Search

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.

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 afterhours 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. [ABSTRACT FROM AUTHOR]

Connective tissue disorders increase the risk of malignancy; conversely, they may manifest as rheumatological paraneoplastic syndromes due to an underlying malignancy. We describe the case of a patient with limited scleroderma whose rapid disease progression coincided with the discovery of a renal tumor. A woman, age 75 years, presented with a 3-month history of progressive difficulty grasping objects, unsteadiness, dyspnea, xerostomia, xerophthalmia, and significant weight loss. She had a 10-year history of gastroesophageal reflux and Raynaud's phenomenon. Pertinent physical examination findings included facial telangiectasias, bibasilar inspiratory rales, sclerodactyly, and absent pinprick and vibratory sensation in her toes. She also had swelling and tenderness in several metacarpophalangeal and interphalangeal joints and in both ankles. A renal mass was demonstrated on abdominal computed tomography. A left partial nephrectomy was performed, confirming an unclassified type of renal cell carcinoma, along with a focal proliferative crescentic pauci-immune glomerulonephritis. Medical therapy with rituximab, pulse methylprednisolone, and prednisone led to improvement in her symptoms. The patient's presentation is consistent with a rapid progression of pre-existing limited scleroderma with the development of new rheumatological symptoms, including vasculitis. We propose that this progression was secondary to paraneoplastic stimulation by the renal cell carcinoma. Clinicians should consider looking for a malignancy in patients with connective tissue disorders who present with a myriad of new symptoms. [ABSTRACT FROM AUTHOR]

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/m 2 vs 26.8 kg/m 2 , p = 0.02), more ischemic heart disease (57.8% vs 32.8%, p < 0.0001), higher left atrial volume index (45.8 ml/m 2 vs 42.0 ml/m 2 , 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%., (Copyright © 2017 Elsevier Inc. All rights reserved.)

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., (© 2013 Marshfield Clinic.)