High-normal QT interval as a predictor of 1-year mortality in hospitalized older adults

Prolongation of the QT interval might be associated with cardiac stress and poor prognosis. Therefore, we sought to study the association between QT interval prolongation and 1‑year mortality in the general population of hospitalized older adults.

A retrospective cohort study. Charts of consecutive older adults (aged ≥ 65 years) admitted to an acute geriatrics department in a tertiary medical center over 15 months were reviewed. Age, gender, chronic comorbidities, functional status, admission corrected QT (QTc) interval ratio and all-cause 1‑year mortality were recorded. The QTc interval ratio was the actual QTc interval divided by 450 ms in males and by 470 ms in females (accepted cut-off of pathologic QT interval prolongation associated with sudden cardiac death). Patients in the upper three quartiles (study group) of the QTc interval ratio were compared to patients in the lowest quartile (control group).

A total of 526 patients were included: 334 (63.5%) females, mean age 84.0 ± 7.3 years. Median admission QTc interval was 443 ms (range: 289-689 ms). Overall, 388 (73.8%) patients were included in the study group (QTc interval ≥ 415 ms in males and ≥ 434 ms in females) and 138 (26.2%) patients were included in the control group (QTc interval ≤ 414 ms in males and ≤ 433 ms in females). Overall, 147 (27.9%) patients died within 1 year: 120 (30.9%) in the study group and 27 (19.6%) in the control group (Kaplan-Meier log-rank p = 0.009). Multivariable Cox regression analysis showed an association between 1‑year mortality and being in the study group (hazard ratio, HR 1.60, 95% confidence interval, CI 1.03-2.48, p = 0.034) independent of age, gender, chronic comorbidities and functional status.

High-normal QT interval on admission, not necessarily prolonged, is associated with all-cause 1‑year mortality in the general population of hospitalized older adults. Accordingly, lower cut-offs may need to be considered in this population to define pathologic QT interval prolongation in its association with all-cause 1‑year mortality rather than with sudden cardiac death.