Claudia Camanini

Cardioverter-defibrillators after MADIT-II: the balance between weight of evidence and treatment costs.

The possibility of using implantable cardioverter‐defibrillators (ICDs) for primary prevention of sudden death in selected high‐risk patients has prompted a series of prospective controlled studies. Recently, the MADIT II study highlighted the possibility of effective primary prevention of sudden death in patients with coronary artery disease selected by straightforward clinical data and without expensive screening (electrophysiological study). For patients with previous myocardial infarction and low left ventricular ejection fraction (≤30%), ICD implantation may reduce mortality risk by approximately 31% in the following 2 years. Implementation of this therapeutic strategy threatens to impact on public health‐care spending. Possible cost‐limiting mechanisms include price cuts because of increasing usage (market forces); identification of subgroups at higher risk of sudden death and use of cheaper devices with limited diagnostic and therapeutic options. Further long‐term evaluation of the cost‐effectiveness and cost‐utility of ICDs should identify subgroups of patients for whom implantation is affordable despite current economic constraints. For heart failure patients, randomized controlled trials are currently evaluating the effects on overall survival of both conventional ICDs and devices with biventricular pacing capabilities. In this perspective, data from the COMPANION trial are expected to stimulate the use of devices with defibrillation back‐up in candidates for biventricular pacing.

Transvenous Low Energy Internal Cardioversion for Atrial Fibrillation: A Review of Clinical Applications and Future Developments

BORIANI, G., et al.: Transvenous Low Energy Internal Cardioversion for Atrial Fibrillation: A Review of Clinical Applications and Future Developments. Low energy internal atrial cardioversion can be performed by delivering biphasic shocks between transvenous catheters positioned within the cardiac chambers or great vessels. Delivery of shocks results in effective cardioversion at energies < 6–10 J and the procedure can be effective even when external cardioversion has failed. Shock induced discomfort varies from patient to patient, but the procedure can be usually performed without general anesthesia and eventually under mild sedation. Nevertheless, tolerability has to be improved by obtaining a substantial reduction in defibrillating thresholds. With regard to safety, delivery of shocks for defibrillating the atria implies a potential risk of inducing ventricular fibrillation; to minimize this risk, shock delivery must be synchronous to the QRS and should be avoided during rapid RR cycles (< 300 ms). Presently, transvenous low energy cardioversion is an investigational procedure, but a widening of indications is expected in the near future. The cost of the procedure, which remains invasive and requires a brief hospital stay, must be balanced with the benefit of restoring sinus rhythm and the possibility of maintaining sinus rhythm for the medium‐ to long‐term. Experimental and clinical investigations of low energy internal cardioversion have resulted in the development of devices for atrial defibrillation whose clinical role and cost‐benefit ratio is currently under evaluation.

Predictors of Atrial Defibrillation Threshold in Internal Cardioversion

This study examined the clinical, echocardiographic, and electrophysiological factors influencing the atrial defibrillation threshold (ADFT) in patients with chronic, persistent AF undergoing transvenous, low energy, atrial cardioversion. Twenty‐two patients (age 57 ± 15 years) with a mean AF duration of 7.8 ± 7.1 months (range 2–32 months) underwent internal cardioversion with catheters placed in the right atrium and coronary sinus. Biphasic shocks (3/3 ms) were delivered in a step‐up protocol. ADFT was defined as the lowest energy shock that converted AF to sinus rhythm. All patients were successfully cardioverted at a mean ADFT of 5.62 ± 2.82 J (range 2.6–12.9 J). Fifteen variables, including clinical characteristics (age, body mass index, AF duration, etiology), echocardiographic measurements (atrial diameter and volumes, indexes of ventricular performance), hemodynamic measurements, and mean atrial cycle during AF were analyzed as possible predictors of ADFT. In univariate regression analysis, AF duration, mean RR interval, and cardiac index correlated with ADFT. In multivariate regression analysis, AF duration remained as the only significant predictor of ADFT (B coefficient 0.311, P < 0.001; 95% confidence interval [CI] 0.194‐0.427). AF duration was the most powerful predictor of ADFT. It should be considered when planning internal CV of AF to limit the number of shocks delivered. Furthermore, long intervals between AF onset and CV should be avoided.

Atrial Signal Analysis and Defibrillation Threshold Assessment in Chronic Persistent and Reinduced Atrial Fibrillation

De. brillation Threshold in Chronic and Reinduced AF. Introduction: Induced versus spontaneous atrial fibrillation (AF) is of interest for assessing atrial defibrillation threshold reproducibility.

Which Is the Ideal Drug for Chronic Prophylaxis of Atrial Fibrillation

A series of antiarrhythmic agents have been demonstrated to be highly effective in terminating recent-onset atrial fibrillation, class IC agents being the most effective [1, 2]. In contrast with the high efficacy shown in treating recent-onset atrial fibrillation, results obtained in preventing recurrences of atrial fibrillation are scanty [3–6]. Table 1 summarizes reported data from the literature. As shown, the percentage of patients who maintain sinus rhythm without arrhythmia recurrence under placebo treatment is around 30% after 3–6 months and around 20%–25% after 12 months. Antiarrhythmic agents may increase the percentage of patients who maintain sinus rhythm, but the overall efficacy is limited and, except for amiodarone, no more than 50% of the treated patients are free from arrhythmia recurrences after 6–12 months. For amiodarone, efficacy rates of 75%–78.5% at 6 months and of 50%–73% at 12 months have been reported.

Cost-Effectiveness of ICD Implantation in Clinical Settings Different From Ischemic Heart Disease: What Do We Know?

Sudden cardiac death is responsible for around 50% of all deaths due to cardiovascular causes [1, 2]. The implantable cardioverter defibrillator (ICD) was initially conceived by Mirowski for preventing sudden death in patients who have already experienced a life-threatening ventricular arrhythmia, such as sustained ventricular tachycardia or ventricular fibrillation. These patients are at high risk of recurrences of these malignant tachyarrhythmias, with recurrence rates around 30%–50% in a 2-year follow-up period [3]. Prospective controlled studies have demonstrated that ICDs prevent sudden death in these patients, with an improvement in overall survival in a 3- to 5-year follow- up[4–6]. The majority of patients enrolled in these trials had coronary artery disease as predominant etiology, and a wide range of ventricular function compromise was present, as well as a wide range of associated clinical conditions

The Real Economic Impact of the MADIT-II Study on the European Medical Community

One of the most relevant problems in current cardiological practice is the possibility of implementing, in patients who have a specific indication, a series of treatments of proven efficacy but of high cost. This problem involves percutaneous transluminal coronary angioplasty (PTCA) and cardioverter-defibrillators (CDs) [1]. Table 1 shows the number of procedures performed in the year 2000 in the European Union (15 countries) and in the whole of Europe (33 countries). As the table shows, the increase in population obtained by adding 18 countries to those within the European Union is not followed by a parallel increase in the number of high-cost procedures, suggesting marked difficulties due to economic reasons in using these treatments in routine daily practice.

Cardiac Resynchronization Therapy: The Low Voltage Road or the High Voltage Road?

Cardiac resynchronization therapy is an additional therapeutic option for heart failure patients that has became available in recent years and aroused great interest among both electrophysiologists and clinical cardiologists managing heart failure patients. The prevalence of conduction disturbances (QRS interval ≥120 ms) among patients with left ventricular dysfunction or overt heart failure has been found to range between 27% and 53% [1–3]. Upon analyzing subjects with varying degrees of functional impairment according to New York Heart Association (NYHA) functional class, wider mean QRS intervals were found in subjects with a higher degree of functional impairment [4]. In subjects with dilated cardiomyopathy the QRS interval was widened in elec- trograms recorded shortly before death as compared to recordings made a mean of 35 months before the terminal event [5]. In unselected patients, left bundle branch block was associated with increased risk of both total mortality and sudden death at 1 year [2]. In another study [6] a QRS duration >110 ms was associated with increased mortality independently of left ventricular ejection fraction. It is a matter for investigation to assess whether left bundle branch block with left QRS axis deviation is most closely related to left ventricular enlargement and left ventricular dysfunction or whether it carries additional prognostic implications [7]. In a recent paper [8], a widening of the QRS interval in patients with heart failure who were followed by a heart failure clinic was a definite and independent predictor of mortality. According to these data, analysis of the QRS interval may provide additional information as a basis for selecting candidates for nonpharmacological treatments.

Pacing, ICD, or Both for the Hybrid Therapy of Atrial Arrhythmias?

Atrial fibrillation (AF) is the most common cardiac arrhythmia, and its prevalence is expected to increase further in the coming years W. The treatment of recurrent paroxysmal AF is frustrating in clinical practice, due to the high rate of recurrences and the lack of uniformly effective treatments [2-4]. Antiarrhythmic drugs are classically the first approach to preventing AF recurrences, but no more than 50% of patients respond to drug therapy within 1 year [2-4]. In view of this limited efficacy and the risk of proarrhythmia, especially in patients with left ventricular dysfunction, new, nonpharmacological treatments for AF are being developed [5,6]. These treatments may be classified as: rescue (catheter-based atrial cardioversion), curative (focal ablation), suppressive (atrial pacing algorithms), and palliative (ablate and pace strategy). No definite algorithms for choosing the most appropriate treatment in the individual patient have been developed. The therapeutic approach for patients with AF remains clinical and is primarily guided by the clinical presentation of the AF. A series of important questions regarding nonpharmacological treatments are still open; they relate to the selection of candidates for any of these treatments or particular combinations of treatments, the true efficacy, the patient acceptance, the risk-benefit and cost-benefit ratios, and the related social costs.

Risk Stratification in Atrial Fibrillation and Congestive Heart Failure

Atrial fibrillation (AF) and heart failure are two common cardiac diseases, affecting 1%-2% of the population [1,2] with a prevalence that rises steeply with age. AF and heart failure are conditioned by common risk factors and frequently coexist [3]; indeed, the prevalence of left ventricular dysfunction and/or congestive heart failure among patients with AF may be as high as 40% [4], and in the Framingham Study the presence of congestive heart failure implied a 6.6-fold increased risk of developing AF in a 2-year period. On the other side, the strong association between AF and congestive heart failure is further attested by the high prevalence of AF found in major heart failure trials dealing with patients in more advanced NYHA functional classes [3].