Single-chamber ICD, single-zone therapy in primary and secondary prevention patients: the simpler the better?

BACKGROUND: It is now well established that implantable cardioverter defibrillator (ICD) implantation reduces mortality in patients at increased risk of sudden cardiac death. However, the best programming parameters remain controversial. Our traditional policy has followed a simple approach in the vast majority of patients. In accordance with ICD programming in the major randomized clinical trials, we programmed a single high-rate, shock-only therapy zone. We aimed to demonstrate in this observational study that simple programming is not associated with higher shock rates or mortality when compared to other published studies. METHODS: Consecutive patients who underwent single-chamber ICD implantation with single-zone, high-rate programming at our institution between 1993 and 2008 were retrospectively studied. Data were collected prospectively in a database regarding details of ICD implantation, demographic data, and indication. RESULTS: Three hundred thirty-two patients were included in our study, 31 % primary prevention and 68 % secondary prevention. Mean ejection fraction (EF) is 33.7 ± 15.3. Over a mean follow-up period of 62.5 ± 38.1 months, 135 patients experienced ICD shock (annualized event rate 7.7 %); 89 patients (26.8 %) appropriate shock in VT-ventricular fibrillation (VF), 68 patients (20.5 %) inappropriate shocks, and 22 patients (6.6 %) both. Twenty-nine patients (8.7 %) were reprogrammed to additional VT-ATP zones. Twenty-two (6.6 %) patients underwent heart transplantation. Sixty-two patients (18.6 %) died during follow-up, 43.6 % out of them due to cardiac cause, mainly progressive heart failure. CONCLUSION: Our results show that simpler settings with single-zone, high-rate programming is associated with ICD shock rates and long-term mortality that does not appear to be worse when compared with contemporary studies which include multizone ICD programming with antitachycardia pacing activated.

Atrial flutter after heart transplantation: mechanism and catheter ablation.

BACKGROUND: Atrial flutter is a frequent arrhythmia after heart transplantation, but little is known about its mechanism and treatment. We report the results of an electrophysiologic study in patients with atrial flutter after orthotopic heart transplantation, describing its mechanism and demonstrating the acute and long-term efficacy of catheter ablation for treating this arrhythmia. METHODS: We included 14 patients with symptomatic atrial flutter after orthotopic heart transplantation. All of them underwent an electrophysiologic study to determine the mechanism of the arrhythmia and catheter ablation when possible. RESULTS: Counterclockwise right atrial circuit around the tricuspid annulus involving the cavotricuspid isthmus was demonstrated in 13 patients (86%). Catheter ablation of the isthmus was performed with good acute results in all but 1. During a mean follow-up of 24 ± 17 months, recurrent atrial flutter was documented in 3 patients and atrial fibrillation in 2. In another patient, we demonstrated a left atrial origin. CONCLUSIONS: The most common mechanism of atrial flutter in heart transplant recipients is a counterclockwise circuit around the tricuspid annulus involving the cavotricuspid isthmus. Catheter ablation of the isthmus between tricuspid annulus and posterior atrial suture line represents an effective treatment in these patients. This condition may be avoided by changing the surgical technique to a bicaval anastomosis.

[Intravascular ultrasonographic evaluation of direct stents, implanted without predilatation. Comparison of results according to lesion types]. / Evaluación con ultrasonografía intravascular de stents implantados sin predilatación (stents directos). Comparación de resultados según el tipo de lesión.

INTRODUCTION AND OBJECTIVES: Direct stenting is a safe and feasible technique in selected lesions yielding excellent angiographic results. However, there are no studies providing intravascular ultrasonographic examination after direct stenting. The aim of this study was to evaluate direct stent expansion with ultrasonography and to know whether there are differences in the results based on lesion types. METHODS: Patients with amenable lesions for direct stenting were enrolled; including patients with no occlusion, no calcification, no significant tortuosity or angulation, a length 15 mm and a reference lumen diameter 2.5 mm. Intravascular ultrasonography was performed after stent implantation. The ultrasonographic criteria for optimal expansion were: complete apposition and a minimal intrastent lumen area > 80% of the average reference luminal area and 90% of the distal reference lumen area. RESULTS: We included 40 patients (50 lesions). The final angiographic result was good in all the patients but in one case an additional stent was used due to dissection. The ultrasonographic examination did not show significant differences between type A and B lesions. Optimal expansion was achieved in 14/21 (66%) of type A lesions and 17/29 (58%) of type B lesions (p = 0.5). The balloon/artery ratio was the only factor significantly related to ultrasonographic results. When this ratio was 1.1-1.2 (25 cases), 76% of the stents were optimally expanded and when the ratio was < 1. 1 (25 cases) only in a 48% an optimal result was achieved (p < 0.05). CONCLUSIONS: Direct stenting in selected lesions provides ultrasonographic results comparable to those expected with conventional stenting and these results could be even improved if a balloon artery ratio 1.1-1.2 is used. Taking into consideration the selection criteria the differences observed between lesion types A and B are not significant.

Evaluation of direct stent implantation without predilatation by intravascular ultrasound.

The present study shows that direct stent implantation without predilatation in selected lesions provides angiographic and ultrasonographic results that could be comparable to those expected with conventional stenting. These results may even safely improve if a balloon-artery ratio of 1.1 to 1.2 is used in combination with implantation pressures of 12 to 16 atm.

[A direct stent without predilatation. Our experience in 300 lesions]. / Stent directo sin predilatación. Experiencia en 300 lesiones.

INTRODUCTION: The stent alone technique, direct stenting without predilatation, aims to reduce cost and procedural time. Other potential benefits are the avoidance of abrupt vessel closure after balloon angioplasty and lessening of the restenosis rate due to the reduced arterial injury. We present our experience with this therapeutic approach in a long series of patients. PATIENTS AND METHODS: 230 patients referred to our unit were included with 300 non-occlusive stenotic lesions without excessive tortuosity, calcification, length or angulation and with a reference vessel diameter > or = 2.5 mm. In these patients stent implantation without predilatation was attempted. The immediate angiographic results and procedural related complications were evaluated. RESULTS: The stent alone technique succeeded in 256 (85%) among the 300 lesions treated. In 43 (14.3%) lesions predilatation was required and in one case the stent could not be positioned. A new dilatation after deployment was required due to suboptimal stent expansion in 27/256 (10.5%) lesions. Stent embolization occurred in 5 patients, 4 stents were retrieved and there were no clinical sequelae. The best results were obtained in non-subtotal and non-bifurcated lesions type A or B1 without moderate calcification, tortuosity or angulation. CONCLUSIONS: Direct stenting is feasible in a large number of patients with a high success rate after an appropriate selection. The most optimal lesions to be treated with this technique are < or = 90% stenotic non-bifurcated lesions type A or B1 without moderate calcification, tortuosity or angulation.