Habib Khan

London Health Sciences Centre · Division of Cardiology

Background: Cognitive decline and dementia are significant global health concerns, with hypertension being a major risk factor. Increasingly, the elderly population is receiving pacemakers, and the pacing rates are set as low as 50bpm. Moreover, the relationship between blood pressure (BP) components, particularly diastolic BP (DBP) and pulse press...

Background Contemporary guidelines recommend Catheter Ablation (CA) in patients with persistent Atrial Fibrillation (AF) with Heart Failure with reduced ejection fraction (HFrEF). It is challenging to prospectively predict who will respond. We have previously described the long-term survival outcomes of patients in this cohort.(1) However, the clin...

Purpose We aim to investigate the atrial anatomical variations in patients with and without atrial fibrillation (AF) using cardiac computed tomography angiography (CCTA) and identify features associated with AF recurrence following pulmonary vein isolation. Materials and Methods We retrospectively reviewed 502 CCTAs of patients with AF performed p...

Importance Sudden death and cardiac arrest frequently occur without explanation, even after a thorough clinical evaluation. Calcium release deficiency syndrome (CRDS), a life-threatening genetic arrhythmia syndrome, is undetectable with standard testing and leads to unexplained cardiac arrest. Objective To explore the cardiac repolarization respon...

BACKGROUND Substantial data support a heritable basis for supraventricular tachycardias, but the genetic determinants and molecular mechanisms of these arrhythmias are poorly understood. We sought to identify genetic loci associated with atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular accessory pathways or atrioventricular...

The incidence and prevalence of cardiovascular diseases (CVD) have risen over the last few decades worldwide, resulting in a cost burden to healthcare systems and increasingly complex procedures. Among many strategies for treating heart diseases, treating arrhythmias using cardiac implantable electronic devices (CIEDs) has been shown to improve qua...

Background: The Resynchronization-Defibrillation for Ambulatory Heart Failure Trial (RAFT) showed a greater benefit with respect to mortality at 5 years among patients who received cardiac-resynchronization therapy (CRT) than among those who received implantable cardioverter-defibrillators (ICDs). However, the effect of CRT on long-term survival i...

Background Cardiac implantable electronic devices (CIEDs) are routinely implanted using intravenous drugs for sedation. However, some patients are poor candidates for intravenous sedation. Objective We present a case series demonstrating the safety and efficacy of a novel, ultrasound‐guided nerve block technique that allows for pre‐pectoral CIED i...

Introduction: In this study, we evaluated the anatomical atrial variations using gated cardiac computed tomography (CCT) between patients with and without atrial fibrillation (AF). Hypothesis: The aim of the study is to evaluate if there are specific anatomical characteristics that are associated with poor clinical outcomes following ablation in pa...

Introduction: Conventional Cardiac implantable electronic devices (CIEDs) implantation requires fluoroscopy. Risks involved with implantation include pneumothorax, lead dislodgement, and perforation of the right ventricular wall. In addition, there are long-term risks of malignancy associated with prolonged and repeated use of radiation over the de...

To broaden our understanding of bradyarrhythmias and diseases of the cardiac conduction system, we performed cross-sectional multi-ancestry genome-wide association study meta-analyses in up to 1.3 million individuals for sinus node dysfunction (SND), distal conduction disease (DCD), and pacemaker implantation (PM). We evaluated the biological relev...

Conduction system pacing (CSP) has been emerging over the last decade as a pacing option instead of conventional right ventricular (RV) pacing and biventricular (BiV) pacing. Numerous case reports, some observational studies and a few randomized control trials have looked at optimum pacing strategies for heart failure (HF) with left bundle branch b...

Ultrasound (US) guidance for implantation of cardiac implantable electronic devices (CIED) is currently not routine practice. This article sought to review published data on the use of ultrasound in each of the major surgical steps involved in implantation of CIEDs, including achieving anesthesia, obtaining venous access and implantation of leads....

Background: Left atrial (LA) function following catheter or surgical ablation of de-novo long-standing persistent atrial fibrillation (AF) and its impact on AF recurrence was studied in patients participating in the CASA-AF trial (Catheter Ablation vs. Thoracoscopic Surgical Ablation in Long Standing Persistent Atrial Fibrillation). Methods: All...

The use of fluoroscopy for visualization of leads used for permanent pacemakers (PPMs) has cumulative effects not only on patients but also on operators and laboratory staff; such effects include malignancy risk, cataract, hypercholesterolemia, and musculoskeletal injuries due to the weight of radiation protection equipment. 1 ,2

Commotio cordis is one of the leading causes of sudden cardiac death in youth baseball. Currently, there are chest protector regulations regarding the prevention of Commotio cordis in baseball and lacrosse; however, they are not fully optimized. For the advancement of Commotio cordis safety, it is vital to include various age groups and a variety o...

Objective: We aimed to study the long-term association of LV mass index (LVMI) and myocardial fibrosis with ventricular arrhythmia (VA) in a population of patients with confirmed hypertrophic cardiomyopathy (HCM) using cardiac magnetic resonance imaging (CMR). Methods: We retrospectively analyzed the data in consecutive HCM patients confirmed on CM...

Background: It is not known whether the optimal Atrioventricular delay (AVopt ) varies between left ventricular (LV) pacing site during endocardial biventricular pacing (BiVP) and may therefore needs consideration. Methods: We assessed the haemodynamic AVopt in patients with chronic heart failure undergoing endocardial LV lead implantation. AVop...

Inherited arrhythmia syndromes are rare genetic conditions that predispose seemingly healthy individuals to sudden cardiac arrest and death. The Hearts in Rhythm Organization is a multidisciplinary Canadian network of clinicians, researchers, patients, and families that aims to improve care for patients and families with inherited cardiac condition...

The aging population of the Western world will lead to an increase in cardiac pathologies. Valvular disorders include a spectrum of progressive diseases that confers mechanical and functional impairment, including issues with the cardiac conduction system. Pacemakers are a therapeutic standard to reinstate the syn-chrony of cardiac contraction. Per...

A woman with type 1 myotonic dystrophy received an implantable cardioverter-defibrillator using a novel combination of ultrasound-guided supraclavicular nerve and pectoral nerve blocks. The entire procedure was completed without any procedural sedation or local anesthetic, and the patient did not experience any pain during or after the procedure. (...

Pacemaker insertion incurs significant costs for fluoroscopy machines and operator-related musculoskeletal injuries from long-term use of radiation protection equipment. Moreover, there are small potential risks to patients from pneumothorax, lead dislodgment, and cardiac perforation. We report a first-in-human case report of successful pacemaker i...

Introduction: Left Bundle Branch area Pacing (LBBaP) is gaining prevalence as a more physiologic alternative to conventional right ventricular pacing. Given limited literature on LBBaP, this retrospective study assessed feasibility and septal perforation rates following LBBaP. Methods: Procedure reports and electrophysiologic parameters were review...

Aims: The ARC-HF and CAMTAF trials randomised patients with persistent atrial fibrillation (AF) and heart failure (HF) to early routine catheter ablation (ER-CA) versus pharmacological rate control (RC). After trial completion, delayed-selective CA (DS-CA) was performed where clinically-indicated in the RC group. We hypothesised that ER-CA would r...

Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is currently diagnosed using a combination of clinical features, imaging, electrocardiographic, and genetic investigations. An abnormal signal averaged ECG (SAECG) is defined as a minor diagnostic criterion by the 2010 Task Force Criteria (TFC), but doubts remain regarding the value...

Background Diagnosis of congenital long‐QT syndrome (LQTS) is complicated by phenotypic ambiguity, with a frequent normal‐to‐borderline resting QT interval. A 3‐step algorithm based on exercise response of the corrected QT interval (QTc) was previously developed to diagnose patients with LQTS and predict subtype. This study evaluated the 3‐step alg...

Background: It is not known whether the optimal Atrioventricular delay (AV ) varies between left ventricular (LV) pacing site during endocardial biventricular pacing (BiVP) and may therefore needs consideration. Methods: We assessed the haemodynamic AV in patients with chronic heart failure undergoing endocardial LV lead implantation. AV was assess...

Background A high proportion of patients undergoing catheter ablation (CA) for atrial fibrillation (AF) experience recurrence of arrhythmia. This meta-analysis aims to identify pre-ablation serum biomarker(s) associated with arrhythmia recurrence to improve patient selection before CA. Methods A systematic approach following PRISMA reporting guide...

Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): NIHR Background Ablation of long-standing persistent atrial fibrillation (LSPAF) is not always successful. The arrhythmia burden was reduced by 75% by 12 months in majority (72%) of patients with LSPAF who underwent surgical or percuta...

Aims Genetic testing is recommended in specific inherited heart diseases but its role remains unclear and it is not currently recommended in unexplained cardiac arrest (UCA). We sought to assess the yield and clinical utility of genetic testing in UCA using whole-exome sequencing (WES). Methods and results Survivors of UCA requiring external defib...

Background Patients with hemodynamically tolerated VT and minimally reduced left ventricular ejection fraction remain a group that presents a prognostic and therapeutic dilemma. Methods We studied patients from our ICD database who received an ICD implant for hemodynamically tolerated VT and mildly reduced LVEF (36-49%) at time of implant between...

Commotio cordis is the second leading cause of sudden cardiac death in young athletes. Currently available chest protectors on the market are ineffective in preventing cases of commotio cordis in young athletes that play baseball. This study focused on using contour maps to identify specific baseball impact locations to the chest that may result in...

Background Ictal bradyarrhythmia is a rare condition defined by temporal lobe epilepsy resulting in bradycardia or asystole and can result in syncope. This needs to be differentiated from isolated syncope in patients with seizure disorder, as treatment strategies differ. Case Summary A 50-year-old female with well-controlled temporal epilepsy and...

BACKGROUND Following an unexplained cardiac arrest, patients and family members typically undergo a comprehensive series of investigations to identify the underlying cause of arrest, with a diagnosis identified in more than half of cardiac arrest survivors. However, the long-term arrhythmic outcomes among cardiac arrest survivors remains unclear....

Background Standalone thoracoscopic surgical ablation may be more effective than catheter ablation in patients with long-standing persistent atrial fibrillation. Objectives To determine whether or not surgical ablation is clinically superior to catheter ablation as the first-line treatment strategy in long-standing persistent atrial fibrillation....

Background Cardiac implantable electronic devices deliver life-sustaining therapy and may be prone to hardware degeneration over time. Functioning transvenous endocardial lead with visible insulation breaks are amenable to lead revision (LRV) or lead repair (LRP), with medical adhesive. The latter being a less invasive, and more cost-effective stra...

Commotio cordis is a sudden death mechanism that occurs when the heart is impacted during the repolarization phase of the cardiac cycle. This study aimed to investigate commotio cordis injury metrics by correlating chest force and rib deformation to left ventricle strain and pressure. We simulated 128 chest impacts using a simulation matrix which i...

Automated and accurate segmentation of the left atrium (LA) and atrial scars from late gadolinium-enhanced cardiac magnetic resonance (LGE CMR) images are in high demand for quantifying atrial scars. The previous quantification of atrial scars relies on a two-phase segmentation for LA and atrial scars due to their large volume difference (unbalance...

Automated and accurate segmentations of left atrium (LA) and atrial scars from late gadolinium-enhanced cardiac magnetic resonance (LGE CMR) images are in high demand for quantifying atrial scars. The previous quantification of atrial scars relies on a two-phase segmentation for LA and atrial scars due to their large volume difference (unbalanced a...

DOI: 10.1016/j.jacep.2020.12.003

Background Modern permanent pacemakers (PPMs) have individual features designed to identify cardiac rhythm abnormalities and improve their performance. Inappropriate pacing inhibition may be an undesired outcome from these features and cause symptoms in patients who require frequent pacing, leading to dizziness, and syncope. Inappropriate inhibitio...

Introduction Tricuspid regurgitation (TR) is a known complication of cardiac implantable devices (CIED). A better understanding of the patient population affected by this complication and their outcomes is needed. The aims of our study were to: 1) describe the incidence of CIED-related tricuspid regurgitation; 2) identify patient characteristics co...

Commotio cordis is a sudden death mechanism that occurs when the heart is impacted during the repolarization phase of the cardiac cycle. This study aimed to investigate commotio cordis injury metrics by correlating chest force and rib deformation to left ventricle (LV) strain and pressure. We simulated 128 chest impacts using a simulation matrix wh...

Introduction: Septal accessory pathway (AP) ablation can be challenging due to the complex anatomy of the septal region. The decision to access the left atrium (LA) is often made after failure of ablation from the right. We sought to establish whether the difference between ventriculo-atrial time (VA) during right ventricular (RV) apical pacing ve...

Aims Long-standing persistent atrial fibrillation (LSPAF) is challenging to treat with suboptimal catheter ablation (CA) outcomes. Thoracoscopic surgical ablation (SA) has shown promising efficacy in atrial fibrillation (AF). This multicentre randomized controlled trial tested whether SA was superior to CA as the first interventional strategy in de...

Cross‐talk is a well‐described phenomenon in a dual‐chamber cardiovascular implantable electronic device. Far‐field ventricular events are more commonly sensed in the atrial channel, the reverse is uncommon, and seeing both at the same time has never been reported. We present a case of double cross‐talk in a dual‐chamber Medtronic ® implantable car...

Abstract Background Capillary leak syndrome (CLS) is a rare connective tissue disease, triggered by the leak of serous fluid into the interstitial spaces, characterized by a hallmark of oedema and effusions in confined spaces. The limiting factor in CLS management appears to be its diagnosis rather than treatment, which is usually to contain the...

Introduction: In patients with a broad QRS and heart failure, the effects on acute systolic blood pressure (SBP) augmentation during biventricular pacing (BVP) when pacing at different LV endocardial sites are not well studied. Detecting true improvement without bias whilst accounting for biological variability remains challenging. Methods: We use...

Keywords: Left ventricular mass; hypertrophic cardiomyopathy; Novel risk score marker; Cardiac MRI; Magnetic resonance imaging; left ventricular scar; ventricular fibrillation; ventricular tachycardia; Risk score for hypertrophic cardiomyopathy; European Society of Cardiology (ESC) risk score

Our data shows that the surgical pen provides robust conduction block assessment when testing at multiple points and is comparable to multipolar electrophysiological catheter testing. The surgical pen is also compatible with a wider range of patient anatomies than the multipolar electrophysiological catheter and is technically less demanding. Multi...

Background Catheter ablation for drug refractory, symptomatic atrial fibrillation (AF), is becoming increasingly common and can be beneficial in alleviating symptoms. However, in the elderly, there are concerns about the risks an invasive procedure poses, with limited published data available in those aged over 80 years. Purpose To determine the c...

Background The successful implantation of cardiac resynchronization therapy (CRT) may be prevented by anatomical variations that preclude the delivery of clinically effective left ventricular (LV) pacing from within the coronary sinus (CS) or its tributaries. Failure of lead delivery, suboptimal LV capture thresholds, or intractable phrenic nerve c...

Background: Radiofrequency ablation (RFA) is the cornerstone of atrial fibrillation (AF) management. Electroanatomical remodeling (EAR) is thought to occur with increasing AF burden reducing success rates. Long-standing persistent atrial fibrillation (LSPAF) is the most challenging to treat and the anatomical effect of RFA on the atria and ventricl...

Background: Left atrial appendage (LAA) exclusion is performed more frequently during minimally invasive thoracoscopic surgical ablation (TSA) in atrial fibrillation(AF) management. The impact of LAA exclusion on left atrial (LA) function is not fully understood in patients with long-standing persistent AF (LSPAF).

Accessory mitral valve tissue is a rare congenital anomaly that is commonly incidentally diagnosed. When symptomatic, it tends to present with features of left ventricular outflow (LVOT) obstruction in about two thirds of cases. It is also commonly associated with other congenital anomalies, notably ventricular septal defects. Transthoracic echocar...