Cardiac resynchronization therapy in heart failure patients: An update

Heart failure continues to be a major public health problem with high morbidity and mortality rates, despite the advances in medical treatment. Advanced heart failure patients have severe persistent symptoms and a poor quality of life. Cardiac resynchronization therapy (CRT), an invasive therapy which involves synchronized pacing of both right and left ventricles, improves ventricular conduction delay and left ventricular performance. Several clinical trials of CRT in medically refractory heart failure patients with wide QRS (> 120 ms), left ventricular ejection fraction &#163; 35% and New York Heart Association (NYHA) class III and IV have shown improved quality of life, NYHA class, left ventricular ejection fraction and reduced mortality. About 30% of heart failure patients who receive CRT do not respond to treatment. Mechanical dyssynchrony may play a role in identifying patients who may respond better to CRT treatment. However, recent large scale clinical trials PROSPECT and RethinQ have challenged this concept. The role of CRT in heart failure patients with narrow QRS (< 120 ms), NYHA class I and II, atrioventricular nodal ablation in patients with atrial fibrillation and triple site pacing are evolving. Our review discusses the current evidence, indications, upcoming trials and future directions

Moxifloxacin-induced torsades de pointes

Torsade de pointes (TdP) is increasingly recognized as a complication of drug therapy. The most common cause of drug-induced QT prolongation is inhibition of the rapidly activating component of the delayed potassium current (IKr). Moxifloxacin, a widely used fluoroquinolone, is a weak IKr inhibitor and has been associated with QT prolongation. We report a case of marked QT prolongation (618 ms) and TdP associated with moxifloxacin use. Although it is difficult to predict which patients are at risk from TdP, careful assessment of the risk/benefit ratio is important before prescribing drugs known to cause QT prolongation. (Cardiol J 2008; 15: 71-73

Catheter ablation of atrial fibrillation in the elderly: Where do we stand?

Catheter ablation has emerged as an important therapy for the management of drug refractory symptomatic paroxysmal and persistent atrial fibrillation (AF). Although the elderly account for the majority of patients with AF, limited data exists regarding the use of catheter ablation for elderly patients with AF. As AF ablation has become more widespread, ablation techniques have improved and the complication rate has decreased. As a result, referrals of elderly patients for catheter ablation of AF are on the rise. Two retrospective analyses have recently demonstrated that catheter ablation of AF in the elderly can safely be performed and results are comparable to a younger population with up to 80% or more of patients maintaining sinus rhythm at 12 months follow-up. We compared the results of 15 consecutive patients &#8805; 70 years old with symptomatic paroxysmal atrial fibrillation who underwent catheter ablation of AF at our institution to 45 randomly sampled younger patients. The primary endpoint of our study, presence of sinus rhythm in the absence of symptoms at 12 months follow-up, was present in 60% of elderly patients and 80% of younger patients (p = 0.17). There was no statistically significant difference in complication rate between the younger and elderly patients. In this article we present the results of our study and review the published literature to date regarding the clinical efficacy and safety of catheter ablation for AF in elderly patients with paroxysmal and persistent atrial fibrillation

Reassessing the role of antitachycardia pacing in fast ventricular arrhythmias in primary prevention implantable cardioverter-defibrillator recipients: Results from MADIT-RIT

BACKGROUND: In Multicenter Automatic Defibrillator Implantation Trial - Reduce Inappropriate Therapy (MADIT-RIT), high-rate cutoff (arm B) and delayed therapy (arm C) reduced the risk of inappropriate implantable cardioverter-defibrillator (ICD) interventions when compared with conventional programming (arm A); however, appropriate but unnecessary therapies were not evaluated. OBJECTIVE: The purpose of this study was to assess the value of antitachycardia pacing (ATP) for fast ventricular arrhythmias (VAs) ≥ 200 beats/min in patients with primary prevention ICD. METHODS: We compared ATP only, ATP and shock, and shock only rates in patients in MADIT-RIT treated for VAs ≥ 200 beats/min. The only difference between these randomized groups was the time delay between ventricular tachycardia detection and therapy (3.4 seconds vs 4.9 seconds vs 14.4 seconds). RESULTS: In arm A, 11.5% patients had events, the initial therapy was ATP in 10.5% and shock in 1%, and the final therapy was ATP in 8% and shock in 3.5%. In arm B, 6.6% had events, 4.2% were initially treated with ATP and 2.4% with shock, and the final therapy was ATP in 2.8% and shock in 3.8%. In arm C, 4.7% had events, 2.5% were initially treated with ATP and 2.3% with shock, and the final therapy was ATP in 1.4% and shock in 3.3%. The final shock rate was similar in arm A vs arm B (3.5% vs 3.8%; P = .800) and in arm A vs arm C (3.5% vs 3.3%; P = .855) despite the marked discrepancy in initial ATP therapy utilization. CONCLUSION: In MADIT-RIT, there was a significant reduction in ATP interventions with therapy delays due to spontaneous termination, with no difference in shock therapies, suggesting that earlier interventions for VAs ≥ 200 beats/min are likely unnecessary, leading to an overestimation of the value of ATP in primary prevention ICD recipients