Clinical Significance of Atrial Tachyarrhythmia Duration for Ventricular Arrhythmia in Patients With Cardiac Resynchronization Therapy

BACKGROUND

Atrial tachyarrhythmias (ATAs) are reportedly associated with ventricular arrhythmias (VAs). However, little is known about the association between ATA duration and the risk of VA. We investigated the relationship between ATA duration and subsequent VA in patients with a cardiac resynchronization therapy defibrillator (CRT-D).

METHODS AND RESULTS

We investigated associations between the longest ATA duration during the first year after cardiac resynchronization therapy (CRT) implantation and VA and VA relevant to ATA (VAATA) in 160 CRT-D patients. ATAs occurred in 63 patients in the first year. During a median follow-up of 925 days from 1 year after CRT implantation, 40 patients experienced 483 VAs. Kaplan-Meier analysis showed a significantly higher risk of VA in patients with than without ATA in the first year (log rank P=0.0057). Hazard ratios (HR) of VA (HR 2.36, 2.10, and 3.04 for ATA >30s, >6 min and >24 h, respectively) and only VAATA (HR 4.50, 5.59, and 11.79 for ATA >30s, >6 min and >24 h, respectively) increased according to the duration of ATA. In multivariate analysis, ATA >24 h was an independent predictor of subsequent VA (HR 2.42; P=0.02).

CONCLUSIONS

Patients with ATA >24 h in the first year after CRT had a higher risk of subsequent VA and VAATA. The risk of VA, including VAATA, increased with the longest ATA duration.

Sex differences in CRT device implantation rates, efficacy, and complications following implantation: protocol for a systematic review and meta-analysis of cohort studies

INTRODUCTION

There is abundant evidence for sex differences in the diagnosis, implantation, and outcomes for cardiac resynchronization therapy (CRT) devices. Controversial data suggesting women are less likely to receive the device regardless of the greater benefit. The aim of this review is to assess sex differences in the implantation rate, clinical effectiveness, and safety of patients receiving CRT devices.

METHODS

We will conduct a systematic literature search of MEDLINE, Embase, and Web of Science to identify cohort studies that meet our eligibility criteria. Title and full text screening will be conducted in duplicate independently. Eligible studies report clinical effectiveness or safety of patients receiving CRT device while providing sex-disaggregated data. Implantation rate will be extracted from the baseline characteristics tables of the studies. The effectiveness outcomes include the following: all-cause death, hospitalization, peak oxygen consumption (pVO₂), quality of life (QoL), 6-min walk test, NYHA class reduction, LVEF, and heart failure hospitalization. The complication outcomes include the following: contrast-induced nephropathy, pneumothorax, pocket-related hematoma, pericardial tamponade, phrenic nerve stimulation, device infection, death, pulmonary edema, electrical storm, cardiogenic shock, and hypotension requiring resuscitation. Description of included studies will be reported in detail and outcomes will be meta-analyzed and presented using forest plots when feasible. Risk of bias will be assessed using the Newcastle-Ottawa Scale (NOS) by two review authors independently. GRADE approach will be used to assess the certainty of evidence.

DISCUSSION

The aim of this review is to determine the presence of differences in CRT implantation between women and men as well as differences in clinical effectiveness and safety of CRT after device implantation. Results from this systematic review will provide important insights into sex differences in CRT devices that could contribute to the development of sex-specific recommendations and inform policy.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020204804.

Impact of atrial fibrillation/flutter on outcomes of patients with implantable cardioverter defibrillators: A sub-analysis of the Nippon Storm study

BACKGROUND

Implantable cardioverter-defibrillator and cardiac resynchronization therapy using a defibrillator (ICD/CRT-D) are established means of reducing mortality due to ventricular arrhythmia. Although atrial fibrillation/flutter (AF) is the most common cardiac arrhythmia in patients with heart disease, the impact of AF on the prognosis of patients with ICD/CRT-D remains controversial.

METHODS AND RESULTS

We analyzed data from the Nippon Storm Study, a prospective observational study of 1570 patients that was conducted at 48 Japanese ICD centers. We allocated 1549 participants to AF and non-AF groups, compared their clinical data at the time of enrollment, and monitored the incidences of mortality, hospitalization, and appropriate and inappropriate ICD/CRT-D therapy during a median 28 months. When the AF (n = 257, 16.6%) and non-AF-(n = 1292, 83.4%) groups were compared, the AF group was older (67.7 vs. 61.4 years; p<0.0001), and had lower left ventricular ejection fraction (38.0 ± 17.0% vs. 43.5 ± 18.9%; p<0.0001). During follow up, mortality was significantly higher in the AF than the non-AF group (p<0.0001). In multivariate analysis, AF was significantly associated with all-cause mortality [p = 0.013; hazard ratio (HR)=1.62]. Inappropriate ICD/CRT-D therapy occurred in 40/257 patients (15.6%) and AF was associated with a higher prevalence of inappropriate ICD/CRT-D therapy (p<0.0001; HR=2.25).

CONCLUSION

The presence of AF at ICD/CRT-D implantation carries subsequent independent risks of 1.62-fold for death and 2.25-fold for inappropriate therapy.

Predicting Electrical Storm Using Episodes' Parameters from ICD Recorded Data

Electrical storm (ES) is a life-threatening heart condition for patients with implantable cardioverter defibrillators (ICDs). ICD patients experienced episodes are at higher risk for ES. However, predicting ES using previous episodes' parameters recorded by ICDs have never been developed. This study aims to predict ES using machine learning models based on ICD remote monitoring-summaries during episodes in the anonymized large number of patients. Episode ICD-summaries from 16,022 patients were used to construct and evaluate two models, logistic regression and random forest, for predicting the short-term risk of ES. Episode parameters in this study included the total number of sustained episodes, shocks delivered and the cycle length parameters. The models evaluated on the data sections not used for model development. Random forest performed significantly better than logistic regression (P <; 0.01), achieving a test accuracy of 0.99 and an Area Under an ROC Curve (AUC) of 0.93 (vs. an accuracy of 0.98 and an AUC of 0.90). The total number of previous sustained episodes was the most relevant variables in the both models.

Electrical storm - still an extremely poor prognosis. Do these acute states of life-threatening arrhythmias require a multidirectional approach from the start?

Electrical storm (ES) is a state of electrical instability of the heart manifesting as multiple and potentially lethal recurring ventricular arrhythmias such as ventricular tachycardia or ventricular fibrillation. This definition is not related to the condition of each patient, who can present from asymptomatic to unconscious and in deep cardiogenic shock. Most patients affected by ES have heart failure (HF) of ischaemic origin. Ischaemia, exacerbation of HF, low ejection fraction, previous ventricular arrhythmias, infection or electrolyte disturbances together with other factors, or a few factors combined, may result in ES. The prognosis of ES survivors is very poor, with 1-year mortality exceeding 40%, which should draw attention to this group of patients as one of extremely high risk. The number of patients with cardioverter-defibrillators is increasing and so is the number of patients suffering from ES. Therefore, each patient should be supported with tailored therapy, and not only restricted to pharmacotherapy or ablation procedures. This paper was written to analyse the most frequent causes of ES and prompt the most appropriate clinical pathways and possibilities, underlining the need for a comprehensive invasive approach to diagnosis, treatment and circulatory stabilization in addition to adequate pharmacotherapy. This approach might help to reduce the mortality rate in this group of patients and improve the prognosis.

Association between changes in the intrathoracic impedance and ventricular arrhythmias in patients with heart failure

BACKGROUND

Ventricular arrhythmias (VAs) are independently related to mortality risk in patients with heart failure (HF). The wide availability of implantable cardioverter defibrillators and cardiac resynchronization therapy devices now offers an opportunity to clinically correlate the two disease processes. We hypothesized that there is an association between changes in the intrathoracic impedance and episodes of VA.

METHODS

Nonconcurrent prospective study of adults (age >20 years) with known HF with reduced ejection fraction (<35%). The OptiVol threshold was categorized as follows: 0-30 Ω-days, 31-60 Ω-days, 61-90 Ω-days, 91-120 Ω-days, and >120 Ω-days. Patients with OptiVol values at 0-30 Ω-days were used as the reference group. Receiver operating characteristic analysis was used to estimate the sensitivity and specificity at each threshold.

RESULTS

Of the 87 eligible patients, 65.5% were males. The mean age of the sample was 73.3 years (±12.7). Compared to patients in the 0-30 Ω-days category, those in the 31-60, 61-90, 91-120, and >120 Ω-days groups had, on average, 1.48, 1.64, 2.24, and 1.6 more VAs, respectively (P = 0.002, 0.009, 0.010 and 0.009, respectively). The sensitivity and specificity of each threshold were as follows: 82.6% and 61.7% at 31-60 Ω-days, 43.5% and 78.3% at 61-90 Ω-days, 30.4% and 85.0% at 91-120 Ω-days, and 21.7% and 88.3% at >121 Ω-days.

CONCLUSION

Our study found a significant positive relationship between changes in intrathoracic impedance and episodes of VAs in patients with HF.

Successful treatment of cardiac electrical storm in dilated cardiomyopathy using esmolol: A case report

The present study reports a case of electrical storm occurring in a 43-year-old woman with dilated cardiomyopathy. The patient suffered from a cardiac electrical storm, with 98 episodes of ventricular tachycardia rapidly degenerating to ventricular fibrillation in hospital. The patient was converted with a total of 120 defibrillations. Recurrent ventricular tachycardia/fibrillation was initiated by premature ventricular beats. The patient did not respond to the use of amiodaronum. However, the administration of esmolol stabilized the patient's heart rhythm. A moderate dose of the β-blocker esmolol, administered as an 0.5-mg intravenous bolus injection followed by an infusion at a rate of 0.15 mg/kg/min, inhibited the recurrence of ventricular fibrillation and normalized the electrocardiographic pattern. The results suggest that esmolol may be able to improve the survival rate of patients with electrical storm in dilated cardiomyopathy and should be considered as a primary therapy in the management of cardiac electrical storms.

Is the coexistence of sustained ST-segment elevation and abnormal Q waves a risk factor for electrical storm in implanted cardioverter defibrillator patients with structural heart diseases?

AIM

The aim of this study was to determine whether or not the coexistence of sustained ST-segment elevation and abnormal Q waves (STe-Q) could be a risk factor for electrical storm (ES) in implanted cardioverter defibrillator (ICD) patients with structural heart diseases.

METHODS AND RESULTS

In all, 156 consecutive patients received ICD therapy for secondary prevention of sudden cardiac death and/or sustained ventricular tachyarrhythmias were included. Electrical storm was defined as ≥3 separate episodes of ventricular tachycardia (VT) and/or ventricular fibrillation (VF) terminated by ICD therapies within 24 h. During a mean follow-up of 1825 ± 1188 days, 42 (26.9%) patients experienced ES, of whom 12 had coronary artery disease, 15 had idiopathic dilated cardiomyopathy, 6 had hypertrophic cardiomyopathy, 4 had arrhythmogenic right ventricular cardiomyopathy, 4 had cardiac sarcoidosis, and 1 had valvular heart disease. Sustained ST-segment elevation and abnormal Q waves in ≥2 leads on the 12-lead electrocardiography was observed in 33 (21%) patients. On the Kaplan-Meier analysis, patients with STe-Q had a markedly higher risk of ES than those without STe-Q (P< 0.0001). The multivariate Cox proportional hazards regression model indicated that STe-Q and left ventricular ejection fraction (LVEF) (<30%) were independent risk factors associated with the recurrence of VT/VF (STe-Q: HR 1.962, 95% CI 1.24-3.12, P= 0.004; LVEF: HR 1.860, 95% CI 1.20-2.89, P= 0.006), and STe-Q was an independent risk factor associated with ES (HR 4.955, 95% CI 2.69-9.13, P< 0.0001).

CONCLUSION

Sustained ST-segment elevation and abnormal Q waves could be a risk factor of not only recurrent VT/VF but also ES in patients with structural heart diseases.

Significant increase in the incidence of ventricular arrhythmic events after an intrathoracic impedance change measured with a cardiac resynchronization therapy defibrillator

BACKGROUND

Cardiac resynchronization therapy defibrillator (CRT-D) devices are now capable of monitoring changes in intrathoracic impedance. Intrathoracic impedance monitoring resulting in a fluid index threshold crossing has been proven to predict heart failure (HF) exacerbations. We retrospectively investigated the relationship between changes in intrathoracic impedance and the occurrence of arrhythmic events.

METHODS AND RESULTS

From 282 patients with New York Heart Association class III or IV HF who were implanted with a CRT-D device with a fluid index feature based on intrathoracic impedance monitoring capabilities, arrhythmic events were retrospectively analyzed in terms of the threshold crossings. The patients were divided into 2 groups: those with fluid index threshold crossings and those without threshold crossings. A total of 4,725 tachyarrhythmic events were reported in 129 patients (46%), and there were 221 fluid index crossing events in 145 patients (51%) during 10.0 ± 3.2 months. Tachyarrhythmic events were more frequently recorded in patients with threshold crossing events than in those who did not experience a threshold crossing (3,241 vs. 1,484 events, P<0.0001). Ventricular tachyarrhythmic events mainly occurred within the first 30 days after the threshold crossing event; however, a similar trend was not observed for the atrial tachyarrhythmic events.

CONCLUSIONS

Intrathoracic impedance monitoring may predict arrhythmic events, especially ventricular arrhythmias, in patients with HF and provides an additional management tool.