Inappropriate Sinus Tachycardia Research Articles

Cardio-COVID clinic – a one-center experience

BackgroundPersistent symptoms affect a relatively large portion of coronavirus disease (COVID) survivors. Hence, specific clinics had been established in order to better characterize and manage this emerging entity of Post-COVID, among them our Cardio-COVID Clinic, which is dedicated to the cardiovascular (CV) aspects of the phenomenon.AimTo present the experience of our Cardio-COVID Clinic.MethodsIncluded in this report are 76 adult patients seen at the clinic between June 2020 and March 2021, who have recovered from a polymerase chain reaction (PCR)-confirmed COVID, and who were suspected by their referring physicians to experience ongoing cardiac sequelae. All participants underwent a structured assessment by a single cardiologist, which consisted of history taking, physical examination (PE), electrocardiogram (ECG), trans-thoracic echocardiogram (TTE), and further tests as deemed appropriate, including any combination of Holter, ischemic provocation test, cardiopulmonary exercise test (CPET), cardiac magnetic resonance (CMR), and cardiac computed tomography (CCT).ResultsInitial visits occurred within a median of 131 days after diagnosis. Most participants (83%) were referred from our general Long-COVID Clinic. About half were males, and the mean age was 53 years. 18% of participants had prior CV conditions, and the majority (72%) had at least one CV risk factor, mostly dyslipidemia. Nearly all participants experienced a symptomatic acute illness, which was graded according to the National Institutes of Health (NIH) criteria as severe in 23% of the study cohort. As for Post-COVID, late symptoms were present in 97% of patients, the most common being dyspnea (57%). While PE was unremarkable in all but 3 patients who exhibited murmurs, ECG findings were revealed in 45% – mostly non-specific ST-T changes (31%) and conduction abnormalities (14%) – and TTE aberrations were discovered in 28% – including pericardial effusion (24%), reduced left ventricular ejection fraction (LVEF) (5%), grade 2 diastolic dysfunction (3%), moderate and up valvular dysfunction (1%), and systolic pulmonary hypertension (1%); right ventricular function was universally normal. Upon conclusion of the work-up, CV diagnoses were made in 8 (11%) patients – including myocarditis (4), myopericarditis (1), inappropriate sinus tachycardia (1), chronotropic incompetence (1), and an aberrant coronary (1). Of note, CPET and CMR had the highest diagnostic yield, in light of 57% positive results on each – followed by CCT, Holter, and provocation test. Interesting as well, among those with abnormal CMR findings, 40% had normal ECG's and TTE's. Also, none of the CV restraints on CPET translated to provocation test anomalies.ConclusionCV symptoms of Post-COVID are highly prevalent, but signify actual CV disease only in a minority of patients. Further research is needed that will help identify predictors for CV morbidity and define optimal clinical pathways.Funding AcknowledgementType of funding sources: None.

Tachycardia and syncope in a15-year-old teenager

Patients with highly symptomatic tachycardia may suffer significantly; in addition to astandardized rule-out of structural heart disease, secondary causes need to be excluded. Disorders such as inappropriate sinus tachycardia and postural tachycardia syndrome are caused by cardiac autonomic dysregulation which may be part of arare underlying noncardiac disease.

Sinus node sparing novel hybrid approach for treatment of inappropriate sinus tachycardia/postural sinus tachycardia: multicenter experience

BackgroundThe ideal treatment of inappropriate sinus tachycardia (IST) and postural orthostatic tachycardia syndrome (POTS) still needs to be defined. Medical treatments yield suboptimal results. Endocardial catheter ablation of the sinus node (SN) may risk phrenic nerve damage and open-heart surgery may be accompanied by unjustified invasive risks.MethodsWe describe our first multicenter experience of 255 consecutive patients (235 females, 25.94 ± 3.84 years) having undergone a novel SN sparing hybrid thoracoscopic ablation for drug-resistant IST (n = 204, 80%) or POTS (n = 51, 20%). As previously described, the SN was identified with 3D mapping. Surgery was performed through three 5-mm ports from the right side. A minimally invasive approach with a bipolar radiofrequency clamp was used to ablate targeted areas while sparing the SN region. The targeted areas included isolation of the superior and the inferior caval veins, and a crista terminalis line was made. All lines were interconnected.ResultsNormal sinus rhythm (SR) was restored in all patients at the end of the procedure. All patients discontinued medication during the follow-up. After a blanking period of 6 months, all patients presented stable SR. At a mean of 4.07 ± 1.8 years, normal SN reduction and chronotropic response to exercise were present. In the 51 patients initially diagnosed with POTS, no syncope occurred. During follow-up, pericarditis was the most common complication (121 patients: 47%), with complete resolution in all cases. Pneumothorax was observed in 5 patients (1.9%), only 3 (1.1%) required surgical drainage. Five patients (1.9%) required a dual-chamber pacemaker due to sinus arrest > 5 s.ConclusionsPreliminary results of this multicenter experience with a novel SN sparing hybrid ablation of IST/POTS, using surgical thoracoscopic video-assisted epicardial ablation combined with simultaneous endocardial 3D mapping may prove to be an efficient and safe therapeutic option in patients with symptomatic drug-resistant IST and POTS. Importantly, in our study, all patients had a complete resolution of the symptoms and restored normal SN activity.

B-PO04-135 PERCUTANEOUS AND THORACOTOMY BASED SINUS NODE ABLATION USING NANOSECOND PULSED ELECTRIC FIELDS

Sinus node (SN) modification/ ablation is a treatment option for inappropriate sinus tachycardia. It is often achieved using radiofrequency ablation which is slow given the point to point nature of treatments. Nanosecond pulse electric fields (nsPEF) are an emerging, rapid energy delivery modality which offers tissue selectivity. We explored whether acute SN ablation can be achieved with nsPEF. In two canine models, general anesthesia was administered along with paralytics. Pericardial access was obtained percutaneously in one animal and via thoracotomy in the other (Fig 1A, 1D). The area of earliest right atrial activation was identified. Electrograms were recorded before and after nsPEF energy delivery near the SN using a CellFX™ generator (Pulse Biosciences, Hayward, CA). SN ablation was achieved in both animals after delivery of 10-20 Joules of energy via nsPEF. Total duration of nsPEF sequences in each animal was <1 min. There was absence of atrial electrograms with a junctional escape rhythm in the first animal (Fig 1B, 1C) after monopolar nsPEF. Atrial activity from a left sided focus was seen in the second animal (Fig 1E, 1F) after bipolar nsPEF. Phrenic capture persisted after both sinus node ablations post paralytic withdrawal. All changes persisted beyond 30 minutes of energy delivery after which the animals were euthanized. In acute canine experiments, energy delivery via nsPEF was able to quickly ablate the SN percutaneously and via thoracotomy. nsPEF effect on cardiac tissue was demonstrated functionally without requiring histology.

B-PO02-139 MAPPING AND ABLATION OF INAPPROPRIATE SINUS TACHYCARDIA: BEST OF BOTH?

Catheter ablation of inappropriate sinus tachycardia (IST) is limited by lack of reliable efficacy coupled with possible complications: need for pacing or phrenic palsy. We review short term results and safety for a novel mapping and ablation strategy for IST. Patients were referred after exhausting conventional therapies, e.g. betablockers and ivabradine. Under general anesthesia, anterior pericardial access was obtained, a Tyshak II 22mm balloon was directed to the anterolateral pericardial space, adjacent to the right atrial-superior vena cava junction and inflated to 0.75 ATM. High density mapping was used to localize endocardial sinus node (SN) activation at resting heart rate and during isoproterenol drug infusion. Ablation targeted SN breakout associated with faster heart rates, while avoiding baseline breakout. Phrenic nerve could not be pace captured with balloon in place. Abrupt heart rate drop was ablation endpoint. Six consecutive patients (all female, mean age 38 years) are reported. Median follow up was 95 days (IQR 67-97). Mapping showed a mean distance of 17mm between baseline SN and maximal isoproterenol SN break out. Ablation (mean total 15, IQR 10-17) was done with a mean heart rate of 138BPM and acutely decreased to an average of 78BPM. No phrenic palsy or bradycardia occurred. All patients have had marked or complete resolution of symptoms without ongoing IST medications; three had pericarditis. We show feasibility, safety and short term efficacy. Ablation targeting only faster SN activation can avoid bradycardia while pericardial balloon prevents phrenic palsy. Long term follow up will assess durability.

Ablation therapy of postural orthostatic tachycardia syndrome, inappropriate sinus tachycardia and primary electrical diseases: new insights in invasive treatment options in severely symptomatic patients.

Achieving the goal management of some arrhythmic syndromes can be challenging; medical treatment for inappropriate sinus tachycardia (IST) and postural orthostatic tachycardia syndrome (POTS) may be ineffective, necessitating multidisciplinary team treatment. Implantable defibrillator devices (ICDs), along with anti-arrhythmic drugs (AADs), remain the first-line treatment for primary electrical diseases that pose arisk of sudden cardiac death (SCD). Ablation of the arrhythmogenic substrate is not always suggested in patients with these pathologies, but it may be avaluable support for reducing arrhythmic burden, improving quality of life, and treating pathologies that are resistant to pharmacological treatment; however, this option is not often considered due to the potential risks associated with an invasive approach. Minimally invasive hybrid ablation in these syndromes, such as ahybrid thoracoscopic approach and the use of non-invasive mapping systems, reduces post-surgery complications and ensures the best possible outcome for the patient.

Perioperative management of post-COVID-19 surgical patients: Indian Society of Anaesthesiologists (ISA National) Advisory and Position Statement.

Perioperative management of post-COVID-19 surgical patients: Indian Society of Anaesthesiologists (ISA National) Advisory and Position Statement.

Inappropriate sinus tachycardia in post-covid-19 Syndrome

Funding AcknowledgementsType of funding sources: None.BackgroundPersistent symptoms after the acute phase of SARS-CoV-2 infection are referred to as "post-COVID-19 syndrome" (PCS), with a reported incidence ranging between 35% and 87%. Fatigue, palpitations and exercise intolerance are common complains among PCS patients in whom unexplained sinus tachycardia, occasionally exacerbated by postural changes, is a frequent observation that remains poorly characterized.PurposeWe sought to characterize the prevalence of inappropriate sinus tachycardia (IST) and postural orthostatic tachycardia (POTS) in a consecutive and prospective population of patients with PCS.MethodsConsecutive patients with persistent symptoms 3 months after an acute SARS-CoV-2 infection were prospectively evaluated at a multi-disciplinary PCS unit. All patients were screened for IST or POTS and those with confirmed criteria underwent comprehensive cardiovascular examination including echocardiography, 24-hour Holter, Minnesota Living with Heart Failure Questionnaire (MLHFQ), six-minute walking test (6MWT) and inflammation and myocardial biomarkers. Two control patients, matched by age and gender, were assigned to each case: one with previous SARS-CoV-2 infection without PCS (group 2) and one without prior SARS-CoV-2 infection (group 3).ResultsIST or POTS criteria were met in 34 out of the 200 PCS patients (17%). The mean age was 39 ± 10 years, with 29 women (91%). The interval from the index COVID-19 disease to the PCS diagnosis was 71 ± 17 days, with a majority of patients (n = 29,85%) not requiring hospital admission during the acute phase. At physical examination, the mean heart rate was 96 ± 3bpm at supine and 112 ± 17bpm at the upright position, with 8 patients fulfilling diagnostic criteria of POTS. No underlying structural heart disease, pro-inflammatory state, myocyte injury or hypoxia were identified among our patient population. The 6MWT showed a significantly diminished exercise capacity with a 59% of the estimated distance after adjustment by age, sex and body mass index; an impaired quality of life was also identified, as suggested by a median MLFHQ total score of 67 out of 105 points. The 24-hour Holter showed an increase in HR predominantly during daytime in group 1 (mean daytime HR of 94 ± 3bpm), an altered heart rate variability with a decrease in time domain parameters [PNN50 4 ± 4 in group 1 (vs. 11 ± 9 in group 2 and 18 ± 9 in group 3; p < 0.002)respectively; SD 100 ± 20 (vs. 127 ± 38 and 136 ± 13; p = 0.009) and a decrease in frequency domain parameters [LF 751 ± 450 (vs. 1721 ± 1009 and 2199 ± 920; p = 0.01), HF 336 ± 280 (vs. 823 ± 1200 and 1229 ± 630; p = 0.01)].ConclusionsIST and its POTS variant are a prevalent condition among PCS patients and may at least partially explain the common symptoms of fatigue, impaired exercise and palpitations that characterize the PCS. Cardiac autonomic nervous system imbalance may account as a plausible pathophysiological mechanism of IST in PCS patients.

Prospective blinded evaluation of smartphone-based ECG for differentiation of supraventricular tachycardia from inappropriate sinus tachycardia

IntroductionSupraventricular tachycardias (SVT) are often difficult to document due to their intermittent, short-lasting nature. Smartphone-based one-lead ECG monitors (sECG) were initially developed for the diagnosis of atrial fibrillation. No data have been published regarding their potential role in differentiating inappropiate sinus tachycardia (IST) from regular SVT. If cardiologists could distinguish IST from SVT in sECG, economic health care burden might be significantly reduced.MethodsWe prospectively recruited 75 consecutive patients with known SVT undergoing an EP study. In all patients, four ECG were recorded: a sECG during SVT and during sinus tachycardia and respective 12-lead ECG. Two experienced electrophysiologists were blinded to the diagnoses and separately evaluated all ECG.ResultsThree hundred individual ECG were recorded in 75 patients (47 female, age 50 ± 18 years, BMI 26 ± 5 kg/m2, 60 AVNRT, 15 AVRT). The electrophysiologists’ blinded interpretation of sECG recordings showed a sensitivity of 89% and a specificity of 91% for the detection of SVT (interobserver agreement κ = 0.76). In high-quality sECG recordings (68%), sensitivity rose to 95% with a specificity of 92% (interobserver agreement of κ = 0.91). Specificity increased to 96% when both electrophysiologists agreed on the diagnosis. Respective 12-lead ECG had a sensitivity of 100% and specificity of 98% for the detection of SVT.ConclusionA smartphone-based one-lead ECG monitor allows for differentiation of SVT from IST in about 90% of cases. These results should encourage cardiologists to integrate wearables into clinical practice, possibly reducing time to definitive diagnosis of an arrhythmia and unnecessary EP procedures.Graphical abstractA smartphone-based one lead ECG device (panel A) can be used reliably to differentiate supraventricular tachycardia (panel B) from inappropriate sinus tachycardia when compared to a simultaneously conducted gold-standard electrophysiology study (panels C, D).

Inappropriate Sinus Tachycardia Following Viral Illness

A 67-year-old female patient with a past medical history of menopause, migraines, and gastro-esophageal disease presented with palpitation, fatigue, and shortness of breath. One month prior to her presentation, she reported having flu-like symptoms. Her EKG showed sinus tachycardia with no other abnormality. Laboratory findings, along with imaging, showed normal results. The event monitor failed to detect any arrythmias. We report a case of inappropriate sinus tachycardia secondary to viral infection as a diagnosis of exclusion.

Pregnancy-related inappropriate sinus tachycardia: A cohort analysis of maternal and fetal outcomes.

Little literature exists regarding the syndrome of inappropriate sinus tachycardia during pregnancy. We aimed to further understand the natural history of inappropriate sinus tachycardia in pregnancy, and to explore maternal and fetal outcomes. A retrospective, observational cohort analysis of 19 pregnant women who presented with inappropriate sinus tachycardia. 42% attended the emergency department on more than one occasion with symptoms of inappropriate sinus tachycardia; 32% required hospital admission and 26% required pharmacological therapy. There were no maternal deaths, instances of heart failure or acute coronary syndrome, and no thromboembolic or haemorrhagic complications during pregnancy. Rates of caesarean section were similar to the background rate of our unit (32% and 27%, respectively). Rates of induction were notably elevated (58% vs 25%). Inappropriate sinus tachycardia in pregnancy is associated with high rates of hospitalization and induction of labour, which may not be mandatory given the clinical findings in this group of women.

Efficacy of medical and ablation therapy for inappropriate sinus tachycardia: A single-center experience.

Effective therapy for inappropriate sinus tachycardia (IST) remains challenging with high rates of treatment failure and symptom recurrence. It is uncertain how effective pharmacotherapy and procedural therapy are long-term, with poor response to medical therapy in general. We retrospectively reviewed all patients with the diagnosis of IST at a tertiary academic medical center from 1998 to 2018. We extracted data related to prescribing patterns and symptom response to medical therapy and sinus node modification (SNM), assessing efficacy and periprocedural complication rates. A total of 305 patients with a formal diagnosis of IST were identified, with 259 (84.9%) receiving at least one prescription medication related to the condition. Beta-blockers were the most commonly used medication (n = 245), with a majority of patients reporting no change or worsening of symptoms, and poor response was seen to other medication classes. Improvement was seen significantly more often with ivabradine than beta blockers, though the sample size was limited (p = .003). Fifty-five patients (18.0% of all IST patients), mean age 32.0 ± 9.1 years, underwent a SNM procedure, with an average of 1.8 ± 0.9 procedures per patient. Acute symptomatic improvement (<6 months) was seen in 58.2% of patients. Long-term complete resolution of symptoms was seen in 5.5% of patients, modest improvement in 29.1%, and no long-term benefit was seen in 65.5% of patients. Among all medical therapies, there were high rates of treatment failure or symptom worsening in over three-quarters of patients in our study. Ivabradine was most beneficial, though the sample size was small. While most patients receiving SNM ablation for IST perceive an acute symptomatic improvement, almost two-thirds of patients have no long-term improvement, and resolution of symptoms is quite rare. AV node ablation with pacemaker implantation following lack of response to SNM offered increased success, though the sample size was limited.

Ivabradine in Cardiovascular Disease Management Revisited: a Review.

Ivabradine is a unique agent that is distinct from beta-blockers and calcium channel blockers as it reduces heart rate without affecting myocardial contractility or vascular tone. Ivabradine is a use-dependent inhibitor targeting the sinoatrial node. It is approved for use in the United States as an adjunct therapy for heart rate reduction in patients with heart failure with reduced ejection fraction. In this scenario, ivabradine has demonstrated improved clinical outcomes due to reduction in heart failure readmissions. However, there has been conflicting evidence from prospective studies and randomized controlled trials for its use in stable ischemic heart disease regarding efficacy in symptom reduction and mortality benefit. Ivabradine may also play a role in the treatment of patients with inappropriate sinus tachycardia, who often cannot tolerate beta-blockers and/or calcium channel blockers. In this review, we highlight the evidence for the nuances of using ivabradine in heart failure, stable ischemic heart disease, and inappropriate sinus tachycardia to raise awareness for its vital role in the treatment of select populations.

Inappropriate sinus tachycardia: a review.

Inappropriate sinus tachycardia (IST) has been defined as a resting heart rate of >100 beats per minute and an average 24-hour heart rate >90 bpm with distressing symptoms resulting from the persistent tachycardia. IST is prevalent in 1% of the middle-aged population, mostly females. Rarely can elderly patients also present with IST. Possible mechanisms of IST include intrinsic sinus node abnormality, beta-adrenergic receptor stimulating autoantibody, beta-adrenergic receptor supersensitivity, muscarinic receptor autoantibody, or hyposensitivity, impaired baroreflex control, depressed efferent parasympathetic/vagal function, nociceptive stimulation, central autonomic overactivity, aberrant neurohumoral modulation, etc. Symptoms associated with IST are palpitations, chest pain, fatigue, shortness of breath, presyncope, and syncope. Despite these distressing symptoms, IST has not been associated with tachycardia-associated cardiomyopathy or increased major cardiovascular events. Various treatment options for patients with IST are ivabradine, beta-adrenergic blockers, calcium channel blockers, psychiatric evaluation, and exercise training. Although, endocardial radiofrequency ablation targeting the sinus node has been used as a treatment modality for otherwise treatment-refractory IST, the results have been dismal. The other modalities used for refractory IST treatment are endocardial modification of the sinus node using radiofrequency energy, combined endo and epicardial ablation of the sinus node, thoracoscopic epicardial ablation of the sinus node, sinus node sparing thoracoscopic and endocardial hybrid ablation. The goal of this review is to provide the readership with the pathophysiological basis of IST and its management options.

Comparative effectiveness of metoprolol, ivabradine, and its combination in the management of inappropriate sinus tachycardia in coronary artery bypass graft patients

BACKGROUND:Inappropriate sinus tachycardia (IST) is an arrhythmic complication observed after coronary artery bypass graft (CABG) surgery which left untreated, commonly increases chances of postoperative stroke. The primary study objective was comparing effectiveness of beta blocker-metoprolol; a specific If blocker-ivabradine and its combination in patients who develop IST as a complication following CABG.MATERIALS AND METHODS:An open-labeled, investigator initiated, clinical study was conducted on 150 patients who developed IST (heart rate [HR] >100 beats/min) following elective CABG surgery. The patients were randomized into three treatment groups. Group I – received ivabradine (5 mg), Group II – metoprolol (25 mg), and Group III – ivabradine (5 mg) and metoprolol (25 mg). Treatment was given orally, twice a day for 7 days in all the three groups postoperatively. Primary endpoints were comparative effectiveness in HR and blood pressure reduction following treatment.RESULTS:IST was diagnosed by an electrocardiogram (12-lead) considering morphological features of P-wave and with 32% increase from baseline HR in all the three groups. Compared to IST arrthymic rate, HR was reduced in all groups following respective treatment (P = 0.05). Reduction in HR was significant (P < 0.05) in combination group followed by ivabradine which was significantly greater than metoprolol treated group. None of the treatments clinically changed the systolic, diastolic and mean blood pressure till discharge. No surgery/treatment-related complications were observed in any groups.CONCLUSION:Ivabradine stands as a pharmacological option for controlling HR and rhythm without associated side effects in postoperative CABG patients with IST.

Abstract 16505: Sinus Node Sparing Surgical Hybrid Thoracoscopic Ablation for Inappropriate Sinus Tachycardia: Results of a Prospective Multicenter Registry (the Susruta Registry)

Background: Medical treatment for inappropriate sinus tachycardia (IST) remains suboptimal. Radiofrequency Sinus node Modification (RFSM) has been used for managing drug-refractory symptomatic IST. Although, acute success is reasonable, it is faced with high complications and recurrence rates. A novel Sinus Node sparing surgical thoracoscopic hybrid ablation (SUSRUTA) has been recently proposed. Objective: To report outcomes of SUSRUTA for IST patients from a prospective multicenter registry. Methods: This is a multicenter, prospective registry of patients who received SUSRUTA which is SN sparing hybrid ablation using surgical thoracoscopic video-assisted epicardial ablation comprised of a RF bipolar clamp which was used for sparing the SN region (identified by endocardial 3D mapping) and isolation of superior and inferior vena cava with creation of a lateral line across the crista terminalis during IST with isoproterenol challenge. Gaps in the epicardial lesion set are filled in by endocardial RFA. Patients were treated with post op Colchicine and were enrolled in cardiac rehabilitation program. Results: Of the 139 patients, mean age was 26±4 yrs, 91% women and mean duration of IST was 40±21.5 months. 90% were on ivabradine, 86% on beta-blocker, 77% on calcium channel blocker and 77% were on class IC antiarrhythmic agent. Heart rate post-procedure was significantly lower when compared with pre-procedure (110±10 vs. 64±11 bpm, p&lt;0.0001). After a blanking period of 3 months, normal sinus rhythm was restored in 100% of patients in the hybrid group. Postop pericarditis was the most common complication in 80%(severe-4%), severe bradycardia (HR &lt;35 bpm) in 5%, pneumothorax 3.5% and pleural effusion requiring drainage in 2.1% of cases. One patient required a permanent pacemaker. Hospital length of stay was 4.5±0.8 days. At 1041±541 days follow up 94.5% (131/139) were free of symptoms after a single procedure and the 8 patients required a redo-RF catheter ablation.95% patients are off all preprocedural rate controlling medications Conclusion: SUSRUTA appears to be efficacious and safe for the treatment of symptomatic drug resistant IST.

Abstract 15694: Atrial Tachycardia Masquerading as Sinus Tachycardia - Electrophysiological Characteristics and Ablation Outcomes

Background: Focal atrial tachycardia (AT) is typically distinguished by P wave morphology and autonomic response. AT arising close to the sinus node can be easily misdiagnosed as Inappropriate sinus tachycardia (IST). Objective: This multicenter study sought to describe the electrophysiological (EP) features and ablation outcomes of perisinus node atrial tachycardia (PNAT). Methods: Baseline as well as procedural characteristics and outcome data of 7 patients with PNAT are described. Results: Mean age of the cohort was 38±17 years (100% female). Time from symptom onset to diagnosis was12.2± 9 months with an average of 1.7 prior hospitalizations. Mean baseline HR was127.8 bpm and all patients carried a diagnosis of IST. Baseline ECG in all patients was identical to sinus tachycardia, with exception of taller P waves in lead II in 5 patients and deeper negative component of P wave in V1. At EP study, mean AT cycle length was 420 msec and significant acceleration was seen with isoproterenol, mimicking IST. Activation mapping was done using Ensite TM Balloon Array (5), Precision TM (1) and Carto TM (1). Site of origin was slightly anterolateral to sinus node in 3 and anterior, inferior and medial to sinus node in 4 (Figure). AT was successfully ablated in all patients without any phrenic injury or sinus node dysfunction. Over 2.9 years of follow-up, only 1 patient had recurrence that was successfully re-ablated. Conclusion: PNAT has similar ECG and EP characteristics and is often misdiagnosed as IST. A high index of suspicion is needed for diagnosis. Evaluation of P wave morphology during tachycardia and careful activation mapping can enable successful ablation with excellent long-term outcomes.

Abstract 12919: Quantitative Assessment of Cardiovascular Autonomic Impairment in Cancer Survivors: A Single Center Experience

Background: Cardiovascular autonomic dysfunction in cancer survivors is poorly understood. Objectives: To better characterize the clinical characteristics and types of autonomic dysfunction in this population. Methods: A retrospective analysis of cancer survivors within an academic cardio-oncology program referred for suspected autonomic dysfunction was performed. Autonomic reflex testing of adrenergic, cardiovagal, and sudomotor function was done. Patients with pre-existing autonomic dysfunction prior to their cancer diagnosis were excluded. Results: Of approximately 282 patients in the UCLA Cardio-Oncology program, twenty-four patients met the inclusion criteria. Twenty-two had autonomic impairment on autonomic reflex testing. Eight patients were female, and the mean age at time of autonomic testing was 51.3 years. The average duration from cancer diagnosis to autonomic testing was 10.3 years. The reasons for referral included dizziness, tachycardia, palpitations, and syncope. The majority of patients (75%) had hematologic disorders. The most common chemotherapies administered were vinca alkaloids (54.2%), alkylating agents (66.7%), and anthracyclines (54.2%). Most patients received radiation to the thorax (66.7%) and neck (53.3%). Eleven patients had mild autonomic impairment, seven had moderate, and four had severe autonomic impairment. Dysfunction was commonly present in the sympathetic and parasympathetic branches, but most pronounced in the sympathetic system. The majority of patients were diagnosed with orthostatic hypotension (50%), inappropriate sinus tachycardia (20.8%), and postural orthostatic tachycardia syndrome (12.5%) and had subjective improvement with treatment. Conclusion: Cardiovascular autonomic dysfunction occurs in cancer survivors, and commonly affects both the sympathetic and parasympathetic systems. Symptom recognition in patients should prompt autonomic testing and treatment where appropriate.

Supraventricular Tachycardia

Supraventricular tachycardias (SVTs) comprise a group of usually benign arrhythmias that originate from cardiac tissue at or above the His bundle. SVTs include inappropriate sinus tachycardia, atrial tachycardias (ATs), atrial flutter (AFL), junctional tachycardia, atrioventricular nodal reentrant tachycardia (AVNRT), and forms of accessory pathway–mediated reentrant tachycardias (atrioventricular reentrant tachycardia [AVRT]). Although mostly benign, symptoms can be debilitating, in the form of palpitations, shortness of breath, chest discomfort, dizziness, and/or syncope; rarely, SVTs can result in cardiomyopathy due to incessant arrhythmia. This review covers the epidemiology, diagnosis, management, and classification of SVTs. This review contains 14 figures, 17 tables, and 61 references. Keywords: Supraventricular tachycardia, cardioversion, arrhythmia, atrial flutter, atrial fibrillation, Wolff-Parkinson-White syndrome, MAZE procedure, catheter ablation

Pregnancy related inappropriate sinus tachycardia: a distinct arrhythmia?

Abstract Background The syndrome of inappropriate sinus tachycardia (IST) is well recognized and affects ∼1% of the population. We believe IST in pregnancy is a relatively frequent yet under-recognized phenomenon that may represent a distinct arrhythmia. To date, there are only three case reports in the literature. Purpose To further understand the natural history of IST in pregnancy, and to explore maternal outcomes. Methods A retrospective, observational cohort analysis. Results 19 pregnant women presented to our institute with a definitive diagnosis of IST (as defined by task force criteria) between January 2016 and January 2017. Symptom onset was 4–36 weeks gestation (mean 20 weeks). Of those in their second or subsequent pregnancy (n=8), 50% described symptoms compatible with IST in previous pregnancies. 42% attended the emergency department on ≥1 occasion with symptoms of IST. 32% required hospital admission. 26% required pharmacological therapy (beta-blockers in all). There were no maternal deaths, instances of heart failure or acute coronary syndrome, no thromboembolic or haemorrhagic complications during pregnancy. Rates of Caesarean section were similar to the background rate of our unit; however, rates of induction were notably elevated (58% vs 25%), with 55% of these women being induced purely for symptoms of IST. Following delivery, symptoms resolved within one week for 17 of the women in the cohort, 1 had symptoms resolve after 4 month and 1 had persistent symptoms as she became pregnant again. Conclusion IST in pregnancy likely represents a distinct arrhythmia; the majority of individuals here had symptoms only during pregnancy, which resolved rapidly postpartum. Additionally, half of the women in a second or subsequent pregnancy had suffered IST symptoms during previous pregnancies, with no symptoms in between pregnancies. It is biologically plausible and may represent an exaggerated cardio-autonomic response to the physiological changes of pregnancy such as increased sympathetic tone and change in baroreceptor reflex sensitivity. Recognition of the condition is important given it is associated with significant morbidity, the distressing nature of symptoms leading to high rates of hospitalization and induction of labour. Funding Acknowledgement Type of funding source: None