Predictors of atrial antitachycardia pacing efficacy in patients affected by brady-tachy form of sick sinus syndrome and implanted with a DDDRP device

Atrial antitachycardia pacing and managed ventricular pacing in bradycardia patients with paroxysmal or persistent atrial tachyarrhythmias: the MINERVA randomized multicentre international trial

Aims

Atrial fibrillation (AF) is a common comorbidity in bradycardia patients. Advanced pacemakers feature atrial preventive pacing and atrial antitachycardia pacing (DDDRP) and managed ventricular pacing (MVP), which minimizes unnecessary right ventricular pacing. We evaluated whether DDDRP and MVP might reduce mortality, morbidity, or progression to permanent AF when compared with standard dual-chamber pacing (Control DDDR).

Methods and results

In a randomized, parallel, single-blind, multi-centre trial we enrolled 1300 patients with bradycardia and previous atrial tachyarrhythmias, in whom a DDDRP pacemaker had recently been implanted. History of permanent AF and third-degree atrioventricular block were exclusion criteria. After a 1-month run-in period, 1166 eligible patients, aged 74 ± 9 years, 50% females, were randomized to Control DDDR, DDDRP + MVP, or MVP. Analysis was intention-to-treat.

The primary outcome, i.e. the 2-year incidence of a combined endpoint composed of death, cardiovascular hospitalizations, or permanent AF, occurred in 102/385 (26.5%) Control DDDR patients, in 76/383 (19.8%) DDDRP + MVP patients [hazard ratio (HR) = 0.74, 95% confidence interval 0.55–0.99, P = 0.04 vs. Control DDDR] and in 85/398 (21.4%) MVP patients (HR = 0.89, 95% confidence interval 0.77–1.03, P = 0.125 vs. Control DDDR). When compared with Control DDDR, DDDRP + MVP reduced the risk for AF longer than 1 day (HR = 0.66, 95% CI 0.52–0.85, P < 0.001), AF longer than 7 days (HR = 0.52, 95% CI 0.36–0.73, P < 0.001), and permanent AF (HR = 0.39, 95% CI 0.21–0.75, P = 0.004).

Conclusion

In patients with bradycardia and atrial tachyarrhythmias, DDDRP + MVP is superior to standard dual-chamber pacing. The primary endpoint was significantly lowered through the reduction of the progression of atrial tachyarrhythmias to permanent AF.

ClinicalTrials.gov Identifier

NCT00262119.

The MINERVA study design and rationale: a controlled randomized trial to assess the clinical benefit of minimizing ventricular pacing in pacemaker patients with atrial tachyarrhythmias

BACKGROUND

Dual-chamber (DDD) pacing has generally been regarded as "physiologic pacing" and therefore expected to be superior to ventricular pacing. Major randomized trials have so far failed to demonstrate significant reductions in the incidences of mortality, stroke, and heart failure. It has been shown that unnecessary ventricular pacing in patients with sinus node dysfunction or only intermittent atrioventricular block is associated with ventricular desynchronization and increased risk of atrial tachyarrhythmias (ATA).

METHODS

The MINimizE Right Ventricular pacing to prevent Atrial fibrillation and heart failure (MINERVA) study is a prospective, multi-center, randomized, international, single-blind, controlled trial designed to determine whether physiologic pacing through the managed ventricular pacing (MVP) algorithm combined with preventive atrial pacing (PAP) and atrial antitachycardia pacing (ATP) is superior to standard DDD pacing in terms of 2-year reduction in death, permanent ATA, and cardiovascular hospitalizations. Patients with standard class I or II indications for permanent DDD pacing and history of ATA will receive a Medtronic EnRhythm implantable pacemaker (Medtronic, Minneapolis, MN). After a 1-month run-in period, patients will be randomized in a 1:1:1 manner to the DDD (control group, all OFF), the DDDRP (MVP + PAP + ATP ON), and the MVP group (only MVP ON). Up to 1,300 patients will be included in approximately 70 centers in Europe, the Middle East, and Asia.

CONCLUSIONS

The MINERVA study will make an important contribution to the management of patients with paroxysmal ATA and accepted indications for dual-chamber pacemaker implantation by determining whether physiologic pacing combined with PAP and ATP is superior to standard DDD pacing in terms of reduction of mortality, incidence of permanent ATA, and cardiovascular hospitalizations.

The Drug And Pace Health cliNical Evaluation (DAPHNE) study: a randomized trial comparing sotalol versus beta-blockers to treat symptomatic atrial fibrillation in patients with brady-tachycardia syndrome implanted with an antitachycardia pacemaker

BACKGROUND

Atrial tachyarrhythmias (ATAs) are mainly treated by pharmacologic therapy for rate control or rhythm control. The aim of our study was to compare sotalol (S) versus beta-blocking agents (BB) in terms of prevention of ATA, cardioversions (CVs), and cardiovascular hospitalizations (H) in patients paced for bradycardia-tachycardia form of sinus node disease (BT-SND).

METHODS

One hundred thirty-five patients (67 males, aged 73 +/- 7 years) were enrolled in a prospective, parallel, randomized, single-blind, multicenter study. All patients received a dual chamber rate adaptive pacemaker; after 1 month, 66 patients were randomly assigned to BB (62 +/- 26 and 104 +/- 47 mg/d for atenolol and metoprolol, respectively) and 69 patients to S (167 +/- 66 mg/d).

RESULTS

After an observation period of 12 months, the percentage of patients free from ATA recurrences was 29% in both BB and S group. Cardioversion and H were significantly (P < .01) fewer in the 12 months after implantation than in the 12 months before both in patients treated with S (CV 69.4% vs 22.2%, H 91.7% vs 33.3%) and in patients treated with BB (CV 58.5% vs 17.1%, H 82.9% vs 26.8%). Kaplan-Meier survival analysis showed a nonsignificant trend toward a lower incidence of the composite end point (CV + H) among BB patients.

CONCLUSIONS

In the complex context of "hybrid therapy" in patients with BT-SND implanted with a modern dual chamber rate adaptive pacemaker device delivering atrial antitachycardia pacing, no differences were found between the use of beta-blocker and the use of S, at the relatively low dose achieved after clinical titration, in terms of prevention of cardiovascular H or need for atrial CV.

A randomized comparison of amiodarone and class IC antiarrhythmic drugs to treat atrial fibrillation in patients paced for sinus node disease: the Prevention Investigation and Treatment: A Group for Observation and Research on Atrial arrhythmias (PITAGORA) trial

BACKGROUND

Rhythm control is an important goal in the treatment of recurrent atrial tachyarrhythmias (AT). The PITAGORA study was a randomized trial in patients paced for sinus node disease (SND), designed to test the noninferiority of class IC antiarrhythmic drugs (AADs) to amiodarone in terms of a primary end point composed of death, permanent AT, cardiovascular hospitalization, atrial cardioversion, or AAD change.

METHODS

Randomization was stratified to assign 2 patients to amiodarone and 2 patients to class IC AADs: propafenone or flecainide. One hundred seventy-six patients (46% men, 72 +/- 8 years) were enrolled. Device diagnostics continuously monitored AT recurrences and duration.

RESULTS

In a mean follow-up of 20 +/- 9 months, the primary end point occurred in 23 (30.7%) of 75 class IC patients and in 28 (40.0%) of 70 amiodarone patients. The absolute difference in the end point incidence (-9.3%; 95% CI between 3.7% and -22.3%) confirmed the noninferiority of class IC to amiodarone (P = .007). Kaplan-Meier 1-year freedom from AT episodes >10 minutes, 1 day, and 7 days was 40%, 73%, and 91% for amiodarone and 28%, 78%, and 86% for class IC AADs (P = nonsignificant).

CONCLUSIONS

In patients paced for SND and suffering from AT, class IC AADs proved not to be inferior to amiodarone in terms of the primary composite end point described or end points which were differently composed of mortality, efficacy, or AAD side effects. The AADs studied also showed similar results in terms of symptoms, quality of life, and freedom from AT recurrences.

Rate control in patients with pacemaker affected by brady-tachy form of sick sinus syndrome

BACKGROUND

In sinus node disease (SND) atrial tachyarrhythmias (ATs) may frequently occur, after implant of a pacemaker for bradycardia, and are to be managed by rate or rhythm control.

METHODS

We evaluated ventricular heart rate (HR) during AT, AT-related symptoms and hospitalizations in 333 patients who received DDDRP pacemakers for SND.

RESULTS

In days with 24 hours of AT, mean daily HR during AT was > 80, 90, 100, 110, and 120 beats per minute (bpm) in 191 (57%), 114 (34%), 55 (16%), 23 (7%), and 11 (3%) patients, respectively. The proportion of patients with a mean daily HR > 80 bpm during AT despite the use of rate control agents was 28% among patients treated with calcium-channel blockers, 43% with digoxin, 49% with a combination of agents, 54% with amiodarone, 64% with sotalol, and 69% with beta blockers. Patients with HR > 100 bpm experienced a higher prevalence of both AT-related hospitalizations and cardiovascular hospitalizations than those with HR < or = 100 bpm (36% vs 21%, P = .013; 42% vs 28%, P = .003) and a significantly higher number of AT-related symptoms (1.8 +/- 0.9 vs 1.4 +/- 1.0, P = .008).

CONCLUSIONS

Limited attention has been dedicated to rate control in patients with pacemaker. This is the first study to evaluate the prevalence and implications of inappropriate rate control in patients with pacemaker. We found that in a substantial proportion of patients with SND who have recurrent ATs despite pacing, mean daily HR during AT is high and that these patients present increased hospitalizations and more symptoms, thus suggesting the need to improve rate control.

How, why, and when may atrial defibrillation find a specific role in implantable devices? A clinical viewpoint

This viewpoint article discusses the potential for incorporation of atrial defibrillation capabilities in modern multi-chamber devices. In the late 1990s, the possibility of using shock-only therapy to treat selected patients with recurrent atrial fibrillation (AF) was explored in the context of the stand-alone atrial defibrillator. The failure of this strategy can be attributed to the technical limitations of the stand-alone device, low tolerance of atrial shocks, difficulties in patient selection, a lack of predictive knowledge about the evolution of AF, and, last but not least, commercial considerations. An open question is how atrial defibrillation capability may now assume a specific new role in devices implanted for sudden death prevention or cardiac resynchronization. For patients who already have indications for implantable devices, device-based atrial defibrillation appears attractive as a "backup" option for managing AF when preventive pharmacological/electrical measures fail. This and several other personalized hybrid therapeutic approaches await exploration, though assessment of their efficacy is methodologically challenging. Achievement of acceptance by patients is an essential premise for any updated atrial defibrillation strategy. Strategies that are being investigated to improve patient tolerance include waveform shaping, pharmacologic modulation of pain, and patient-activated defibrillation (patients might also perceive the problem of discomfort somewhat differently in the context of a backup therapy). The economic impact of implementing atrial defibrillation features in available devices is progressively decreasing, and financial feasibility need not be a major issue. Future studies should examine clinically relevant outcomes and not be limited (as occurred with stand-alone defibrillators) to technical or other soft endpoints.

Optimization of pacing algorithms to prevent and treat supraventricular tachyarrhythmias

Preventive atrial pacing and antitachycardia pacing have been proposed for the treatment of atrial fibrillation and associated arrhythmias in patients with indications for device implantation. Preventive algorithms provide overdrive atrial pacing, reduction of atrial premature beats, and prevent short-long atrial cycles with good patient tolerance. However, clinical trials testing preventive algorithms have shown contradictory results, possibly because of different trial designs, end points and patient populations. Factors probably responsible for neutral results include an already high atrial pacing percentage with the conventional DDDR mode, suboptimal atrial pacing site, and the deleterious effects of high percentages of right ventricular apical pacing. Atrial antitachycardia pacing therapies are effective in treating organized atrial tachyarrhythmias (that precede atrial fibrillation), mainly when delivered early after the onset particularly if the tachycardia is relatively slow. Antitachycardia pacing therapies might influence atrial fibrillation burden, but clinical studies have shown conflicting results about this issue. Consistent monitoring of atrial and ventricular rhythm including progression to persistent forms of atrial arrhythmias, variability of atrial arrhythmia recurrence patterns and onset mechanisms as well as antitachycardia pacing efficacy should be recorded in the stored device memory and used for optimal individual programming of these new functions.

Pharmacotherapy changes following pacemaker implantation in patients with bradycardia-tachycardia syndrome

The management of bradycardia-tachycardia syndrome (BTS) includes bradycardia and tachyarrhythmia therapy. At present, the treatment for symptomatic bradycardia in BTS patients is permanent cardiac pacing. The pharmacological treatment of atrial tachyarrhythmias comprises of rhythm and rate control, and prevention of thromboembolism. Patients with BTS often require both pacemaker and drug therapy. This article reviews the interactions of pacing and drug therapies in BTS. Drugs that alter cardiac electrophysiological properties may influence pacemaker indications, pacing mode selection, efficacy of pacing algorithms and pacing performance. Pacing by preventing drug-induced bradycardia increases the safety of pharmacotherapy and, thus, allows the intensification of those treatments. Pacing therapy and antiarrhythmic drugs used together as a hybrid therapy have a synergistic effect in the prevention of atrial tachyarrhythmias. Atrial-based pacing may reduce atrial tachyarrhythmia burden, allowing reduction of rhythm and rate control. Contemporary pacemakers' memory functions may help guide rhythm and rate control, as well as anticoagulation pharmacotherapy.

Randomized comparison between Ramp and Burst+ atrial antitachycardia pacing therapies in patients suffering from sinus node disease and atrial fibrillation and implanted with a DDDRP device

AIMS

Atrial tachycardia and flutter frequently occur in association with atrial fibrillation and may be treated by overdrive pacing in patients who receive pacemakers with antitachycardia pacing (ATP) capabilities. The PITAGORA trial was a multi-centre, randomized, cross-over study aimed at comparing two different ATP modes for atrial tachyarrhythmia (AT) termination in patients suffering from sinus node disease (SND).

METHODS AND RESULTS

One hundred and seventy-six patients (72 M, age 71+/-9 years) received a Medtronic AT500 pacemaker. All patients were on class IC or III antiarrhythmic drugs. After a 5-month observation period, 170 patients were randomized to either Ramp or Burst+ ATP therapy; 4 months later they crossed over. One hundred and fifty-seven patients completed the 13 months of follow-up; 114 (72.6%) suffered 6088 AT episodes. In 75 patients, 1904 AT episodes were treated and 934 (49.1%) successfully terminated. The median value of individual patients' ATP efficacy was 60%. Burst+ terminated 387 out of 873 AT episodes (44%) in 58 patients. Ramp terminated 547 out of 1031 AT episodes (53%, P<0.001) in 56 patients. Ramp efficacy was significantly (P<0.01) and directly correlated with AT cycle length (ATCL), whereas Burst+ efficacy was not. Ramp showed higher (P<0.001) termination efficacy than Burst+ for ATCL >240 ms. Quality of life, as measured by the EuroQoL questionnaire, and number of symptoms significantly improved in the overall population. This improvement was significantly higher in patients with ATP efficacy >60%.

CONCLUSION

In patients suffering from SND and AT, Ramp therapy shows higher termination efficacy than Burst+ therapy in AT episodes with ATCL >240 ms. Further studies are required to show the impact of ATP on clinical outcomes.

Design and rationale of a randomized study to compare amiodarone and Class IC anti-arrhythmic drugs in terms of atrial fibrillation treatment efficacy in patients paced for sinus node disease: the PITAGORA trial

AIMS

Many sinus node disease (SND) patients suffer from atrial fibrillation (AF). Anti-arrhythmic drugs (AADs) are the therapeutic mainstay for AF prophylaxis. The PITAGORA trial has a multicentre, prospective, randomized, single blind design to compare amiodarone with Class IC AADs in patients who have an AF history and are paced for SND.

METHODS AND RESULTS

Starting from January 2001, 176 patients received a Medtronic AT500 pacemaker. AADs were randomly assigned with a 3 : 2 ratio between Class III and Class IC. Randomization was stratified in order to assign two patients to amiodarone and one patient to sotalol every three Class III AAD patients. After a 5-month observational period, Ramp or Burst+ ATP therapies were enabled in a randomized way, maintained for 4 months, and then crossed over. Total follow-up period is 21 months. The primary long-term objective is to show the non-inferiority of IC AADs compared with amiodarone in terms of time to first occurrence of a composite endpoint (death, atrial cardioversion, hospitalizations due to AF or heart failure, or change of AADs). Data will be analysed on an intention-to-treat basis. The primary short-term objective is to compare Ramp vs. Burst+ efficacy in terminating atrial tachyarrhythmias treated by the device. Secondary endpoints are major clinical events, medication toxicity, symptoms, AF burden, and quality-of-life.

CONCLUSION

Given the high morbidity and healthcare costs associated with AF, new therapeutic strategies are needed. The results of the PITAGORA trial may help in guiding AADs therapy and ATP programming in SND patients suffering from AF.

Long-term reduction of atrial tachyarrhythmia recurrences in patients paced for bradycardia-tachycardia syndrome

BACKGROUND

Atrial tachyarrhythmias (AT) are considered progressive diseases. Several rhythm control therapies for treatment of AT have been proposed.

OBJECTIVES

The Italian AT500 Registry was designed to prospectively study long-term AT evolution in patients paced for the brady-tachy form of sinus node disease (BT-SND).

METHODS

Three hundred forty-six BT-SND patients received an antitachycardia dual-chamber pacemaker and were followed-up for a minimum of 12 months (median 19 months). Prevention and antitachycardia pacing (ATP) features were enabled in all patients.

RESULTS

During the observation period, 224 (65%) patients were treated by antiarrhythmic drugs and 45 (13%) patients were cardioverted. Five patients suffered a stroke, 4 transient ischemic attack, 22 permanent AT, and 98 AT recurrences longer than 7 days. AT mean cycle length changed from 246 to 270 ms, and the percentage of patients with AT-related hospitalizations significantly decreased with an annual 28% relative reduction. AT burden and the percentage of patients with AT recurrences longer than 2 days remained constant with time in the overall population but decreased significantly in the subgroup of patients who did not develop permanent AT. High ATP efficacy was associated with an increasingly higher prevention of AT recurrences longer than 2 days.

CONCLUSION

In a long-term observation of BT-SND patients, AT-related hospitalizations decreased significantly and mean AT cycle length increased significantly. The data suggest that rhythm control therapies induce inversion of AT progression.