• Users Online: 263
  • Home
  • Print this page
  • Email this page
Home About us Editorial board Search Ahead of print Current issue Archives Submit article Instructions Subscribe Contacts Login 


 
 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 31  |  Issue : 2  |  Page : 136-141

Prolonged QTc interval in adults with diabetic ketoacidosis: is it only electrolyte disturbance?


Department of Internal Medicine, Zagazig University, Zagazig, Sharkia Governorate, Egypt

Date of Submission10-Dec-2018
Date of Acceptance16-Jan-2019
Date of Web Publication28-Jun-2019

Correspondence Address:
Ayman M.E.M Sadek
Shoubak Basta, Zagazig 44519, Sharkia Governorate
Egypt
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ejim.ejim_112_18

Rights and Permissions
  Abstract 

Context Cardiac arrhythmia in diabetic ketoacidosis (DKA) is a well-known complication that is usually a result of electrolyte imbalance. Another frequently missed cause of arrhythmia is the QT interval prolongation, which is not always attributed to electrolytes disturbance.
Aim We aimed to explore the frequency of QTc interval prolongation among patients with DKA in the medical ICU, the association with serum electrolytes and pH, and the implication on the outcome.
Patients and methods We carried out a cross-sectional cohort study on patients with DKA admitted to medical ICU. We had worked on 72 patients with DKA by performing the routine investigation including ECG follow-up during the hospital stay. Maximum QT interval in all measured leads (QTmax) and heart rate-corrected QTmax (QTmaxc) were calculated in milliseconds according to Bazett’s formula. We used SPSS, version 20.0, with the following statistical tests: Shapiro–Walk, Student’s t, Pearson’s correlation, logistic regression, receiver operating characteristic curve analysis, and relative risk.
Results The frequency of QTmaxc interval prolongation without electrolyte imbalance was seen in 46 (63.9%) patients. pH revealed to be the most significant independent risk factor for QTmaxc interval prolongation (odds ratio=8.39, 95% confidence interval: 1.67–18.06) with a cutoff value less than 7.03, with sensitivity of 56% and specificity of 44%. QTmaxc prolongation carried a relative risk of ∼1.7-fold for mortality in patients with DKA.
Conclusion Acidosis carries an independent risk for QTmaxc interval prolongation in the absence of electrolytes abnormalities, with related poor ICU outcome in patients with DKA.

Keywords: diabetic ketoacidosis, ICU, QT interval


How to cite this article:
Khalil OA, Samir GM, Sadek AM. Prolonged QTc interval in adults with diabetic ketoacidosis: is it only electrolyte disturbance?. Egypt J Intern Med 2019;31:136-41

How to cite this URL:
Khalil OA, Samir GM, Sadek AM. Prolonged QTc interval in adults with diabetic ketoacidosis: is it only electrolyte disturbance?. Egypt J Intern Med [serial online] 2019 [cited 2019 Sep 22];31:136-41. Available from: http://www.esim.eg.net/text.asp?2019/31/2/136/261722




  Introduction Top


Egypt has the highest prevalence of type 1 diabetes mellitus in middle-income Arabian countries, with diabetic ketoacidosis (DKA) frequency ranging from 17 to 61% [1].

Cardiac arrhythmia and cardiac arrest have been attributed to electrolyte abnormalities during DKA treatment [2].

During DKA, ketosis or acidosis may directly affect cardiac repolarization with prolongation of QTc interval, leading to arrhythmia and cardiac arrest [3].

Previous studies had reported prolongation of QTc interval in children during DKA with a suggestion of whether ketosis or acidosis may directly affect cardiac repolarization and cause arrhythmia and cardiac arrest during DKA, but to our knowledge, few data were reported in adult [3],[4],[5],[6].

We aimed to explore the frequency of QTc interval prolongation among patients with DKA in the medical ICU, the association with serum electrolytes and pH, and the implication on the outcome.


  Patients and methods Top


Study design and settings

We conducted a prospective observational cohort study in the period from August 2016 to March 2018 on patients with DKA who were selected from medical ICU as presented in the flowchart diagram (Supplementary 1).

Patients

A total of 72 patients with DKA were recruited, including 26 patients who were newly diagnosed with diabetes, whereas the other 46 patients were known diabetic cases. The estimated sample size was 72 patients at 80% power and 95% confidence interval (Open Epi, Open Source Epidemiologic Statistics for Public Health, Atlanta, Georgia, USA).

Ethical clearance

Written informed and oral consents were taken from the relatives of patients who participated in the study in addition to the approval for performing the study that was obtained from medical ICU of Internal Medicine Department after taking the Institutional Review Board (IRB) approval (IRB:871/8-5-2013). We performed the study according to the Helsinki declaration guidelines.

Inclusion criteria and exclusion criteria

We considered patients admitted to medical ICU for DKA, of either sex, with age above 13 years old. DKA was diagnosed by all of the following criteria: blood glucose more than 250 mg/dl, arterial pH of less than or equal to 7.30, bicarbonate level of less than or equal to 18 mEq/l, and an anion gap of more than 12 (adjusted for albumin) [7]. We excluded patients having any underlying condition that may predispose to the prolongation of the QTc interval, for example, structural heart disease (left ventricular hypertrophy, heart failure, myocardial ischemia), hyperthyroidism, hypercholesterolemia, and BMI more than 30 kg/m2. In addition, we omitted patients who were taking medications known to affect QTc.

Process

We subjected the patients to history taking and clinical examination, and routine laboratory investigations (urine analysis, complete blood picture, blood gases and electrolytes, kidney function tests, liver chemistry, lipid profile, thyroid-stimulating hormone, C-reactive protein, and HbA1c). We recorded resting ECG in the first 6 h of admission and after the control of DKA episode. QT interval was measured manually from at least 8-leads. At least two consecutive QT intervals were measured in each lead. Maximum QT interval in all measured leads (QTmax) and heart rate-corrected QTmax (QTmaxc) were calculated in milliseconds. QTmaxc=QTmax/√R−R interval according to Bazett’s formula [8], where QTmaxc equal to or above 450 ms in men or equal to or above 460 ms in women was considered a sign for prolonged QT interval. We calculated Acute Physiology and Chronic Health Evaluation (APACHE) II score within 48 h from admission.

Statistical analysis

We used the SPSS program (version 20.0) for Windows (SPSS Inc., Chicago, Illinois, USA). Data were expressed in the form of mean±SD for continuous variables, and we tested it for normality by using Shapiro–Wilk test. The data were normally distributed, and we interpreted it by independent Student’s t-test. We used Pearson’s correlation coefficient to assess the correlation between QTmaxc interval and study parameters, as the data was parametric. (+) sign as an indication for direct correlation, that is, increase in the frequency of independent leads to increase in the frequency of dependent, and (−) sign as an indication for inverse correlation, that is, increase in the frequency of independent leads to decrease in the frequency of dependent. Moreover, we consider values near to 1 as strong correlation and values near 0 as weak correlation. We used receiver operating characteristic curve analysis to establish the optimal cutoff value of pH with maximum sensitivity and specificity for the differentiation of patients with QTmaxc prolongation from those without. A two-sided (α=2) P value less than 0.05 was considered significant.


  Results Top


This study included 72 patients with age ranging from 14 to 57 years old. A total of 32 patients were males and 40 of patients were females, with ICU stay ranging from 4 to 13 days. We found that 46 (63.9%) patients had a prolonged QTmaxc at the time of admission. All the demographic, clinical, and laboratory data are demonstrated in [Table 1].
Table 1 Demographic and laboratory parameters of the studied patients at the time of admission

Click here to view


Comparison of the data between the patients with prolonged QTmaxc and patients without revealed that pH, anion gap, heart rate, white blood cell, and Acute Physiology and Chronic Health Evaluation II score were the statistically significant factors ([Table 2]).
Table 2 Comparison between nonprolonged heart rate-corrected maximum QT interval in all measured leads (ms) cases and prolonged ones regarding the laboratory data and Acute Physiology and Chronic Health Evaluation II score at the time of admission

Click here to view


Multivariate logistic regression was used after Pearson’s correlation (Supplementary 3) to purify the most significant independent risk factor for QTmaxc prolongation, which was pH ([Table 3]).
Table 3 Multivariate logistic regression for Independent predictors of heart rate-corrected maximum QT interval in all measured leads prolongation

Click here to view


We tried to figure out a cutoff value for pH that may predict the occurrence of QTmaxc prolongation by constructing a receiver operating characteristic curve model ([Figure 1]), which showed that pH below 7.03 had a sensitivity of 56% and specificity of 44% in prediction.
Figure 1 The specificity and sensitivity in the receiver operating characteristic (ROC) curve considering pH as a predictor of mortality.

Click here to view


We found that QTmaxc prolongation carried a relative risk of ∼1.7-fold for mortality in patients with DKA ([Table 4]).
Table 4 Relative risk of heart rate-corrected maximum QT interval in all measured leads prolongation for adverse outcome in diabetic patients admitted with diabetic ketoacidosis

Click here to view


Mortality in prolonged QTmaxc group was mainly owing to sudden cardiac arrest because of malignant ventricular tachycardia captured on the monitors, except for one patient who died from cerebral edema (Supplementary 2).

The study showed a significant resolution of QTmaxc interval prolongation after treatment of DKA ([Figure 2]).
Figure 2 The mean pretreatment heart rate-corrected maximum QT interval in all measured leads (QTmaxc) values were significantly decreased after resolution of diabetic ketoacidosis.

Click here to view



  Discussion Top


The main results of our study can be summarized that the frequency of QTmaxc interval prolongation without electrolyte imbalance was seen in 46 (63.9%) patients. pH revealed to be the most significant independent risk factor for QTmaxc interval prolongation (odds ratio=8.388, 95% confidence interval: 1.673–18.057) with a cutoff value less than 7.03 with sensitivity 56% and specificity 44%. QTmaxc prolongation carried a relative risk of ∼1.7-fold for the development of adverse outcome in patients with DKA.

None of the enrolled patients experienced hypoglycemia, hypokalemia, hypocalcemia, or hypomagnesemia, during DKA treatment, which could account for QTmaxc prolongation, embracing the findings of multiple studies [3],[6],[9],[10],[11]. Therefore, the role of ketoacidosis in causing such prolongation and delayed cardiac repolarization is considered. In contrast, Glaser et al. [2] claimed that the prolongation of QTc interval, cardiac arrhythmias, and arrest presumed to be solely attributed to the electrolyte abnormalities during DKA.

Regarding the heart rate, it had been significantly higher in prolonged QTmaxc cases, which is convenient with the results of Kuppermann et al. [3] and Burkett et al. [12], which considered the heart rate as a strongest independent variable for QTmaxc prolongation. However, Pearson’s correlation in our study abolished this finding and revealed an absence of correlation between QTmaxc and heart rate.

Patients with prolonged QTmaxc in our study had a significantly lower pH at presentation compared with those with nonprolonged QTmaxc values, with a significant positive correlation between QTmaxc and Anion gap, and a significant negative correlation between QTmaxc and pH. The QTmaxc interval prolongation in the current study was significantly decreased (P<0.001) with the recovery from DKA in 35 patients; meanwhile, 11 patients had persistent prolonged QTmaxc even after recovery from DKA, which had returned to normal after one week of hospital discharge. This illustrated the effect of acidosis that may precipitate arrhythmias such as re-entry, pulsus alternans, and early/delayed afterdepolarization, supporting the findings of several studies [3],[6],[9],[13].

Leukocytosis, which is common in patients with DKA, was noted in the current study to have a significant positive correlation with QTmaxc. It may not be indicative of an infectious process, particularly when total white blood cell counts are below 25 000. The reason for this elevation has not been established, and leukocytosis more than 25 000 requires further assessment for an underlying infection [14].

We performed a multivariate logistic regression analysis to confirm that pH was a significant independent predictor for QTmaxc prolongation, with a cutoff value of 7.03, enforcing the results of Adeva-Andany et al. [15].

We found a significant positive correlation between QTmaxc prolongation and APACHE II score in our patients. Furthermore, prolongation of QTmaxc increases the relative risk of mortality in diabetic patients with DKA by 1.7-fold, confirming the findings of some studies [16],[17].

To our knowledge, the present study is the first to address QTmaxc interval prolongation in adults with DKA, yet we need to compare these results with patients having acidosis owing to other causes, to reach the definite cause of QTc prolongation without electrolytes imbalance: is it the acidosis or ketone bodies?

Therefore, our study concluded that acidosis carries an independent risk for QTmaxc interval prolongation in the absence of electrolytes abnormalities, with a related poor ICU outcome in patients with DKA. We recommend a strict continuous cardiac monitoring during DKA management.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Zayed H. Epidemiology of diabetic ketoacidosis in Arab patients with type 1 diabetes: a systematic review. Int J Clin Pract 2016; 70:186–195.  Back to cited text no. 1
    
2.
Glaser N, Barnett P, McCaslin I, Nelson D, Trainor J, Louie J et al. Risk factors for cerebral oedema in children with diabetic ketoacidosis. N Engl J Med 2001; 344:264–269.  Back to cited text no. 2
    
3.
Kuppermann N, Park J, Glatter K, Marcin JP, Glaser NS. Prolonged QT interval corrected for heart rate during diabetic ketoacidosis in children. Arch Pediatr Adolesc Med 2008; 162:544–549.  Back to cited text no. 3
    
4.
Suys B, Heuten S, de Wolf D, Verherstraeten M, de Beeck LO, Matthys D et al. Glycemia and corrected QT interval prolongation in young type 1 diabetic patients: what is the relation? Diabetes Care 2006; 29:427–429.  Back to cited text no. 4
    
5.
Szabo A, Andrássy G. Prolonged QT interval corrected for heart rate during diabetic ketoacidosis in children: psychological stress could be another explanation. Arch Pediatr Adolesc Med 2009; 163:92.  Back to cited text no. 5
    
6.
Youssef OI, Farid SM. QTc and QTd in children with type 1 diabetes mellitus during diabetic ketoacidosis. ISRN Pediatr 2012; 2012:619107.  Back to cited text no. 6
    
7.
Kitabchi AE, Umpierrez GE, Miles JM, Fisher JN. Hyperglycemic crises in adult patients with diabetes. Diabetes Care 2009; 32:1335–1343.  Back to cited text no. 7
    
8.
Bazett HC. An analysis of the time-relations of electrocardiograms. Ann Noninvasive Electrocardiol 1997; 2:177–194.  Back to cited text no. 8
    
9.
Best TH, Franz DN, Gilbert DL, Nelson DP, Epstein MR. Cardiac complications in pediatric patients on the ketogenic diet. Neurology 2000; 54:2328–2330.  Back to cited text no. 9
    
10.
Stevens A, Robinson DP, Turpin J, Groshong T, Tobias JD. Sudden cardiac death of an adolescent during dieting. South Med J 2002; 95:1047–1049.  Back to cited text no. 10
    
11.
George TK, Chase D, Peter JV, Satyendra S, Kavitha R, George LR et al. Association between a prolonged corrected QT interval and outcomes in patients in a Medical Intensive Care Unit. Indian J Crit Care Med 2015; 19:326–332.  Back to cited text no. 11
[PUBMED]  [Full text]  
12.
Burkett E, Keijzers G, Lind J. The relationship between blood glucose level and QTc duration in the critically ill. Crit Care Resusc 2009; 11:8–13.  Back to cited text no. 12
    
13.
Orchard CH, Cingolani HE. Acidosis and arrhythmias in cardiac muscle. Cardiovasc Res 1994; 28:1312–1319.  Back to cited text no. 13
    
14.
Nyenwe EA, Kitabchi AE. The evolution of diabetic ketoacidosis: an update of its aetiology, pathogenesis and management. Metabolism 2016; 65:507–521.  Back to cited text no. 14
    
15.
Adeva-Andany MM, Fernández-Fernández C, Mouriño-Bayolo D, Castro-Quintela E, Domínguez-Montero A. Sodium bicarbonate therapy in patients with metabolic acidosis. ScientificWorldJournal 2014; 2014:627673.  Back to cited text no. 15
    
16.
Rossing P, Breum L, Major-Pedersen A, Sato A, Winding H, Pietersen A et al. Prolonged QTc interval predicts mortality in patients with type 1 diabetes mellitus. Diabet Med 2001; 18:199–205.  Back to cited text no. 16
    
17.
Straus SMJM, Kors JA, de Bruin ML, van Der Hooft CS, Hofman A, Heeringa J et al. Prolonged QTc interval and risk of sudden cardiac death in a population of older adults. J Am Coll Cardiol 2006; 47:362–367.  Back to cited text no. 17
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

Top
 
 
  Search
 
Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

 
  In this article
Abstract
Introduction
Patients and methods
Results
Discussion
References
Article Figures
Article Tables

 Article Access Statistics
    Viewed203    
    Printed13    
    Emailed0    
    PDF Downloaded38    
    Comments [Add]    

Recommend this journal


[TAG2]
[TAG3]
[TAG4]