Predictors of appropriate shock after generator replacement in patients with an implantable cardioverter defibrillator.

BACKGROUND: Implantable cardioverter defibrillators (ICDs) are indicated for the primary prevention of sudden cardiac death in patients with reduced left ventricular ejection fraction (LVEF). The ongoing risk/benefit profile of an ICD at generator replacement is unknown. This study aimed to identify predictors of appropriate ICD shocks and therapies after first ICD generator replacement, and its procedure-related complications. METHODS: We conducted a multicenter, retrospective cohort study including patients with primary prevention ICDs who underwent generator replacement between April 2005 and July 2015 at three Canadian centers. The primary and secondary outcomes were appropriate ICD shock and any appropriate ICD therapy, respectively. Procedure-related complication rates were also reported. RESULTS: Of the 219 patients in the cohort, 61 (28%) experienced an appropriate shock while 40 (18%) experienced appropriate antitachycardia pacing over a median follow up of 2.2 years. Independent predictors of appropriate ICD shocks included: LVEF at time of replacement (adjusted odds ratio [OR] 0.4 per 10% increase in LVEF, P < .001), a history of appropriate ICD shocks prior to replacement (OR 4.9, P < .001), and a history of inappropriate ICD shocks (OR 4.2, 95%, P < .002). Similar predictors were identified for the secondary outcome of any appropriate ICD therapy. Device-related complications were reported in 25 (11%) patients, with 1 (0.5%) resulting in death, 14 (6.3%) requiring site re-operation, and 6 (2.7%) requiring cardiac surgical management. CONCLUSION: Not all primary prevention ICD patients undergoing generator replacement will require appropriate device therapies afterwards. Generator replacement is associated with several risks that should be weighed against its anticipated benefit. A comprehensive assessment of the risk-benefit profile of patients undergoing generator replacement is warranted.

Autoimmune heparin-induced thrombocytopenia and venous limb gangrene after aortic dissection repair: in vitro and in vivo effects of intravenous immunoglobulin.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is a prothrombotic disorder characterized by heparin-dependent antibodies that activate platelets (PLTs) via PLT FcγIIa receptors. "Autoimmune" HIT (aHIT) indicates a HIT subset where thrombocytopenia progresses or persists despite stopping heparin; aHIT sera activate PLTs strongly even in the absence of heparin (heparin-independent PLT-activating properties). Affected patients are at risk of severe complications, including dual macro- and microvascular thrombosis leading to venous limb gangrene. High-dose intravenous immunoglobulin (IVIG) offers an approach to interrupt heparin-independent PLT-activating effects of aHIT antibodies. CASE REPORT: A 78-year-old male who underwent cardiopulmonary bypass for aortic dissection developed aHIT, disseminated intravascular coagulation, and deep vein thrombosis; progression to venous limb gangrene occurred during partial thromboplastin time (PTT)-adjusted bivalirudin infusion (underdosing from "PTT confounding"). Thrombocytopenia recovered with high-dose IVIG, although the PLT count increase began only after the third dose of a 5-day IVIG regimen (0.4 g/kg/day × 5 days). We reviewed case reports and case series of IVIG for treating HIT, focusing on various IVIG dosing regimens used. RESULTS: Patient serum-induced PLT activation was inhibited in vitro by IVIG in a dose-dependent fashion; inhibition of PLT activation by IVIG was much more marked in the absence of heparin versus the presence of heparin (0.2 U/mL). Our literature review indicated 1 g/kg × 2 IVIG dosing as most common for treating HIT, usually associated with rapid PLT count recovery. CONCLUSION: Our clinical and laboratory observations support dose-dependent efficacy of IVIG for decreasing PLT activation and thus correcting thrombocytopenia in aHIT. Our case experience and literature review suggests dosing of 1 g/kg IVIG × 2 for patients with severe aHIT.

Right ventricular pacing is associated with increased rates of appropriate implantable cardioverter defibrillator shocks.

BACKGROUND: Right ventricular (RV) pacing has been associated with increased risk of pacemaker-induced cardiomyopathy, hospitalization and death among patients with implantable cardioverter defibrillators (ICDs). Little is known about its association with ventricular tachyarrhythmias. We hypothesize that RV pacing is associated with increased incidence of appropriate ICD shocks and death. METHODS: Retrospective study of consecutive patients with de novo ICD insertion (excluding cardiac resynchronization therapy devices) from a single tertiary care center. Patients were classified into <10% RV pacing (low-pace group) and ≥10% RV pacing (high-pace group). Data were compared using two-tailed t tests and Fisher's exact test. Binomial logistic regression was performed to identify predictors of appropriate ICD therapies. RESULTS: A total of 178 patients (54 high paced and 124 low paced) were included. Mean follow-up was 43 ± 11 months. Appropriate shocks occurred in 27 patients (15%) and were significantly higher in the high-pace group (35% vs. 10%, p = 0.008), as the number of deaths (31% vs. 11%, p = 0.001). Binary logistic regression showed a significantly increased risk of shock (OR 2.99, p = 0.01) and death (OR 3.61, p = 0.002) in high-paced patients. Multivariable analysis showed no difference in risk of shocks based on age, sex or ejection fraction. Older patients had higher risk of death. CONCLUSIONS: In this population of ICD patients, those with a high prevalence of RV pacing experienced more shocks for VF/VT and had higher mortality. Further studies should be done to determine whether minimizing RV pacing reduces arrhythmias, shock burden and death in patients with ICDs.

Atrial fibrillation in elderly patients with implantable loop recorders for unexplained syncope.

BACKGROUND: An implantable loop recorder (ILR) assists in the diagnosis of unexplained syncope and atrial fibrillation (AF). Both become prevalent with age. Limited data exist describing the incidence of AF as the diagnostic rhythm underlying syncope in the elderly. This study aims to report the incidence of AF in older adults with ILRs for unexplained syncope and identify clinical characteristics associated with AF in this population. METHODS: Retrospective observational study on patients with unexplained syncope seen in syncope clinics from two Canadian centers. Participants were ≥65 years old, without a history of AF, and received an ILR for unexplained syncope. Data were collected from patient's clinic charts. Arrhythmia diagnosis was based on ILR electrocardiogram reading during syncope (symptom-rhythm correlation). Fisher's exact test and the Student's t test were used to compare participants with and without AF. RESULTS: In our cohort of 222 patients, 124 were females and 98 were males. Mean age at implant was 80 ± 8 years. Arrhythmia was diagnosed in 98 patients (44.1%). Median time to diagnosis was 18 months. AF was diagnosed in 17 (7.7%) participants. There were fewer males in the AF group than the no AF group (11.8%, 46.8%, p = 0.01). Age, baseline EKG, and prevalence of hypertension, diabetes, stroke, or ischemic heart disease were not statistically different between patients with AF and without AF. CONCLUSIONS: Atrial fibrillation was a common diagnostic rhythm in this cohort of adults, aged 65 and older, with ILRs for unexplained syncope. It was observed more frequently in females.

The Role of the Autonomic Nervous System in Vasovagal Syncope.

The mechanism of vasovagal syncope (VVS) is multifaceted and involves a delicate balance within the autonomic nervous system (ANS). This review delves into the complex interplay between the ANS and VVS, elucidating the pivotal role that autonomic imbalance plays in the pathophysiology of this condition. Through a comprehensive exploration of the sympathetic and parasympathetic branches of the ANS, this review provides insights into the mechanisms that underlie VVS. In addition, this article discusses established and emerging research on the management of VVS.

Complications related to pacemakers and other cardiac implantable electronic devices: essentials for internists and emergency physicians.

With the aging population, improving technology, and expanding indications for diagnosing and treating arrhythmias and heart failure, many patients are receiving cardiac implantable electronic devices (CIEDs) such as pacemakers and implantable cardioverter defibrillators. Consequently, patients with CIEDs are frequently encountered in the emergency department and in the wards. It is imperative that emergency physicians and internists have a strong foundation on CIEDs and their potential complications. This review aims to help physicians develop a framework in approaching CIEDs and to recognize and manage clinical scenarios that may arise from CIED complications.

Validation of the Emory Risk Score in the Transcatheter Aortic Valve Implantation Population: A Canadian Perspective.

Background: Permanent pacemaker (PPM) implantation may be indicated post-transcatheter aortic valve implantation (TAVI). The Emory Risk Score (ERS) is a validated predictive risk score of the need for a PPM post-TAVI using a balloon-expandable valve. Our objectives were to determine the validity of the ERS in our local TAVI population with both balloon-expandable and self-expanding valves and to identify additional electrocardiographic (ECG) parameters predictive of the need for a PPM post-TAVI. Methods: Retrospective chart and electronic database reviews were performed to collect demographic and procedural information. Two expert readers reviewed all ECGs. Independent factors associated with PPM implantation were examined with multivariable logistic regression via a stepwise selection process with calculation of the area under the receiver operating characteristic curve to assess model discrimination. Results: The overall PPM implantation rate was 11.7%; rates were 9% for the Sapien 3 valves, 10% for the Evolut Pro valves, and 17% for the Evolut R valves. The ERS was found to not be predictive of need for PPM post-TAVI for the entire cohort. Right bundle branch block was the only ERS parameter independently associated with new PPM implant (8.5% vs 25%, odds ratio = 3.59, P = 0.01). No additional ECG parameters met the criteria for statistical significance. Conclusions: The poor predictive value of the ERS in determining the need for a PPM post-TAVI in our patient population suggests that further refinement of a formula (or risk-calculator) is warranted. Identification of a precise risk-calculator is likely to facilitate patient mobilization and reduce inpatient healthcare resource utilization.

Introduction: L'implantation d'un stimulateur cardiaque permanent (SCP) peut être indiquée après l'implantation valvulaire aortique par cathéter (post-IVAC). L'Emory Risk Score (ERS) est un score de prédiction du risque validé de la nécessité d'un SCP post-IVAC au moyen d'une valve expansible par ballonnet. Nous avions pour objectif de déterminer la validité de l'ERS auprès de notre population ayant eu une IVAC soit par valve expansible par ballonnet ou valve auto-expansible, et de déterminer d'autres paramètres électrocardiographiques (ECG) prédictifs de la nécessité d'un SCP post-IVAC. Méthodes: Nous avons réalisé des revues rétrospectives de dossiers et de bases de données électroniques pour collecter les données démographiques et interventionnelles. Deux experts ont lu et interprété tous les ECG. Les facteurs indépendants associés à l'implantation du SCP ont été examinés en effectuant la régression logistique multivariée par processus de sélection pas-à-pas au moyen du calcul de la surface sous la courbe caractéristique d'efficacité du récepteur afin d'évaluer la discrimination du modèle. Résultats: Le taux global d'implantation d'un SCP était de 11,7 % ; les taux étaient de 9 % pour les valves Sapien 3, de 10 % pour les valves Evolut Pro et de 17 % pour les valves Evolut R. Nous avons observé que l'ERS ne permettait pas de prédire si l'implantation d'un SCP post-IVAC était nécessaire pour la cohorte entière. Le bloc de branche droit était le seul paramètre de l'ERS indépendamment associé à la nouvelle implantation d'un SCP (8,5 % vs 25 %, rapport de cotes = 3,59, P = 0,01). Aucun autre paramètre ECG ne satisfaisait au critère de signification statistique. Conclusions: La faible valeur prédictive de l'ERS à déterminer la nécessité d'un SCP post-IVAC au sein de notre population de patients montre que des améliorations de la formule (ou calculateur de risques) sont justifiées. L'identification d'un calculateur de risques précis devrait favoriser l'adhésion des patients et réduire l'utilisation des ressources en soins de santé en milieu hospitalier.

Prevalence and Functional Implication of Silent Coronary Artery Disease in Marathon Runners Over 40 Years of Age: The MATCH-40 Study.

BACKGROUND: Marathon participation is becoming increasingly popular among individuals ≥40 years of age. Little is known about the prevalence of subclinical coronary artery disease (CAD) and corresponding ischemia in this patient population. The study objectives are: (1) to characterize the prevalence of silent CAD in marathoners ≥ 40 years old using cardiac computed tomography angiography (CCT); and (2) if subclinical CAD was detected, to determine the functional significance of occult lesions by stress echocardiography (SE). METHODS: Marathoners aged ≥ 40 years who completed a full marathon between 2018 and 2019 were recruited to undergo a prospective CCT. Coronary artery stenosis was graded as zero, mild (1%-49%), moderate (50%-69%), or severe (> 70%). All study participants diagnosed with mild-to-severe atherosclerotic CAD on CCT further underwent functional imaging with exercise treadmill SE. RESULTS: A total of 65 individuals (53 ± 7 years, 65% males, 24 ± 3 kg/m2) underwent a prospective CCT within 12 months of marathon completion. Of the total study population, 13 participants (20%) were diagnosed with CAD, of whom 10 (77%) had mild disease, 1 (8%) had moderate disease, and 2 (15%) had severe disease by CCT. Despite the identification of subclinical CAD on CCT, none of the 13 patients had any evidence of inducible ischemia on SE. CONCLUSIONS: This is the first study to incorporate both CCT and SE in the evaluation of subclinical CAD in marathoners ≥40 years old. Although the overall prevalence of anatomic CAD was 20%, there was no evidence of functional ischemia in this highly competitive cohort.

CONTEXTE: Les marathons ont gagné en popularité auprès des individus âgés de 40 ans ou plus. On en sait toutefois peu sur la prévalence de la coronaropathie subclinique et de l'ischémie qui lui est associée dans cette population de patients. L'étude visait à 1) caractériser la prévalence de la coronaropathie silencieuse chez les marathoniens âgés de 40 ans ou plus à l'aide d'une angiographie cardiaque par tomodensitométrie (ACTDM) si une coronaropathie subclinique était détectée, à déterminer l'importance fonctionnelle des lésions occultes par une échocardiographie d'effort (EE). MÉTHODOLOGIE: Des marathoniens âgés de 40 ans ou plus ayant réalisé un marathon entre 2018 et 2019 ont été recrutés et soumis à une ACTDM prospective. Les sténoses des artères coronaires étaient classées selon une échelle allant de zéro, légère (1 à 49 %), modérée (50 à 69 %) à sévère (> 70 %). Tous les participants à l'étude ayant reçu un diagnostic de coronaropathie athéroscléreuse légère à sévère à la suite de l'ACTDM ont été soumis à une imagerie fonctionnelle avec EE sur tapis roulant. RÉSULTATS: Au total, 65 sujets (53 ± 7 ans, 65 % d'hommes, 24 ± 3 kg/m2) ont été soumis à une ACTDM prospective dans un délai de 12 mois à la suite de leur dernier marathon. Dans l'ensemble de la population à l'étude, 13 participants (20 %) ont reçu un diagnostic de coronaropathie; 10 (77 %) présentaient une maladie bénigne, 1 (8 %) présentait une maladie modérée et 2 (15 %) présentaient une maladie sévère selon l'ACTDM. Même si une coronaropathie subclinique a été diagnostiquée lors de l'ACTDM, aucun des 13 patients ne présentait de signe d'ischémie inductible à l'EE. CONCLUSIONS: Il s'agit de la première étude à utiliser l'ACTDM et l'EE pour évaluer la présence d'une coronaropathie chez des marathoniens âgés de 40 ou plus. Même si la prévalence globale de la coronaropathie anatomique était de 20 %, il n'y avait aucun signe d'ischémie fonctionnelle au sein de cette cohorte hautement compétitive.

"I Tripped and Broke My Heart": A Case Report of Right Atrial Rupture.

A 66-year-old woman tripped and fell onto outstretched hands. She did not hit her chest. She developed chest pain and presented to the emergency department in shock. Transthoracic echocardiography demonstrated a large pericardial effusion with cardiac tamponade. Despite recurrent pericardiocentesis, the fluid did not decrease on echocardiography, and she continued to be in profound shock. Emergent surgical exploration identified rupture of the right atrium at its insertion into the superior vena cava. This case demonstrates atrial rupture despite no obvious direct chest impact and emphasizes the need for emergent surgical exploration in patients with hemopericardium and persistent tamponade despite pericardiocentesis.

Après avoir trébuché, une femme âgée de 66 ans est tombée sur ses mains étendues. Son thorax n'a pas touché le sol. Elle a par la suite éprouvé une douleur thoracique et s'est présentée au service des urgences en état de choc. Une échocardiographie transthoracique a révélé un important épanchement péricardique et une tamponnade cardiaque. Malgré des péricardiocentèses répétées, le volume de liquide observé à l'échocardiographie ne diminuait pas et la patiente était toujours en état de choc profond. Une exploration chirurgicale d'urgence a permis de détecter une rupture de l'oreillette droite au lieu de son insertion dans la veine cave supérieure. Le cas de cette patiente démontre qu'une rupture auriculaire est possible même sans impact direct au thorax et fait ressortir l'importance d'une exploration chirurgicale d'urgence chez les patients hémopéricardiques présentant une tamponnade qui persiste malgré une péricardiocentèse.

Multimodality Imaging of a Giant Right Coronary Artery Aneurysm.

We describe a case of a 54-year-old woman who had a right cardiac mass found on coronary angiography. Echocardiography, computed tomography, and cardiac magnetic resonance imaging characterized it as a thrombosed giant right coronary artery aneurysm. This was confirmed on pathology. We present the role of multimodality cardiovascular imaging in the diagnosis and characterization of a giant coronary artery aneurysm.