QT interval and short-term outcome in acute heart failure

Abstract

Objective: To investigate the association of corrected QT (QTc) interval duration and short-term outcomes in patients with acute heart failure (AHF).

Methods: We analyzed AHF patients enrolled in 11 Spanish emergency departments (ED) for whom an ECG with QTc measurement was available. Patients with pace-maker rhythm were excluded. Primary outcome was 30-day all-cause mortality and secondary outcomes were need of hospitalization, in-hospital mortality and prolonged hospitalization (> 7 days). Association between QTc and outcomes was explored by restricted cubic spline (RCS) curves. Results were expressed as odds ratios (OR) and 95%CI adjusted by patients baseline and decompensation characteristics, using a QTc = 450 ms as reference.

Results: Of 1800 patients meeting entry criteria (median age 84 years (IQR = 77-89), 56% female), their median QTc was 453 ms (IQR = 422-483). The 30-day mortality was 9.7%, while need of hospitalization, in-hospital mortality and prolonged hospitalization were 77.8%, 9.0% and 50.0%, respectively. RCS curves found longer QTc was associated with 30-day mortality if > 561 ms, OR = 1.86 (1.00-3.45), and increased up to OR = 10.5 (2.25-49.1), for QTc = 674 ms. A similar pattern was observed for in-hospital mortality; OR = 2.64 (1.04-6.69), for QTc = 588 ms, and increasing up to OR = 8.02 (1.30-49.3), for QTc = 674 ms. Conversely, the need of hospitalization had a U-shaped relationship: being increased in patients with shorter QTc [OR = 1.45 (1.00-2.09) for QTc = 381 ms, OR = 5.88 (1.25-27.6) for the shortest QTc of 200 ms], and also increasing for prolonged QTc [OR = 1.06 (1.00-1.13), for QTc = 459 ms, and reaching OR = 2.15 (1.00-4.62) for QTc = 588 ms]. QTc was not associated with prolonged hospitalization.

Conclusion: In ED AHF patients, initial QTc provides independent short-term prognostic information, with increasing QTc associated with increasing mortality, while both, shortened and prolonged QTc are associated with need of hospitalization.

Keywords: Acute heart failure; Electrocardiogram; Emergency department; Mortality; Outcome; QTc interval.

Fig. 1

Flow chart for patient inclusion and patient distribution according to the QTc interval duration. ED emergency department, ECG electrocardiogram

Fig. 2

Restricted cubic spline curves showing the observed probability of primary and secondary outcomes according to the duration of the QTc interval duration

Fig. 3

Unadjusted and adjusted representation of the magnitude of the effect of QTc duration on the primary outcome (30-day all-cause mortality) expressed in a dose–response manner as odds ratio (OR) with 95% confidence intervals (CI) taking QTc duration of 450 ms as reference. Tables on the right present some selected OR, with 95% CI (LL lower limit, UL upper limit), in the adjusted models. Bold numbers in table denote statistical significance (p < 0.05). Adjusted by baseline patient characteristics and characteristics of decompensation (Table 1). *Patients with left brunch-bundle block were eliminated in this sensitivity analysis. **QT duration was corrected with the Rautaharju’s formula in patients with left brunch-bundle block

Fig. 4

Adjusted* representation of the magnitude of the effect of QTc duration on the secondary outcomes (left: need of hospitalization; middle: in-hospital all-cause mortality; right: prolonged hospitalization) expressed in a dose–response manner expressed as odds ratio (OR) with 95% confidence intervals (CI) taking QTc duration of 450 ms as reference. Tables beside graphs present some selected OR, with 95% CI (LL lower limit, UL upper limit). Bold numbers in table denote statistical significance (p < 0.05). *Adjusted by baseline patient characteristics and characteristics of decompensation (Table 1)

Fig. 5

Analysis of interactions in the adjusted model (with imputation) for 20 selected variables in the relationship between QTc interval duration and the primary outcome (30-day all-cause mortality). Bold p values denote statistical significance (< 0.05). NYHA Ney York Health Association, LVEF left ventricular ejection fraction, RAS renin-angiotensin system inhibitors, MRA mineralocorticosterid receptor antagonists, OR odds ratio, 95% CI 95% confidence interval