Coexisting fascicular ventricular tachycardia and papillary muscle ventricular tachycardia in the setting of coronary artery disease in a master athlete.

A 73-year old male developed syncope during a bicycle race. Exercise stress testing demonstrated non-sustained ventricular tachycardia (NSVT) and ischemic changes. Coronary angiography revealed a 99% occluded right coronary artery which was stented; repeat stress testing demonstrated normal perfusion and NSVT. An electrophysiology study demonstrated left posterior fascicular ventricular tachycardia, which was ablated at two lower turnaround points. NSVT was observed during subsequent stress testing, prompting a repeat electrophysiology study. The inferoseptum and inferior wall were extensively ablated, along with a posteromedial papillary muscle premature ventricular complex. With no further demonstrable NSVT, the patient was cleared to return to competition.

MYBPC3 Haplotype Linked to Hypertrophic Cardiomyopathy in Rhesus Macaques (Macaca mulatta).

In humans, abnormal thickening of the left ventricle of the heart clinically defines hypertrophic cardiomyopathy (HCM), a common inherited cardiovascular disorder that can precede a sudden cardiac death event. The wide range of clinical presentations in HCM obscures genetic variants that may influence an individual's susceptibility to sudden cardiac death. Although exon sequencing of major sarcomere genes can be used to detect high-impact causal mutations, this strategy is successful in only half of patient cases. The incidence of left ventricular hypertrophy (LVH) in a managed research colony of rhesus macaques provides an excellent comparative model in which to explore the genomic etiology of severe HCM and sudden cardiac death. Because no rhesus HCM-associated mutations have been reported, we used a next-generation genotyping assay that targets 7 sarcomeric rhesus genes within 63 genomic sites that are orthologous to human genomic regions known to harbor HCM disease variants. Amplicon sequencing was performed on 52 macaques with confirmed LVH and 42 unrelated, unaffected animals representing both the Indian and Chinese rhesus macaque subspecies. Bias-reduced logistic regression uncovered a risk haplotype in the rhesus MYBPC3 gene, which is frequently disrupted in both human and feline HCM; this haplotype implicates an intronic variant strongly associated with disease in either homozygous or carrier form. Our results highlight that leveraging evolutionary genomic data provides a unique, practical strategy for minimizing population bias in complex disease studies.

Clinical Outcomes of Various Management Strategies for Symptomatic Bradycardia.

OBJECTIVE: To determine clinical outcomes of various management strategies for reversible and irreversible causes of symptomatic bradycardia in the inpatient setting. DESIGN: Retrospective observational study. SETTING: Emergency room and inpatient. PARTICIPANTS: Patients presenting to the emergency department with symptomatic bradycardia. METHODS: We retrospectively reviewed electronic health records of 518 patients from two Mayo Clinic campuses (Rochester and Phoenix) who presented to the emergency department with symptomatic bradycardia (heart rate ≤50 beats/minute) from January 1, 2010 through December 31, 2015. Sinus bradycardia was excluded. The following management strategies were compared: observation, non-invasive management (medications with/without transcutaneous pacing), early permanent pacemaker (PPM) implantation (≤2 days), and delayed PPM implantation (≥3 days). Study endpoints included length of stay and adverse events related to bradycardia (syncope, central line-associated bloodstream infections, cardiac arrest, and in-hospital mortality). Patients who received a PPM were further stratified by weekend hospital admission. RESULTS: Heart block occurred in 200 (38.6%) patients, and atrial arrhythmias with slow ventricular response occurred in 239 (46.1%) patients. Reversible causes of bradycardia included medication toxicity in 22 (4.2%) patients and hyperkalemia in 44 (8.5%) patients. Adverse events were similar in patients who underwent early compared to delayed PPM implantation (6.6% vs 12.5%, P=.20), whereas adverse events were higher in patients who received temporary transvenous pacing (19.1% vs 3.4%, P<.001). Weekend admissions were associated with increased temporary transvenous pacing, prolonged median time to PPM implantation by 1 day, and prolonged median length of stay by 2 days. CONCLUSIONS: Delayed PPM implantation was not associated with an increase in adverse events. Weekend PPM implantation should be considered to reduce temporary transvenous pacing and shorten length of stay.

Achieving durable mitral isthmus block: Challenges, pitfalls, and methods of assessment.

BACKGROUND AND OBJECTIVES: Macroreentrant atrial tachycardias often occur following atrial fibrillation ablation, most commonly due to nontransmural lesions in prior ablation lines. Perimitral atrial flutter is one such arrhythmia which requires ablation of the mitral isthmus. Our objectives were to review the literature regarding ablation of the mitral isthmus and to provide our approach for assessment of mitral isthmus block. METHODS: We review anatomical considerations, ablation strategies, and assessment of conduction block across the mitral isthmus, which is subject to several pitfalls. Activation sequence and spatial differential pacing techniques are discussed for assessment of both endocardial and epicardial bidirectional mitral isthmus block. RESULTS: Traditional methods for verifying mitral isthmus block include spatial differential pacing, activation mapping, and identification of double potentials. Up to 70% of cases require additional ablation in the coronary sinus (CS) to achieve transmural block. Interpretation of transmural block is subject to six pitfalls involving pacing output, differentiation of endocardial left atrial recordings from epicardial CS recordings, identification of a slowly conducting gap in the line, and catheter positioning during spatial differential pacing. Interpretation of unipolar electrograms can identify nontransmural lesions. We employ a combined epicardial and endocardial assessment of mitral isthmus block, which involves using a CS catheter for epicardial recording and a duodecapolar Halo catheter positioned around the mitral annulus for endocardial recording. CONCLUSIONS: The assessment of transmural mitral isthmus block can be challenging. Placement of an endocardial mapping catheter around the mitral annulus can provide a precise assessment of conduction across the mitral isthmus.

Left atrial appendage exclusion during mitral valve surgery and stroke in atrial fibrillation.

PURPOSE: The purpose of this study was to determine whether surgical left atrial appendage (LAA) exclusion performed during mitral valve surgery is associated with a reduction in cerebrovascular events in patients with atrial fibrillation. METHODS: We retrospectively studied patients with atrial fibrillation who underwent mitral valve surgery from 1/1/2001 through 12/31/2014. We screened 1352 patients using ICD-9 codes and included 281 patients in the study. The primary end point was a composite of strokes and transient ischemic attacks occurring within 5 years after surgery. Secondary end points were stroke, transient ischemic attack, and all-cause mortality. RESULTS: The LAA exclusion group (n = 188) had a lower prevalence of female gender, hypertension, and diabetes mellitus compared with the non-LAA exclusion group (n = 93). The CHA2DS2VASc scores were comparable between groups (2.6 vs 2.9, P = .11), as was anticoagulant use (82.4% vs 85.0%, P = .60). Concomitant surgical ablation was performed in 73.9% of patients who underwent LAA exclusion. Nine cerebrovascular events occurred in the LAA exclusion group and 13 in the non-LAA exclusion group (HR 0.30 [0.12-0.75], P = .01). There was no difference in all-cause mortality between groups. On multivariate analysis of the primary end point of strokes or transient ischemic attacks, significant variables were LAA exclusion (HR 0.31 [0.12-0.76], P = .01) and CHA2DS2VASc score (HR 1.44 [1.11-1.87], P = .006). The benefit of LAA exclusion was detected only when performed together with surgical ablation (HR 0.27 [0.09-0.72], P = .01). CONCLUSIONS: LAA exclusion was associated with fewer cerebrovascular events. However, this benefit was seen only with concomitant surgical ablation.

Prevalence and Prognostic Significance of Nonsustained Ventricular Tachycardia in Patients With a Left Ventricular Ejection Fraction from 35% to 50.

The risk of life-threatening ventricular arrhythmias in patients with mild-to-moderately reduced left ventricular ejection fraction (LVEF) is unknown. This retrospective case-control study aims to identify the prevalence, risk factors, and outcomes associated with the development of nonsustained ventricular tachycardia (NSVT) as documented on permanent pacemakers or implantable loop recorders in tertiary care center patients with an LVEF of 35% to 50%. Data pertaining to patient demographics, previous medical history, heart failure functional class, echocardiographic parameters, and survival were compared between the groups. Of the 326 patients with an LVEF within the target range, 90 patients (27.6%) had NSVT recorded on their device and 236 patients (72.4%) did not. Compared with patients without NSVT, patients with NSVT had a higher body mass index (28.4 kg/m2 vs 26.8 kg/m2, p = 0.02), more ischemic heart disease (57.8% vs 32.8%, p < 0.0001), higher left atrial volume index (45.8 ml/m2 vs 42.0 ml/m2, p = 0.04), and lower use of antiarrhythmic medications (4.4% vs 11.9%, p = 0.04). The presence of NSVT and the duration of NSVT had no relation to survival, supporting the notion that NSVT is a benign finding in patients with an LVEF of 35% to 50%.

Atrial Fibrillation in Patients with Congenital Heart Disease.

Advances in surgical techniques have led to the survival of most patients with congenital heart disease (CHD) up to their adulthood. During their lifetime, many of them develop atrial tachyarrhythmias due to atrial dilatation and scarring from surgical procedures. More complex defects and palliative repairs are linked to a higher incidence and earlier occurrence of arrhythmias. Atrial fibrillation (AF) is common in patients who have atrial septal defects repaired after age 55 and in patients with tetralogy of Fallot repaired after age 45. Patients with dextrotransposition of the great arteries who undergo Mustard or Senning atrial switch procedures have an increased risk of atrial flutter due to atrial baffle suture lines. Patients with Ebstein's anomaly are also prone to supraventricular tachycardias caused by accessory bypass tracts. Patients with a single ventricle who undergo Fontan palliation are at risk of developing persistent or permanent AF due to extreme atrial enlargement and hypertrophy. In addition, obtaining vascular access to the pulmonary venous atrium can present unique challenges during radiofrequency ablation for patients with a Fontan palliation. Patients with cyanotic CHD who develop AF have substantial morbidity because of limited hemodynamic reserve and a high viscosity state. Amiodarone is an effective therapy for patients with arrhythmias from CHD, but its use carries long-term risks for toxicity. Dofetilide and sotalol have good short-term effectiveness and are reasonable alternatives to amiodarone. Pulmonary vein isolation is associated with better outcomes in patients taking antiarrhythmic medications. Anticoagulants are challenging to prescribe for patients with CHD because of a lack of data that can be extrapolated to this patient population. Surgical ablation is the gold standard for invasive rhythm control in patients with CHD and should be considered at the time of surgical repair or revision of congenital heart defects. When possible, patients with complex CHD should be referred for care to an adult congenital heart disease center of excellence.

The possible role of propofol in drug-induced torsades de pointes: A real-world single-center analysis.

BACKGROUND: Torsades de pointes (TdP) is a polymorphic ventricular tachycardia associated with QT prolongation. Propofol is a sedative-anesthetic with proarrhythmic effects on cardiac myocytes. We performed a retrospective study to determine the incidence of TdP following propofol exposure at Mayo Clinic (Rochester, MN) from 08/11/1998-11/20/2015. METHODS: We queried our database using key search terms to identify patients exposed to propofol who developed TdP perioperatively or during non-surgical sedation. QT intervals were obtained from electrocardiograms (ECGs) performed before propofol exposure and after documented TdP and were corrected using Fridericia and Framingham methods. T wave peak-to-end (Tp-e)/QT ratios were also calculated. RESULTS: A total of 628,784 patients received propofol over 17.3years. Of these patients, 21 developed TdP (12, postoperatively; 3, intraoperatively; 6, during sedation). There were 17 patients who were exposed to at least one factor associated with QT-prolongation, including QT-prolonging medications in 8 patients, heart rate <60 beats per minute in 8 patients, potassium <3.5mmol/L in 4 patients, magnesium <1.8mg/dL in 2 patients, and subarachnoid hemorrhage in 2 patients. The number of patients with QTc>500ms using Fridericia correction was significantly higher from baseline following exposure to propofol (1 patient vs 6 patients, P=0.04); however no significant difference was observed with Framingham correction. CONCLUSION: In our study, TdP after propofol administration occurred with an annual incidence of 1.93 per million and was often associated with other risk factors. Nevertheless, propofol should be administered with caution in patients at risk of developing TdP.

Variability of door-to-device times at a rural tertiary care center.

OBJECTIVES: Target door-to-device (DTD) time for ST-elevation myocardial infarction (STEMI) patients has been 90 minutes, with no distinction between urban and rural hospitals. Rural hospitals have longer DTD times for transferred patients attributed to long transportation times from referring hospitals. Longer DTD times have also been reported during after-hours. The aim of the study was to determine whether DTD times at our rural facility were impacted by arrival method, arrival time period, and season. DESIGN: Retrospective chart review. SETTING: Rural tertiary care center in central Wisconsin. METHODS: We studied 412 patients presenting with STEMI after initiation of the Rescue One program for rapid triage and transfer from October 2006 through December 2012. They were subdivided by arrival method, arrival time (ON=Monday-Friday, 8 AM-5 PM; OFF=after-hours, weekends, holidays), and season. Median DTD times and proportions below and above 90 minutes were compared. RESULTS: Median DTD time for all groups, which include both directly admitted and transferred patients, was 85 minutes with 60% of patients achieving DTD times below 90 minutes while 30-day mortality was 5.3%. Median DTD time was 67 minutes for the Emergency Department (ED) (n=164), 95 minutes for Transfers (n=204), 68 minutes for Urgent Care (n=22) and 86 minutes for Field (n=22). ED had the highest proportion of patients achieving goal DTD time (81%) compared to Transfers (42%). Patients arriving by ED during OFF hours had a median DTD time 28 minutes longer than during ON hours with 21% fewer patients achieving goal DTD time, attributed to the time required to call in the catheterization team. Seasonal variability was observed due to differences in pre-hospital ambulance transportation times in the Field group. CONCLUSIONS: Our data confirm that in a rural facility such as ours, ED patients arriving during after-hours and transferred patients have longer DTD times. Methods are being implemented to shorten the time to assemble the catheterization lab team during after-hours. Better performance will be seen once the first medical contact to device (FTD) time goal of 120 minutes for transferred patients is adopted at our institution. Fibrinolytic therapy should be considered at referring institutions where the FTD time is expected to exceed 120 minutes.