Tachycardiomyopathy: mechanisms and clinical implications

Tachycardia-Induced Cardiomyopathy in an Infant with Atrial Flutter and Prolonged Recovery of Cardiac Function

Background: Tachycardia-induced cardiomyopathy (TIC) is caused by prolonged tachycardia, leading to left ventricular dilatation and systolic dysfunction with heart failure. Although TIC is more common in adults, it is rare in early infancy. Methods: Clinical testing was performed as part of medical evaluation and management. Next-generation sequencing (NGS) was conducted for a patient with TIC. A literature review on TIC was also conducted. Results: The case involved a 5-month-old infant referred to the hospital due to symptoms of heart failure lasting at least two months. The infant's heart rate was 200 beats per minute, the left ventricular ejection fraction fell below 14%, and electrocardiograms showed atrial flutter, suggesting TIC. After cardioversion, there was no recurrence of atrial flutter, and cardiac function improved 98 days after tachycardia arrest. The NGS did not identify any pathogenic variants. The literature review identified eight early infantile cases of TIC. However, no previous reports described a case with such a prolonged duration of TIC as ours. Conclusions: This is the first report of a case of prolonged TIC in a child with the documented time to recover normal cardiac function. The improvement of cardiac function depends on the duration of TIC. Early recognition and intervention in TIC are essential to improve outcomes for infantile patients, as timely treatment offers the potential for recovery.

Definition and management of arrhythmia-induced cardiomyopathy: findings from the European Heart Rhythm Association survey

AIMS

Arrhythmia-induced cardiomyopathy (AiCM) represents a subtype of acute heart failure (HF) in the context of sustained arrhythmia. Clear definitions and management recommendations for AiCM are lacking. The European Heart Rhythm Association Scientific Initiatives Committee (EHRA SIC) conducted a survey to explore the current definitions and management of patients with AiCM among European and non-European electrophysiologists.

METHODS AND RESULTS

A 25-item online questionnaire was developed and distributed among EP specialists on the EHRA SIC website and on social media between 4 September and 5 October 2023. Of the 206 respondents, 16% were female and 61% were between 30 and 49 years old. Most of the respondents were EP specialists (81%) working at university hospitals (47%). While most participants (67%) agreed that AiCM should be defined as a left ventricular ejection fraction (LVEF) impairment after new onset of an arrhythmia, only 35% identified a specific LVEF drop to diagnose AiCM with a wide range of values (5-20% LVEF drop). Most respondents considered all available therapies: catheter ablation (93%), electrical cardioversion (83%), antiarrhythmic drugs (76%), and adjuvant HF treatment (76%). A total of 83% of respondents indicated that adjuvant HF treatment should be started at first HF diagnosis prior to antiarrhythmic treatment, and 84% agreed it should be stopped within six months after LVEF normalization. Responses for the optimal time point for the first LVEF reassessment during follow-up varied markedly (1 day-6 months after antiarrhythmic treatment).

CONCLUSION

This EHRA Survey reveals varying practices regarding AiCM among physicians, highlighting a lack of consensus and heterogenous care of these patients.

Atrial fibrillation-induced cardiomyopathy presenting with bilateral intermittent claudication associated with intracardiac thrombi

Systemic thromboembolism associated with atrial fibrillation (AF) is usually caused by thrombi in the left atrial appendage and acute onset. We experienced an unusual case of a woman in her 60s who presented to the outpatient district having bilateral intermittent claudication for more than 1 month, which turned out to be multiple thromboembolism from asymptomatic AF with tachycardia. She was also complicated with non-ischaemic dilated cardiomyopathy with reduced ejection fraction, consistent with arrhythmia-induced cardiomyopathy (AiCM), along with left atrial and left ventricular thrombi and thromboembolism in multiple organs. Rate control with beta-blockers was not effective. With the administration of amiodarone after adequate anticoagulation therapy, she returned to sinus rhythm, and the ejection fraction was restored. This case is instructive in that AiCM with AF can cause thrombosis in the left ventricle, and the patient may present with worsening intermittent claudication as a result of systemic embolism.

Thrombus entrapment with left atrial appendage closure to facilitate early cardioversion in tachycardiomyopathy: a case report

Background

The aetiological spectrum of heart failure with reduced ejection fraction is various. Tachycardiomyopathy is recognized as one of the cause, usually made retrospectively. In this clinical context, rhythm control with restoration of sinus rhythm is considered crucial to minimize ventricular function damage and allow contractility recovery. However, the presence of a thrombus in the left atrial appendage is a limiting factor, typically requiring anticoagulation until the thrombus resolves, at least 3 weeks, thus delaying the therapy.

Case summary

We present a case of 65-year-old man with diagnosis of new-onset acute symptomatic heart failure with severe reduced ejection fraction (left ventricular ejection fraction 15%), in the context of a typical tachycardic atrial flutter and concomitant thrombus in the left atrial appendage confirmed by transoesophageal echocardiography. We successfully performed a thrombus entrapment procedure by means of percutaneous left atrial appendage closure, which allowed immediate restoration of sinus rhythm through cavotricuspid isthmus ablation. After the institution of the heart failure therapy, titrated up to the maximum tolerated dose, we observed a complete restoration of left ventricular function after 6 months.

Discussion

Thrombus entrapment by means of left atrial appendage closure is a valid strategy that enables early cardioversion with arrhythmia ablation and rapid restoration of normal cardiac rhythm in severe heart failure with reduced ejection fraction, even in acute situations and typical atrial flutter.

Iatrogenic cardiomyopathy in patients with manifest right supero-paraseptal accessory pathways

INTRODUCTION

We describe two patients with right supero-paraseptal accessory pathway (SPAP) who developed left ventricular dysfunction associated with an increased degree of ventricular pre-excitation and frequent orthodromic reciprocating tachycardia (ORT) due to worsening atrioventricular (AV) node conduction.

METHODS AND RESULTS

Case 1: 48-year-old female with a history of normally functioning mechanical mitral valve, CABG, and ventricular pre-excitation that worsened after her open heart surgery. She presented with frequent palpitations with documented supraventricular tachycardia (SVT) and found to have a new left ventricular dysfunction with decrease in left ventricular ejection fraction (LVEF) from 55% to 46% with dyssynchrony. An electrophysiological study confirmed a right SPAP and ORT. The pathway was successfully ablated from the antegrade approach after careful mapping. After ablation and 6-month follow up echocardiogram showed improvement of EF to 54% and the LV dyssynchrony resolved. Case 2: 51-year-old male with a history of frequent SVT with recent unsuccessful ablations that resulted in worsening ventricular pre-excitation, more frequent SVT, and new left ventricular dysfunction (LVEF from 60% to 40%). He was started on amiodarone which resulted in significant sinus bradycardia, intermittent ventricular pre-excitation, and first degree AV block with significant increase in ORT events. His electrophysiology study confirmed SPAP which was successfully ablated from the antegrade approach after careful mapping. After 1 month, follow-up echocardiogram showed an improved ejection fraction to 60%.

CONCLUSION

Left ventricular dysfunction due to dyssynchrony and symptomatic frequent ORT of right SPAP can develop in the setting of new iatrogenic diminished AV node conduction. Successful ablation will result in LV function recovery to baseline.

Emerging concepts in heart failure management and treatment: focus on tachycardia-induced cardiomyopathy

Tachycardia-induced cardiomyopathy is an entity characterized by reversible dysfunction of the left ventricle, which can be induced by different types of arrhythmia such as atrial fibrillation, atrial flutter, incessant supraventricular tachycardia and ventricular arrhythmia (more frequent causes). Correct identification of the causative arrhythmia and normalization of the heart rate (e.g through medical treatment, electrical cardioversion, ablation) can lead to recovery of left ventricular function. Tachycardia-induced cardiomyopathy should be suspected in patients with tachycardia and left ventricular dysfunction (heart failure setting), especially when there is no history of previous heart disease. Its usual phenotype is that of non-ischaemic/non-valvular dilated cardiomyopathy and it can occur in both children (main cause: permanent junctional reciprocating tachycardia) and adults (main cause: atrial fibrillation). With proper treatment, most cases recover within a few months, though there is a risk of relapse, especially when the causal arrhythmia reappears or its control is lost. This is a narrative review that comprehensively addresses the pathophysiology, clinical manifestations, and therapeutic management of tachycardia-induced cardiomyopathy. This article is part of the Emerging concepts in heart failure management and treatment Special Issue: https://www.drugsincontext.com/special_issues/emerging-concepts-in-heart-failure-management-and-treatment.

[Tachycardiomyopathy]

Tachycardiomyopathy (TMP) is the development of heart failure due to a cardiac arrhythmia - triggered by rapid and/or irregular ventricular actions. TMP is in principle a (at least partially) reversible disease, so that control of the arrhythmia is of central importance. This article provides an overview of the causes, diagnosis and therapy.

Predictors of tachycardia-induced cardiomyopathy in patients with first-time decompensation of chro­nic heart failure with reduced left ventricular ejection fraction of nonischemic etiology and persistent atrial tachyarrhythmia

Aim    To identify possible predictors of tachycardia-induced cardiomyopathy (TICMP) in patients with newly developed decompensated chronic heart failure (CHF) of nonischemic origin with reduced left ventricular ejection fraction (LV EF) and with persistent atrial tachyarrhythmias. Material and methods    This study included 88 patients with newly developed decompensated CHF of nonischemic origin with reduced LV EF and persistent atrial tachyarrhythmias. Resting 12-lead electrocardiography (EGC) and transthoracic echocardiography (EchoCG) were performed upon admission and following the electrical impulse therapy for all patients. Also, 24-h ECG monitoring was performed to confirm sinus rhythm stability. After recovery of sinus rhythm, outpatient monitoring was performed for three months, including repeated EchoCG to evaluate the dynamics of heart chamber dimensions and LV EF. Results    The patients were divided into two groups based on the increase in LV EF: 68 responders (TICMP patients with a LV EF increase by >10%) and 20 non-responders (patients with an increase in LV EF by <10% during 3 months following the sinus rhythm recovery). According to results of the baseline EchoCG, LV EF did not significantly differ in the two subgroups (TICMP, 40±8.3 %, 18–50 % and non-responders, 38.55±7.9 %, 24–50 %); moreover, the incidence of cases with LV EF <30% did not differ either (9 patients TICMP and 2 non-responders, р=1.0). TICMP patients compared to non-responders, had significantly smaller left atrial dimensions (4.53±1.14 (2–7) cm and 5.68±1.41 (4–8) cm, р=0.034; 80.8±28.9 (27–215) ml and 117.8±41.3 (46–230) ml, р=0.03, respectively) and left ventricular end-systolic volume (ESV) (67.7±33.1 (29–140) ml and 104.5±44.7 (26–172) ml, р=0.02, respectively). The effect of major EchoCG parameters on the probability of TICMP development was assessed by one-factor and multifactor regression analyses with adjustments for age and sex. The probability of TICMP increased with the following baseline EchoCG parameters: end-diastolic volume (EDV) <174 ml [odd ratio (OR), 0.115, 95 % confidence interval (CI): 0.035–0.371], ESV <127 ml [OR, 0.034, 95 % CI: 0.007–0.181], left atrial volume <96 ml [OR, 0.08 , 95 % CI: 0.023–0.274], right ventricular dimension <4 cm [OR, 0.042 , 95 % CI: 0.005–0.389].Conclusion    Among patients with newly developed decompensation of CHF with reduced LV EF of non-ischemic origin and persistent atrial arrhythmias, TICMP was detected in 72 % of patients. The probability of TICMP did not depend on baseline EF and duration of arrhythmias, but increased with the following baseline EchoCG parameters: EDV< 174 ml, ESV< 127 ml, left atrial volume <96 ml, right ventricular dimension <4 cm. The multifactorial analysis showed that a right atrial volume <96 ml is an independent predictor for the development of TICMP.

Tachycardia-Induced Cardiomyopathy in a Young Healthy Patient: A Case Report

Tachycardia-induced cardiomyopathy (TIC) can result in both systolic and/or diastolic ventricular dysfunction as a result of the prolonged fast heart rate which is reversible upon controlling the fast heart rate or arrhythmia. The exact heart rate that can lead to this is not clear, however, a heart rate > 100 in general needs attention. Tachycardia-induced cardiomyopathy is a well-established cause of left ventricular dysfunction which usually happens due to an increased atrial or ventricular rate. The incidence of TIC is very low although the exact incidence is unclear. It should be considered in all patients with dilated cardiomyopathy or those with no obvious explanation for dilated cardiomyopathy and in presence of tachycardia or atrial fibrillation with a rapid ventricular response. Tachycardia-induced cardiomyopathy has also been labeled as arrhythmia-induced cardiomyopathy lately. We present a case of a 50-year-old patient who presented with a fever of 39^oC, feeling generally unwell, had a sore throat, and collapsed at home after several episodes of vomiting after two days of intense exercise. He was diagnosed with suspected tonsillitis and was treated with co-amoxiclav. He was exercising over 10 hours weekly for the last two months in the gym for the Ironman triathlon in London. An echocardiogram showed severe left ventricular systolic dysfunction (LVSD) with a left ventricular ejection fraction (LVEF) of 25%. An electrocardiogram showed sinus tachycardia with a right bundle branch block (RBBB). Cardiac magnetic resonance imaging (CMR) showed normal biventricular function with an ejection fraction (EF) of 71% four months later. The patient was diagnosed with tachycardia-induced cardiomyopathy. This case is unique as the patient presented with transient severe LVSD after training for the ironman triathlon and spontaneous recovery.

Atrial fibrillation-induced tachycardiomyopathy and heart failure: an underappreciated and elusive condition

Many patients with persistent, chronic, or frequently recurring paroxysmal atrial fibrillation (AF) may develop a tachycardiomyopathy (TCM) with left ventricular (LV) dysfunction and heart failure (HF), which is reversible upon restoration and maintenance of sinus rhythm, when feasible, or via better and tighter ventricular rate (VR) control. Mechanisms involved in producing this leading cause of TCM (AF-TCM) include loss of atrial contraction, irregular heart rate, fast VR, neurohumoral activation, and structural myocardial changes. The most important of all mechanisms relates to optimal VR control, which seems to be an elusive target. Uncontrolled AF may also worsen preexisting LV dysfunction and exacerbate HF symptoms. Data, albeit less robust, also point to deleterious effects of slow VRs on LV function. Thus, a J-shaped relationship between VR and clinical outcome has been suggested, with the optimal VR control hovering at ~ 65 bpm, ranging between 60 and 80 bpm; VRs above and below this range may confer higher morbidity and mortality rates. A convergence of recent guidelines is noted towards a stricter rather than a more lenient VR control with target heart rate < 80 bpm at rest and < 110 bpm during moderate exercise which seems to prevent TCM or improve LV function and exercise capacity and relieve TCM-related symptoms and signs. Of course, restoring and maintaining sinus rhythm is always a most desirable target, when feasible, either with drugs or more likely with ablation. All these issues are herein reviewed, current guidelines are discussed and relevant data are tabulated and pictorially illustrated.

Genotype–phenotype correlation in IARS2‐related diseases: A case report and review of literature

Isoleucyl‐tRNA synthetase 2 (IARS2) encodes mitochondrial isoleucine‐tRNA synthetase. Pathogenic variants in the IARS2 gene are associated with mitochondrial disease. We report a female with IARS2 compound heterozygous variants, p.Val499Glyfs*14 and p.Arg784Trp who presented with infantile spasms, Leigh disease and Wolff‐Parkinson White (WPW) pattern. This report expands the phenotypic spectrum of IARS2‐related disease.

Atrial fibrillation in patients with systolic heart failure: pathophysiology mechanisms and management

Heart failure (HF) and atrial fibrillation (AF) demonstrate a constantly increasing prevalence during the 21^st century worldwide, as a result of the aging population and the successful interventions of the clinical practice in the deterioration of adverse cardiovascular outcomes. HF and AF share common risk factors and pathophysiological mechanisms, creating the base of a constant interrelation. AF impairs systolic and diastolic function, resulting in the increasing incidence of HF, whereas the structural and neurohormonal changes in HF with preserved or reduced ejection fraction increase the possibility of the AF development. The temporal relationship of the development of either condition affects the diagnostic algorithms, the prognosis and the ideal therapeutic strategy that leads to euvolaemia, management of non-cardiovascular comorbidities, control of heart rate or restoration of sinus rate, ventricular synchronization, prevention of sudden death, stroke, embolism, or major bleeding and maintenance of a sustainable quality of life. The indicated treatment for the concomitant HF and AF includes rate or/and rhythm control as well as thromboembolism prophylaxis, while the progress in the understanding of their pathophysiological interdependence and the introduction of the genetic profiling, create new paths in the diagnosis, the prognosis and the prevention of these diseases.

Catheter ablation for atrial fibrillation in patients with congestive heart failure

BACKGROUND

We evaluated the 1-year success rate of maintaining sinus rhythm after catheter ablation (CA) for atrial fibrillation (AF) in patients with or without congestive heart failure (CHF).

METHODS

In this single-centre retrospective matched-pair cohort study of 3,018 AF patients who underwent initial CA between January 2012 and June 2018, 227 pairs with (CHF group) or without CHF (control group) were matched using propensity scores. In the CHF group, 108 patients were assigned to the arrhythmia-induced cardiomyopathy (AIC) group whose left ventricular systolic dysfunction was explained only by lasting AF or atrial tachycardia; the remaining 119 had organic heart diseases (non-AIC group). We evaluated the 1-year AF-free survival and changes in clinical findings before and after CA.

RESULTS

The CHF and control groups showed similar AF-free survival; however, AIC patients had significantly better survival than non-AIC patients. AF recurrence was significantly related to CHF re-hospitalisation, which was significantly more frequent in the non-AIC group than in the AIC group. The clinical outcomes of left atrial dilation, brain natriuretic peptide level, and left ventricular ejection function improved significantly before and after CA in both groups. The degree of improvement was significantly better in the AIC group than in the non-AIC group.

CONCLUSIONS

The 1-year success rate was not significantly different between the CHF and control groups. The 1-year success rate in the AIC group was similar to that in the AIC-control group and was better than that in the non-AIC group. CHF clinical outcomes were improved significantly.

Radiofrequency ablation for fascicular ventricular tachycardia causing tachycardiomyopathy and brief literature review

A 10-years-old boy presented with a history of effort intolerance and palpitations for 4 months. His electrocardiogram showed wide complex tachycardia suggestive of fascicular ventricular tachycardia (VT). The echocardiogram showed moderate-to-severe left ventricular systolic dysfunction without any structural lesion. The tachycardia was unresponsive to adenosine and direct current cardioversion. It responded to oral verapamil. The electrophysiology study confirmed the tachycardia as left posterior fascicular VT. The tachycardia was successfully ablated guided by Purkinje potential on three-dimensional mappings. He showed improvement in ventricular functions before discharge. He is doing well on short-term follow-up.

Canine atrial fibrillation: Pathophysiology, epidemiology and classification

Atrial fibrillation (AF) is the most common non-physiological arrhythmia in dogs and humans. Its high prevalence in both species and the impact it has on survival time and quality of life of affected patients, makes it a very relevant topic of medical research. Significant developments in understanding the mechanisms underlying this arrhythmia in humans has occurred over the last decades and some of this knowledge is being applied to veterinary medicine, despite the many differences between species. This article reviews the current understanding of the pathophysiology of AF. The epidemiology and classification of AF in dogs will also be discussed.

Supraventricular tachycardia in 23 cats; comparison with 21 cats with atrial fibrillation (2004-2014)

INTRODUCTION

Supraventricular tachycardia (SVT) has not been well described in cats. The aim of this study was to describe the signalment, clinical findings, and outcome for cats with SVT versus cats with atrial fibrillation (AF).

ANIMALS

Forty-four client owned cats are included in the study. 23 cats with SVT and 21 with AF.

METHODS

This is a retrospective study. Clinical characteristics were compared between groups using a two-sample t-test or Mann-Whitney U test. Kaplan-Meier survival curves were generated to assess for impact of rhythm diagnosis, presence of ventricular arrhythmia, left atrial diameter, heart rate and congestive heart failure (CHF) status on cardiac death. Differences in survival between groups were compared using Mantel-Cox logrank comparison of Kaplan-Meier survival curves.

RESULTS

Cats with supraventricular arrhythmias most commonly presented with respiratory distress (10 of 44 cats). Cats with AF had a slower median heart rate (220 [range: 180-260 beats per minute (bpm)] compared with cats with SVT (300 [range: 150-380] bpm, p < 0.001). All cats with AF had structural heart disease, whereas 4 cats with SVT had no structural abnormalities. Left atrial diameter was significantly larger in cats with AF (23.7 (16.2-40.1) mm compared with 19.1 (12.8-31.4) mm in SVT cats; p = 0.02). Median survival was 58 days (1-780) in cats with AF and 259 days (2-2295) in cats with SVT (p = 0.1). Cats with signs of CHF had a shorter survival time (p = 0.001).

CONCLUSIONS

Most cats with AF or SVT have advanced structural heart disease. Some cats with SVT had structurally normal hearts, suggesting that SVT in cats is not always a consequence of atrial enlargement.

Arrhythmia-Induced Cardiomyopathy

BACKGROUND

Heart failure affects 1–2% of the population and is associated with elevated morbidity and mortality. Cardiac arrhythmias are often a result of heart failure, but they can cause left-ventricular systolic dysfunction (LVSD) as an arrhythmia-induced cardiomyopathy (AIC). This causal relationship should be borne in mind by the physician treating a patient with systolic heart failure in association with cardiac arrhythmia.

METHODS

This review is based on pertinent publications retrieved by a selective search in PubMed (1987–2017) and on the recommendations in current guidelines.

RESULTS

The key criterion for the diagnosis of an AIC is the demonstration of a persistent arrhythmia (including pathological tachycardia) together with an LVSD whose origin cannot be explained on any other basis. Nearly any type of tachyarrhythmia or frequent ventricular extrasystoles can lead, if persistent, to a progressively severe LVSD. The underlying pathophysiologic mechanisms are incompletely understood; the increased ventricular rate, asynchronous cardiac contractions, and neurohumoral activation all seem to play a role. The most common precipitating factors are supraventricular tachycardias in children and atrial fibrillation in adults. Recent studies have shown that the causal significance of atrial fibrillation in otherwise unexplained LVSD is underappreciated. The treatment of AIC consists primarily of the treatment of the underlying arrhythmia, generally with drugs such as beta-blockers and amiodarone. Depending on the type of arrhythmia, catheter ablation for long-term treatment should also be considered where appropriate. The diagnosis of AIC is considered to be well established when the LVSD normalizes or improves within a few weeks or months of the start of targeted treatment of the arrhythmia.

CONCLUSION

An AIC is potentially reversible. The timely recognition of this condition and the appropriate treatment of the underlying arrhythmia can substantially improve patient outcomes.

Tachycardiomyopathy in Patients without Underlying Structural Heart Disease

Tachycardiomyopathy (TCM) is an underestimated cause of reversible left ventricle dysfunction. The aim of this study was to identify the predictors of recurrence and incidence of major cardiovascular events in TCM patients without underlying structural heart disease (pure TCM). The prospective, observational study enrolled all consecutive pure TCM patients. The diagnosis was suspected in patients admitted for heart failure (HF) with a reduced ejection fraction and concomitant persistent arrhythmia. Pure TCM was confirmed after the clinical and echocardiographic recovery during follow-up. From 107 pure TCM patients (9% of all HF admission, the median follow-up 22.6 months), 17 recurred, 51 were hospitalized for cardiovascular reasons, two suffered from thromboembolic events and one died. The diagnosis of obstructive sleep apnoea syndrome (OSAS, hazard ratio (HR) 5.44), brain natriuretic peptide on admission (HR 1.01 for each pg/mL) and the heart rate at discharge (HR 1.05 for each bpm) were all independent predictors of TCM recurrence. The left ventricular ejection fraction at discharge (HR 0.96 for each%) and the heart rate at discharge (HR 1.02 for each bpm) resulted as independent predictors of cardiovascular-related hospitalization. Pure TCM is more common than previously thought and associated with a good long-term survival but recurrences and hospitalizations are frequent. Reversing OSAS and controlling the heart rate could prevent TCM-related complications.

Atrial Fibrillation Ablation Should Be First-line Therapy in Patients with Heart Failure Reduced Ejection Fraction

Catheter ablation for atrial fibrillation in patients with heart failure with reduced ejection fraction is associated with improvement in patient-centered outcomes, such as mortality, heart failure readmission, and atrial fibrillation recurrence, compared with standard medical therapy with or without device therapy. The evidence is not as robust in patients with atrial fibrillation and heart failure with preserved ejection fraction.

Management of asymptomatic arrhythmias: a European Heart Rhythm Association (EHRA) consensus document, endorsed by the Heart Failure Association (HFA), Heart Rhythm Society (HRS), Asia Pacific Heart Rhythm Society (APHRS), Cardiac Arrhythmia Society of Southern Africa (CASSA), and Latin America Heart Rhythm Society (LAHRS)

Asymptomatic arrhythmias are frequently encountered in clinical practice. Although studies specifically dedicated to these asymptomatic arrhythmias are lacking, many arrhythmias still require proper diagnostic and prognostic evaluation and treatment to avoid severe consequences, such as stroke or systemic emboli, heart failure, or sudden cardiac death. The present document reviews the evidence, where available, and attempts to reach a consensus, where evidence is insufficient or conflicting.

Atrioventricular accessory pathways in 89 dogs: Clinical features and outcome after radiofrequency catheter ablation

Background

Atrioventricular accessory pathways (APs) in dogs have been reported rarely. Data regarding clinical presentation and long‐term outcome after radiofrequency catheter ablation (RFCA) are limited.

Hypothesis/Objectives

To study clinical features, electrophysiologic characteristics, and outcome of RFCA in dogs with APs.

Animals

Eighty‐nine dogs presented consecutively for RFCA of APs.

Methods

Case series.

Results

Labrador retrievers (47.2% of dogs) and male dogs (67.4% of dogs) were most commonly affected. Labrador retrievers were more likely to be male than non‐Labrador breeds (P = .043). Clinical signs were nonspecific and most commonly included lethargy and gastrointestinal signs. Concealed APs were more prevalent in Labrador retrievers than other breeds (P = .001). Right‐sided APs (91.7%) predominated over left‐sided (8.3%). Tachycardia‐induced cardiomyopathy (TICM) occurred in 46.1% of dogs, with complete resolution or substantial improvement noted on one‐month postablation echocardiograms. Radiofrequency catheter ablation successfully eliminated AP conduction long term in 98.8% of dogs in which it was performed. Complications occurred in 5/89 dogs. Recurrence in 3 dogs was eliminated long term with a second procedure.

Clinical Importance/Conclusions

Accessory pathways are challenging to recognize in dogs because of nonspecific clinical signs, frequency of concealed APs that show no evidence of their presence during sinus rhythm, and intermittent occurrence of tachyarrhythmias resulting from APs. Tachycardia‐induced cardiomyopathy commonly occurs with AP‐mediated tachycardias and should be considered in any dog presenting with a dilated cardiomyopathic phenotype because of its good long‐term prognosis with rhythm control. Radiofrequency catheter ablation is a highly effective method for eliminating AP conduction and providing long‐term resolution.

Arrhythmia induced cardiomyopathy

Arrhythmia induced cardiomyopathies (AIC) refer to the collective condition of Arrhythmia, Tachycardia, and ectopy-induced Cardiomyopathy. Atrial fibrillation (AF) and heart failure (HF) are modern epidemics that often coexist and exacerbate one another. We aim to provide an overview of the current understanding and evidence for treatment and management in AIC with a particular focus on AF-mediated cardiomyopathy and suggest approaches to recognize, screen, and manage AIC.

Reversal of premature ventricular complexes induced cardiomyopathy. Influence of concomitant structural heart disease

BACKGROUND

We examined the effect of radiofrequency (RF) catheter ablation of premature ventricular complexes (PVCs) on left ventricle (LV) function recovery in patients with LV dysfunction, regardless the presence of structural heart disease (SHD).

METHODS

Seventy seven patients with impaired LV ejection fraction (EF) (37.1±9.4), suspected to have PVCs cardiomyopathy (PVC-CM) (>10% PVCs burden), referred for RF ablation were enrolled, and divided into 2 groups according to the presence of SHD. SHD was ruled out by echocardiography, coronary angiography or MRI. CARTO 3 mapping system was used employing activation mapping in the majority of cases. Initial success was defined as complete elimination or residual PVCs≤10 beats/30min. Long term success was defined as reduction in PVCs burden >80% on follow-up holter. Echocardiography was done after 6 months. Improvement of EF >5% was considered significant.

RESULTS

Forty two (55.8%) cases had SHD. PVCs burden was 28.4±9.8%. EF improved to 48.6±10.3. Initial success, overall success, post procedural PVCs burden and EF were comparable in both groups. EF improved in 47(75%) of successful cases with no significant differences between both groups. Post-MI Patients were the least category to improve. PVCs burden before and after ablation were the independent predictors of LVEF recovery by multivariate analysis. Cutoff values of >18%, <8% had 100% sensitivity and 85%, 87% specificity, respectively.

CONCLUSIONS

PVCs elimination by RF ablation results in significant improvement even restoration of LV function regardless of PVC origin, or the presence of concomitant SHD. PVCs burden before and after ablation are the main predictors of LVEF recovery.

Application of Neonatologist Performed Echocardiography in the Assessment and Management of Neonatal Heart Failure unrelated to Congenital Heart Disease

Neonatal heart failure (HF) is a progressive disease caused by cardiovascular and non-cardiovascular abnormalities. The most common cause of neonatal HF is structural congenital heart disease, while neonatal cardiomyopathy represents the most common cause of HF in infants with a structurally normal heart. Neonatal cardiomyopathy is a group of diseases manifesting with various morphological and functional phenotypes that affect the heart muscle and alter cardiac performance at, or soon after birth. The clinical presentation of neonates with cardiomyopathy is varied, as are the possible causes of the condition and the severity of disease presentation. Echocardiography is the selected method of choice for diagnostic evaluation, follow-up and analysis of treatment results for cardiomyopathies in neonates. Advances in neonatal echocardiography now permit a more comprehensive assessment of cardiac performance that could not be previously achieved with conventional imaging. In this review, we discuss the current and emerging echocardiographic techniques that aid in the correct diagnostic and pathophysiological assessment of some of the most common etiologies of HF that occur in neonates with a structurally normal heart and acquired cardiomyopathy and we provide recommendations for using these techniques to optimize the management of neonate with HF.

Right ventricular endomyocardial biopsy in children and adolescents with drug-refractory arrhythmia

Purpose This study aimed to assess the results of endomyocardial biopsy from the right ventricle to establish the possible cause for drug-refractory arrhythmias in children. Materials and methods We enrolled 19 consecutive young patients with drug-refractory arrhythmia, from 2010 to 2013, who underwent endomyocardial biopsy. Inclusion criteria were as follows: age <18 years with a structurally normal heart or mild changes in a structure of the heart initially diagnosed as arrhythmia-induced cardiomyopathy. Overall, 86 biopsies were performed in 19 patients. Histopathological analysis, immunohistochemistry, and polymerase chain reaction were used for the interpretation of the endomyocardial biopsy.

RESULTS

The mean age of the patient population was 14.1±2.9 year (range from 7 to 17 years). All these patients had a history of drug-refractory arrhythmia for >5 months (mean 30 months). Patients underwent a complete history investigation, physical examination, laboratory studies, echocardiography, electrocardiography, treadmill test, and Holter monitoring before endomyocardial biopsy; two patients with arrhythmogenic right ventricular dysplasia had implantable cardioverter defibrillator implantation and further appropriate successful device shocks. Myocarditis was diagnosed based on histopathological and immunohistological analyses in nine (47.4%) patients. Polymerase chain reaction was positive for viral genome in four of them; five patients had active myocarditis. Radiofrequency ablation was performed in 17 patients; five out of six (83%) endomyocardial biopsy-proved myocarditis patients had successful radiofrequency ablation. No significant complication was reported during ablation and endomyocardial biopsy.

CONCLUSIONS

Approximately half of the children with drug-refractory arrhythmia had unsuspected myocarditis according to the results of the endomyocardial biopsy.

Clinical Utility of Longitudinal Strain to Predict Functional Recovery in Patients With Tachyarrhythmia and Reduced LVEF

OBJECTIVES

This study sought to assess the time course of presumptive tachycardia-induced cardiomyopathy and the predictors of left ventricular (LV) functional recovery in such patients.

BACKGROUND

Tachycardia-induced cardiomyopathy is a potentially reversible cardiomyopathy with effective treatment of the tachyarrhythmia. However, cases without improvement of LV systolic function were found occasionally. The diagnosis of tachycardia-induced cardiomyopathy can be challenging, and the role of echocardiographic imaging in the prediction of LV functional recovery is limited.

METHODS

LV segmental longitudinal strains (LS) were evaluated by 2-dimensional speckle tracking in 71 consecutive patients (65 ± 16 years; 61% men) with tachyarrhythmia and reduced left ventricular ejection fraction (LVEF) without any other known cardiovascular disease, and 30 age and sex-matched control subjects. Relative apical LS ratio (RALSR) was defined using the equation: average apical LS / (average basal LS + average mid LS) as a marker of strain distribution.

RESULTS

Compared with control subjects, patients with tachyarrhythmia had significantly lower global LS. Improvement in LVEF within 6 months after treatment of index arrhythmia was observed in 41 patients, and LVEF did not improve in 30 patients. In univariate analysis, lower LVEF at baseline (hazard ratio: 0.59 per 1 SD; p = 0.04) and higher RALSR (hazard ratio: 11.2 per 1 SD; p < 0.001) were associated with no recovery in LVEF during follow-up. In a multivariate logistic regression model, the significant predictor of LV systolic functional recovery was RALSR (hazard ratio: 22.9 per 1 SD; p = 0.001). A RALSR of 0.61 was sensitive (71%) and specific (90%) in differentiating LV systolic functional recovery (area under the curve: 0.88).

CONCLUSIONS

The RALSR was associated with LV systolic functional recovery. This information might be useful for clinical evaluation and follow-up in patients with reduced LVEF.

Respiratory Distress in an Infant: An Uncommon Cause for a Common Complaint

BACKGROUND

Respiratory distress and tachycardia are common presenting complaints in infants and young children, and evaluation typically focuses on respiratory infections. Tachydysrhythmias causing heart failure are rare and can be difficult to diagnose in young children, but are reversible if recognized and treated early.

CASE REPORT

We discuss a 7-week-old female infant who presented with respiratory distress and persistent tachycardia. Evaluation revealed severe cardiac dysfunction with an underlying atrial flutter discovered on electrocardiography after adenosine administration. Rate control by synchronized electrocardioversion resulted in resolution of symptoms and restoration of cardiac function, confirming the diagnosis of atrial flutter-induced cardiomyopathy. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Persistent or inappropriate tachycardia in a young child should not be dismissed and underlying dysrhythmia should be considered.

Arrhythmia-Induced Cardiomyopathies: Mechanisms, Recognition, and Management

Arrhythmia-induced cardiomyopathy (AIC) is a potentially reversible condition in which left ventricular dysfunction is induced or mediated by atrial or ventricular arrhythmias. Cellular and extracellular changes in response to the culprit arrhythmia have been identified, but specific pathophysiological mechanisms remain unclear. Early recognition of AIC and prompt treatment of the culprit arrhythmia using pharmacological or ablative techniques result in symptom resolution and recovery of ventricular function. Although cardiomyopathy in response to an arrhythmia may take months to years to develop, recurrent arrhythmia can result in rapid decline in ventricular function with development of heart failure, suggesting residual ultrastructural abnormalities. Reports of sudden death in patients with normalized left ventricular ejection fraction cast doubt on the complete reversibility of this condition. Several aspects of AIC, including specific pathophysiological mechanisms, predisposing factors, optimal therapeutic strategies to prevent ultrastructural changes, and long-term risk of sudden death remain unresolved and need further research.

Novel perspectives on arrhythmia-induced cardiomyopathy: pathophysiology, clinical manifestations and an update on invasive management strategies

Arrhythmia-induced cardiomyopathy is a partially or completely reversible form of myocardial dysfunction due to sustained supraventricular and ventricular arrhythmias. Asynchrony, rapid cardiac rates and rhythm irregularities are the main factors involved in the development of the disease. The reversible nature of arrhythmia-induced cardiac dysfunction allows only for a retrospective diagnosis of the disease once cardiac function is restored following heart rate control. A high level of suspicion is needed to make a diagnosis at an early stage and prevent further progression of the disease. Although reversible, arrhythmia-induced cellular and molecular changes may remain, increasing the risk for sudden death even when normal ejection fraction is restored as well as causing rapid deterioration of cardiac function and development of heart failure symptoms if arrhythmia recurs. Appropriate management based on a combination of pharmacologic and nonpharmacologic strategies to achieve rate control and prevent arrhythmia recurrence is pivotal to avoid further cardiac function deterioration and to control symptoms, significantly reducing the risk of heart failure and sudden cardiac death.

Management of tachycardia

Tachycardia, conventionally, but arbitrarily, defined as an atrial and/or ventricular rate of >100 beats per minute, is encountered commonly and can be physiological or pathological in origin. Various adverse consequences from tachycardia have been recognized, and an important one is the association between persistent tachycardia and cardiomyopathy. In this article, we provide an up-to-date review on the etiology of tachycardia, management strategies, and the prognosis of patients presenting with tachycardia and cardiomyopathy.