Roles of atrial arrhythmias in triggering torsade de pointes in patients with acquired long QT syndrome

Abstract

Abstract Background Little is known about a role of atrial arrhythmias (AAs) in triggering Torsade de Pointes (TdP) in patients with long QT syndrome (LQTS). Purpose To determine the prevalence of AAs-induced TdP in acute acquired LQTS patients and to classify the AAs’ roles in the development of TdP. Methods Initiation patterns of 81 episodes of TdP obtained from 34 consecutive acquired LQTS patients (14 men; median age, 69 years; median QTc, 645.5 ms) with documented TdP were analysed. The patients were divided into 2 groups based on the presence or absence of AAs involvement in triggering TdP: AAs-induced and non-AAs-induced groups. Results AAs-induced group comprised 52.9% (18/34) of the patients studied. TdP was preceded by AAs-induced short-long sequences (SLSs) in 41.2% (14/34) of the patients and directly induced by R-on-T AAs (AAs coincidentally encounter a vulnerable repolarizing region during the T wave) in 23.5% (8/34). AAs-induced group experienced TdP after initiating therapy more frequently than non-AAs-induced group (2.5 vs. 1, p=0.008). AAs triggered 48 (59.3%) of the 81 TdP episodes. AAs-induced SLS comprised 67.8% (40 /59) of the SLS-induced TdP episodes. R-on-T AAs accounted for 23.5% (19/81) of the TdP episodes. Conclusions Our observations suggest that AAs are associated with the onset mechanism of TdP in more than half of acute acquired LQTS patients and even increase TdP frequency. Thus, AAs are not benign but rather can be lethal in acute acquired LQTS patients.Representative casesAnalysis of Torsade de Pointes episodes