Relative prolongation of the terminal part of the QT segment is associated with sudden death in the elderly

Holter-based QT parameters were measured in 40 matched participants (age 73.03 ± 4.51, 24 M, 8 F), 20 with SCD (sudden cardiac death) and 20 without SCD who had recordings in the Cardiovascular Health Study. Time to SCD was 6.5±2.8 years. Beat-by-beat QT_onset, QT_peak, and QT_end times were measured and averaged for one 2-min segment/hr and results compared between cases and controls. QT interval was significantly longer among cases (445 ± 88 vs. 405 ± 45 ms, p<0.001). Correcting the QT for heart rate did not affect this relationship. % QT in the pre-peak interval was significantly shorter in SCD cases (23.7 ± 3.1% vs. 24.2 ± 3.7%, p=0.040). % QT in the post-peak interval was significantly longer in SCD cases (23.4 ± 3.9% vs. 22.0 ± 2.5%, p<0.001). Results did not differ by the channel examined. Findings are consistent with a prolonged Holter-based QT and an additional relative prolongation of the terminal QT, in older adults with SCD.