International Journal of Cardiology, 36 (1992) 87-93 0 1992 Elsevier Science Publishers B.V. All rights reserved 0167-5273/92/$05.00 x7 CARDIO 01481 Atria1 premature beats coupling interval determines lone paroxysmal atria1 fibrillation onset Alessandro Capucci, Andrea Santarelli, Giuseppe Boriani and Bruno Magnani Institute of Cardiovascular Diseases, University of Bologna, Italy (Received 13 May 1991; revision accepted 10 February 1992) Capucci A, Santarelli A, Boriani G, Magnani B. Atria1 premature beats coupling interval determines lone paroxysmal atria1 fibrillation onset. Int J Cardiol 1992;36:87-93. In 20 patients with recurrent episodes of lone paroxysmal atria1 fibrillation we assessed the onset pattern of each episode of either atria1 fibrillation or of atria1 flutter during a 24-h Holter monitoring. We evaluated 24 twenty-four-hour Holter tape recordings and our data are related to 168 episodes of paroxysmal atria1 fibrillation and 27 episodes of paroxysmal atria1 flutter. Eighty-five percent of atria1 fibrillations and 67% of atria1 flutters were of short duration ( < 5 min). The majority of patients (80%) had either nocturnal or daily episodes of arrhythmia and PP intervals immediately before onset of arrhythmia did not show significant variations in 77% of cases. The coupling interval of the supraventric- ular premature beats eliciting atria1 fibrillation was significantly shorter than the coupling intervals of the spontaneous isolated supraventricular premature beats (p < 0.0001); again, in 6 patients with either atria1 fibrillation or flutter, the coupling interval at onset of fibrillation was significantly shorter in comparison to flutter (p < 0.0001). In conclusion, vagal or sympathetic prevalence does not seem to influence significantly the beginning of the arrhythmia, while the coupling interval of the atria1 premature beats plays a critical role in the inducibility of atria1 flutter or fibrillation. Key words: Atria1 fibrillation; Atria1 premature beat; Coupling interval zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQ Introduction Atria1 fibrillation is the most common sus- tained rhythm disorder observed in clinical prac- tice. It may be manifest either as a paroxysmal or established form, Paroxysmal atria1 fibrillation in the absence of any associated heart disease is a Correspondence to: A. Capucci, M.D., Institute of Cardio- vascular Diseases, Policlinico S. Orsola, Via Massarenti 9. I-40136-Bologna, Italy. condition seldom related to an increased risk of embolic complications [ 11; however, particularly long-lasting forms at high ventricular rate can favour the inducibility of a reversible congestive heart failure even in the absence of significant underlying myocardial disease [2], or produce a significant impairment of the quality of life. The electrophysiological mechanisms which form the basis for lone paroxysmal atria1 fibrilla- tion are still controversial. Allessie recently demonstrated in experimental preparations how reentry can be functionally determined without