Simon Modi

Risk of Arrhythmia and Sudden Death in Patients With Asymptomatic Preexcitation A Meta-Analysis

Background— The incidence of sudden cardiac death (SCD) and the management of this risk in patients with asymptomatic preexcitation remain controversial. The purpose of this meta-analysis was to define the incidence of SCD and supraventricular tachycardia in patients with asymptomatic Wolff-Parkinson-White ECG pattern. Methods and Results— We performed a systematic search of prospective, retrospective, randomized, or cohort English-language studies in EMBASE and Medline through February 2011. Studies reporting asymptomatic patients with preexcitation who did not undergo ablation were included. Twenty studies involving 1869 patients met our inclusion criteria. Participants were primarily male with a mean age ranging from 7 to 43 years. Ten SCDs were reported involving 11 722 person-years of follow-up. Seven studies originated from Italy and reported 9 SCDs. The risk of SCD is estimated at 1.25 per 1000 person-years (95% confidence interval [CI], 0.57–2.19). A total of 156 supraventricular tachycardias were reported involving 9884 person-years from 18 studies. The risk of supraventricular tachycardia was 16 (95% CI, 10–24) events per 1000 person-years of follow-up. Children had numerically higher SCD (1.93 [95% CI, 0.57–4.1] versus 0.86 [95% CI, 0.28–1.75]; P=0.07) and supraventricular tachycardia (20 [95% CI, 12–31] versus 14 [95% CI, 6–25]; P=0.38) event rates compared with adults. Conclusion— The low incidence of SCD and low risk of supraventricular tachycardia argue against routine invasive management in most asymptomatic patients with the Wolff-Parkinson-White ECG pattern.

Sudden Cardiac Arrest Without Overt Heart Disease

The topic of sudden unexplained cardiac arrest without overt heart disease is a highly emotive and important subject with a rapidly advancing knowledge base. The correct identification of those conditions predisposing to cardiac arrest is paramount, and is part of the role of every practicing cardiologist. This review article is designed to give the practicing cardiologist an up-to-date insight into a subspecialized field of cardiac electrophysiology and cardiac genetics. It seeks to help to formulate diagnoses with advanced electrophysiological testing and genetic profiling and also with a reminder of basic clinical presentations and pathophysiological features of the conditions in question. This article seeks to encapsulate the field in general and at the same time to provide a select amount of useful detail, both contemporary and historical, and to provide references from a resource of excellent reviews in the literature. We hope that the reader will develop confidence in identifying rare causes of cardiac arrest and an insight into the sort of patients that should be referred to subspecialist clinics. Structural or coronary heart disease is by far the most common cause of sudden cardiac arrest.1 Once overt heart disease has been excluded in the cardiac arrest survivor, the differential diagnosis includes manifest or latent primary electrical disease and latent structural causes (Tables 1 and 2). These conditions predispose the patient to recurrent ventricular arrhythmia and cardiac arrest without overt heart disease. The overriding immediate concern in these patients is recurrence of unheralded ventricular tachycardia or fibrillation. Every effort must be made to define the underlying pathophysiology in order to understand prognosis, direct therapy, and identify family members who may be at risk if the culprit is an inherited condition. View this table: Table 1. Causes of Sudden Cardiac Arrest View this table: Table 2. Summary of Conditions Causing Sudden Cardiac Arrest Without Overt Heart Disease The conditions in question …

How to Perform and Interpret Provocative Testing for the Diagnosis of Brugada Syndrome, Long-QT Syndrome, and Catecholaminergic Polymorphic Ventricular Tachycardia

Sudden cardiac death (SCD) is predominantly related to coronary artery disease and its sequelae, cardiomyopathy, and congenital or valvular heart disease. No structural abnormalities are detectable in 5–8% of SCDs.1 Identified ion channelopathies such as Brugada syndrome, long-QT syndrome (LQTS), and catecholaminergic polymorphic ventricular tachycardia (CPVT) contribute to this incidence. The diagnosis requires a high level of suspicion because of a resting ECG that is often borderline, intermittently normal, or frankly normal. Genetic testing does not provide a simple solution to this issue, as it is often neither sensitive nor specific even when the phenotype points to a specific entity and may yield results that are difficult to interpret (ie, variants of unknown significance). Pharmacological and/or exercise testing by manipulation/stressing the cardiac action potential can accentuate the desired abnormality or provoke a characteristic arrhythmia response. A systematic approach to clinical testing that includes drug provocation results in unmasking of the cause of apparently unexplained aborted SCD in >50% of patients and is very helpful in directing genetic testing of the index case and family to diagnose genetically mediated arrhythmia syndromes.2 This review will seek to highlight the clinical utility of provocative testing and describe how to perform and interpret provocative testing for the diagnosis of Brugada syndrome, LQTS, and CPVT. ### Performing Provocative Testing Pharmacological challenge should be performed in an area that has comprehensive monitoring and resuscitation equipment (including an external cardioverter-defibrillator). Testing should be performed with continuous monitoring of the patient by adequately trained/experienced personnel in an area equipped with advance resuscitation equipment (including external defibrillator) and personnel trained in advance resuscitation and an expert physician promptly available. Given the potential risk for hemodynamically compromising ventricular arrhythmias during exercise stress testing (particularly when exercise stress testing for CPVT), we advise the presence of physically capable personnel to prevent the patient …

Ablation index, a novel marker of ablation lesion quality: prediction of pulmonary vein reconnection at repeat electrophysiology study and regional differences in target values

Aims Force-Time Integral (FTI) is commonly used as a marker of ablation lesion quality during pulmonary vein isolation (PVI), but does not incorporate power. Ablation Index (AI) is a novel lesion quality marker that utilizes contact force, time, and power in a weighted formula. Furthermore, only a single FTI target value has been suggested despite regional variation in left atrial wall thickness. We aimed to study AIs and FTIs relationships with PV reconnection at repeat electrophysiology study, and regional threshold values that predicted no reconnection. Methods and results Forty paroxysmal atrial fibrillation patients underwent contact force-guided PVI, and the minimum and mean AI and FTI values for each segment were identified according to a 12-segment model. All patients underwent repeat electrophysiology study at 2 months, regardless of symptoms, to identify sites of PV reconnection. Late PV reconnection was seen in 53 (11%) segments in 25 (62%) patients. Reconnected segments had significantly lower minimum AI [308 (252-336) vs. 373 (323-423), P < 0.0001] and FTI [137 (92-182) vs. 228 (157-334), P < 0.0001] compared with non-reconnected segments. Minimum AI and FTI were both independently predictive, but AI had a smaller P value. Higher minimum AI and FTI values were required to avoid reconnection in anterior/roof segments than for posterior/inferior segments (P < 0.0001). No reconnection was seen where the minimum AI value was ≥370 for posterior/inferior segments and ≥480 for anterior/roof segments. Conclusion The minimum AI value in a PVI segment is independently predictive of reconnection of that segment at repeat electrophysiology study. Higher AI and FTI values are required for anterior/roof segments than for posterior/inferior segments to prevent reconnection.

Biatrial linear ablation in sustained nonpermanent AF: Results of the substrate modification with ablation and antiarrhythmic drugs in nonpermanent atrial fibrillation (SMAN-PAF) trial

BACKGROUND More advanced atrial fibrillation (AF) is associated with lower success rates after pulmonary vein isolation (PVI), and the optimal ablation strategy is uncertain. OBJECTIVES To assess the impact of additional linear ablation (lines) compared to PVI alone. METHODS In this multicenter randomized controlled trial, 122 patients (mean age 61.9 ± 10.5 years; left atrial diameter 43 ± 6 mm) with persistent AF (PeAF) or sustained (>12 hours) paroxysmal AF (SusPAF) with risk factors for atrial substrate were included and followed up for 12 months. Patients were randomized to PVI-only or PVI + lines (left atrial roof line, mitral isthmus line, and tricuspid isthmus line) group. Holter monitoring was performed at 3, 6, and 12 months and according to symptoms. The primary outcome was atrial tachyarrhythmia recurrence lasting ≥30 seconds. RESULTS Baseline characteristics were comparable between groups; 61% had PeAF and 39% SusPAF. Successful PVI was achieved for 98% of pulmonary veins, and bidirectional block was obtained in 90% of lines. The primary end point occurred in 38% of the PVI + lines group and 32% of the PVI-only group (P = .50), which was consistent in both PeAF (36% vs 28%; P = .45) and SusPAF (42% vs 39%; P = .86). Compared with the PVI-only group, the PVI + lines group had higher procedure duration (209 ± 52 minutes vs 172 ± 44 minutes; P < .001), ablation time (4352 ± 1084 seconds vs 2503 ± 1061 seconds; P < .001), and radiation exposure (Dose-area product 3992 ± 6496 Gy·cm(2) vs 2106 ± 1679 Gy·cm(2); P = .03). Quality of life (disease-specific Atrial Fibrillation Effect on Quality of Life questionnaire and mental component scale of the Short Form 36 Health Survey) improved significantly during the study but did not differ between groups. CONCLUSION Adding lines to wide antral PVI in substrate-based AF requires significantly more ablation, increases procedure duration and radiation dose, but provides no additional clinical benefit.

Improving Safety in Catheter Ablation for Atrial Fibrillation: A Prospective Study of the Use of Ultrasound to Guide Vascular Access

The most frequent complications of AF ablation (AFA) are related to vascular access, but there is little evidence as to how these can be minimized.

Recurrence of Atrial Tachyarrhythmia During the Second Month of the Blanking Period Is Associated With More Extensive Pulmonary Vein Reconnection at Repeat Electrophysiology Study

Background—Current guidelines recommend a 3-month blanking period after pulmonary vein isolation (PVI) as early recurrence of atrial tachyarrhythmia (ERAT) may be due to transient proarrhythmic factors. However, studies have suggested that these factors resolve by 1 month. PV reconnection (PVrc) is strongly associated with postblanking AT recurrence in paroxysmal atrial fibrillation. We hypothesized that ERAT occurring beyond 4 weeks after PVI is associated with PVrc at repeat electrophysiology study. Methods and Results—Forty patients with paroxysmal atrial fibrillation underwent mandatory repeat electrophysiology study 2 months after PVI, regardless of symptoms, to document the number of reconnected PVs. Antiarrhythmic drugs, including &bgr;-blockers, were discontinued 4 weeks after PVI. Patients were instructed to record a 30-second ECG everyday between the 2 procedures using a portable monitor, with additional recordings for symptoms. ERAT was defined as ≥30 seconds of AT. Patients recorded a total of 3293 ECGs. Four (10%) patients had ERAT in the first 4 weeks (M1) only, 2 (5%) in month 2 (M2) only, and 11 (28%) in both. PVrc of 1 PV was identified in 12 (30%) patients and of >1 PV in 13 (32%) patients. ERAT in M2 was associated with PVrc, whereas M1 was not (11/13 [85%] versus 0/4 [0%]; P=0.006). M2 ERAT was strongly associated with PVrc of >1 PV (10/13 [77%] versus 3/27 [11%] without M2 ERAT; P<0.0001). Conclusions—ERAT occurring beyond 4 weeks after PVI is associated with PVrc and particularly of PVrc of >1 PV. ERAT confined to M1 is unrelated to underlying PVrc. The relationship between ERAT beyond 4 weeks after PVI and postblanking AT recurrence merits further investigation.

Tachycardia induction with ventricular extrastimuli differentiates atypical atrioventricular nodal reentrant tachycardia from orthodromic reciprocating tachycardia.

BACKGROUND Differentiating atypical atrioventricular nodal reentrant tachycardia (AVNRT) from septal orthodromic reentrant tachycardia (ORT(Septal)) is challenging in nonsustained tachycardia. When sustained, the postpacing interval minus tachycardia cycle length following entrainment (PPI(Entrainment) - TCL) and stimulation to atrial interval minus ventriculoatrial interval (Stim-A(Entrainment) - VA) are utilized. OBJECTIVE We hypothesized that the first tachycardia cycle after tachycardia induction with right ventricular apical extrastimulation would yield comparable information to entrainment, precluding the need for sustained tachycardia. METHODS Twenty-four patients with AVNRT (age 47 ± 18 years), 19 with ORT(Septal) (age 42 ± 17 years), and 15 with ORT over a left lateral accessory pathway (ORT(Left)) (age 41 ± 16 years) were included. The ventricular extrastimulus to atrial depolarization at tachycardia initiation (Stim-A(Initiation)) and tachycardia VA interval were measured to establish the Stim-A(Initiation) minus VA interval (Stim-A(Initiation) - VA). The ventricular extrastimulus to the subsequent right ventricular apical depolarization (postpacing interval at initiation, PPI(Initiation)) was utilized to obtain the PPI(Initiation) minus TCL (PPI(Initiation) - TCL). The AH interval associated with the PPI(Initiation) minus the AH in tachycardia was utilized to establish a corrected PPI(Initiation) minus TCL (cPPI(Initiation) - TCL). RESULTS The intervals after tachycardia initiation were longer for AVNRT than for ORT: mean PPI(Initiation) - TCL (193 ± 44 vs 91 ± 73; P <.001), cPPI(Initiation) - TCL (174 ± 44 ms vs 88 ± 50 ms; P <.001), and Stim-A(Initiation) - VA (161 ± 45 ms vs 69 ± 53 ms; P <.001). The correlation coefficient for Stim-A(Initiation) minus VA against Stim-A(Entrainment) minus VA was 0.79 and for cPPI(Initiation) minus TCL against PPI(Entrainment) minus TCL was 0.71. cPPI(Initiation) minus TCL <115 ms or Stim-A(Initiation) - VA <85 ms was observed only in ORT. The converse was observed in AVNRT but also in ORT(Septal) over decremental accessory pathways and ORT(Left). CONCLUSION Stim-A(Initiation) - VA < 85 ms or cPPI(Initiation) - TCL < 115 ms excludes AVNRT.

Tako-tsubo, hypertrophic obstructive cardiomyopathy & muscle bridging--separate disease entities or a single condition?

We report a case of an apical ballooning syndrome using classical and high quality imagery. Co-existing features of asymmetrical septal hypertrophy, outflow tract obstruction, systolic anterior mitral valve motion and LAD myocardial bridging make the underlying patho-physiology difficult to ascertain. In conclusion we believe that this single case will promote discussion and add to an expanding literature base of the tako-tsubo cardiomyopathy syndrome.

Radiofrequency ablation of the interventricular septum to treat outflow tract gradients in hypertrophic obstructive cardiomyopathy: a novel use of CARTOSound® technology to guide ablation.

AIMS Septal reduction is needed for hypertrophic obstructive cardiomyopathy (HOCM) patients with severe left ventricular outflow tract (LVOT) gradients and symptoms despite medication. Myectomy cannot be performed in all. Alcohol septal ablation cannot be performed in 5-15% due to technical difficulties. A method of delivering percutaneous tissue damage to the septum that is not reliant on coronary anatomy is desirable. To directly ablate the interventricular septum at the mitral valve (MV) systolic anterior motion (SAM)-septal contact point using radiofrequency (RF) energy guided by CARTOSound. METHODS AND RESULTS Five patients underwent RF ablation (RFA); we describe follow-up at 6 months in four patients. Intracardiac echocardiography (ICE) images are merged with CARTO to create a shell of the cardiac chambers. The SAM-septal contact area is marked from ICE images and mapped on to the CARTO shell; this becomes the target for RF delivery. Conduction tissue is mapped and avoided where possible. Twenty-eight to 42 min of RF energy was delivered to the target area using retrograde aortic access and SmartTouch catheters. Resting LVOT gradient improved from 64.2 (±50.6) to 12.3 (±2.5) mmHg. Valsalva/exercise-induced gradient reduced from 93.5 (±30.9) to 23.3 (±8.3) mmHg. Three patients improved New York Heart Association status from III to II, one patient improved from class III to I. Exercise time on bicycle ergometer increased from 612 to 730 s. Cardiac magnetic resonance shows late gadolinium enhancement up to 8 mm depth at LV target myocardium. One patient died following a significant retroperitoneal haemorrhage. CONCLUSION Radiofrequency ablation using CARTOSound(®) guidance is accurate and effective in treating LVOT gradients in HOCM in this preliminary group of patients.