Background: The growing population with Fontan operation surviving into adulthood has significant morbidity and mortality rates from recurrent atrial tachyarrhythmias. We hypothesized that the structural characteristics and electrical behavior of atria may differ in these patients compared with those without arrhythmias.
Methods and results: We studied 33 consecutive patients (age, 25.4+/-9.5 years) with Fontan circulation, of whom 19 had a history of documented sustained atrial tachyarrhythmias. We analyzed their clinical and investigational data, including echocardiographic assessment of atrial dimensions and surface 12-lead ECG measurement of the P-wave duration and its dispersion between leads. Twenty age- and sex-matched healthy control subjects were also studied. First, patients who had the Fontan procedure overall had longer P-wave duration (144+/-33 versus 100+/-7 ms, P<0.001) and greater P-wave dispersion (74+/-33 versus 34+/-9 ms, P<0.001) than control subjects. Among the patients who had the Fontan procedure, those with atrial tachyarrhythmias had longer P-wave duration (159+/-28 versus 123+/-28 ms, P<0.001) and greater P-wave dispersion (91+/-30 versus 50+/-19 ms, P<0.001) than those without. Second, the patients with atrial tachyarrhythmias who had the Fontan procedure had larger right atrial dimension than those without arrhythmias (6.4+/-1.4 versus 5.0+/-1.0 cm, P=0.01). Third, both P-wave duration and dispersion were significantly correlated to right atrial dimension within the Fontan group (r=0.55, P=0.002, and r=0.56, P=0.002, respectively).
Conclusions: Patients with atrial tachyarrhythmias late after Fontan operation have longer P-wave duration and P-wave dispersion and larger right atrial dimension than those without the arrhythmias; these abnormalities are interrelated. This observation represents an atrial mechano-electrical remodeling phenomenon in parallel to an increase in arrhythmia propensity in this vulnerable population and warrants further investigation.