Pre-hospital ambulance care of patients following a suspected seizure: A cross sectional study.

PURPOSE: We aimed to investigate the characteristics of patients presenting to the ambulance service with suspected seizures, the costs of managing these patients and the factors which predicted transport to hospital. METHODS: We employed a cross-sectional design using routine clinical data from a UK regional ambulance service. Logistic regression was used to identify predictors of transport to hospital from ambulance response times, demographics, clinical (physiological) findings and treatments. RESULTS: There were 177,715 emergency incidents recorded in 2011/12 of which 2.9% (5139/177,715) were classified as seizures by ambulance call handlers and 2.7% (4884/177,715) by paramedics on the scene. Suspected seizures were the seventh most common call type. The annual cost of managing these incidents was £890,148. Clinical and physiological variables were normal for most patients. 59.3% (2894/4884) of patients were transported to hospital. 1/4884 (0.02%) patient died. Administration of diazepam, insertion of an airway and pyrexia perfectly predicted transport to hospital, tachycardia had a modest association, but other variables were only weak predictors of transport to hospital. CONCLUSIONS: This study shows that most patients after a suspected seizure are not acutely unwell but nevertheless most patients are transported to hospital. Further research is required to determine which factors are important in decisions to transport to hospital and to create evidence-based tools to help paramedics identify patients who could be safely managed without transport to hospital.

Association between myocardial substrate, implantable cardioverter defibrillator shocks and mortality in MADIT-CRT.

OBJECTIVE: The aim of the present study was to assess a possible association between myocardial substrate, implantable cardioverter defibrillator (ICD) shocks, and subsequent mortality. METHODS: Within the multicentre automatic defibrillator implantation trial-cardiac resynchronization therapy (MADIT-CRT) population (n = 1790), we investigated the association between myocardial substrate, ICD shocks and subsequent mortality using multivariate Cox regression analyses and landmark analyses at 1-year follow-up. RESULTS: The 4-year cumulative probability of ICD shocks was 13% for appropriate shock and 6% for inappropriate shock. Compared with patients who never received ICD therapy, patients who received appropriate shock had an increased risk of mortality [HR = 2.3 (1.47-3.54), P < 0.001], which remained increased after adjusting for echocardiographic remodelling at 1 year (HR = 2.8, P = 0.001). Appropriate anti-tachycardia pacing (ATP) only was not associated with increased mortality (P = 0.42). We were not able to show an association between inappropriate shocks (P = 0.53), or inappropriate ATP (P = 0.10) and increased mortality. Advanced myocardial structural disease, i.e. higher baseline echocardiographic volumes and lack of remodelling at 1 year, was present in patients who received appropriate shocks but not in patients who received inappropriate shocks or no shocks. CONCLUSION: In the MADIT-CRT study, receiving appropriate ICD shocks was associated with an increased risk of subsequent mortality. This association was not evident for appropriate ATP only. These findings, along with advanced cardiac structural disease in the patients who received appropriate shocks, suggest that the compromised myocardium is a contributing factor to the increased mortality associated with appropriate ICD shock therapy. Clinical trials.gov identifier: NCT00180271.

Temporal variability of atrial tachyarrhythmia burden in bradycardia-tachycardia syndrome patients.

AIMS: Several studies have tested non-pharmacological therapies for atrial tachyarrhythmias (ATs) by measuring the cumulative time (burden) the patient spends in arrhythmia. Contradictory results questioned either therapy efficacy or statistical power of the trials. We studied AT burden variability in patients paced for sinus node disease (SND) in order to interpret currently published data appropriately and to evaluate reliable sample sizes. METHODS AND RESULTS: One hundred and five patients with AT and SND received a dual chamber pacemaker with antitachyarrhythmia-pacing capability, and were followed for 13 months. Seventy-eight patients (74%) suffered AT recurrences. Device-gathered diagnostic measures were used to simulate results of randomized studies both with crossover and parallel design. The sample size required for statistically significant results was calculated as a function of the expected therapy-induced burden reduction. AT burden intra-patient variability was high: 43% of patients showed intrinsic fluctuations hiding any therapy-induced burden reduction lower than 30%. Demonstrating therapeutic breakthrough through a 6 month study would require 290 patients with crossover design and 5800 patients with parallel design. Doubling the study period requires 400 and 3000 patients, respectively. CONCLUSION: Patients with AT and paced for SND showed high intra-patient burden variability, which could possibly hide an AT burden reduction induced by a therapy. Previous studies involving non-pharmacological therapies utilizing AT burden endpoints could lack the power to reach statistical significance.

Influence of left ventricular function on outcome of patients treated with implantable defibrillators.

BACKGROUND: The outcomes of patients treated with implantable defibrillators were compared between patients with left ventricular ejection fraction greater than or equal to 30% and less than 30%. METHODS AND RESULTS: Of 68 consecutive patients treated with implantable defibrillators, 40 patients (group 1) had left ventricular ejection fraction greater than or equal to 30%, and 28 patients (group 2) had left ventricular ejection fraction less than 30%. Sudden death, surgical mortality, nonsudden arrhythmia-related death (death within 24 hours after an arrhythmic event despite initial termination of the arrhythmia by the implantable defibrillator), total arrhythmia-related death (including sudden death, surgical death, and nonsudden arrhythmia-related death), and total cardiac death were compared between the two groups. Surgical mortality was 4.4% (0% in group 1, 11% in group 2). During the follow-up of 31 +/- 27 months, actuarial survival rates free of events were 97%, 97%, and 97% in group 1 and 96%, 91%, and 82% in group 2 at 12, 24, and 36 months, respectively, for sudden death (p = NS); 97%, 97%, and 97% in group 1 and 85%, 81%, and 72% in group 2 at 12, 24, and 36 months, respectively, for sudden death and surgical mortality (p less than 0.05); 97%, 97%, and 97% in group 1 and 82%, 78%, and 70% in group 2 at 12, 24, and 36 months, respectively, for total arrhythmia-related death (p less than 0.05); and 95%, 95%, and 95% in group 1 and 82%, 69%, and 57% in group 2 at 12, 24, and 36 months, respectively, for total cardiac death (p less than 0.05). Four (57%) of seven nonsudden cardiac deaths during the initial 36-month follow-up period were causally related to arrhythmia (three surgical deaths and one arrhythmia-related nonsudden death). CONCLUSIONS: The outcome of patients treated with implantable defibrillators is strongly influenced by the degree of left ventricular dysfunction. In group 1 patients, surgical mortality, sudden death, and total cardiac death are rare. In group 2, sudden death rate may not be markedly different from that of group 1 patients. However, the risk of therapy (surgical mortality) is high. Many nonsudden cardiac deaths are causally related to arrhythmia (surgical mortality or nonsudden arrhythmia-related death). Therefore, the survival rate free of total arrhythmia-related death is significantly lower in group 2 (70% versus 97% in group 1 at 3 years). Further studies are needed to determine the roles of defibrillator therapy and other therapies in various clinical settings.

Role of implantable cardioverter defibrillator therapy in the management of high-risk patients.

Cardiovascular mortality from ventricular tachycardia (VT) and ventricular fibrillation (VF) continues to be a major health problem. Several therapeutic approaches are now available to treat patients with known VT/VF. Among the various therapeutic options are antiarrhythmic drugs, catheter or surgical ablation of VT focus, and implantable cardioverter defibrillator (ICD). The overall 2-year cardiovascular mortality is significantly reduced by ICD therapy. The ICD is particularly useful in patients with 1) no inducible but clinical VT/VF, 2) drug refractory VT/VF, and 3) VT/VF in association with left ventricular ejection fraction of less than or equal to 30%. Significant improvements in ICD therapy have already been made; these improvements include tiered antitachycardia therapy, antibradycardia pacing, lower defibrillation threshold, and longer life of generator. Further improvements are expected, including nonthoracotomy approach to defibrillation, pectoral implant, and dual chamber sensing. It is likely that with all of the advances in ICD therapy its acceptance as a therapeutic option will increase.

Long-term prognostic assessment of ventricular tachycardia with respect to sudden death in patients with and without overt heart disease.

The purpose of this study is to investigate the long-term prognosis of ventricular tachycardia (VT) mainly with respect to sudden death (SCD) in patients with ischemic heart disease (IHD), idiopathic cardiomyopathy (ICM), miscellaneous heart disease (MHD) and idiopathic ventricular tachycardia (IVT). The study included 117 patients with VT (80 male, 37 female). The number of patients with IHD, ICM, MHD and IVT were 40, 18, 26 and 33, respectively. Follow-up was conducted by means of a mailed standardized questionnaire. The mean follow-up period was 46.8 +/- 32.0 months (range from 6 to 125 months). In 24 out of the 117 patients the cause of death was SCD, in 9 there was no sudden cardiac death and in 5 no cardiac death. The other 76 were surviving. The number of SCD in IHD, ICM, MHD and IVT was 14/40 (35%), 4/17 (24%), 6/25 (24%) and zero (0%), respectively. The number of having had syncope in IHD, ICM, MHD and IVT was 19/40 (48%), 7/18 (39%), 6/26 (23%) and 6/33 (18%), respectively. Out of the 19 IHD patients with syncope, 15 had had ventricular fibrillation (VF). As for IVT with syncope, only one of the 6 had VF, which was induced by a disopyramide injection. In IVT, the patients with syncope had a significantly higher VT rate than those without syncope (p less than 0.01). There were no significant differences in the electrocardiographical high risk parameters for SCD, the age, follow-up periods, the presence or absence of VF and ejection fraction between the SCD and the surviving groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Prognostic significance of the number of induced ventricular complexes during assessment of therapy for ventricular tachyarrhythmias.

We analyzed 255 long-term trials of antiarrhythmic therapy, each of which had been evaluated at electrophysiologic study, to identify the maximum number of induced ventricular complexes consistent with the long-term efficacy of antiarrhythmic therapy. All patients had spontaneous and inducible sustained ventricular tachycardia or ventricular fibrillation. The incidence of therapeutic efficacy at 1 month and throughout follow-up was similar for trials in which zero, one, two, three, four, five, six to 10, and 11 to 15 complexes were induced, but significantly lower (p less than .001) for trials in which 16 or more complexes were induced. The cumulative incidence of efficacy at 1 year was 75 +/- 5% for 0 to 5 induced complexes, 72 +/- 11% for six to 10 complexes, 83 +/- 15% for 11 to 15 complexes, 42 +/- 10% for 16 complexes to 15 sec, and 48 +/- 6% for sustained ventricular tachycardia. At 1 year, the incidence of "sudden death-free" survival was higher for patients in trials that prevented initiation of sustained ventricular tachycardia than for those in trials that permitted initiation of sustained ventricular tachycardia (91 +/- 3% vs 75 +/- 6%; p = .01). The duration of the arrhythmia induced at therapy assessment was in the range of 11 to 20 complexes for only 4% of trials. Antiarrhythmic therapy is likely to be effective if as many as 15 complexes are induced at therapy assessment. The best cutoff, between 11 and 20 complexes, is difficult to identify because of the small fraction of trials in this range. Patients in whom initiation of sustained ventricular tachycardia is not prevented are at high risk for arrhythmia recurrence and sudden death.