Catheter ablation provides an effective cure for patients with typical atrial flutter. However, these patients may have the potential to develop atrial tachyarrhythmias other than common atrial flutter. This study examines clinical and echocardiographic predictors for the occurrence of uncommon atrial flutter or atrial fibrillation after abolition of common atrial flutter. The study population comprised 17 patients (12 men, 5 women, age 32-74 years) who underwent successful radiofrequency catheter ablation of common atrial flutter. Common atrial flutter did not recur in any patient during a median follow-up time of 8 (range 1-25) months. Within a median of 7 (range 1-223) days, however, symptomatic atrial tachyarrhythmias occurred in 8 of 17 patients (47%): uncommon atrial flutter (n = 4); atrial fibrillation (n = 3); and both uncommon atrial flutter and atrial fibrillation in one patient. Preablation left atrial volume was significantly larger in patients who developed secondary arrhythmias compared with patients who remained in sinus rhythm (57.9 +/- 15.6 vs 43.7 +/- 16.4 cm3, P < 0.05). Enlarged left atrial volume dichotomized at 51 cm3 independently predicted postablation atrial arrhythmias (X2 = 5.11, rel. risk = 5.3, P < 0.05). On Kaplan-Meier analysis, time to occurrence of postablation atrial arrhythmias was significantly shorter in patients with enlarged left atrium (P < 0.02). In conclusion, symptomatic uncommon atrial flutter and atrial fibrillation develops in a substantial proportion of patients after successful ablation of common atrial flutter. Out of a series of clinical and echocardiographic parameters, preablation left atrial size is the best predictor for the occurrence of these postablation atrial arrhythmias.