%). The mean age of the sampled population was 44 ± 16.5 years with 56% women. The mean age of participants with AF was 71 ±7.8 years; males were 71%. Except for one, all were non-valvular AF. Majority had a CHA2D2S2Vasc score of ≥2. Three had history of stroke. Two were on anticoagulant therapy but without INR monitoring. CONCLUSION: The prevalence of AF is lower in this study compared to studies from the developed countries. Non-rheumatic cardiovascular risk factors were primary causes for AF. Non-adherence to stroke prophylaxis is a major threat that needs to be addressed.

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.

A case of cardiac sarcoidosis mimicking Brugada syndrome.

A 17-year-old boy was admitted for management of ventricular fibrillation (VF) with intermittent Brugada pattern on ECG. On evaluation, cardiac MRI revealed myocardial scar and mediastinal lymphadenopathy. 18-Fluorodeoxyglucose positron emission tomography scan showed inflammation in the heart, lungs, and lymph nodes. He was diagnosed as a case of cardiac sarcoidosis (CS) and treated with steroids. However, there was a reactivation of cardiac inflammation and the development of a second VF storm. Following catheter ablation, the patient's arrhythmia improved. This report highlights the inflammation due to CS mimicking channelopathic features.

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.

Looking above the heart: A rare cause of ventricular tachycardia.

We describe a 56-year old man with medically refractory ventricular tachycardia (VT) who was referred for catheter ablation. His examination revealed features suggestive of acromegaly. The diagnosis was confirmed by elevated levels of insulin like growth factor-1 and the presence of a pituitary adenoma. Following trans-sphenoidal surgery, there was a reduction in PVC burden and no recurrence of VT.

Prevalence, clinical profile, and stroke risk of atrial fibrillation in rural Andhra Pradesh, India (The AP-AF study) - Rationale and design.

INTRODUCTION: The epidemiology of atrial fibrillation (AF) in India has not been studied systematically in large scale population based surveys. Stroke is one of the leading causes of death and disability in India. As AF is a major contributor of stroke, it is important to know the burden of AF and stroke risk in the population. The Andhra Pradesh Atrial Fibrillation (AP-AF) study aims to assess the prevalence, etiology, risk factors and stroke risk among the rural population in Andhra Pradesh, India. METHODS: This is a cross-sectional survey done using a two-stage sampling process. Adults (≥18years) from villages in East and West Godavari districts were sampled. Field investigators used a structured questionnaire to collect information on basic demographics, cardiovascular risk factors and medical history. Anthropometric measurements were performed, blood pressure measured and fasting capillary blood glucose was assessed. Electrocardiogram was done using a hand-held mobile ECG device-KardioMobile. ECGs were interpreted by study cardiologists. Participants diagnosed to have AF were invited to participate in a camp conducted by cardiologists where echocardiogram was done and also a focused history related to AF was collected. Along with age and sex stratified prevalence of AF, descriptive statistics will be used to present demographics, clinical profile, and cardiovascular risk factors. Stroke risk will be calculated using CHA 2 DS 2 -Vasc score. CONCLUSION: The AP-AF study is expected to provide important information on AF epidemiology in rural India. The information may help improve health care policies in preventing stroke and other complications of AF.

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.

Inappropriate defibrillator shock due to oversensing. What is the mechanism?

Implantable cardioverter defibrillator (ICD) is often advised for secondary prevention of sudden cardiac death. Inappropriate shocks from ICD is uncommon but can seriously affect the quality of life. One of the reasons for inappropriate ICD shock is loose set screw, which may remain undetected by device interrogation and/or fluoroscopy. A 55-year lady presented with multiple inappropriate shocks few hours after an ICD implantation. The discrepancy between near field (NF, tip to ring) and far field (FF, Can to RV coil) signals helped us to suspect noise related to loose set screw, as the underlying problem. Re-exploration of the pocket had to be performed as the last resort to confirm the diagnosis and rectify the problem.

Mitral valve tuberculoma: Role of sequential multimodality imaging of an unusual intracardiac mass.

We present an unusual intracardiac mass posing a diagnostic dilemma. A middle-aged male patient was referred for workup of a symptomatic cardiac mass involving the mitral valve. Multimodality imaging consisting of cardiac magnetic resonance (CMR) imaging and 18F-fluorodeoxyglucose positron emission computerized tomography (18FDG-PET) scan was utilized to further characterize the mass after initial echocardiographic identification. CMR imaging identified extent of valvular mass into the interatrial septum and basal portion of the interventricular septum. On 18FDG-PET scan, the intracardiac mass was found to be metabolically active. It also revealed the presence of FDG avid lymph nodes in the abdomen. Histology of the lymph node revealed active granulomatous inflammation suggestive of tuberculosis. Treatment with antitubercular therapy resulted in resolution of the mass and mitral regurgitation, avoiding surgery.

Underdiagnosis of VT due to cycle length variation among cardiac sarcoidosis patients having ICD: Problem with stability discriminator.

BACKGROUND: Implantable cardioverter defibrillator (ICD) is recommended for patients with ventricular tachycardia (VT) due to cardiac sarcoidosis (CS). Programming supraventricular tachycardia (SVT) discriminators (onset, stability, and morphology/template match) is generally recommended to minimize inappropriate therapies. However, VT in patients with CS is known to show cycle length variability (CLV) and pleomorphism. OBJECTIVE: To determine whether the stability criterion, designed to prevent inappropriate therapy during atrial fibrillation with rapid ventricular rates, could potentially lead to incorrect classification of VT as SVT and inappropriately delay or inhibit ICD therapy. METHODS: Cases of biopsy-proven CS with VT were analyzed. For patients with implanted devices, all recorded electrograms of tachycardia episodes and ICD therapies were analyzed at last follow up. RESULTS: A total of 142 patients were included (mean age 38 years, 87 males). One hundred and three of 142 patients had implanted devices (ICD or CRT-D). Thirty eight of 103 (36.9%) patients received appropriate ICD therapies over 3 ± 2.2 years follow up. Four of 38 (10.5%) of patients experienced delayed-detection or underdetection of VT related to CLV, resulting in VT counters being repeatedly "reset" (classified as "unstable" rhythms). Retrospective analysis of other VT episodes in 70 of 103 (68%) patients revealed that 25 of 80 (31.3%) episodes had > 50 ms cycle length oscillations. CONCLUSION: Among CS patients with VT, CLV is a common occurrence seen in two-thirds of VT episodes. Routine programming of the stability criterion may result in underdetection of VT in a subset of such patients. We recommend that the stability criterion should be programmed "OFF" for patients with CS, unless the patient has documented atrial fibrillation.