Wide QRS-T Angle on the 12-Lead ECG as a Predictor of Sudden Death Beyond the LV Ejection Fraction.

INTRODUCTION: Improvements in risk stratification for sudden cardiac arrest (SCA) will require discovery of markers that extend beyond the LV ejection fraction (LVEF). The frontal QRS-T angle has been shown to predict risk of SCA but the value of this marker independent of the LVEF has not been investigated. METHODS AND RESULTS: Cases of adult SCA with an archived electrocardiogram (12-lead ECG) available before the event, with a computable frontal QRS-T angle, were identified from the Oregon Sudden Unexpected Death Study (Oregon SUDS) ongoing in the Portland, Oregon metro area. A total of 666 SCA cases (mean age 67.2 years; 95% CI, 52.3-82.1 years; 68.6% males) were compared to 863 controls (mean age 66.6 years, 55.2-78.0 years; 68.1% males; 75.0% had CAD) from the same geographical region. The mean frontal QRS-T angle was wider in cases (74(o) ; 95% CI, 17(o) -131(o) ) compared to controls (51(o) ; 95% CI, 5(o) -97(o;) P< 0.0001). A frontal QRS-T angle of more than 90(o) remained associated with increased risk of SCD after adjusting for age, gender, heart rate, prolonged intraventricular conduction, electrocardiographic left ventricular hypertrophy (ECG LVH), baseline comorbidities, and left ventricular ejection fraction (LVEF) (OR 2.2; 95% CI, 1.60-3.09; P< 0.0001). CONCLUSION: A wide QRS-T angle greater than 90(o) is associated with an increased risk of SCA independent of the left ventricular ejection fraction.

Catheter ablation of recurrent polymorphic tachycardia: Use of sodium channel blockade to organize the tachycardia: A case report.

A 55 year old male presented with recurrent implantable cardioverter defibrillator (ICD) shocks due to polymorphic ventricular tachycardia (PMVT). He had undergone prior catheter ablation for VT three years ago. During the prior attempt he underwent voltage guided substrate ablation. With programmed ventricular extrastimulation (PVES), PMVT was repeatedly induced requiring DC shock. Intravenous procainamide was administered and PVES was repeated which induced sustained monomorphic ventricular tachycardia (MMVT). This VT had pseudo delta waves with maximum deflection index of 0.68, suggestive of epicardial origin. Activation mapping was performed epicardially. Presystolic potentials were recorded in mid anterolateral wall of left ventricular epicardial region. Radiofrequency (RF) ablation at this site terminated the VT. Post ablation there was no inducible tachycardia and patient is free of arrhythmias during 2 years of follow-up.

Interpreting device diagnostics for lead failure.

Implantable cardioverter-defibrillators (ICDs) incorporate automated, lead-monitoring alerts (alerts) and other diagnostics to detect defibrillation lead failure (LF) and minimize its adverse clinical consequences. Partial conductor fractures cause oversensing, but pacing or high-voltage alerts for high impedance detect only complete conductor fracture. In both pacing and high-voltage insulation breaches, low-impedance alerts require complete breach with metal-to-metal contact. Oversensing alerts for pace-sense LF also require complete breach, but not metal-to metal contact. Electrograms (EGMs) from leads with confirmed fractures have characteristics findings. In insulation breach, however, oversensed EGMs reflect characteristics of the source signal. Oversensing alerts that operate on the sensing channel analyze R-R intervals for 2 patterns typical of LF but uncommon in other conditions: a rapidly increasing count of "nonphysiological" short intervals and rapid "nonsustained tachycardias." These alerts are sensitive but nonspecific. Alerts that compare sensing and shock channels define oversensing as sensed events that do not correlate temporally with EGMs on the shock channel. Their performance depends on implementation. Specific advantages and limitations are reviewed. Most ICDs measure impedance using subthreshold pulses. Patterns in impedance trends provide diagnostic information, whether or not an alert is triggered. Gradual increases in impedance do not indicate structural LF, but they may cause failed defibrillation if shock impedance is high enough. Because impedance-threshold alerts are insensitive, normal impedance trends never exclude LF, but an abrupt increase that triggers an alert almost always indicates a header connection issue or LF. Methods for discriminating connection issues from LF are reviewed.

An association between right ventricular dysfunction and sudden cardiac death.

BACKGROUND: The effectiveness of severely reduced left ventricular ejection fraction (LVEF <35%) as a predictor of sudden cardiac death (SCD) has diminished, and improvements in risk stratification await discovery of novel markers. Right ventricular (RV) abnormalities can be observed in conditions such as chronic obstructive pulmonary disease and sleep apnea, which have been linked to SCD. OBJECTIVE: The purpose of this study was to evaluate whether RV abnormalities were associated with SCD after accounting for LVEF and other patient characteristics. METHODS: In a large, prospective ongoing community-based study of SCD in the Portland, Oregon, metropolitan area, SCD cases (age ≥18 years; 2002-2014) were compared to controls with coronary artery disease but no SCD. Using a novel archive of digital echocardiograms, a standardized approach was used to evaluate RV basal diameter, RV end-diastolic area, and right ventricular fractional area change (RVFAC). RESULTS: A total of 350 subjects were studied, including 81 SCD cases (age 68.7 ± 13.6 years; 73% male) and 269 controls (age 66.5 ± 10.2 years; 69% male). In multivariate analysis, RVFAC was significantly associated with SCD (odds ratio 1.14 for each 5% decrease; 95% confidence interval 1.03-1.25; P = .01). When modeled with LVEF ≤35%, RVFAC ≤35% was significantly associated with increased risk of SCD. Individuals with both left ventricular and RV dysfunction had a 3× higher odds of SCD than those with neither (odds ratio 3.19; 95% confidence interval 1.33-7.68; P = .01). CONCLUSION: RV dysfunction was associated with a significantly increased risk of SCD independent of LVEF and, when combined with LVEF, had additive effects on SCD risk.

Monitoring for and Diagnosis of Lead Dysfunction.

The predominant structural mechanisms of transvenous lead dysfunction (LD) are conductor fracture and insulation breach. LD typically presents as an abnormality of electrical performance; the earliest sign usually is either oversensing or out-of-range pacing or shock impedance. Accurate diagnosis of LD requires discriminating patterns of oversensing and impedance trends that are characteristic of LD from similar patterns that occur in other conditions. Implantable cardioverter-defibrillators have advanced features to detect and mitigate the consequences of LD; these features operate both independently and in conjunction with remote monitoring networks.

Device implantation for patients on antiplatelets and anticoagulants: Use of suction drain.

BACKGROUND AND OBJECTIVES: Cardiovascular implantable electronic devices (CIED) are frequently implanted in patients on anti-thrombotic agents. Pocket hematomas are more likely to occur in these patients. The use of a sterile surgical drain in the pulse generator pocket site could prevent hematomas, but fear of infection precludes its use. The objective of the present study is to study the safety and efficacy of surgical drain in patients on antithrombotics undergoing CIED implantations. METHODS: This is a single-centre, retrospective study involving patients undergoing CIED implantations on antithrombotics (antiplatelets and anticoagulants) from August 2013 to July 2016. Patients with high risk of thromboembolism were continued on oral antithrombotics or were bridged with heparin after stopping oral antithrombotics. A sterile close wound suction drain was placed in device pockets following CIED implantations. Post procedure, pressure dressing was applied and removed after 12 h once the drain volume was less than 10 ml in 24 h. RESULTS: Sixty seven patients required surgical drain implantation. Major indications for antithrombotic use were presence of intracoronary stent, atrial fibrillation and mechanical valve replacements. The mean post-procedural hospital stay was 3 ±â€¯0.9 days and mean overall drain was 16.6 ±â€¯8.2 ml. At a mean follow up of 17.6 ±â€¯8.2 months, one patient (1.4%) had pocket hematoma. There were no infections. CONCLUSION: The use of a surgical drain in CIED implantation significantly reduces the risk of hematoma formation without increasing the risk of infection. Antithrombotic drugs can be safely continued at the time of implantation of cardiac devices.

Novel measure of autonomic remodeling associated with sudden cardiac arrest in diabetes.

BACKGROUND: Diabetes is independently associated with an increased risk of sudden cardiac arrest (SCA), with a need to identify novel methods for risk stratification. Diabetic patients can develop autonomic dysfunction that has been associated with an increased risk of ventricular arrhythmogenesis and manifests as reduced heart rate variability (HRV). However, previously published studies have not accounted for resting heart rate (HR), important from both pathophysiological and prognosticating standpoints. OBJECTIVE: We sought to evaluate autonomic remodeling of the sinus node response in SCA and diabetes while accounting for HR. METHODS: We performed a case-control study in SCA cases (age 35-59 years; 2002-2014) from the ongoing Oregon Sudden Unexpected Death Study (catchment population ∼1 million), and archived 12-lead electrocardiograms recorded prior to the SCA event were compared with those of geographic controls. Short-term HRV was calculated from digitized 10-second electrocardiograms by using established methods. We analyzed 313 subjects (mean age 52.0 ± 5.5 years; 216 men, 69.0%) and compared 4 groups: 111 diabetic (49 cases, 62 controls) and 202 nondiabetic (80 cases, 122 controls) subjects. RESULTS: Analysis of covariance showed an absence of the expected interaction between HRV and HR (HRV-HR) in diabetic patients with SCA (regression slope -0.008; 95% confidence interval -0.023 to 0.0071; P = .26). This finding, unique to this population of diabetic patients with SCA, was not detected using traditional HRV measures. CONCLUSION: By incorporating resting HR in this analysis, we observed that this population of diabetic patients with SCA had loss of the expected HRV-HR relationship. This potentially novel noninvasive risk measurement warrants further investigation, especially at the level of the individual patient.

Prevalence of atrial fibrillation in an urban population in India: the Nagpur pilot study.

OBJECTIVES: Atrial fibrillation (AF) is the most common sustained arrhythmia encountered in clinical practice with major public health impact mainly due to the increased risk of stroke. The recent Global Burden of Disease Study reported a lack of prevalence data from India. Our goal was to conduct a pilot study to evaluate the feasibility of assessing AF prevalence and stroke prophylaxis in an urban Indian community. METHODS: A screening camp was conducted in Nagpur, India, that evaluated adults aged ≥18 years. We collected demographics, recorded blood pressure, height, weight and the 12-lead electrocardiogram (ECG). The presence of diabetes and hypertension was recorded by self-reported history. Patients diagnosed with AF were evaluated further to assess aetiology and management. RESULTS: Of the total 4077 randomly selected, community-dwelling adults studied, 0.196% (eight patients) were found to have AF. Mean age of the population was 43.9±14.8, and 44.5% were female. The mean age of the patients with AF was 60.5±15.8 years (five females). Rheumatic heart disease was found in five patients with AF. Three patients had history of stroke (37.5%) and one had peripheral arterial thrombosis. Three patients were on warfarin, but without routine international normalised ratio (INR) monitoring. One patient was on aspirin. Five patients were on ß-blockers and one on both ß-blocker and digoxin. CONCLUSIONS: The prevalence of AF was low compared with other regions of the world and stroke prophylaxis was underused. A larger study is needed to confirm these findings. This study demonstrates that larger evaluations would be feasible using the community-based techniques employed here.

A stepwise approach to the induction of idiopathic fascicular ventricular tachycardia.

PURPOSE: Noninducibility of the clinical tachycardia is a major limitation while mapping and ablating idiopathic fascicular ventricular tachycardia (FVT). There is very little data on systematic induction protocols in this entity. Our aim was to study the role of systematic induction protocols in patients with clinically documented ventricular tachycardia (VT). METHODS: Programmed electrical stimulation was performed at baseline from high right atrium, right ventricular apex, right ventricular outflow tract and from left ventricle as per the protocol. Programmed ventricular stimulation was performed at two drive cycle lengths up to three extrastimuli and short-long-short sequence. If FVT remained non inducible at baseline, pharmacological provocation with isoprenaline/atropine/phenylephrine was used based on the baseline atrio-ventricular Wenckebach cycle length. RESULTS: This systematic induction protocol was studied in 68 patients with clinically documented FVT and sustained FVT was inducible in 64 patients (94 %). Of these 64 patients, pharmacological provocation was required in 18 patients (28 %) while in the remaining, sustained VT was induced at baseline. This high induction rate allowed ablation during tachycardia, which resulted in 100 % acute procedural success in the patients where sustained tachycardia could be induced. At a follow up of 29 ± 13 months, two patients (3 %) had recurrence. CONCLUSIONS: Systematic induction protocol along with the appropriate use of pharmacological agents results in a high induction rate of FVT. This may result in more defined and limited ablation during tachycardia with better success rates and lesser recurrence.