PT - JOURNAL ARTICLE AU - V N Nathwani AU - K W Wong AU - M J Jones AU - C H Hayes AU - K R Rajappan AU - T B Betts AU - Y B Bashir TI - 069 CASE SERIES OF ATRIAL FLUTTER WITH 1:1 CONDUCTION: A COMPARATIVE ANALYSIS AMONG GROUPS OF PATIENTS SUFFERING SPONTANEOUS VERSUS DRUG INDUCED 1:1 CONDUCTING ATRIAL FLUTTER AID - 10.1136/heartjnl-2013-304019.69 DP - 2013 May 01 TA - Heart PG - A45--A45 VI - 99 IP - suppl 2 4099 - http://heart.bmj.com/content/99/suppl_2/A45.1.short 4100 - http://heart.bmj.com/content/99/suppl_2/A45.1.full SO - Heart2013 May 01; 99 AB - Background Atrial flutter with 1:1 (AFL 1:1) conduction may be spontaneous or secondary to anti-arrhythmic drug (AAD) use. This group of patients are not well characterised. We aimed to compare various characteristics between patients suffering 'spontaneous' AFL 1:1 (the development of 1:1 Atrioventricular conducting Atrial Flutter in the absence of concomitant AAD use) and 'Drug-induced' AFL 1:1. View this table: Table 1 Methods This is a retrospective study of patients referred to our institution over an 8 year period. Sixty-eight patients had confirmed and documented atrial flutter with 1:1 conduction. Results Baseline clinical characteristics and differences between the study populations are summarised in Table. Patients with spontaneous AFL 1:1 had a significantly higher flutter rate and were less likely to have concomitant AF. Drug-induced AFL 1:1 was mainly secondary to Class 1 AAD's despite the use of AV blocking agents in a third of these patients. Sixty-three patients underwent a successful cavotricuspid isthmus ablation with no recurrence. Conclusions We have reported the largest series of patients with atrial flutter and 1:1 conduction. Patients suffering spontaneous AFL 1:1 had a significantly faster flutter rate compared to the drug-induced population.