Pathophysiology, diagnosis and treatment of tachycardiomyopathy

When, Why and How to Re-challenge Clozapine in Schizophrenia Following Myocarditis

Clozapine-induced myocarditis (CIM) is among the most important adverse events limiting the use of clozapine as the most effective treatment for schizophrenia. CIM necessitates the immediate termination of clozapine, often resulting in its permanent discontinuation with considerable detrimental effects on patients' psychopathology and long-term outcome. Consequently, a clozapine re-challenge after CIM is increasingly regarded as a viable alternative, with published reports indicating a success rate of approximately 60%. However, published cases of re-challenges after CIM remain limited. Here, we provide a narrative review of the current state of research regarding the epidemiology, pathophysiology, risk factors, diagnosis and clinical management of CIM as well as a synthesis of current recommendations for re-challenging patients after CIM. This includes a step-by-step guide for this crucial procedure based on the current evidence regarding the pathophysiology and risk factors for CIM. Slow dose titration regimes and addressing risk factors including concomitant valproate and olanzapine are crucial both to prevent CIM and to ensure a safe and successful re-challenge. Furthermore, we discuss the utility of C-reactive protein, troponin, N-terminal-pro hormone and brain natriuretic peptide, therapeutic drug-monitoring and cardiac magnetic resonance imaging for CIM screening and diagnosis as well as for post-CIM re-challenges.

Longitudinal analysis of echocardiographic and cardiac biomarker variables in dogs with atrial fibrillation: The optimal rate control in dogs with atrial fibrillation II study

BACKGROUND

Rate control (RC; meanHRHolter ≤ 125 bpm) increases survival in dogs with atrial fibrillation (AF). The mechanisms remain unclear.

HYPOTHESIS/OBJECTIVES

Investigate echocardiographic and biomarker differences between RC and non-RC (NRC) dogs. Determine if changes post-anti-arrhythmic drugs (AAD) predict successful RC in subsequent Holter monitoring. Evaluate if early vs late RC affects survival.

ANIMALS

Fifty-two dogs with AF.

METHODS

Holter-derived mean heart rate, echocardiographic and biomarker variables from dogs receiving AAD were analyzed prospectively at each re-evaluation and grouped into RC or NRC. The primary endpoint was successful RC. Between group comparisons of absolute values, magnitude of change from admission to re-evaluations and end of study were performed using Mann-Whitney tests or unpaired t-tests. Logistic regression explored variables associated with inability to achieve RC at subsequent visits. Kaplan-Meier survival analysis was used to compare survival time of early vs late RC.

RESULTS

At visit 2, 11/52 dogs were RC; at visit 3, 14/52 were RC; and at visit 4, 4/52 were RC. At the end of study, 25/52 remained NRC. At visit 2, both groups had increased cardiac dimensions, but NRC dogs had larger dimensions; biomarkers did not differ. At the end of study, RC showed decreased cardiac dimensions and end-terminal pro-brain natriuretic peptide (NT-proBNP) compared with NRC. No variables were useful at predicting RC success in subsequent visits. Survival analysis found no differences between early vs late RC.

CONCLUSIONS AND CLINICAL IMPORTANCE

The RC dogs had decreased cardiac dimensions and NT-proBNP, suggesting HR-mediated reverse-remodeling might benefit survival, even with delayed RC achievement. Pursuit of RC is crucial despite initial failures.

Predictors of systolic function recovery after atrial fibrillation ablation in heart failure patients

INTRODUCTION AND OBJECTIVES

Atrial fibrillation (AF) and heart failure (HF) often coexist. AF catheter ablation improves left ventricular ejection fraction (LVEF), but its impact varies between patients. We aimed to identify predictors of LVEF improvement in HF patients with impaired LVEF undergoing AF ablation.

METHODS

We conducted a retrospective single-center study in HF patients with LVEF <50% undergoing AF catheter ablation between May 2016 and May 2022. The primary endpoint was the LVEF recovery rate ('responders'). Secondary endpoints were one-year safety and effectiveness. We also aimed to validate a prediction model for LVEF recovery.

RESULTS

The study included 100 patients (79% male, median age 60 years, 70% with probable tachycardia-induced cardiomyopathy [TIC], mean LVEF 37%, 29% with paroxysmal AF). After a median follow-up of 12 months after catheter ablation, LVEF improved significantly (36±10% vs. 53±10%, p<0.001), with an 82% responder rate. A suspected diagnosis of TIC (OR 4.916 [95% CI 1.166-20.732], p=0.030), shorter QRS duration (OR 0.969 [95% CI 0.945-0.994], p=0.015), and smaller left ventricle (OR 0.893 [95% CI 0.799-0.999], p=0.049) were independently associated with LVEF improvement. Freedom from any documented atrial arrhythmia was 86% (64% under antiarrhythmic drugs), and the rate of adverse events was 2%. The prediction model had a good discriminative performance (AUC 0.814 [95% CI 0.681-0.947]).

CONCLUSION

In AF patients with HF and impaired LVEF, suspected TIC, shorter QRS duration, and smaller LV diameter were associated with LVEF recovery following AF catheter ablation.

Combination of electrophysiological mapping, radiofrequency catheter ablation, and atrial appendectomy in a 5-year-old girl with tachycardia-induced cardiomyopathy: a case report

BACKGROUND

Atrial tachycardia (AT) originating from the left atrial appendage (LAA) is uncommon and the most difficult arrhythmia to eliminate. Therefore, we present the case of a 5-year-old girl with tachycardia-induced cardiomyopathy (TIC) caused by AT originating from the LAA and successfully treated with RFCA associated to left atrial appendectomy. With resolution of AT, we observed a progressive improvement of LV function. The effectiveness and safety of this combination therapy were evaluated over a one-month follow-up period.

CASE PRESENTATION

A 5 -year-old female was evaluated for three days of incessant cough and a syncopal episode. Surface echocardiography and 24-hour monitoring showed that the infant had persistent atrial tachycardia. Echocardiography revealed an enlarged tele diastolic diameter (46.1 mm) and malfunctioning (EF 28.53%) left ventricle. The location of the lesion at the apex of the LAA was further confirmed by electrophysiological study and RFCA. After RFCA, the infant's ECG monitor showed that sinus rhythm was maintained for up to 22 h. Subsequently, atrial tachycardia recurred and sinus rhythm disappeared. Finally, atrial appendectomy was performed and sinus rhythm returned to normal.

CONCLUSIONS

The heart function of the infant improved and sinus rhythm was maintained, further demonstrating the safety and effectiveness of combined treatment with RFCA and atrial appendectomy after electrophysiological localization of AT from LAA to TIC.

Tachycardia-induced metabolic rewiring as a driver of contractile dysfunction

Prolonged tachycardia-a risk factor for cardiovascular morbidity and mortality-can induce cardiomyopathy in the absence of structural disease in the heart. Here, by leveraging human patient data, a canine model of tachycardia and engineered heart tissue generated from human induced pluripotent stem cells, we show that metabolic rewiring during tachycardia drives contractile dysfunction by promoting tissue hypoxia, elevated glucose utilization and the suppression of oxidative phosphorylation. Mechanistically, a metabolic shift towards anaerobic glycolysis disrupts the redox balance of nicotinamide adenine dinucleotide (NAD), resulting in increased global protein acetylation (and in particular the acetylation of sarcoplasmic/endoplasmic reticulum Ca2+-ATPase), a molecular signature of heart failure. Restoration of NAD redox by NAD+ supplementation reduced sarcoplasmic/endoplasmic reticulum Ca2+-ATPase acetylation and accelerated the functional recovery of the engineered heart tissue after tachycardia. Understanding how metabolic rewiring drives tachycardia-induced cardiomyopathy opens up opportunities for therapeutic intervention.

Tachycardia and Atrial Fibrillation-Related Cardiomyopathies: Potential Mechanisms and Current Therapies

Atrial fibrillation (AF) is associated with an increased risk of new-onset ventricular contractile dysfunction, termed arrhythmia-induced cardiomyopathy (AIC). Although cardioembolic stroke remains the most feared and widely studied complication of AF, AIC is also a clinically important consequence of AF that portends significant morbidity and mortality to patients with AF. Current treatments are aimed at restoring sinus rhythm through catheter ablation and rate and rhythm control, but these treatments do not target the underlying molecular mechanisms driving the progression from AF to AIC. Here, we describe the clinical features of the various AIC subtypes, discuss the pathophysiologic mechanisms driving the progression from AF to AIC, and review the evidence surrounding current treatment options. In this review, we aim to identify key knowledge gaps that will enable the development of more effective AIC therapies that target cellular and molecular mechanisms.

Relationship between coronary blood flow and improvement of cardiac function after catheter ablation for persistent atrial fibrillation

BACKGROUND

The relationship between coronary blood flow during atrial fibrillation (AF) and improvement of cardiac function after catheter ablation (CA) for persistent AF (PeAF) is not prominent; this study was conducted to evaluate this relationship.

METHODS

This was a retrospective case-control study. Eighty-five patients with PeAF (resting heart rate < 100 bpm) and heart failure with reduced ejection fraction (left ventricular ejection fraction (LVEF) < 40%) who had undergone coronary angiography within 1 week before CA were included. All patients could maintain a sinus rhythm for > 6 months after CA. The primary outcome was improvement of cardiac function with an LVEF cutoff value of > 50% during sinus rhythm 6 months after CA.

RESULTS

In the LVEF improvement group (N = 57), patients were younger, with a higher baseline diastolic blood pressure and lower baseline brain natriuretic peptide level than the no LVEF improvement group (N = 28). Heart rate at baseline and 6 months after CA and AF duration did not differ between the two groups. Thrombolysis in myocardial infarction frame count parameters was significantly higher in the LVEF improvement (P < 0.001) than in the no LVEF improvement group. Multivariate logistic regression analysis revealed mean thrombolysis in myocardial infarction frame count as an independent factor for LVEF improvement (odds ratio, 1.72 (95% confidence interval 1.17-2.54); P = 0.006).

CONCLUSION

Coronary blood flow in patients with PeAF is strongly associated with improved left ventricular systolic function after the restoration of sinus rhythm by CA for PeAF and heart failure with reduced ejection fraction.

Reply to Kataoka, N.; Imamura, T. How to Improve Clinical Outcomes in Patients with Tachycardia-Induced Cardiomyopathy. Comment on "Katz et al. Long-Term Outcomes of Tachycardia-Induced Cardiomyopathy Compared with Idiopathic Dilated Cardiomyopathy. J. Clin. Med. 2023, 12, 1412"

In a letter to the editor titled "How to improve clinical outcomes in patients with tachycardia-induced cardiomyopathy", Dr. Naoya Kataoka and Dr. Teruhiko Imamura [...].

Effectiveness of Catheter Ablation in Left Ventricular Ejection Fraction, Stroke, Quality of Life, All-Cause Mortality, Sinus Rhythm Maintenance, and Hospitalization Rates as Compared to Medical Therapy

Atrial fibrillation (AF) in the setting of heart failure (HF) accounts for a significant proportion of mortality. AF can be managed either with rate control or rhythm control strategies. Rate control involves the use of beta blockers or calcium channel blockers. Rhythm control methods use antiarrhythmic drugs or catheter ablation (CA) to abolish the rhythm. Articles from PubMed and Google Scholar were chosen for review. The literature was reviewed for data from the last 10 years to be chosen for interpretation. Clinical trials, meta-analyses, and systematic analysis were included in this study. Various health parameters such as all-cause mortality, hospitalization rates, sinus rhythm (SR) maintenance, quality of life improvement, stroke risk, left ventricular ejection fraction (LVEF) improvement, and healthcare costs were analyzed. We demonstrated that CA was superior to medical therapy in reducing all-cause mortality and hospitalization. It leads to significant improvement in LVEF as SR was maintained consistently. Overall, quality of life improved in those who underwent ablation as compared to those who did not. Stroke risk reduction was seen in observational studies only. We recommend CA as first-line therapy for treating patients with AF in the setting of HF. More clinical trials are needed to determine the effectiveness of ablation in reducing stroke risk.

Long-Term Outcomes of Tachycardia-Induced Cardiomyopathy Compared with Idiopathic Dilated Cardiomyopathy

BACKGROUND

data on the natural course and prognosis of tachycardia-induced cardiomyopathy (TICMP) and comparison with idiopathic dilated cardiomyopathies (IDCM) are scarce.

OBJECTIVE

To compare the clinical presentation, comorbidities, and long-term outcomes of TICMP patients with IDCM patients.

METHODS

a retrospective cohort study of patients hospitalized with new-onset TICMP or IDCM. The primary endpoint was a composite of death, myocardial infarction, thromboembolic events, assist device, heart transplantation, and ventricular tachycardia or fibrillation (VT/VF). The secondary endpoint was recurrent hospitalization due to heart failure (HF) exacerbation.

RESULTS

the cohort was comprised of 64 TICMP and 66 IDCM patients. The primary composite endpoint and all-cause mortality were similar between the groups during a median follow-up of ~6 years (36% versus 29%, p = 0.33 and 22% versus 15%, p = 0.15, respectively). Survival analysis showed no significant difference between TICMP and IDCM groups for the composite endpoint (p = 0.75), all-cause mortality (p = 0.65), and hospitalizations due to heart failure exacerbation. Nonetheless, the incidence of recurrent hospitalization was significantly higher in TICMP patients (incidence rate ratio 1.59; p = 0.009).

CONCLUSIONS

patients with TICMP have similar long-term outcomes as those with IDCM. However, it portends a higher rate of HF readmissions, mostly due to arrhythmia recurrences.

Rate of atrial fibrillation and flutter induced tachycardiomyopathy in a cohort of hospitalized patients with heart failure and detection of indicators for improved diagnosis

Background

Atrial fibrillation (AF) and atrial flutter (AFL) induced tachycardiomyopathy (TCM) has been known to cause reversible heart failure (HF) for many years. However, the prevalence of the disease is unknown, and diagnosis is challenging. Therefore, the aim of the present study was (1) to assess the rate of AF/AFL induced TCM and (2) to identify indicators for diagnosis.

Methods

Consecutively, all patients with a diagnosis of HF who were hospitalized in our department within 12 months were reviewed. For the main analysis, all patients with HF with reduced ejection fraction (HFrEF) and AF or AFL were included. AF/AFL induced TCM was diagnosed when there was at least a 10% improvement in left ventricular ejection fraction under rhythm or rate control within 3 months. Patients with HFrEF with AF/AFL but without TCM served as control group.

Results

A total of 480 patients were included. AF/AFL induced TCM occurred in 26 patients (5.4%) and HFrEF with AF/AFL in 53 patients (11%). Independent indicators of AF/AFL induced TCM were age<79 years [Odds ratio 5.887, confidence interval (CI) 1.999-17.339, p < 0.001], NT-pro-BNP <5,419 pg/mL (Odds ratio 2.327, CI 1.141-4.746, p = 0.004), and a resting heart rate >112 bpm (Odds ratio 2.503, CI 1.288-4.864, p = 0.001).

Conclusion

Approximately 5% of all patients hospitalized for HF suffer from AF/AFL induced TCM. Improved discrimination of AF/AFL induced TCM to HFrEF with AF/AFL is possible considering age, NT-pro-BNP level, and resting heart rate >112 beats/minute. Based on these parameters, an earlier diagnosis and improved therapy might be possible.

Case report: Efficacy analysis of radiofrequency catheter ablation combined with atrial appendage resection for atrial tachycardia originating from the atrial appendage in children

Objective

The aim of this study was to investigate the efficacy of radiofrequency catheter ablation (RFCA) combined with atrial appendage (AA) resection to treat atrial tachycardia (AT) originating from the AA in children.

Materials and methods

Using the Ensite three-dimensional electroanatomic mapping system, three children with AT originating from the AA were diagnosed. Clinical features and electrocardiographic (ECG) manifestations were analyzed. Ablations were performed using a cold saline-infused catheter at appendages targeting loci of AT origin under the guidance of the Ensite system. Atrial appendage resection was performed in combination with cardiac surgery, and the curative effect was evaluated.

Results

The ages of the three patients were 3.5, 5.75, and 12.9 years. Two cases originated from the right atrial appendage (RAA) and one originated from the left atrial appendage (LAA). The ECG characteristics of AT from the RAA were as follows: (1) negative P waves in lead V1; (2) positive P waves in leads II, III, and aVF; (3) positive P wave in lead I with varying shapes in lead aVL; and (4) prolonged PR interval with no QRS wave after some P waves. The ECG of the LAA was characterized by (1) positive P waves in lead V1 with a bimodal pattern; (2) positive P waves in leads II, III, and aVF; and (3) negative P waves in leads I and aVL. Preoperative echocardiography showed cardiac enlargement and a decreased left ventricular ejection fraction (LVEF) in all three cases. One case was cured after RFCA, and the remaining two cases required AA resection after RFCA. No recurrence was detected at 1-18 months of follow-up, and the left ventricular end-diastolic diameter and LVEF returned to normal.

Conclusion

Atrial tachycardia originating from the AA in children showed a characteristic P-wave presentation on ECG, and sustained episodes of AT resulted in tachycardia-induced cardiomyopathy. Children who are not successfully controlled by RFCA or who have a recurrence after RFCA could benefit from AA resection.

Catheter Ablation versus Medical Therapy of Atrial Fibrillation in Patients with Heart Failure: An Updated Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: Atrial fibrillation (AF) and heart failure (HF) often coexist and synergistically contribute to an increased risk of hospitalization, stroke, and mortality. Objective: To compare the efficacy of catheter ablation (CA) versus medical therapy (MT) in HF patients with AF. Methods: Electronic databases were queried for randomized controlled trials (RCTs) of CA versus MT of AF in patients with HF. Risk ratios (RRs), mean differences (MDs), and 95% confidence intervals (CIs) were measured using the Mantel−Haenszel method. Results: A total of nine RCTs enrolling 2155 patients met the inclusion criteria. Compared to MT, CA led to a significant reduction in the composite of all-cause mortality and HF hospitalization (24.6% vs. 37.1%; RR: 0.65 (95% CI: 0.53−0.80); p < 0.0001), all-cause mortality (8.8% vs. 13.6%; RR: 0.65 (95% CI: 0.51−0.82); p = 0.0005), HF hospitalization (15.4% vs. 22.4%; (RR: 0.67 (95% CI: 0.54−0.82); p = 0.0001), AF recurrence (31.8% vs. 77.0%; RR: 0.36 (95% CI: 0.24−0.54); p < 0.0001), and cardiovascular (CV) death (4.9% vs. 8.4%; RR: 0.58 (95% CI: 0.39−0.86); p = 0.007). CA improved the left ventricular ejection fraction (MD:4.76% (95% CI: 2.35−7.18); p = 0.0001), 6 min walk test (MD: 20.48 m (95% CI: 10.83−30.14); p < 0.0001), peak oxygen consumption (MD: 3.1 2mL/kg/min (95% CI: 1.01−5.22); p = 0.004), Minnesota Living with Heart Failure Questionnaire score (MD: −6.98 (95% CI: −12−03, −1.93); p = 0.007), and brain natriuretic peptide levels (MD:−133.94 pg/mL (95% CI: −197.33, −70.55); p < 0.0001). Conclusions: In HF patients, AF catheter ablation was superior to MT in reducing CV and all-cause mortality. Further significant benefits occurred within the ablation group in terms of HF hospitalizations, AF recurrences, the systolic function, exercise capacity, and quality of life.

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.

Early prediction of clinical scores for left ventricular reverse remodeling using extreme gradient random forest, boosting, and logistic regression algorithm representations

Objective

At present, there is no early prediction model of left ventricular reverse remodeling (LVRR) for people who are in cardiac arrest with an ejection fraction (EF) of ≤35% at first diagnosis; thus, the purpose of this article is to provide a supplement to existing research.

Materials and methods

A total of 109 patients suffering from heart attack with an EF of ≤35% at first diagnosis were involved in this single-center research study. LVRR was defined as an absolute increase in left ventricular ejection fraction (LVEF) from ≥10% to a final value of &gt;35%, with analysis features including demographic characteristics, diseases, biochemical data, echocardiography, and drug therapy. Extreme gradient boosting (XGBoost), random forest, and logistic regression algorithm models were used to distinguish between LVRR and non-LVRR cases and to obtain the most important features.

Results

There were 47 cases (42%) of LVRR in patients suffering from heart failure with an EF of ≤35% at first diagnosis after optimal drug therapy. General statistical analysis and machine learning methods were combined to exclude a number of significant feature groups. The median duration of disease in the LVRR group was significantly lower than that in the non-LVRR group (7 vs. 48 months); the mean values of creatine kinase (CK) and MB isoenzyme of creatine kinase (CK-MB) in the LVRR group were lower than those in the non-LVRR group (80.11 vs. 94.23 U/L; 2.61 vs. 2.99 ng/ml; 27.19 vs. 28.54 mm). Moreover, AUC values for our feature combinations ranged from 97 to 94% and to 87% when using the XGBoost, random forest, and logistic regression techniques, respectively. The ablation test revealed that beats per minute (BPM) and disease duration had a greater impact on the model’s ability to accurately forecast outcomes.

Conclusion

Shorter disease duration, slightly lower CK and CK-MB levels, slightly smaller right and left ventricular and left atrial dimensions, and lower mean heart rates were found to be most strongly predictive of LVRR development (BPM).

The effects of catheter ablation of outflow tract premature ventricular complexes on atrial electromechanical delay

BACKGROUND

Consistent data from several studies have shown that catheter ablation of frequent premature ventricular complexes (PVCs) results in substantial improvement in left ventricular ejection fraction (LVEF), left ventricular diastolic function, and left atrial volume and mechanics. However, the effects of catheter ablation of PVCs on atrial electromechanical properties have not been documented yet.

AIMS

In the present study, we investigated the short-term effects of radiofrequency catheter ablation (RFCA) of outflow tract PVCs on atrial electromechanical delay (EMD).

METHODS

A total of 71 subjects with idiopathic outflow tract PVCs who underwent RFCA were included. Interatrial and intra-atrial EMDs were measured by tissue Doppler imaging before and 3 months after catheter ablation.

RESULTS

The study population was divided into normal ejection fraction (EF) and low-EF subgroups according to their LVEF. In all study groups, substantial improvement was found in lateral electromechanical coupling time (PA), septal PA, right ventricular PA, interatrial EMD, left-sided intra-atrial EMD, and right-sided intra-atrial EMD. No treatment heterogeneity was observed when comparing low-EF and normal-EF subgroups with respect to atrial EMDs (interatrial EMD, interaction p = .29; left-sided intra-atrial EMD, interaction p = .13; right-sided intra-atrial EMD, interaction p = .88).

CONCLUSION

RFCA of outflow tract PVC has a favorable early effect on intra- and inter-atrial EMDs irrespective of preprocedural LVEF.

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.

Catheter ablation for atrial fibrillation: impact on mortality, morbidity, quality of life, and implications for the future

Despite the advances in technologies and techniques in the field of catheter ablation for cardiac arrhythmias, it is estimated that the prevalence of atrial fibrillation (AF) will further increase in the nearest future. The latest trials have proven the beneficial effect on mortality after pulmonary vein isolation in patients with impaired left ventricular function, while no such effect has been seen in patients without left ventricular dysfunction. This raises the question of whether catheter ablation for AF is still suited for the latter patient cohort or whether the endpoint of mortality is not adequate enough. Not only does pulmonary vein isolation reduce the burden of atrial fibrillation, but it also somehow alters the patients’ perception of it in the case of recurrence. Independent of the presence of ventricular dysfunction, patients experience a relief of AF-related symptoms, which is accompanied by an increase in quality of life based on the available patient-reported outcome measures, despite AF recurrence. Trials that are currently recruiting patients seek to unveil the accountable circumstances for these remaining uncertainties and help expand our understanding of a procedure that has been routinely performed for two decades.

Machine Learning Using a Single-Lead ECG to Identify Patients With Atrial Fibrillation-Induced Heart Failure

Aims

Atrial fibrillation (AF) and heart failure often co-exist. Early identification of AF patients at risk for AF-induced heart failure (AF-HF) is desirable to reduce both morbidity and mortality as well as health care costs. We aimed to leverage the characteristics of beat-to-beat-patterns in AF to prospectively discriminate AF patients with and without AF-HF.

Methods

A dataset of 10,234 5-min length RR-interval time series derived from 26 AF-HF patients and 26 control patients was extracted from single-lead Holter-ECGs. A total of 14 features were extracted, and the most informative features were selected. Then, a decision tree classifier with 5-fold cross-validation was trained, validated, and tested on the dataset randomly split. The derived algorithm was then tested on 2,261 5-min segments from six AF-HF and six control patients and validated for various time segments.

Results

The algorithm based on the spectral entropy of the RR-intervals, the mean value of the relative RR-interval, and the root mean square of successive differences of the relative RR-interval yielded an accuracy of 73.5%, specificity of 91.4%, sensitivity of 64.7%, and PPV of 87.0% to correctly stratify segments to AF-HF. Considering the majority vote of the segments of each patient, 10/12 patients (83.33%) were correctly classified.

Conclusion

Beat-to-beat-analysis using a machine learning classifier identifies patients with AF-induced heart failure with clinically relevant diagnostic properties. Application of this algorithm in routine care may improve early identification of patients at risk for AF-induced cardiomyopathy and improve the yield of targeted clinical follow-up.

Left Ventricular Systolic Dysfunction Due to Atrial Fibrillation: Clinical and Echocardiographic Predictors

Background: Diagnosis of AF-induced cardiomyopathy can be challenging and relies on ruling out other causes of cardiomyopathy and, after restoration of sinus rhythm, recovery of left ventricular (LV) function. The aim of this study was to identify clinical and echocardiographic predictors for developing cardiomyopathy with systolic dysfunction in patients with atrial tachyarrhythmia. Methods: This retrospective study was conducted in a large tertiary care centre and compared patients who experienced deterioration of LV ejection fraction (EF) during paroxysmal AF, demonstrated by precardioversion transoesophageal echocardiography with patients with preserved LV function during AF. All patients had documented preserved LVEF at baseline (EF >50%) while in sinus rhythm. Results: Of 482 patients included in the final analysis, 80 (17%) had reduced and 402 (83%) had preserved LV function during the precardioversion transoesophageal echocardiography. Patients with reduced LVEF were more likely to be men and to have a more rapid ventricular response during AF or atrial flutter (AFL). A history of prosthetic valves was also identified as a risk factor for reduced LVEF. Patients with reduced LVEF also had higher incidence of tricuspid regurgitation and right ventricular dysfunction. Conclusion: In ‘real-world’ experience, male patients with rapid ventricular response during paroxysmal AF or AFL are more prone to LVEF reduction. Patients with prosthetic valves are also at risk for LVEF reduction during AF/AFL. Finally, tricuspid regurgitation and right ventricular dysfunction may indicate relatively long-standing AF with an associated reduction in LVEF.

Acute myocarditis presenting as accelerated junctional rhythm in Graves’ disease: A case report

BACKGROUND

Acute myocarditis is an acute myocardium injury that manifests as arrhythmia, dyspnea, and elevated cardiac enzymes. Acute myocarditis is usually caused by a viral infection but can sometimes be caused by autoimmunity. Graves’ disease is an autoimmune disease that is a rare etiology of acute myocarditis. Accelerated junctional rhythm is also a rare manifestation of acute myocarditis in adults.

CASE SUMMARY

A rare case of new-onset Graves’ disease combined with acute myocarditis and thyrotoxic periodic paralysis is reported. The patient was a 25-year-old young man who suddenly became paralyzed and felt palpitations and dyspnea. He was then sent to our emergency department (ED). Upon arrival, electrocardiography revealed an accelerated junctional rhythm and ST-segment depression in all leads, and laboratory findings showed extreme hypokalemia and elevated troponin I, with the troponin I level being 0.32 ng/mL (reference range, 0-0.06 ng/mL). Coronary computer tomography angiography was performed, and there were no abnormal findings in the coronary arteries. Subsequently, the patient was admitted to the ED ward, where further testing revealed Graves’ disease, along with continued elevated cardiac enzyme levels and B-type natriuretic peptide (BNP) levels. The troponin I level was 0.24 ng/mL after admission. All of the echocardiography results were normal: Left atrium 35 mm, left ventricle 48 mm, end-diastolic volume 102 mL, right atrium 39 mm × 47 mm, right ventricle 25 mm, and ejection fraction 60%. Cardiac magnetic resonance was performed on the fifth day of admission, revealing myocardial edema in the lateral wall and intramyocardial and subepicardial late gadolinium enhancement in the lateral apex, anterior lateral, and inferior lateral segments of the ventricle. The patient refused to undergo an endomyocardial biopsy. After 6 d, the patient’s cardiac enzymes, BNP, potassium, and electrocardiography returned to normal. After the patient’s symptoms were relieved, he was discharged from the hospital. During a 6-mo follow-up, the patient was asymptomatic and subjected to thyroid function, liver function, kidney function, troponin I, and electrocardiograph routine tests for medicine adjustments. The hyperthyroid state was controlled.

CONCLUSION

Acute myocarditis is a rare manifestation of Graves’ disease. Accelerated junctional rhythm is also a rare manifestation of acute myocarditis in adults. When the reason for hypokalemia and elevated cardiac enzymes in patients is unknown, cardiologists should consider Graves’ disease and also pay attention to accelerated junctional rhythm.

Cardiovascular magnetic resonance-based predictors of complete left ventricular systolic functional recovery after rhythm restoration in patients with atrial tachyarrhythmia

AIMS

To establish a cardiovascular magnetic resonance (CMR)-based prediction model for complete systolic left ventricular ejection fraction (LVEF) recovery for the distinction of 'arrhythmia-induced' from 'arrhythmia-mediated' cardiomyopathy in patients with atrial tachyarrhythmias.

METHODS AND RESULTS

Two hundred and fifty-three tachyarrhythmia patients referred for catheter ablation were enrolled and underwent CMR baseline imaging; patients with a reduced LVEF <50% at baseline and CMR imaging at 3-month follow-up after successful rhythm restoration constituted the final study population (n = 134). CMR at baseline consisted of standard functional cine imaging, determination of extracellular volume, and late gadolinium enhancement (LGE) imaging; follow-up CMR comprised standard functional cine imaging. Left ventricular end-diastolic volume index (LVEDVI) measurements were categorized in 'opposite', 'normal', and 'enlarged'. At follow-up, 80% (107/134) presented with complete LVEF recovery, while in 20% (27/134) persistent LVEF impairment was observed. LVEDVI and LGE were independent predictors of complete LVEF recovery with LGE adding significant incremental value on logistic regression modelling. Model-derived probabilities for complete LVEF recovery in LVEDVI categories of opposite, normal, and enlarged for LGE negativity and positivity were 94%, 85%, and 29% and 77%, 55%, and 8%, respectively.

CONCLUSION

CMR-derived assessment of LVEDVI category and LGE allowed for identification of arrhythmia-induced cardiomyopathy with acceptable discriminative performance. Probabilities for complete LVEF recovery for the combination of opposite LVEDVI/LGE negativity and enlarged LVEDVI/LGE positivity were 94% and 8%, respectively. The CMR-based prediction model of complete LVEF recovery can be used to perform upfront stratification in atrial tachyarrhythmia-related LVEF impairment.

Tachycardiomyopathy managed by successful ablation of right ventricular outflow tract premature ventricular complexes

Tachycardiomyopathy is a common reversible cause of left ventricular dysfunction. Prompt diagnosis and treatment of this condition is essential to ensure a good prognosis for the patient. We report a case of tachycardiomyopathy due to frequent premature ventricular complexes arising from the right ventricular outflow tract midseptum managed with successful ablation.

[Incessant focal atrial tachycardia as a cause of cardiomyopathy. About a case]

Focal atrial tachycardia is a rare type of supraventricular tachyarrhythmia, generally present in young people, and is a rare cause of tachycardiomyopathy (10%). We present a clinical case of tachycardiomyopathy in a 30-year-old man, without comorbidities, who was diagnosed with incessant focal atrial tachycardia, refractory to medical therapy, and electrical cardioversion. Successful endocardial ablation was performed, and in outpatient follow-up at 6 months, he showed a recovery of the left ventricular ejection fraction and reduction of the left chambers to normal ranges, with progressive decrease of dyspnea.

Characteristics of Blood Metabolic Profile in Coronary Heart Disease, Dilated Cardiomyopathy and Valvular Heart Disease Induced Heart Failure

Purpose: Metabolic impairment is one key contributor to heart failure (HF) pathogenesis and progression. The major causes of HF, coronary heart disease (CHD), dilated cardiomyopathy (DCM), and valvular heart disease (VHD) remains poorly characterized in patients with HF from the view of metabolic profile. We sought to determine metabolic differences in CHD-, VHD-, and DCM-induced HF patients and identify significantly altered metabolites and their correlations.

Procedure: In this study, a total of 96 HF cases and 97 controls were enrolled. The contents of 23 amino acids and 26 carnitines in fasting plasma were measured by a targeted liquid chromatography and mass spectrometry (LC-MS) approach.

Results: Nine metabolites (Histidine, Arginine, Citrulline, Glutamine, Valine, hydroxyhexadecenyl-carnitine, acylcarnitine C22, hydroxytetradecanoyl-carnitine, and carnitine) were found to be related with the occurrence of HF. Arginine, Glutamine and hydroxytetradecanoyl-carnitine could effectively distinguish CHD and DCM patients, and hydroxytetradecanoyl-carnitine and aspartic acid were able to classify CHD and VHD cohorts.

Conclusion: This study indicated that circulating amino acids and long-chain acylcarnitine levels were closely associated with progression of heart failure. Monitoring these metabolic alterations by LC-MS may help the differentiation of CHD, VHD, and DCM in the early stage, and provide new diagnostics targets or therapeutic interventions.

Incessant Focal Atrial Tachycardia Leading to Tachycardiomyopathy

A 22-year-old man presented with severe left ventricular (LV) dysfunction and progressive heart failure. The 12-lead electrocardiogram showed short runs of supraventricular tachycardia suggestive of focal atrial tachycardia. The patient underwent successful radiofrequency ablation. There was a complete recovery of symptoms and LV function at six months of follow-up. We discuss the importance of identifying tachycardiomyopathy as a reversible cause of heart failure.

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.

Impact of the Temporal Relationship Between Atrial Fibrillation and Heart Failure on Prognosis After Ablation

BACKGROUND

The purpose of this study was to elucidate the effect of the temporal relationship between atrial fibrillation (AF) and heart failure (HF) on clinical outcomes after catheter ablation.Methods and Results:We included 129 consecutive patients with AF and HF who underwent catheter ablation in hospital from December 2014 to September 2017. The patients were divided into 2 groups based on the temporal relationship between AF and HF. Group 1 consisted of 42 patients with AF following HF while Group 2 consisted of 87 patients with AF preceding HF or those who developed both of them simultaneously at the timing of first visit to a doctor. The primary endpoint was a composite of death and hospitalization due to HF during a 2-year follow-up. AF recurrence was more common in Group 1 (45% vs. 23%; hazard ratio [HR], 2.49; 95% confidence interval [CI], 1.25-4.94; P=0.009). Death and HF hospitalization were more frequent in Group 1 (19 [45%], 6 [7%] patients, respectively, P<0.0001). After adjustment for several covariates, patients in Group 1 were independently associated with poorer outcomes after AF ablation (HR, 8.66; 95% CI, 2.942-5.5; P<0.0001).

CONCLUSIONS

Adverse clinical outcomes of death, HF hospitalization and AF recurrence were more frequent in patients with AF following HF than in those with AF preceding HF.

High-risk catheter ablation of refractory atrial fibrillation using Impella CP in a patient with cardiogenic shock

BACKGROUND

Impella CP support during Posterior Vein Isolation/Posterior Wall Isolation (PVI/PWI) in the setting of persistent cardiogenic shock from refractory atrial fibrillation with rapid ventricular response (AF/RVR), has not been reported in the literature to the best of our knowledge.

CASE

A 61-year-old male truck driver was admitted with acute HFrEF with AF/RVR 130 - 150. His EF was 20% with global hypokinesis. He was diuresed and cardioverted to sinus rhythm and had QTc of 532. He reverted to AF/RVR in less than 24 hours, requiring amiodarone drip. Shortly, amiodarone was discontinued because of intense anorexia, nausea, and vomiting. Class III and Class 1c agents were contraindicated due to prolonged QTc and cardiomyopathy. He developed cardiogenic shock, worsening cardiorenal syndrome, and shock liver requiring continuous renal replacement therapy (CRRT). Inotropes and vasopressors were contraindicated. AVN ablation was refused because he wanted to return to truck driving. EF dropped to 10%, and moderate RV dysfunction ensued. Right heart catheterization showed PASP 53, PADP 38, and PCWP 37 with RAP 28mmHg. Coronary angiogram was normal. An Impella device was inserted, and support was set to P6 with 3.4 L/min cardiac output. PVI with cryoablation, PWI, and anterior mitral isthmus ablation was successful. The adequacy of isolation was verified by demonstrating a complete exit block 30 mins after ablation. Normal sinus rhythm was restored after cardioversion. Echo 48 hours later revealed improvement in EF from 10% to 40% in sinus rhythm. Impella and CRRT were weaned. He was discharged on GDMT.

CONCLUSION

There are no recommendations regarding PVI for AF/RVR on mechanical circulatory support (MCS). MCS assisted PVI/PWI may be the only resort to restore hemodynamic stability in cases where a pacemaker is not desirable. PVI/PWI is a lengthy procedure; the use of the Impella support for PVI/PWI in cardiogenic shock allows adequate time for exit block testing and PWI. The operator can do thorough mapping and ablation, knowing that the patient is receiving adjustable support based on hemodynamic demands. We had a good outcome; nevertheless, the potential pitfalls are unknown.

Antithrombotic Treatment after Atrial Fibrillation Ablation

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Atrial fibrillation is a major cause of debilitating strokes and anticoagulation is an established and indispensable therapy for reducing their rate. Ablation of the arrhythmia has emerged as a putative means of disrupting its natural course by isolating its triggers and modifying its substrate, dependent on the chosen method. An important dilemma lies in the need for continuation of anticoagulation therapy in those previously receiving it following an, apparently, successful intervention, purportedly preventing arrhythmia recurrence with considerably high rates. Current guidance, given scarcity of high-quality data from randomized trials, focuses on established knowledge and recommends anticoagulation continuation based solely on estimated thromboembolic risk. In the present review, it will be attempted to summarize the pathophysiological rationale for maintaining anticoagulation post-successful ablation, along with the latter’s definition, including the two-fold effects of the procedure per se on thrombogenicity. Available evidence pointing to an overall clinical benefit of anticoagulation withdrawal following careful patient assessment will be discussed, including ongoing randomized trials aiming to offer definitive answers. Finally, the proposed mode of post-ablation anticoagulation will be presented, including the emerging, guideline-endorsed, role of direct oral anticoagulants in the field, altering cost/benefit ratio of anticoagulation and potentially affecting the very decision regarding its discontinuation.

Genetic Factors Involved in Cardiomyopathies and in Cancer

Cancer therapy-induced cardiomyopathy (CCM) manifests as left ventricular (LV) dysfunction and heart failure (HF). It is associated withparticular pharmacological agents and it is typically dose dependent, but significant individual variability has been observed. History of prior cardiac disease, abuse of toxics, cardiac overload conditions, age, and genetic predisposing factors modulate the degree of the cardiac reserve and the response to the injury. Genetic/familial cardiomyopathies (CMY) are increasingly recognized in general populations with an estimated prevalence of 1:250. Association between cardiac and oncologic diseases regarding genetics involves not only the toxicity process, but pathogenicity. Genetic variants in germinal cells that cause CMY (LMNA, RAS/MAPK) can increase susceptibility for certain types of cancer. The study of mutations found in cancer cells (somatic) has revealed the implication of genes commonly associated with the development of CMY. In particular, desmosomal mutations have been related to increased undifferentiation and invasiveness of cancer. In this article, the authors review the knowledge on the relevance of environmental and genetic background in CCM and give insights into the shared genetic role in the pathogenicity of the cancer process and development of CMY.

Outcomes in patients with dual antegrade conduction in the atrioventricular node: insights from a multicentre observational study

BACKGROUND

Supraventricular tachycardias induced by dual antegrade conduction via the atrioventricular (AV) node are rare but often misdiagnosed with severe consequences for the affected patients. As long-term follow-up in these patients was not available so far, this study investigates outcomes in patients with dual antegrade conduction in the AV node.

METHODS AND RESULTS

In this multicentre observational study, patients from six European centres were studied. Catheter ablation was performed in 17 patients (52 ± 16 years) with dual antegrade conduction via both AV nodal pathways between 2012 and 2018. Patients with the final diagnosis of a manifest dual AV nodal non-re-entrant tachycardia had a mean delay of the correct diagnosis of over 1 year (range 2-31 months). Two patients received prescription of non-indicated oral anticoagulation, two further patients suffered from inappropriate shocks of an implantable cardioverter defibrillator. In 12 patients, a co-existence of dual antegrade and re-entry conduction in the AV node was present. Mean fast pathway conduction time was 138 ± 61 ms and mean slow pathway conduction time was 593 ± 134 ms. Successful radiofrequency catheter ablation was performed in all patients. Post-procedurally oral anticoagulation was discontinued, without detection of cerebrovascular events or atrial fibrillation during a long-term follow-up of median 17 months (range 6-72 months).

CONCLUSION

This first multicentre study investigating patients with supraventricular tachycardia and dual antegrade conduction in the AV node demonstrates that catheter ablation is safe and effective while long-term patient outcome is good. Autonomic tone dependent changes in ante- vs. retrograde conduction via slow and/or fast pathway can challenge the diagnosis and therapy in some patients.

Ectopic Atrial Tachycardia in a 12-Month-Old Girl Treated With Ivabradine and Beta-Blocker, a Case Report

We report on a 12-month-old girl with an ectopic atrial tachycardia successfully treated with the combination of a beta blocking agent and Ivabradine that acts on cardiac pacemaker cells by selectively inhibiting the I_f channel. Standard therapy had failed to control the tachycardia before. No side effects attributable to Ivabradine were noticed. Due to its mechanism of action Ivabradine is a promising novel agent for the therapy of tachycardia due to increased automaticity. Reports on the use of Ivabradine in young children or infants are rare, but show promising results for congenital junctional ectopic tachycardia. This report adds the second case of ectopic atrial tachycardia in this age group and novel treatment with Ivabradine to the literature.

Influence of heart rate control on exercise capacity and quality of life in patients with permanent atrial fibrillation

BACKGROUND

The optimal level of heart rate (HR) control in patients with atrial fibrillation (AF) is unknown. To assess the effect of rate control on cardiopulmonary exercise capacity and quality of life (QoL) in permanent AF.

METHODS

One hundred forty-three patients with permanent AF were enrolled in this study. All patients received rate control medications and were followed up for 1 year. After 1-year therapy, the exercise capacity and QoL were evaluated by cardiopulmonary exercise testing (CPET) and 36-item Short-Form Health Survey, respectively. Data were compared by dividing the patients according to the following criteria: (1) whether the resting HR was ≤80 or > 80 bpm; (2) whether the exercise HR during moderate exercises on CPET was ≤110 or > 110 bpm; and (3) whether the resting HR was ≤80 bpm and exercise HR was ≤110 bpm.

RESULTS

No significant differences in peak oxygen uptake, peak metabolic equivalent, and anaerobic threshold were found between the strict control and lenient control groups. Both physical component summary (PCS) and mental component summary (MCS) were significantly higher for the strict rate control group than for the lenient control group. The single-factor correlation analysis revealed a negative correlation between resting HR and both PCS and MCS. The multivariable linear regression analysis indicated that both exercise HR and duration of AF linearly correlated with PCS and MCS.

CONCLUSIONS

Therefore, in patients with permanent AF, exercise capacity may not be affected by the stringency of rate control, and strict rate control may be associated with better QoL.

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.

Tachycardia-induced cardiomyopathy in a patient with left-sided accessory pathway and left bundle branch block: A case report

RATIONALE

Tachycardia-induced cardiomyopathy (TIC) is defined as systolic and/or diastolic dysfunction of the left ventricle resulting from prolonged elevated heart rates, completely reversible upon control of the arrhythmia. Atrioventricular reentrant tachycardia (AVRT) is one of the most frequent causes of TIC. In its incessant form, it is unlikely to be controlled by pharmacological treatment, catheter ablation being the principal therapeutic option. The coexistence of left bundle branch block (LBBB) in patients with AVRT may cause difficulties in the early diagnosis and management of tachycardia because of the wide complex morphology, making it harder to localize the accessory pathway (AP).

PATIENT CONCERNS

A 60-year-old woman, presented incessant episodes of palpitations and shortness of breath due to a LBBB tachycardia leading to hemodynamic instability.

DIAGNOSIS

The patient had a wide QRS tachycardia, with LBBB morphology and a heart rate of 160/minute. Echocardiography showed global hypokinesia with 25% left ventricular ejection fraction (LVEF). Considering the patient's clinical picture, TIC was suspected.

INTERVENTIONS

The electrophysiological study revealed a left lateral accessory pathway. Catheter ablation was successfully performed at the level of the lateral mitral ring.

OUTCOMES

One week after the ablation the patient had no signs of heart failure and the LVEF normalized to 55%. During 6-months follow-up the patient presented no more episodes of tachycardia or heart failure and the LVEF remained normal.

LESSONS

AVRT is rarely associated with intrinsic LBBB, being a potential cause of TIC. In these patients, it is unlikely to control the arrhythmia pharmacologically, catheter ablation being the best therapeutic option. The variation of QRS complex duration between LBBB pattern in SR and AVRT could be useful for early diagnosis of an ipsilateral AP on surface ECG.

Thyrotoxicosis-induced cardiomyopathy treated with venoarterial extracorporeal membrane oxygenation

A 37-year-old woman with no past medical history presented with longstanding untreated hyperthyroidism and consequentially developed thyrotoxicosis-induced cardiomyopathy. Upon admission, she was noted with a heart rate of 172 beats per minute and an EKG consistent with supraventricular tachycardia which was unresponsive to adenosine. Shortly after the initiation of a non-cardioselective beta-blocker for the treatment of persistent tachycardia, she developed profound cardiogenic shock refractory to vasopressors and inotropes. She was diagnosed with thyroid storm, which was ultimately attributed to Graves' Disease and controlled with propylthiouracil, potassium iodide drops, and hydrocortisone. Extracorporeal membrane oxygenation (ECMO) was successfully used as a temporizing measure while her thyroid hormone level normalized and cardiac function recovered. Patients with longstanding untreated hyperthyroidism may be dependent on the induced hyperadrenergic state to compensate for low-output cardiac failure, therefore it is important to exercise caution when initiating beta-adrenergic blockade. Given the expected disease time-course in cases of acute decompensation, ECMO remains a viable option for short-term mechanical circulatory support.

Left Atrial Function Is Improved in Short-Term Follow-Up after Catheter Ablation of Outflow Tract Premature Ventricular Complexes

Background: Association of premature ventricular complexes (PVC) with left ventricular systolic dysfunction (LVSD) and efficacy of catheter ablation treatment have been demonstrated in studies. The role of left atrial (LA) mechanics in the etiopathogenesis of PVC-induced cardiomyopathy (PVC-CMP) as well as changes in LA mechanics with catheter ablation have not been studied before. Methods: A total number of 61 patients (Mean Age 43 ± 3) with idiopathic outflow tract (OT) PVCs undergoing radiofrequency catheter ablation (RFCA) were enrolled. ECG, 24 h Holter, and echocardiographic evaluation with left ventricular (LV) diastolic functions and LA volumetric assessments were performed before and three months after RFCA. Results: Along with a marginal increase in left ventricle ejection fraction (LVEF), improvement in diastolic functions and left atrial mechanics were observed in the study (LVEF 53 ± 7 versus 57 ± 6, p < 0.01) in short-term follow-up. The frequency of LV diastolic dysfunction (LVDD) decreased with catheter ablation (n = 5 to 0, p = 0.02). The overall LA function improved. Left atrium passive and overall emptying fraction (LAEF) increased significantly (0.32 ± 0.04 to 0.41 ± 0.04, p < 0.05 and 0.62 ± 0.04 to 0.65 ± 0.004, p < 0.05, respectively). Active LAEF decreased significantly (0.29 ± 0.005 to 0.24 ± 0.006, p < 0.05). Conclusions: The results of this study are indicative of “PVC-induced atriomyopathy” which responds to RFCA in short-term follow-up. Atrial dysfunction might play a role in symptoms and etiopathogenesis of LVSD.

Delayed efficacy of radiofrequency catheter ablation on arrhythmias originating in the interventricular basal septum

Delayed efficacy of radiofrequency energy can suppress ventricular arrhythmias after a failed ablation procedure. The implant of cardiac defibrillator for arrhythmia-induced cardiomyopathy should be procrastinated after a period of follow-up. Waiting for delayed efficacy is a reasonable choice to reduce the risk of complications associated with aggressive ablative approaches.