Progression of Device-Detected Subclinical Atrial Fibrillation and the Risk of Heart Failure

Background

Long-term continuous monitoring detects short-lasting, subclinical atrial fibrillation (SCAF) in approximately one-third of older individuals with cardiovascular conditions. The relationship between SCAF, its progression, and the development of heart failure (HF) is unclear.

Impact of rate versus rhythm control on quality of life in patients with persistent atrial fibrillation. Results from a prospective randomized study.

AIMS: Despite the high prevalence of atrial fibrillation (AF), there are only limited data on quality of life (QoL) stemming from prospective trials comparing rate versus rhythm control. This prospective study evaluated QoL in patients with symptomatic persistent AF randomized to therapy aiming at rate versus rhythm control. METHODS AND RESULTS: Patients with symptomatic persistent AF (7 to 360 days duration) were prospectively randomized to ventricular rate control (n=125) or to cardioversion and maintenance of sinus rhythm (n=127). QoL was assessed by the Medical Outcomes Study Short Form health survey (SF-36) at baseline and during 1 year of follow-up. Changes in QoL were compared on an intent-to-treat basis, and subsequently between patients in sinus rhythm versus AF. At baseline, all SF-36 scales were reduced compared to healthy controls. At 1 year, six of eight items had improved significantly in patients assigned to rate control, and five of eight items on rhythm control (p=ns). The physical component summary showed a comparable increase with both treatment strategies (rate control: p=0.004; rhythm control: p<0.001) whereas no significant changes were found for the mental component summary. At 1 year, 55% of patients reported a positive health transition with no inter-group differences. There were no significant differences in QoL in patients in sinus rhythm or AF at the end of the observation period. CONCLUSION: In patients with symptomatic persistent AF, the two treatment strategies of rate versus rhythm control are associated with similar improvements in QoL.     

Analysis During Sinus Rhythm of Critical Sites in Reentry Circuits of Postinfarction Ventricular Tachycardia

Background: Critical sites within reentry circuits of postinfarction ventricular tachycardia (VT) were identified during sinus rhythm (SR) and VT to determine whether electrogram characteristics during SR may be helpful in identifying successful ablation sites. Methods: In 33 patients (mean age 67 ± 11 yrs) with prior infarction, mapping and radiofrequency (RF) catheter ablation of 57 hemodynamically-tolerated VT's (cycle length 478 ± 96) were performed. The morphologies of electrograms (EGM) at sites of concealed entrainment (CE) were compared during SR and VT. RF energy was delivered at 94 sites (51 successful and 43 unsuccessful ablation sites). Results: During SR, isolated potentials (IP), but not late potentials (LP) recorded via the mapping catheter, were associated with successful ablation. At 29/39 sites with an IP during sinus rhythm, an isolated diastolic potential (IDP) also was present during VT, whereas at 4 sites IP's were present only during SR (p < 0.001). At 11/29 sites where isolated potentials were present during SR and VT, the morphology of the isolated potential during VT and SR was similar; and all but one of these sites were successful ablation sites (p = 0.01). The EGM amplitude during VT correlated with the amplitude during SR (R = 0.9, p < 0.001). An identical pacemap was present during SR at 33/94 sites; this was not associated with successful ablation. Conclusion: SR mapping may be helpful in identifying critical sites of reentry in postinfarction VT. At sites within the reentry circuit, characteristics of sinus rhythm EGM's that are associated with successful ablation include the presence of IP's, but not the presence of LP's.     

Sustained monomorphic ventricular tachycardia ablation from the aortic sinus of valsalva

INTRODUCTION: The aim of this study was to delineate the electrophysiologic mechanisms of a novel type of ventricular tachycardia (VT) originating from the aortic sinus of Valsalva. METHODS AND RESULTS: Endocardial mapping was performed in four patients with symptomatic VT originating from the aortic sinus of Valsalva. Two patients suffered from dilative cardiomyopathy; the other two patients had no structural heart disease. Five VTs could be induced and terminated by programmed ventricular stimulation. Successful ablation was performed in the noncoronary sinus of Valsalva in three VTs and in the left aortic sinus in two. Abnormal (diastolic or presystolic) potentials were recorded during sinus rhythm (mean interval from the end of QRS complex to the potential 121+/-98 msec) and during VT (mean interval from the potential to QRS complex 64+/-45 msec) at effective sites in the aortic sinuses of Valsalva. Concealed entrainment was demonstrated at all successful sites. VT recurred in one patient after 1 month, whereas no recurrences were observed during follow-up of 8+/-6 months in the other three patients. CONCLUSION: Reentry constitutes one mechanism of VT originating from the aortic sinus of Valsalva. Entrainment mapping is useful to characterize the reentrant circuit of these VTs and to guide ablation.     

Ventricular rate stabilization for the prevention of pause dependent ventricular tachyarrhythmias: results from a prospective study in 309 ICD recipients

Reviews of stored electrograms from ICDs revealed a 5-30% incidence of short-long-short intervals preceding the onset of recurrent ventricular tachyarrhythmias. Rate stabilization by dedicated antibradycardia pacing algorithms has, therefore, been suggested to prevent onset of pause dependent tachyarrhythmias. However, the clinical efficacy of this approach has not been studied systematically. In a prospective multicenter crossover study, patients were randomized to activation or deactivation of an implemented ventricular rate stabilization algorithm (VRS) after first implant of a dual chamber ICD. After 3 months, all patients were crossed over to the alternate programming. The rate of appropriate spontaneous VA episodes was compared between VRS On and VRS Off. Stored electrograms were reviewed for evaluation of the mode of onset of tachyarrhythmias. Overall efficacy analysis was based on 309 patients enrolled in the study. Forty percent (124/309) of the patients experienced 4,973 VA episodes. Based on an intention-to-treat analysis, VRS Off and On arrhythmia incidence was 10.2 and 6.6 normalized to 3 months, respectively (risk reduction 35%; P = 0.18) On an on-treatment basis, a reduction from 9.0 episodes to 8.1 episodes (10% risk reduction, P = 0.24) was seen. In an extended Cox model adjusting for confounding variables, the relative risk for recurrent episodes was 0.92 during VRS On compared to Off (95% CI: 0.58-1.48; P = 0.74). During VRS Off, pause dependent onset was documented in only 36 (8%) of 427 visually analyzed episodes. There was no significant reduction in the incidence of recurrent ventricular tachyarrhythmias with VRS On compared to the Off programming in this prospective study.     

Efficacy and Safety of ICD Therapy in a Population of Elderly Patients Treated with Optimal Background Medication

Introduction: Implantable cardioverter-defibrillator (ICD) therapy has been shown to improve survival in patients with structural heart disease and at high risk for life threatening ventricular arrhythmias. Whether elderly patients benefit from device therapy in a similar way as younger patients is largely unknown. Methods: We retrospectively analyzed data from 375 consecutive ICD recipients with structural heart disease. Patients were divided into two groups, younger than 70 years at time of ICD implantation (group 1) or 70 years or older (group 2). Main outcome measures were time to death from any cause and time from first appropriate ICD therapy to death. Results: Group 1 and 2 patients were comparable with respect to clinical presentation and average follow-up duration. In the elderly patient group, 78% received an ICD for secondary prevention versus 63% in group 1 (p = 0.007). During a mean follow-up period of 26.5 ± 18.1 months, there was no significant difference in overall mortality among the two groups: 47 patients died, 34 (12.5%) of group 1 versus 13 (12.7%) of group 2. The average time to death was 28.4 ± 16.7 vs 30.4 ± 22.1 months after device implantation, respectively (p = ns). There was no difference in time from device implantation to first adequate ICD therapy and time from first appropriate ICD therapy to death among the two groups (p = ns). Device associated complications were comparable in both groups. Conclusions: Elderly ICD recipients had comparable survival rates and appropriate use of the ICD compared to younger individuals. There was no external financial support of this study.     

Prevention of sudden cardiac death: lessons from recent controlled trials.

Sudden cardiac death (SCD), presumably because of ventricular tachyarrhythmias, remains one of the major challenges of contemporary cardiology. Major randomized controlled trials conducted in patients with coronary artery disease (CAD) with the aim of primary prevention of SCD are providing insights. Several large-scale studies have demonstrated that treatment with beta-blockers, angiotensin-converting enzyme inhibitors, aldosterone antagonists, and statins results not only in a reduction in all-cause mortality but specifically also in SCD. On top of this optimized pharmacological therapy, implantable cardioverter-defibrillators (ICD) further decrease the risk of overall and SCD mortality in carefully selected patient groups. The sum of these trials indicates, however, that the benefit associated with ICD therapy is most prominent in patients with chronic stable CAD. In contrast, patients early after myocardial infarction derive less benefit from ICD treatment, presumably because of a high competing risk of non-arrhythmic cardiovascular death. Optimized pharmacological therapy, together with the ICD, can substantially improve the prognosis of high-risk CAD patients.     

Pharmacological therapy of atrial fibrillation and atrial flutter

BACKGROUND: Despite the increasing availability of nonpharmacological treatment options for atrial fibrillation, drug therapy targeted at restoration and maintenance of sinus rhythm, or aimed at symptomatic ventricular rate control remains the mainstay of therapy for the majority of patients. METHOD: Available data suggest that these two treatment approaches yield similar responder rates with regard to symptomatic improvement. RESULTS: Detailed results from major prospective studies investigating the prognostic effects of different atrial fibrillation treatment modalities are expected to become available soon. At present, however, the choice of the primary treatment strategy, i.e. rate control or rhythm control, still remains upon the clinical decision and expertise of the treating physician. Cardioversion by means of external biphasic shock delivery has shown to effectively convert atrial fibrillation to sinus rhythm in more than 90% of patients. Pharmacological cardioversion, in contrast, has a far lower success rate and may be followed by severe complications mandating in-hospital administration with the majority of drug regimens. For the maintenance of sinus rhythm, the proarrhythmic side effects of Class I antiarrhythmic drugs currently limit their use to those patients without any structural heart disease. Clinical investigation of newer "pure" Class III drugs have shown to excite considerable prolongation of ventricular repolarization duration resulting in a significant risk for torsade-de-pointes tachycardia. Betablockers are beneficial in many clinical situations associated with the occurrence of atrial fibrillation, such as heart failure, arterial hypertension and coronary artery disease. These substances, however, do not seem to improve cardioversion rates and their effect in maintaining sinus rhythm is only moderate. Patients with structural heart disease in whom maintenance of sinus rhythm is strongly desired, therefore, are left to amiodarone therapy. The cardiac safety profile as well as the proven effectiveness are unsurpassed by any other available drug at present. This paper reviews major studies published during the last decade implementing recent guidelines regarding pharmacological rate control, cardioversion and maintenance of sinus rhythm and the approach towards patients suffering from paroxysmal atrial fibrillation.     

Refinement of CARTO-guided substrate modification in patients with ventricular tachycardia after myocardial infarction

Background Substrate modification guided by CARTO system has been introduced to facilitate linear ablation of ventricular tachycardia （VT） after myocardial infarction （MI）. However, there is no commonly accepted standard approach available for drawing these ablation lines. Therefore, the aim of the present study was to practically refine this time consuming procedure.
Methods Substrate modification was performed in 23 consecutive patients with frequent VTs after MI using the CARTO system. The initial target site （ITS） for ablation was identified by pace mapping （PM） during sinus rhythm and/or entrainment pacing （EM） during VT. According to the initial target site, two approaches were used. The initial target site in approach one has a similar QRS morphology as VT and an interval from the stimulus to the onset of QRS cmplex （S-QRS） of ≥50 ms during PM in sinus rhythm or a difference of the post pacing interval and VT cycle length ≤30 ms during concealed entrainment pacing of VT; The initial target site in approach two has an similar QRS morphology as VT and an S-QRS of 〈50 ms during PM in sinus rhythm.
Results Overall, 50 lines were performed with a length of （35±11） mm. Procedure time averaged （232±56） minutes, fluoroscopy time （10±8） minutes. Sixteen patients were initially involved into approach one. After completion of 3±1 ablation lines, no further VT was inducible in 13 patients. The remaining 3 patients were switched to use the alternative approach. However, in none of them the alternative approaches were successful. Approach two was initially used in 7 patients. After completion of 3±1 ablation lines, no further VT was inducible in only 2 patients. The remaining 5 patients were switched to approach one, which resulted in noninducibility of VT in 4 of them. The initial successful rate was significantly higher in the group of approach one compared to that in the group of approach two （13/16 patients vs 2/7 patients, P=-0.026）.
Conclusions The approach for     

Prevention of immediate reinitiation of atrial tachyarrhythmias by high-rate overdrive pacing: results from a prospective randomized trial

INTRODUCTION: Immediate reinitiation of atrial tachyarrhythmia (IRAT) is an important cause of failure to maintain sinus rhythm. IRAT prevention by overdrive pacing has not been evaluated in a prospective randomized trial. METHODS AND RESULTS: Patients with a DDDRP pacemaker offering temporary atrial overdrive pacing after AT termination (Post Mode Switching Overdrive Pacing [PMOP]) were enrolled into the prospective PIRAT (Prevention of IRAT) trial if paroxysmal AT episodes occurred after implantation. PMOP was randomly activated (120 beats/min for 2 min) or inactive. After 3 months, device memory was interrogated, symptoms and quality of life assessed, and patients crossed over to the alternative treatment arm for another 3 months. Primary study endpoint was the number of AT episodes; secondary endpoints were the cumulative time in AT (AT burden), percentage of AT episodes with IRAT, symptoms, and quality of life with PMOP active versus inactive. In 37 patients (21 men; 69 +/- 9 years), there was no difference in the median number of AT episodes (0.37 vs 0.34 per day), AT burden (both 1%), percentage of episodes with IRAT (30%vs 28%), symptoms, and quality of life during PMOP off versus on. With PMOP active, 29% of 439 ATs restarted during and 18% before PMOP intervention. The PMOP-induced rate increase appeared to be associated with IRAT in 9% of AT episodes. CONCLUSION: Automatic overdrive pacing after AT termination did not prevent IRAT, mainly due to insufficient overdrive suppression even at 120 beats/min and the delay between AT termination and PMOP intervention.