Key result
Patients with lone paroxysmal AF had a higher incidence of inducible AF with one extrastimulus compared to controls (54.2% vs 0%, P=0.0014), along with prolonged local conduction time.
Why the study?
Does an electrophysiological study reveal differences in intraatrial conduction, atrial refractoriness, and arrhythmia inducibility between patients with lone paroxysmal AF and controls?
Case-Control (n=36)
Does an electrophysiological study reveal differences in intraatrial conduction, atrial refractoriness, and arrhythmia inducibility between patients with lone paroxysmal AF and controls?
Electrophysiological studies reveal intrinsic atrial substrate abnormalities, such as prolonged conduction time and lack of functional refractory period rate adaptation, in patients with lone paroxysmal atrial fibrillation.
Answers are grounded in this paper and cite their sources.
Supports atrial substrate abnormalities in lone paroxysmal AF; hypothesis-generating and should not yet change practice or guide therapy.
Little is known about the electrophysiological properties of the atrium predisposing to paroxysmal atrial fibrillation (AF), especially in patients without structural heart disease. This study was conducted to analyze intraatrial conduction, atrial refractoriness, and arrhythmia inducibility in patients with lone paroxysmal AF. An electrophysiological study was performed in 24 patients with a documented history of lone paroxysmal AF but in sinus rhythm at the time of the electrophysiological study. Twelve patients without any history of atrial arrhythmias served as controls. The patients with lone paroxysmal AF showed a significant prolonged local conduction time S1A1 (70 +/- 21 ms vs 36 +/- 12 ms, P < 0.0001), a lack of rate adaptation of the functional refractory period (FRP changes/cycle length changes < 10% in 15 of 24 patients with lone paroxysmal AF vs 1/12 controls, P = 0.002) and a higher incidence of inducible AF with only one extrastimulus (13/24 vs 0/12, P = 0.0014). The total P wave duration in the surface ECG (89 +/- 14 ms vs 83 +/- 8 ms, P = 0.15), the intraatrial conduction time (36 +/- 14 ms vs 28 +/- 8 ms, P = 0.07), the presence of a fragmented atrial electrogram (16/24 vs 7/12, P = 0.62), the absolute value of the effective refractory period (204 +/- 28 ms vs 212 +/- 23 ms, P = 0.42), and the vulnerability index (3.0 +/- 1.5 vs 3.6 +/- 1.5, P = 0.26) were not statistically different between the two groups. The presence of a prolonged (> 50 ms) S1A1 and/or the presence of a lack of rate adaptation of the FRP and/or the presence of inducible AF identified patients with spontaneous lone paroxysmal AF with a sensitivity of 96%, a specificity of 67%, a positive predictive value of 85%, and a negative predictive value of 89%. In patients with lone paroxysmal AF, the electrophysiological study using conventional techniques allows not only to detect AF inducibility using a nonaggressive protocol, but also to reveal several electrophysiological abnormalities related to the atrial substrate itself. This atrial vulnerability may explain the high incidence of recurrences in patients with lone paroxysmal AF.
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Zimmermann et al. (1998) conducted a case-control in Paroxysmal "lone" atrial fibrillation (n=36). Electrophysiological study vs. Patients without any history of atrial arrhythmias was evaluated on Inducible AF with only one extrastimulus (p=0.0014). Patients with lone paroxysmal AF had a higher incidence of inducible AF with one extrastimulus compared to controls (54.2% vs 0%, P=0.0014), along with prolonged local conduction time.
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