[High risk syncope in a young patient: An uncommon cause]. / Sincope de alto riesgo en paciente joven: Una causa poco frecuente.

Syncope is a frequent consult. It's responsible for 1 to 3% of consults to the emergency room in the United States. The cause is generally benign; however, high-risk cases are potentially deadly and must be identified. We present a case report of a 40-year-old female who presents with syncope, Torsade de Pointes, and ventricular fibrillation. The coronary angiography showed no disease of the coronary arteries. The ventriculography, transthoracic echocardiogram, and cardiac magnetic resonance revealed a mid-ventricular Takotsubo cardiomyopathy. The ECG showed a prolonged QT interval with an inverted T wave. During the first 48 hours, she presented multiple episodes of non-sustained polymorphic ventricular tachycardia. The patient evolved with diminished QTc interval and regression of the wall motion abnormalities. At the 6-month follow-up the patient was asymptomatic, without new episodes.

The triglyceride-glucose index, ventricular arrhythmias and major cardiovascular events in patients at high risk of sudden cardiac death.

BACKGROUND: The association between the triglyceride-glucose (TyG) index and ventricular arrhythmias (VAs) is unclear. This study aimed to investigate the relationship between the TyG index, VAs, and major cardiovascular events in patients at high risk of sudden cardiac death (SCD). METHODS: We enrolled 1046 patients at high risk of SCD with an indication for implantable cardioverter-defibrillator (ICD) implantation at the Chinese National Center for Cardiovascular Diseases. The primary outcome was VAs, defined as sustained ventricular tachycardia and ventricular fibrillation documented by the ICD. The secondary outcomes were cardiac mortality, heart transplantation, and rehospitalization for heart failure. RESULTS: The mean (± SD) age was 59.6 ± 14.0 years old, and 25.7% were female. During the mean follow-up of 36.1 months, 342 (32.7%) patients had VAs, and 185 (17.7%) patients had major cardiovascular events. The mean fasting glucose and triglyceride levels were 111.9 ± 42.7 mg/dL and 140.0 ± 95.4 mg/L, respectively, with a TyG index range of 6.96-11.8. In the Fine-Gray subdistribution hazard model analysis, an increase in the TyG index was associated with a significant increase in the VAs (per 1 TyG index, hazard ratio [HR] 2.95; 95% confidence interval [CI], 2.29-3.80) and secondary outcome (HR 2.84; 95% CI 1.86-4.34). When stratified into tertiles, the risk of VAs was significantly higher in the highest tertile (HR 4.08; 95% CI, 2.81-5.92) than in the lowest tertile. Analysis of the secondary outcome revealed similar findings (HR 3.18; 95% CI, 1.73-5.85). CONCLUSIONS: In our cohort, the pre-operational TyG index is significantly associated with VAs and major cardiovascular events for patients with high risk of SCD.

Exploring the relationship between ventricular fibrillation recurrence after defibrillation in myocardial infarction and the effectiveness of renal sympathetic denervation therapy.

OBJECTIVE: This study aimed to explore the association between electrophysiological markers of early recurrence after defibrillation in post-myocardial infarction ventricular fibrillation and the therapeutic effects of sympathetic renal denervation, as well as to investigate the potential underlying mechanisms. METHODS: Experimental research was conducted using an animal model. Myocardial infarction was induced, followed by defibrillation treatment for ventricular fibrillation cases, and the electrophysiological markers of early recurrence were recorded. Subsequently, a subset of animals underwent sympathetic renal denervation intervention, and the therapeutic effects were compared between the sympathetic renal denervation group and the control group. Electrocardiogram monitoring, histological analysis of myocardial tissue, and neurotransmitter measurements were also performed. RESULTS: Following defibrillation treatment, early recurrence was observed in ventricular fibrillation cases. The electrophysiological markers revealed significantly higher ST segment elevation and T wave changes in the early recurrence group. However, in the sympathetic renal denervation intervention group, the early recurrence rate was significantly reduced, and the electrocardiogram showed improved stability and regularity. Additionally, histological analysis of myocardial tissue demonstrated less cellular damage and lower levels of myocardial fibrosis in the sympathetic renal denervation group. Neurotransmitter measurements revealed a significant decrease in sympathetic nerve activity in the sympathetic renal denervation intervention group. CONCLUSION: The results of this study indicate an association between electrophysiological markers of early recurrence after defibrillation in post-myocardial infarction ventricular fibrillation and the therapeutic effects of sympathetic renal denervation. Sympathetic renal denervation intervention can significantly reduce the early recurrence rate, improve electrocardiogram characteristics, and alleviate myocardial damage and fibrosis. Furthermore, the reduction in sympathetic nerve activity may be one of the potential underlying mechanisms of sympathetic renal denervation intervention.

Induction of ventricular fibrillation during programmed ventricular stimulation in a patient with CASQ2 heterozygous mutation.

INTRODUCTION: We report the case of a 37-year-old male athlete, who developed during exercise atrial and ventricular arrhythmias. No structural heart disease. RESULTS: Invasive programmed ventricular stimulation induced ventricular fibrillation. A heterozygous mutation in the CASQ2 gene (c.775G>T, p.E259X) was found. CONCLUSIONS: The findings in our patient may suggest some increased ventricular excitability using programmed ventricular stimulation in CASQ2 polymorphic ventricular tachycardia patients.

Substrate Characterization and Outcomes of Ventricular Tachycardia Ablation in Amyloid Cardiomyopathy: A Multicenter Study.

BACKGROUND: Sustained ventricular tachycardia (VT) in cardiac amyloidosis is uncommon, and the substrate and outcomes of catheter ablation are not defined. METHODS: We included 22 consecutive patients (mean age, 68±10 years; male sex, 91%) with cardiac amyloidosis (ATTR [transthyretin], n=16; light chain, n=6) undergoing catheter ablation for VT/ventricular fibrillation (VF) between 2013 and 2023 in a retrospective, observational, international study. The primary efficacy outcome was recurrent VT/VF during follow-up, while the primary safety end point included major procedure-related adverse events. RESULTS: The indication for ablation was drug-refractory VT in 17 patients (77%), and premature ventricular complex-initiated polymorphic VT/VF in 5 patients (23%). Catheter ablation was performed using endocardial (n=17.77%) or endo-epicardial approaches (n=5.23%). Complete endocardial electroanatomical voltage maps of the left and right ventricles were obtained in 17 (77%) and 10 (45%) patients, respectively. Each patient had evidence of low-voltage areas, most commonly involving the interventricular septum (n=16); late potentials were recorded in 16 patients (73%). A median of 1 (1-2) VT was inducible per patient; 12 of the 26 mappable VTs (46%) originated from the interventricular septum. Complete procedural success was achieved in 16 patients (73%), with 4 (18%) major procedure-related adverse events. After a median follow-up of 32 (14-42) months, sustained VT/VF recurrence was observed in 9 patients (41%); survival free from VT/VF recurrence was 56% (95% CI, 36%-86%) at 36-month follow-up, and most patients remained on antiarrhythmic drugs. A significant reduction in per patient implantable cardioverter defibrillator therapies was noted in the 6-month period after ablation (before: 6 [4-9] versus after: 0 [0-0]; P<0.001). In multivariable analysis, complete procedural success was associated with reduced risk of recurrent VT/VF (hazard ratio, 0.002; P=0.034). CONCLUSIONS: Catheter ablation can achieve control of recurrent VT/VF in more than half of patients with cardiac amyloidosis, and the reduction in VT/VF burden post-ablation may be relevant for quality of life. Septal substrate and risk of procedure-related complications challenge successful management of patients with cardiac amyloidosis and VT/VF.

[Characteristics of electrocardiogram in fulminant myocarditis].

Objective: To investugate the unique electrocardiogram (ECG) characteristics of fulminant myocarditis (FM) patients and provide important clues for the diagnosis of FM. Methods: This was a retrospective study. Patients diagnosed with acute myocarditis at Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology from February 2017 to April 2022 were enrolled and divided into fulminant myocarditis group (FM) and non-fulminant myocarditis group (NFM) according to clinical diagnosis. A total of 246 healthy people who underwent physical examination in the Health examination Center of Tongji Hospital at the same period were selected as the control group. The clinical data and ECG characteristics of the above 3 groups were analyzed and compared. Logistic regression model was used to analyze the influence of ECG parameters on left ventricular ejection fraction in FM patients. Receiver operating curves were constructed to evaluate the predictive value of different ECG parameters for FM. Results: A total of 180 patients were included in this study (FM group: n=123; NFM group: n=57), with an age of (35.0±16.2) years and 106 males (58.89%). Compared with NFM group, ECG was significantly abnormal in FM group, with a higher incidence of sinus tachycardia, ventricular tachycardia or ventricular fibrillation, escape rhythm, right bundle branch block, third degree atrioventricular block, ST-segment elevation, low voltage, prolonged QTc interval, and widened QRS wave in the FM group (all P<0.05). The ECG parameters showed that the amplitude of the full lead QRS wave in FM group was lower than that in NFM group (P<0.01). The average heart rate and QTc interval of FM group were significantly higher than those of NFM and control groups (all P<0.05). Although ST-segment elevation had a higher incidence in the FM group, ECG parameters showed that except for leads Ⅲ and aVF, the ST segment levels in all leads in the FM group were lower than those in the control group (all P<0.05). There was a statistically significant difference in some ST segment changes between FM and NFM groups, while there was no statistical difference between the NFM and control groups. Multivariate regression analysis showed that widened QRS wave and increased heart rate were the influencing factors for left ventricular systolic dysfunction in FM patients (OR=16.914, 95%CI: 1.367-209.224, P=0.028; OR=1.026, 95%CI: 1.010-1.042, P=0.001). Receiver operating curve analysis showed that heart rate>86.90 beat/min, QTc>431.50 ms, and RV5+SV1<1.72 mV had certain predictive value for FM diagnosis. Conclusions: FM patients displayed marked and severe ECG abnormalities, and characteristic changes in ECG can provide important first clues for the diagnosis of FM.

First human safety and effectiveness study of defibrillation with a novel patch wearable cardioverter-defibrillator.

AIMS: Wearable cardioverter-defibrillators (WCDs) are indicated in patients at risk of sudden cardiac arrest who are not immediate candidates for implantable defibrillator therapy. Limitations of existing WCDs include poor compliance and high false alarm rates. The Jewel is a novel patch-WCD (P-WCD) that addresses these limitations with an adhesive-based design for near-continuous wear and a machine learning algorithm designed to minimize inappropriate detections. This was a first-in-human study of the Jewel P-WCD conducted in an electrophysiology (EP) lab to determine the safety and effectiveness of the device in terminating ventricular tachycardia/ventricular fibrillation (VT/VF) with a single shock. The aim was to evaluate the safety and effectiveness of terminating VT/VF with a single shock using the Jewel P-WCD. METHODS AND RESULTS: This was a first-in-human, prospective, single-arm, single-centre study in patients scheduled for an EP procedure in which VT/VF was expected to either spontaneously occur or be induced. The Jewel P-WCD was placed on consented patients; upon confirmation of VT/VF, a single shock (150 J) was delivered via the device. A group sequential design and Pocock alpha spending function was used to measure the observed proportion of successful VT/VF single-shock terminations. The endpoint was achieved if the lower confidence limit exceeded the performance goal of 62%, using a one-sided lower 97.4% exact confidence bound. Of 18 eligible subjects, 16 (88.9%, 97.4% confidence bound: 65.4%) were successfully defibrillated with a single shock, exceeding the primary endpoint performance goal with no adverse events. CONCLUSION: This first-in-human evaluation of the Jewel P-WCD demonstrated the safety and effectiveness of terminating VT/VF. CLINICAL TRIAL REGISTRATION: URL: https://clinicaltrials.gov/; Unique identifier: NCT05490459.

Observable Atrial and Ventricular Fibrillation Episode Durations Are Conformant With a Power Law Based on System Size and Spatial Synchronization.

BACKGROUND: Atrial fibrillation (AF) and ventricular fibrillation (VF) episodes exhibit varying durations, with some spontaneously ending quickly while others persist. A quantitative framework to explain episode durations remains elusive. We hypothesized that observable self-terminating AF and VF episode lengths, whereby durations are known, would conform with a power law based on the ratio of system size and correlation length ([Formula: see text]. METHODS: Using data from computer simulations (2-dimensional sheet and 3-dimensional left-atrial), human ischemic VF recordings (256-electrode sock, n=12 patients), and human AF recordings (64-electrode basket-catheter, n=9 patients; 16-electrode high definition-grid catheter, n=42 patients), conformance with a power law was assessed using the Akaike information criterion, Bayesian information criterion, coefficient of determination (R2, significance=P<0.05) and maximum likelihood estimation. We analyzed fibrillatory episode durations and [Formula: see text], computed by taking the ratio between system size ([Formula: see text], chamber/simulation size) and correlation length (xi, estimated from pairwise correlation coefficients over electrode/node distance). RESULTS: In all computer models, the relationship between episode durations and [Formula: see text] was conformant with a power law (Aliev-Panfilov R2: 0.90, P<0.001; Courtemanche R2: 0.91, P<0.001; Luo-Rudy R2: 0.61, P<0.001). Observable clinical AF/VF durations were also conformant with a power law relationship (VF R2: 0.86, P<0.001; AF basket R2: 0.91, P<0.001; AF grid R2: 0.92, P<0.001). [Formula: see text] also differentiated between self-terminating and sustained episodes of AF and VF (P<0.001; all systems), as well as paroxysmal versus persistent AF (P<0.001). In comparison, other electrogram metrics showed no statistically significant differences (dominant frequency, Shannon Entropy, mean voltage, peak-peak voltage; P>0.05). CONCLUSIONS: Observable fibrillation episode durations are conformant with a power law based on system size and correlation length.

A case of early repolarization syndrome in which hyponatremia and coronary vasospasms induced ventricular fibrillation.

A 60-year-old man was referred to our hospital presenting with unconsciousness due to severe hyponatremia. The twelve­lead ECG on admission exhibited prominent J waves in the inferolateral leads. During the treatment for hyponatremia, ventricular fibrillation (VF) occurred and the electrogram (ECG) after the VF incident exhibited marked ST elevation in the inferolateral leads. An Ach provocation test induced vasospasms in the right and left coronary arteries and J wave augmentation, suggesting a high risk for vasospastic angina. Finally, a subcutaneous implantable cardioverter defibrillator was implanted in the patient. We hereby discuss the possible contribution of hyponatremia to VF episodes in early repolarization syndrome based on the present case.

The yield of a comprehensive investigation protocol for the diagnosis of true idiopathic ventricular fibrillation in a real-life clinical setting.

Traditionally, aborted cardiac arrest (ACA) due to documented ventricular fibrillation (VF) in the absence of structural heart disease has been termed idiopathic VF. By careful evaluation, a specific etiology can be found in a substantial proportion of patients. The aim of this survey was to assess the yield of an advanced diagnostic work-up to reveal a causative etiology in a real-life clinical setting. Patients from the University Hospital Brno's ACA database were analyzed (514 patients in total). Forty-six patients (31 males) fulfilled the inclusion criteria, which were: (1) absence of structural pathology on echocardiography; (2) absence of coronary artery disease; and (3) absence of reversible cause of ACA. The diagnostic work-up consisted in cardiac magnetic resonance imaging, stress testing, sodium channel blocker challenge, and genetic testing according to the availability of the method and patient compliance. A specific disease was found in 17 individuals (37.0%), although at least one diagnostic step was refused by 13 patients (28.3%). True idiopathic VF was confirmed in 7 patients (15.2%), for whom the entire diagnostic work-up did not reveal any specific pathology. Our real-life survey shows that, even with an incomplete diagnostic work-up (due to the unavailability of a particular method or variable patient compliance), a specific diagnosis can be identified in more than one third of the cases of "idiopathic" VF, which can thus enable targeted treatment and family screening.

Extravascular Implantable Cardioverter-Defibrillator Sensing and Detection in a Large Global Population.

BACKGROUND: The extravascular (EV) implantable cardioverter-defibrillator (ICD) includes features to address sensing and arrhythmia detection challenges presented by its substernal lead location. OBJECTIVES: In this study, the authors sought to evaluate sensing and detection performance in 299 patients discharged with an EV-ICD in the global pivotal study. METHODS: We reviewed and adjudicated all induced ventricular fibrillation (VF) episodes and spontaneous device-stored episodes that satisfied rate and duration criteria in a programmed ventricular tachycardia (VT)/VF therapy zone. RESULTS: At implantation, all EV-ICDs detected induced VF at the programmed sensitivity; 95.9% detected VF with a 3× safety margin. In follow-up, EV-ICDs detected all 59 VT/VF episodes that sustained until therapy. Of 1,034 non-VT/VF episodes, oversensing caused 87.9% and supraventricular tachycardia caused 12.1%. Therapy was withheld in 80.9%, aborted in 10.6%, and delivered in 8.5%. The most common causes of oversensing were myopotentials (61.2%) and P-wave oversensing (PWOS) (19.9%). Inappropriate shocks occurred in only 3.2% of myopotential episodes, but in 21.8% of PWOS episodes. Myopotential oversensing was more common with Ring-Can sensing (P < 0.0001) and correlated with low R-wave amplitude (P < 0.0001). PWOS occurred almost exclusively with Ring1-Ring2 sensing (P = 0.0001) and began with transient decrease in R-wave or increase in P-wave amplitude (P < 0.0001). In software emulation, a new PWOS discriminator significantly reduced total inappropriate detections. CONCLUSIONS: In a global population, EV-ICD detected induced and spontaneous VT/VF accurately. Although discriminators withheld detection from most non-VT/VF episodes, inappropriate shocks were common. The most common cause was PWOS, which may be reduced by optimizing sensing at implantation and incorporation of the PWOS discriminator, which is now in the current device. (Extravascular ICD Pivotal Study [EV ICD]; NCT04060680).

Risk stratification for the occurrence of ventricular fibrillation in patients with early repolarization syndrome.

BACKGROUND: Several signs of malignant early repolarizations have been proposed in patients with early repolarization syndrome (ERS). However, reports have challenged the efficacy of these signs in predicting future ventricular fibrillation (VF) in patients with ERS. OBJECTIVE: This study aimed to assess the predictive value of various electrocardiogram (ECG) markers for future VF events in patients with ERS. METHODS: We retrospectively evaluated the clinical characteristics of 44 patients with ERS to identify risk factors for VF during follow-up. RESULTS: After the initial event, 16 patients experienced VF (VF group), whereas 28 did not (non-VF group). The VF group had a longer QRS interval, more fragmented QRS (fQRS), and a higher T/R voltage ratio than the non-VF group. Wide J waves were more prevalent in the VF group; however, other J-wave markers did not differ between the groups. Positive late potentials recorded on signal-averaged ECGs were more frequent in the VF group. Whereas none of the patients showed spontaneous Brugada syndrome on ECG, the VF group frequently exhibited pilsicainide-induced ST-segment elevation. These ECG markers were significantly associated with the occurrence of VF during follow-up. Patients with multiple ECG factors, including QRS abnormalities (wide QRS or fQRS), wide J waves, and a high T/R ratio, had a worse prognosis than patients without multiple factors, effectively stratifying patient risk. CONCLUSION: The occurrence of VF in patients with ERS may be associated with conduction abnormalities such as QRS widening, fQRS, high T/R ratio, positive late potentials, and pilsicainide test results. Therefore, ECG factors could be useful in identifying high-risk patients.

Competing risks of monomorphic vs. non-monomorphic ventricular arrhythmias in primary prevention implantable cardioverter-defibrillator recipients: Global Electrical Heterogeneity and Clinical Outcomes (GEHCO) study.

AIMS: Ablation of monomorphic ventricular tachycardia (MMVT) has been shown to reduce shock frequency and improve survival. We aimed to compare cause-specific risk factors for MMVT and polymorphic ventricular tachycardia (PVT)/ventricular fibrillation (VF) and to develop predictive models. METHODS AND RESULTS: The multicentre retrospective cohort study included 2668 patients (age 63.1 ± 13.0 years; 23% female; 78% white; 43% non-ischaemic cardiomyopathy; left ventricular ejection fraction 28.2 ± 11.1%). Cox models were adjusted for demographic characteristics, heart failure severity and treatment, device programming, and electrocardiogram metrics. Global electrical heterogeneity was measured by spatial QRS-T angle (QRSTa), spatial ventricular gradient elevation (SVGel), azimuth, magnitude (SVGmag), and sum absolute QRST integral (SAIQRST). We compared the out-of-sample performance of the lasso and elastic net for Cox proportional hazards and the Fine-Gray competing risk model. During a median follow-up of 4 years, 359 patients experienced their first sustained MMVT with appropriate implantable cardioverter-defibrillator (ICD) therapy, and 129 patients had their first PVT/VF with appropriate ICD shock. The risk of MMVT was associated with wider QRSTa [hazard ratio (HR) 1.16; 95% confidence interval (CI) 1.01-1.34], larger SVGel (HR 1.17; 95% CI 1.05-1.30), and smaller SVGmag (HR 0.74; 95% CI 0.63-0.86) and SAIQRST (HR 0.84; 95% CI 0.71-0.99). The best-performing 3-year competing risk Fine-Gray model for MMVT [time-dependent area under the receiver operating characteristic curve (ROC(t)AUC) 0.728; 95% CI 0.668-0.788] identified high-risk (> 50%) patients with 75% sensitivity and 65% specificity, and PVT/VF prediction model had ROC(t)AUC 0.915 (95% CI 0.868-0.962), both satisfactory calibration. CONCLUSION: We developed and validated models to predict the competing risks of MMVT or PVT/VF that could inform procedural planning and future randomized controlled trials of prophylactic ventricular tachycardia ablation. CLINICAL TRIAL REGISTRATION: URL:www.clinicaltrials.gov Unique identifier:NCT03210883.

Machine learning for prediction of ventricular arrhythmia episodes from intracardiac electrograms of automatic implantable cardioverter-defibrillators.

BACKGROUND: Despite effectiveness of the implantable cardioverter-defibrillator (ICD) in saving patients with life-threatening ventricular arrhythmias (VAs), the temporal occurrence of VA after ICD implantation is unpredictable. OBJECTIVE: The study aimed to apply machine learning (ML) to intracardiac electrograms (IEGMs) recorded by ICDs as a unique biomarker for predicting impending VAs. METHODS: The study included 13,516 patients who received Biotronik ICDs and enrolled in the CERTITUDE registry between January 1, 2010, and December 31, 2020. Database extraction included IEGMs from standard quarterly transmissions and VA event episodes. The processed IEGM data were pulled from device transmissions stored in a centralized Home Monitoring Service Center and reformatted into an analyzable format. Long-range (baseline or first scheduled remote recording), mid-range (scheduled remote recording every 90 days), or short-range predictions (IEGM within 5 seconds before the VA onset) were used to determine whether ML-processed IEGMs predicted impending VA events. Convolutional neural network classifiers using ResNet architecture were employed. RESULTS: Of 13,516 patients (male, 72%; age, 67.5 ± 11.9 years), 301,647 IEGM recordings were collected; 27,845 episodes of sustained ventricular tachycardia or ventricular fibrillation were observed in 4467 patients (33.0%). Neural networks based on convolutional neural networks using ResNet-like architectures on far-field IEGMs yielded an area under the curve of 0.83 with a 95% confidence interval of 0.79-0.87 in the short term, whereas the long-range and mid-range analyses had minimal predictive value for VA events. CONCLUSION: In this study, applying ML to ICD-acquired IEGMs predicted impending ventricular tachycardia or ventricular fibrillation events seconds before they occurred, whereas midterm to long-term predictions were not successful. This could have important implications for future device therapies.

Life-saving fall detection by a smartwatch in a case of ventricular fibrillation.

New smart devices that have the potential to support the health and well-being of their owners have become available. In particular, smart watches are able to identify a fall by the person who is wearing the watch and report it to pre-defined contacts and the local emergency control center. Falls in older people are common and only rarely caused by malignant cardiac arrhythmia. The case of an elderly male whose smart watch automatically reported his fall due to ventricular fibrillation to the local emergency control center is described. Through the intervention of the wearer's device, the activated dispatcher called the patient's wife, who found her husband lying unresponsive on the floor. Emergency medical services responded immediately and were able to successfully resuscitate the patient. A hospital discharge without any long-term complications was achieved.

A case report of ventricular fibrillation following Shockwave intravascular lithotripsy during percutaneous coronary intervention.

BACKGROUND: Shockwave intravascular lithotripsy (S-IVL) is widely used during percutaneous coronary intervention (PCI) of calcified coronary arteries. Ventricular capture beats during S-IVL are common but arrhythmias are rare. CASE PRESENTATION: A 75-year-old woman was scheduled for PCI to a short, heavily calcified chronic total occlusion of the right coronary artery. After wiring of the occlusion, S-IVL was used to predilated the calcified stenosis. During S-IVL, the patient developed ventricular fibrillation twice. CONCLUSION: To our knowledge, this is only the second reported case of VF during S-IVL. Although very rare, it is important to be aware of this potential and serious complication.

Association of device detected atrial and ventricular tachyarrhythmia with adverse events in patients with an implantable cardioverter-defibrillator.

INTRODUCTION: Heart failure patients with a history of atrial fibrillation (AF) and ventricular tachycardia/ventricular fibrillation (VT/VF) are known to have worse outcomes. However, there are limited data on the temporal relationship between development of these arrhythmias and the risk of subsequent congestive heart failure (CHF) exacerbation and death. METHODS: The study cohort comprised 5511 patients implanted with an implantable cardioverter-defibrillator (ICD) in landmark clinical trials (MADIT-II, MADIT-RISK, MADIT-CRT, MADIT-RIT, and RAID) who were in sinus rhythm at enrollment. Multivariate cox analysis was performed to evaluate the time-dependent association between development of in-trial device detected AF and VT/VF with subsequent CHF exacerbation and death. RESULTS: Multivariate analysis showed that AF occurrence and VT/VF occurrence were both associated with a similar magnitude of risk for subsequent CHF exacerbation (HR = 1.73 and 1.87 respectively, p < .001 for both). In contrast, only in-trial VT/VF was associated with a significant > two-fold increase in the risk of subsequent mortality (HR = 2.13, p < .001) whereas AF occurrence was not associated with a significant mortality increase after adjustment for in-trial VT/VF (HR = 1.36, p = .096). CONCLUSION: Our findings from a large cohort of ICD recipients enrolled in landmark clinical trials show that device detected AF and VT/VF can be used to identify patients with increased risk for CHF exacerbation and mortality. These findings suggest a need for early intervention in CHF patients who develop device-detected atrial and ventricular tachyarrhythmias.

A Case of Ventricular Fibrillation in Masked Long-QT Syndrome Coexisting with Coronary Vasospasm.

Although long-QT syndrome (LQTS) with a normal range QT interval at rest leads to fatal ventricular arrhythmias, it is difficult to diagnose. In this article, we present a rare case of a patient who suffered a cardiac arrest and was recently diagnosed with LQTS and coronary vasospasm. A 62-year-old man with no syncopal episodes had a cardiopulmonary arrest while running. During coronary angiography, vasospasm was induced and we prescribed coronary vasodilators, including calcium channel blockers. An exercise stress test was performed to evaluate the effect of medications and accidentally unveiled exercise-induced QT prolongation. He was diagnosed with LQTS based on diagnostic criteria. Pharmacotherapy and an implantable cardioverter defibrillator were used for his medical management. It is extremely rare for LQTS and coronary vasospasm to coexist. In cases of exercise-induced arrhythmic events, the exercise stress test might be helpful to diagnose underlying disease.