Skip to main content

New-onset QT prolongation is a novel predictor of mortality in critically ill patients

QT prolongation is associated with increased mortality in different types of patients [1, 2]. QT prolongation is common in critically ill patients [3], and the association between heart rate corrected QT (QTc) and outcome in critically ill patients has raised broad interests most recently [4]. However, the prevalence of new-onset QT prolongation and its significance in these patients was not well studied yet.

Here, we prospectively recruited 505 consecutive ICU patients without known previous QT prolongation to evaluate the risk factors for new-onset QT prolongation and the prognostic value of QTc calculated by different methods. The baseline clinical and laboratory characteristics of subjects were shown in Table 1. The mean Bazett QT interval was 413.6 ± 33.8 ms. New-onset QT prolongation occurred in 99 patients (19.6%). This occurrence is about 200-fold higher than that in the general population [5]. Intriguingly, the occurrence of nonthyroidal illness syndrome (NTIS) is significantly higher in patients with QT prolongation than those without (Table 1), indicating that NTIS might be a risk factor of QT prolongation. Indeed, multivariate linear regression showed that QTc was independently associated with NTIS, heart rate, level of serum potassium, gender, and estimated glomerular filtration rate (eGFR).

Table 1 Clinical and laboratory characteristics of subjects

There was a significantly graded increase in mortality rate across increasing QTc quintile (p = 0.004) (Fig. 1a). The overall mortality rate in patients with a new-onset QTc prolongation is more than two times higher than those patients without (22.2% vs 9.6, OR = 2.69, p = 0.001) (Fig. 1b). Multivariate logistic regression showed that QT prolongation is still independently associated with ICU mortality even after adjusted for age and gender (p = 0.001, 95% C.I., 1.51–4.79). However, QT prolongation is no longer a predictor of ICU mortality if APACHE-II score was further adjusted (p = 0.329), likely due to that QTc itself is strongly associated with APACHE-II score (r = − 0.235, p < 0.001).

Fig. 1
figure 1

a ICU mortality rates among patients with different QTc quintile. *Linear-by-Linear Association by chi-square test. b Overall ICU mortality rates among patients with or without QT prolongation

As Bazett’s formula can over-correct QT at high heart rates and under-correct it at low heart rates, we then evaluated the prognostic value of QTc calculated using additional formulas including Fridericia’s, Framingham’s, and Hodges’s. We found that patients in quintile 5 have significantly higher mortality than patients in the combination of quintiles 1–4 regardless of which formula was used (all p < 0.05).

In summary, QT prolongation determined by baseline ECG can serve as a novel indicator of the severity of illness in critically ill patients. NTIS is a new risk factor of QT prolongation in critically ill patients.

Availability of data and materials

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.


APACHE-II score:

Acute Physiology and Chronic Health Evaluation II score


Estimated glomerular filtration rate


Intensive care unit


Nonthyroidal illness syndrome


Heart rate-corrected QT


  1. O'Neal WT, Singleton MJ, Roberts JD, Tereshchenko LG, Sotoodehnia N, Chen LY, Marcus GM, Soliman EZ. Association between QT-interval components and sudden cardiac death: the ARIC study (atherosclerosis risk in communities). Circ Arrhythm Electrophysiol. 2017;10:e005485.

  2. Zhang Y, Post WS, Dalal D, Blasco-Colmenares E, Tomaselli GF, Guallar E. QT-interval duration and mortality rate: results from the Third National Health and Nutrition Examination Survey. Arch Intern Med. 2011;171:1727–33.

    Article  Google Scholar 

  3. Fukui S, Katoh H, Tsuzuki N, Ishihara S, Otani N, Ooigawa H, Toyooka T, Ohnuki A, Miyazawa T, Nawashiro H, Shima K. Multivariate analysis of risk factors for QT prolongation following subarachnoid hemorrhage. Crit Care. 2003;7:R7.

    Article  Google Scholar 

  4. Javanainen T, Ishihara S, Gayat E, Charbit B, Jurkko R, Cinotti R, Mebazaa A. Prolonged corrected QT interval is associated with short-term and long-term mortality in critically ill patients: results from the FROG-ICU study. Intensive Care Med. 2019;11:1–3.

    Google Scholar 

  5. van Noord C, Eijgelsheim M, Stricker BH. Drug- and non-drug-associated QT interval prolongation. Br J Clin Pharmacol. 2010;70:16–23.

    Article  Google Scholar 

Download references




This work was supported by the “Gaoyuan” project from Pudong Health and Family Planning Commission (PWYgy2018-06).

Author information

Authors and Affiliations



FW conceived and designed the study. YD, RJ, LR, and WP contributed to data acquisition and analysis. QL interpreted the data and provided insightful input to this study. All authors read and approved the final manuscript.

Corresponding authors

Correspondence to Feilong Wang or Qiang Li.

Ethics declarations

Ethics approval and consent to participate

The study was approved by the Shanghai Jiaotong University Xinhua Hospital Ethics Committee (XHEC2011-002).

Consent for publication

Not applicable

Competing interests

The authors declare that they have no competing interests.

Additional information

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Ding, Y., Jeon, R., Ran, L. et al. New-onset QT prolongation is a novel predictor of mortality in critically ill patients. Crit Care 23, 229 (2019).

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: