Electrophysiological effects of disopyramide phosphate in patients with sinus node dysfunction

Area of Science:

• Electrophysiology
• Cardiology

Background:

• Sinus node dysfunction (SND) presents complex electrophysiological challenges.
• Supraventricular arrhythmias often coexist with SND, requiring effective treatment strategies.

Purpose of the Study:

• To investigate the electrophysiological effects of disopyramide in patients with SND.
• To evaluate the efficacy of disopyramide in managing supraventricular arrhythmias in this patient population.

Main Methods:

• Intravenous administration of disopyramide (1.5 mg/kg) in 26 patients with SND.
• Electrophysiological measurements including spontaneous cycle length (SCL), sinus node recovery time (max SRT), sinoatrial conduction time (SACT), and atrial/AV nodal refractoriness.
• Long-term oral administration in a subset of patients with supraventricular arrhythmias.

Main Results:

• Disopyramide did not significantly alter SCL, max SRT, or SACT, though individual variations were observed.
• Significant lengthening of HV intervals and atrial refractory periods was noted.
• Disappearance of atrial echo and premature beats in 7 of 12 patients, correlated with increased atrial refractoriness.
• Oral disopyramide resolved supraventricular arrhythmias and symptoms, and increased sinus rate in 4 patients.

Conclusions:

• Disopyramide significantly prolongs atrial refractoriness, leading to the suppression of atrial arrhythmias.
• The drug appears effective for managing supraventricular arrhythmias in patients with SND.
• Disopyramide demonstrates potential as a therapeutic agent for SND patients experiencing concurrent supraventricular arrhythmias.