Cardiac arrest in myocardial infarction with non-obstructive coronary artery (MINOCA) secondary to thyroid dysfunction.

A man in his 40s who was previously well had an out-of-hospital cardiac arrest. Postresuscitation ECG showed ST-elevation myocardial infarction (MI). Emergency coronary angiogram revealed MI with non-obstructive coronary arteries (MINOCA) with evidence of spasm in the right coronary artery. Both his echocardiogram and cardiac MRI revealed a normal heart. Further workup showed markedly elevated free T4 (99.5 pmol/L) and free T3 (26.7 pmol/L) with low thyroid stimulating hormone (<0.02 pmol/L) in keeping with thyroid storm. He also had an elevated adjusted calcium level (2.84 mmol/L), which could have contributed to his coronary artery spasm. His peak troponin T was elevated at 798 ng/L (<14) suggesting myocardial damage. He was treated with propylthiouracil, steroids, beta-blocker, calcium channel blocker and intravenous fluids. The patient achieved a full recovery and was discharged home. This is an unusual case of thyroid dysfunction resulting in coronary artery spasm, cardiac arrest and MINOCA.

Contemporary Management of Complex Ventricular Arrhythmias.

Percutaneous catheter ablation is an effective and safe therapy that can eliminate ventricular tachycardia, reducing the risks of both recurrent arrhythmia and shock therapies from a defibrillator. Successful ablation requires accurate identification of arrhythmic substrate and the effective delivery of energy to the targeted tissue. A thorough pre-procedural assessment is needed before considered 3D electroanatomical mapping can be performed. In contemporary practice, this must combine traditional electrophysiological techniques, such as activation and entrainment mapping, with more novel physiological mapping techniques for which there is an ever-increasing evidence base. Novel techniques to maximise energy delivery to the tissue must also be considered and balanced against their associated risks of complication. This review provides a comprehensive appraisal of contemporary practice and the evidence base that supports recent developments in mapping and ablation, while also considering potential future developments in the field.

Short-coupled ventricular ectopics leading to cardiac arrest in a young woman.

BACKGROUND: This case report highlights the importance of recognizing that ventricular ectopy may be a cause for syncope and sudden cardiac death, through triggered disorganized arrhythmia. In the context of syncope, ventricular ectopy should be carefully assessed for coupling interval and morphology. CASE PRESENTATION: A 39-year-old woman, who had presented with recurrent syncope, had a cardiac arrest shortly after admission that required emergency defibrillation. Review of her cardiac monitoring revealed an episode of polymorphic ventricular tachycardia which had degenerated into ventricular fibrillation. The dysrhythmia had been initiated by a short-coupled (R-on-T) ventricular ectopic (VE) beat. Anti-arrhythmic therapy was initiated in the form of hydroquinidine, but the patient continued to have frequent VEs of right bundle branch block (RBBB) morphology with a relatively narrow QRS complex and a variation in frontal axis. A cardiac MRI revealed late gadolinium enhancement of the posterior papillary muscle (indicative of focal scarring). The patient underwent electrophysiological mapping and catheter ablation of her ectopy. The patient made a good recovery and was discharged from hospital with a secondary prevention implantable cardioverter-defibrillator (ICD) in situ. CONCLUSIONS: Short-couped VEs that are superimposed onto the preceding T wave (R-on-T) are indicative of electrical instability of the heart and should prompt urgent investigation. By studying the morphologies and axes of the QRS complexes produced by VEs, we can identify their likely origins and ascertain their clinical significance.

Hourly variability in outflow tract ectopy as a predictor of its site of origin.

INTRODUCTION: Before ablation, predicting the site of origin (SOO) of outflow tract ventricular arrhythmia (OTVA), can inform patient consent and facilitate appropriate procedural planning. We set out to determine if OTVA variability can accurately predict SOO. METHODS: Consecutive patients with a clear SOO identified at OTVA ablation had their prior 24-h ambulatory ECGs retrospectively analysed (derivation cohort). Percentage ventricular ectopic (VE) burden, hourly VE values, episodes of trigeminy/bigeminy, and the variability in these parameters were evaluated for their ability to distinguish right from left-sided SOO. Effective parameters were then prospectively tested on a validation cohort of consecutive patients undergoing their first OTVA ablation. RESULTS: High VE variability (coefficient of variation ≥0.7) and the presence of any hour with <50 VE, were found to accurately predict RVOT SOO in a derivation cohort of 40 patients. In a validation cohort of 29 patients, the correct SOO was prospectively identified in 23/29 patients (79.3%) using CoV, and 26/29 patients (89.7%) using VE < 50. Including current ECG algorithms, VE < 50 had the highest Youden Index (78), the highest positive predictive value (95.0%) and the highest negative predictive value (77.8%). CONCLUSION: VE variability and the presence of a single hour where VE < 50 can be used to accurately predict SOO in patients with OTVA. Accuracy of these parameters compares favorably to existing ECG algorithms.

Bipolar Radiofrequency Ablation of Septal Ventricular Tachycardia Facilitated by an Intramural Catheter.

Intramural septal substrate presents a challenge in patients undergoing ventricular tachycardia ablation, in terms of both accurate mapping and ablation with unipolar radiofrequency energy. We present the first use of the novel 2-F octapolar catheter in accurately defining intramural septal scar and facilitating bipolar ablation. (Level of Difficulty: Advanced.).

Percutaneous management of lead-related cardiac perforation with limited use of computed tomography and cardiac surgery.

BACKGROUND: Cardiac implantable electronic device (CIED)-related perforation is uncommon but potentially lethal. Management typically includes the use of computed tomography (CT) scanning and often involves cardiac surgery. METHODS: Patients presenting to a single referral centre with CIED-related cardiac perforation between 2013 and 2019 were identified. Demographics, diagnostic modalities, the method of lead revision, and 30-day complications were examined. RESULTS: A total of 46 cases were identified; median time from implantation to diagnosis was 14 days (interquartile range = 4-50). Most were females (29/46, 63%), 9/46 (20%) had cancer, 18 patients (39%) used oral anticoagulants, and no patients had prior cardiac surgery. Active fixation was involved in 98% of cases; 9% involved an implantable cardioverter defibrillator lead. Thirty-seven leads perforated the right ventricle (apex: 24) and 9 punctured the right atrium (lateral wall: 5). Abnormal electrical parameters were noted in 95% of interrogated cases. Perforation was visualized in 41% and 6% of cases with chest X-ray (CXR) and transthoracic echocardiography, respectively. CXR revealed a perforation, gross lead displacement, or left-sided pleural effusion in 74% of cases. Pericardial effusion occurred in 26 patients (57%) of whom 11 (24%) developed tamponade, successfully drained percutaneously. Pre-extraction CT scan was performed in 19 patients but was essential in four cases. Transvenous lead revision (TLR) was successfully performed in all cases with original leads repositioned in six patients, without recourse to surgery. Thirty-day mortality and complications were low (0% and 26%, respectively). CONCLUSION: CT scanning provides incremental diagnostic value in a minority of CIED-related perforations. TLR is a safe and effective strategy.

Contact force sensing in ablation of ventricular arrhythmias using a 56-hole open-irrigation catheter: a propensity-matched analysis.

PURPOSE: The effect of adding contact force (CF) sensing to 56-hole tip irrigation in ventricular arrhythmia (VA) ablation has not been previously studied. We aimed to compare outcomes with and without CF sensing in VA ablation using a 56-hole radiofrequency (RF) catheter. METHODS: A total of 164 patients who underwent first-time VA ablation using Thermocool SmartTouch Surround Flow (TC-STSF) catheter (Biosense-Webster, Diamond Bar, CA, USA) were propensity-matched in a 1:1 fashion to 164 patients who had first-time ablation using Thermocool Surround Flow (TC-SF) catheter. Patients were matched for age, gender, cardiac aetiology, ejection fraction and approach. Acute success, complications and long-term follow-up were compared. RESULTS: There was no difference between procedures utilising either TC-SF or TC-STSF in acute success (TC-SF: 134/164 (82%), TC-STSF: 141/164 (86%), p = 0.3), complications (TC-SF: 11/164 (6.7%), TC-STSF: 11/164 (6.7%), p = 1.0) or VA-free survival (TC-SF: mean arrhythmia-free survival time = 5.9 years, 95% CI = 5.4-6.4, TC-STSF: mean = 3.2 years, 95% CI = 3-3.5, log-rank p = 0.74). Fluoroscopy time was longer in normal hearts with TC-SF (19 min, IQR: 14-30) than TC-STSF (14 min, IQR: 8-25; p = 0.04). CONCLUSION: Both TC-SF and TC-STSF catheters are safe and effective in treating VAs. The use of CF sensing catheters did not improve safety or acute and long-term outcomes, but reduced fluoroscopy time in normal heart VA.

Isolating the entire pulmonary venous component versus isolating the pulmonary veins for persistent atrial fibrillation: A propensity-matched analysis.

BACKGROUND: The outcomes of pulmonary vein isolation (PVI) for persistent atrial fibrillation (AF) are suboptimal. The entire pulmonary venous component (PV-Comp), consisting of the pulmonary veins, their antra, and the area between the antra, provides triggers and substrate for AF. PV-Comp isolation is an alternative strategy for persistent AF ablation. METHODS: Among 328 patients with persistent AF who underwent a first radiofrequency ablation procedure, 200 patients (PVI, n = 100; PV-Comp isolation, n = 100) were selected by propensity score matching. Both groups were followed up for 1 year. RESULTS: At 6- and 12-month follow-up, atrial tachyarrhythmia (AF/atrial tachycardia) recurred in 41 and 61 patients in PVI group and 22 (P = .006) and 33 patients (P < .001) in PV-Comp isolation group, respectively. PV-Comp isolation was associated with longer mean time to recurrence (PVI: 8 months, PV-Comp isolation: 10 months, log-rank P < .001) and a lower probability of recurrence (odds ratio [OR] = 0.32; 95% confidence of interval [CI] = 0.18-0.56, P < .001), with no increase in procedural complications (PVI: 5 of 100, PV-Comp isolation: 6 of 100, P = .76). Procedure duration was longer in PV-Comp isolation group (PVI: 186 ± 42 min, PV-Comp isolation: 238 ± 44 min, P < .001), as well as fluoroscopy time (PVI: 22 ± 16 min, PV-Comp isolation: 31 ± 21 min, P = .001). CONCLUSION: PV-Comp isolation for persistent AF reduced atrial tachyarrhythmia recurrence up to 1 year compared with PVI alone. While procedure and fluoroscopy time increased, there was no difference in procedural complications.

Mapping and Ablation of Ventricular Outflow Tract Arrhythmias.

Arrhythmias arising from the ventricular outflow tracts are commonly encountered. Although largely benign, they can also present with heart failure and sudden cardiac death. Mapping and ablation of these arrhythmias is commonly performed in the electrophysiology laboratory with a high success rate, but occasionally can prove challenging to abolish. This article discusses the mapping and ablation of outflow tract arrhythmias and the challenges that can be overcome by a systematic approach.

The rationale for isolation of the left atrial pulmonary venous component to control atrial fibrillation: A review article.

Catheter ablation of persistent atrial fibrillation (AF) is an evolving field. In this review, we discuss the rationale for isolation of the pulmonary venous component of the left atrium to control AF. The review describes the embryologic origin of this component and makes the important distinction between the true posterior wall and the pulmonary venous component, which forms the dome of the left atrium. Studies that have examined the role of left atrial posterior wall isolation in AF ablation have loosely referred to the pulmonary venous component as the posterior wall. We critically reexamine this nomenclature and provide a sound argument underpinned by fundamental anatomic considerations, a clear understanding of which is critical to the operator. We discuss the various techniques used in isolating this region and review the outcome data of studies targeting this region in AF ablation.

Endocardial ablation of ventricular ectopic beats arising from the basal inferoseptal process of the left ventricle.

BACKGROUND: Idiopathic ventricular ectopy (VE) shows predilection to sites within the left ventricular (LV) base such as the outflow tract/aortic sinuses, LV summit, and areas adjacent to the aortomitral continuity. We characterize VE arising from the inferior septum of the LV base that was successfully managed by LV endocardial ablation from the inferoseptal recess of the LV. OBJECTIVE: The purpose of this study was to determine the incidence, electrocardiographic (ECG) findings, electrophysiological findings, and anatomical features associated with VE arising from the basal inferoseptal process of the LV (ISP-LV) ablated using an LV endocardial approach via the inferoseptal recess of the LV. METHODS: A total of 425 consecutive patients undergoing VE ablation between January 1, 2012 and December 31, 2016 at 3 centers were evaluated. Demographic characteristics, ECG findings, and procedural data were analyzed for patients with ISP-LV VEs. RESULTS: Seven (1.5%) had a site of origin from the ISP-LV. Common ECG findings were a right bundle branch block concordant pattern or an atypical left bundle branch block early transition pattern, suggestive of a basal origin with a left superior axis, a biphasic QRS complex in lead aVR, and a small s wave in lead V6. Earliest activation was seen in an area below the outflow tract accessed from the inferoseptal recess inferior to the His bundle. In 3 cases, transient junctional rhythm was seen during ablation. All cases were ablated successfully with no complications. CONCLUSION: VE arising from the ISP-LV represents a distinct subset of idiopathic arrhythmia and can be successfully treated by endocardial catheter ablation from the inferoseptal recess. They share common surface ECG and electrophysiological findings with special anatomical features that need recognition for successful catheter ablation.

Cardiac sarcoidosis: electrophysiological outcomes on long-term follow-up and the role of the implantable cardioverter-defibrillator.

OBJECTIVES: The objectives of this study were to identify the predictors of life-threatening ventricular arrhythmias in patients with cardiac sarcoidosis (CS) and to evaluate the role of the implantable cardioverter-defibrillator (ICD) in this patient population. BACKGROUND: ICD implantation is a class IIA recommendation for patients with CS. However, some indications for ICD implantation in CS patients are still unclear and not enough data are available to establish predictors of malignant ventricular tachyarrhythmias in this group of patients. METHODS: We retrospectively identified all consecutive patients who were diagnosed with CS, during the period from March 2002 to April 2010. Cardiac rhythm devices were regularly interrogated and clinical data recorded during follow-up visits. RESULTS: Thirty-three patients (17 male) with CS were identified. The mean age was 53 ± 11. The mean left ventricular ejection fraction (LVEF) was 41 ± 18%. Thirty patients received an ICD. Twelve patients (36.3%) had sustained ventricular arrhythmias. Eleven patients received appropriate therapies and 9 patients received inappropriate shocks, representing 36.7% and 30.0% of the ICD population, respectively. Patients who received appropriate ICD therapies were younger with mean age 47.4 ± 7.8, and had a lower mean LVEF 33.0 ± 12.0 compared to those who did not receive ICD therapies (P = 0.0301 and 0.0341, respectively). There were no other demographic, clinical, electrocardiographic, electrophysiological, or imaging markers that predicted the future occurrence of appropriate ICD therapies in our cohort of patients. CONCLUSIONS: CS is strongly associated with malignant ventricular arrhythmias. No specific predictors of such tachyarrhythmias emerged, other than young age and low LVEF.

Genetic biomarkers in Brugada syndrome.

Brugada syndrome is an inherited arrhythmia syndrome predisposing to sudden cardiac death. Six years after its initial description as a clinical entity, the first mutations in SCN5A encoding the cardiac sodium channel Nav1.5 were reported. Over 300 mutations in SCN5A have since been described in addition to mutations in genes encoding Nav1.5 auxiliary units, potassium and calcium channels. This review summarizes the current knowledge on the genetics of Brugada syndrome, focusing on SCN5A, and discusses its use as a biomarker for diagnosis, prognosis and treatment.

Functional Pulmonary Vein Isolation During Atrial Fibrillation Ablation.

We report a case of apparent isolation of the right inferior pulmonary vein during atrial fibrillation ablation coincident with the onset of an atrial tachycardia. This report highlights the importance of assessing pulmonary vein conduction during sinus or paced rhythm at relatively long cycle length, rather than in atrial fibrillation or atrial tachycardia.

Idiopathic ventricular fibrillation in a 10-year-old boy: technical aspects of radiofrequency ablation and utility of antiarrhythmic therapy.

Idiopathic ventricular fibrillation (VF) is defined as spontaneous VF in the absence of structural heart disease. No prior reports exist addressing the technical aspects of idiopathic VF ablation in a child. We present the case of a 10-year-old boy with idiopathic VF, who presented a unique management challenge, particularly as regards the technical aspects of the ablation procedure. Ablation of idiopathic VF is feasible in a 10-year-old boy and oral quinidine seems more effective than other antiarrhythmic drugs in this condition.