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Saudi Journal of Kidney Diseases and Transplantation
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ORIGINAL ARTICLE  
Year : 2013  |  Volume : 24  |  Issue : 2  |  Page : 274-280
The clinical factors' prediction of increased intradialytic qt dispersion on the electrocardiograms of chronic hemodialysis patients


1 Department of Internal Medicine, Faculty of Medicine, University of Indonesia-Cipto Mangunkusumo National General Hospital, Jakarta, Indonesia
2 Division of Nephrology-Hypertension, Faculty of Medicine, University of Indonesia-Cipto Mangunkusumo National General Hospital, Jakarta, Indonesia
3 Division of Cardiology, Faculty of Medicine, University of Indonesia-Cipto Mangunkusumo National General Hospital, Jakarta, Indonesia
4 Division of Geriatric Medicine, Faculty of Medicine, University of Indonesia-Cipto Mangunkusumo National General Hospital, Jakarta, Indonesia

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Date of Web Publication26-Mar-2013
 

   Abstract 

Ventricular arrhythmias and sudden death are common in patients on maintenance hemodialysis (HD). The increase in QT dispersion (QTd) on the electrocardiogram (ECG) reflects increased tendency for ventricular repolarization that predisposes to arrhythmias. The purpose of the study was to identify the clinical factors that may predict the increased intradialytic QTd and to assess differences in QTd before and after HD. Each of 61 chronic HD patients underwent 12-lead ECG and blood pressure (BP) measurement before and every 1 h during a single HD session. The QT intervals were corrected for heart rate using Bazett's formula. Intradialytic QTd increased in 30 (49%) patients. There was no correlation between the increased QTd and the clinical factors including hypertension, pulse pressure, intradialytic hypotension, left ventricular hypertrophy, old myocardial infarct, diabetes mellitus, and nutritional status. The means of QT interval and QTd increased after HD session (from 382 ± 29 to 444 ± 26 ms, P <0.05; and from 74 ± 21 to 114 ± 53 ms, respectively, P <0.05). We conclude that the increased intradialytic QTd could not be predicted by any of the clinical factors evaluated in this study. There was significant difference in the means of QTd before and after HD session.

How to cite this article:
Oktavia D, Suhardjono, Nasution SA, Setiati S. The clinical factors' prediction of increased intradialytic qt dispersion on the electrocardiograms of chronic hemodialysis patients. Saudi J Kidney Dis Transpl 2013;24:274-80

How to cite this URL:
Oktavia D, Suhardjono, Nasution SA, Setiati S. The clinical factors' prediction of increased intradialytic qt dispersion on the electrocardiograms of chronic hemodialysis patients. Saudi J Kidney Dis Transpl [serial online] 2013 [cited 2019 Aug 21];24:274-80. Available from: http://www.sjkdt.org/text.asp?2013/24/2/274/109571

   Introduction Top


Although dialysis technology has improved over the last three decades, mortality rate on chronic hemodialysis (HD) is still high. Cardiovascular disease is the major cause of death accounting for 43% of all-cause mortality. Arrhythmias or sudden death are responsible for 64% of all cardiac deaths or 27% of all-cause mortality in HD patients. [1]

Non-homogeneity repolarization in the different parts of ventricle can predispose for arrhythmias. [2],[3] Increased QT dispersion (QTd) predicts cardiac death following myocardial infarction, heart failure, congenitally prolonged QT interval, diabetes mellitus, hypertension, and peripheral vascular disease. [4],[5],[6] Non-homogeneity of ventricular repolarization in chronic uremic patients may be due to myocyte hypertrophy, increased collagen interstitial matrix, and autonomic neuropathy. Hypoperfusion of myocardial segments could happen during hemofiltration and also influence the homogeneity of repolarization. [2]

Although the QTd on a standard surface 12-lead electrocardiogram (ECG) is a non-invasive measurement, it is not done routinely in HD patients.

We aim in our study to determine the predicting clinical factors of the increased intra-dialytic QTd in HD patients in order to identify those at risk of developing arrhythmias during dialysis.


   Materials and Methods Top


We studied the ECG of 77 patients maintained on chronic HD, which was carried out thrice a week for a duration of 4½-5 h, by using Fresenius bicarbonate dialysate containing (in mmol/L) 140 Na + , 2.0 K + , 1.3 Ca +2 , and 0.2 Mg +2 . Sixteen patients were excluded from the study according to the findings of the ECG; 12 had atrial fibrillation, one had premature atrial complex, one had premature ventricular complex, and two had artifacts. The maintenance drugs therapy including anti-hypertensive agents and anti-angina and beta-blocking agents were not changed. None of the remaining 61 patients received drugs that may lengthen the QT interval, such as class IA, IB, IC, or III antiarrhytmic drugs; antibiotic or antiparasite such as azithromycin, trimethoprimsulfamethoxazole, or chloroquine; and psychiatric drugs such as amyriptline, phenytoin, or haloperidol.

Arterial blood pressure and heart rate were recorded every 1 h of the procedure by Omron SEM-1 sphygmomanometer digital with a coefficient of variance of 2.5%. Intradialytic hypotension was defined as a decrease in systolic BP by ≥20 mmHg or a decrease in mean arterial pressure (MAP) by 10 mmHg, and was associated with symptoms including abdominal discomfort, yawning, sighing, nausea, vomiting, muscle cramps, restlessness, dizziness, fainting, and anxiety. [7] Nutritional status was assessed by modified subjective global assessment of Kalantar-Zadeh et al. [8] The study was approved by the local ethics committee, and informed consent was obtained.

Conventional 12-lead ECG was performed at the start and at each hour of a single HD session. The ECGs were obtained with the patients lying comfortably in supine position. For the analysis of the QT interval, the 12-lead ECG tracings were enlarged on Canon 6000 photocopier by a factor of 4. The QT intervals for each lead were measured manually with calipers by one observer. The QT interval was measured from the first deflection of the QRS complex to the point of T wave offset, defined by the return of the terminal T wave to the isoelectric TP baseline. In the presence of U wave interrupting the T wave, the terminal portion of the visible T wave was extrapolated to the TP baseline to define the point of T wave offset. If the end of T wave could not be reliably determined, the lead was not included in the analysis. Each QT interval was corrected for patient's heart rate using Bazett's formula: QTc = QT√RR (ms), where QTc is the corrected QT interval. QTd was defined as differences between the minimal and maximal QTc values in each of the studied 12-lead ECGs. Baseline QTd 140 ms or more was excluded from the analysis. The increase of intra-dialytic QTd was defined as QTd 140 ms or more at least once during the ECG measurement session.


   Statistical Analysis Top


Data were expressed as mean ± standard deviation (SD). Significant differences in the proportions of the predicting clinical factors were assessed by the chi-square test. Multi-variable adjusted logistic regression models were used to detemine the association between the increase of QTd and the predicting clinical factors.

Linear regression models were used to examine the relationship between QTd and the hemodynamic parameters. The difference in QTd before and after HD was assessed by paired paired t-test. All statistical analyses were performed using SPSS version 17.


   Results Top


There were 30 (49%) patients with increased intradialytic QTd. The two groups of patients, with increased and unincreased intradialytic QTd, had similar age, nutritional status, and vascular access. The most common causes of end-stage renal disease (ESRD) were chronic glomerulonephritis and diabetes mellitus [Table 1].
Table 1: Baseline characteristics of the study patients.

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During the HD session, ECG revealed atrial fibrillation in one patient and occurred in the 3 rd hour of the session. None of the ECGs revealed any ventricular arrhythmias or acute myocardial infarction.

The incidence of pre-HD hypertension in the patients with intradialytic QTd was comparable with that of those without intradialytic QTd (94% and 93%, respectively). Intradialytic hypotension occurred in 53% of the patients with intradialytic QTd compared with 68% in those without intradialytic QTd. The mean of blood pressure was at the lowest point during the last hour of HD [Figure 1].
Figure 1: Hemodynamic parameters during hemodialysis session.

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Univariate and multivariate analysis was performed between the increasing intradialytic QTd and clinical factors, and showed no statistically significant correlation between them [Table 2].
Table 2: Association between the increasing QTd and possible predicting clinical factors.

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[Figure 2] shows the mean of the QTd, which increased significantly post-HD from 72 ± 21 to 114 ± 53 ms (P <0.05).
Figure 2: Individual values of QTd before and after hemodialysis.

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   Discussion Top


Our results showed no relationship between the studied clinical factors and the increased intradialytic QTd. We used ECG criteria to detect left ventricular hypertrophy and old myocardial infarction. Although some previous studies used the same metods, others used more sensetive tools such as echocardiogaphy and/or coronary arteriography. [9],[10],[11],[12]

Previous studies showed that essential hypertension and type-2 diabetes mellitus correlated with the increased QTd, but their cut-off values of the QTd were lower than ours. [12],[13] In the study of Morris et al, the univariate analysis showed that the change in diastolic BP during dialysis was associated with increased QTd post-HD, but this was not significant in the multiple linear regression analysis. [14] Several studies included patients under treatment with amiodaron or digitalis, while we excluded the study of such patients. [2],[15] However, 6% of our patients used beta-blockers which are known to have an effect on QT duration.

Chronic dialysis patients form a heterogenous population, often in unstable clinical conditions, which may influence the results of the cardiovascular tests. We found no relationship of the increased intradialytic QTd and pulse pressure, intradialytic hypotension, and nutritional status. To our knowledge, these relationships were not extensively studied previously. Lörincz et al found no patient with serious hypotension episodes in their study, [2] and Cupisti et al excluded patients with hemodynamic instability from their study. [10]

Palpitation or syncope can be found in patients with congenital prolonged QT intervals; however, no one of our patients showed such clinical symptoms.

The relationship of the QTd and absolute changes in electrolyte values during dialysis was inconsistent according to previous studies, and we also had similar findings. Morris et al had demonstrated that the absolute changes in electrolyte levels in dialysis patients did not correlate with the changes in QTd, although there were statistically significant differences of electrolyte after the dialysis session. [14] Furthermore, Malhis et al found no relationship in multivariate analysis. [16] However, Cupisti et al found that QTd correlates with the change of potassium and magnesium levels in dialysis patients. [10] In the study of Nappi et al, the QTd increased after dialysis only when a low-calcium dialysate (1.25 mmol/L) was used. [17] Another study showed correlation of QTd with parathormone. [18]

The changes in the QTd remained significant across dialysis [Table 3]. Compared to several previous studies, our results were similar with the study results of Morris et al and Howse et al. [14],[15] The QTd in our study was higher than that in Covic et al's study because they excluded patients with diabetes mellitus, ischemic heart disease, and left ventricular hypertrophy. [9] The blood pressure of our patients was higher than that in the study of Covic et al because they excluded patients with hypertension. [9]
Table 3: Comparison of several studies in their evaluation of QTd in dialysis patients.

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   Limitations of the Study Top


Our study used a manual method to measure QTd. This method is in agreement with some previous studies. Several studies used different methods such as tangential method, automatic with Holter monitor, or by developing computer software. [3],[5],[17] In addition, the measurement of QTd suffers from several methodological problems including inadequate reproducibility and imprecision of measurement of repolarization abnormalities. Therefore, we used the highest cut-off value of 140 ms, [5] and the 12-lead ECG tracings were enlarged on the same photocopier by factor of 4.

Some studies use two or more observers for QTd measurement. We had only one observer, and the intra-observer coefficient of variation was 6%. QT intervals cannot always be reliably measured in every lead; Higham and Campbell have pointed out that an observer should omit a measurement in a lead if there is uncertainty, rather than force a QT measurement, which could create a spurious QT maximum or minimum. [19]

Although the number of patients in our study was twice that of most previous studies, [2],[10],[11],[17] it was too small a sample size when compared with other population studies such as QTd in type-2 diabetes mellitus or essential hypertension, which have several hundreds of patients. [12],[13]

Finally, discrepancies between the studies may be attributed to population selection, methods of QT measurement, and dialysis techniques.

In summary, our study suggests that there was a significant increase in the QTd after single HD session in our patients. However, the studied clinical factors could not predict the increase of the intradialytic QTd. Further larger cohort studies with more sensitive parameters are warranted.

 
   References Top

1.Herzog C, Mangrum JM, Passman R. Evaluation of sudden cardiac arrest and sudden cardiac death in dialysis patients. Uptodate [CD-ROM]. Version 17.1 [Last cited on 2009 Jan 24].  Back to cited text no. 1
    
2.Lörincz I, Matyus J, Zilahi Z, Kun C, Karanyi Z, Kakuk G. QT dispersion in patient with end state renal failure and during hemodialysis. J Am J Soc Nephrol 1999;10(6):1297-302  Back to cited text no. 2
    
3.Genovesi S, Rivera R, Fabbrini P, et al. Dynamic QT interval anlysis in uremic receiving chronic haemodialysis. J Hypertens 2003;21: 1921-6.  Back to cited text no. 3
[PUBMED]    
4.Shah MJ, Wiend TS, Rhodes LA, Berul CL, Vetter VL. QT and JT dispersion in children with long QT syndrome. J Cardiovasc Electro-physiol 1997;8:6421-8.  Back to cited text no. 4
    
5.Pinsky D, Sciacca RR, Steinberg J. QT dispersion as a marker of risk in patients awaiting heart transplantation. J Am Coll Cardiol 1997; 29:1576-84.  Back to cited text no. 5
    
6.Day CP, McComb JM, Cambell RW. QT dispersion: An indication of arrhythmias risk in patients with long QT intervals. Br Heart J 1990;63:342-4.  Back to cited text no. 6
    
7.NKF-K/DOQI. 2006 updates clinical practice guidelines and recommendations: hemodialysis adequacy, peritoneal dialysis adequacy and vascular access. Dari sitasi available from: http://www.NKF_K/DOQI Guidelines. Download on May 15 th 2010.   Back to cited text no. 7
    
8.Kalantar-Zadeh K, Kleiner M, Dunne E, Lee GH, Luft FC. A modified quantitative subjective global assessment of nutritition for dialysis patients. Nephrol Dial Transplant 1999;14:1732-8.  Back to cited text no. 8
[PUBMED]    
9.Covic A, Diaconita M, Gusbeth-Tatomir P, et al. Haemodialysis increases QTc interval but not QTc dispersion in ESRD patients without manifest cardiac disease. Nephrol Dial Transplant 2002;17:2170-7.   Back to cited text no. 9
[PUBMED]    
10.Cupisti A, Galetta F, Caprioli R, et al. Potassium removal increased QTc interval dispersion during haemodialysis. Nephron 1999;82: 122-6.   Back to cited text no. 10
[PUBMED]    
11.Perkiomaki JS, Ikaheimo MJ, Pikkujamsa SM, et al. Dispersion of the QT interval and autonomic modulation of heart rate in hypertensive men with and without left ventricular hypertrophy. Hypertension 1996;28:16-21.   Back to cited text no. 11
    
12.Veglio M, Bruno G, Borra M, et al. Prevalence of increased QT interval duration and dispersion in type 2 diabetic patients and its relationship with coronary heart disease: A population-based cohort. J Intern Med 2002;251:317-24.  Back to cited text no. 12
[PUBMED]    
13.Salles GF, Cardoso CR, Deccache W. Multi-variat association of QT interval parameters in diabetic patients with arterial hypertension: importance of left ventricular mass and geometric patterns. J Human Hypertens 2003;17: 561-7,13-21.  Back to cited text no. 13
[PUBMED]    
14.Morris ST, Galiatsou E, Stewart GA, Rodger RS, Jardine AG. QT dispersion before and after hemodialysis. J Am Soc Nephrol 1999;10:160-3.  Back to cited text no. 14
[PUBMED]    
15.Howse M, Sastry S, Bell GM. Changes in the corrected QT interval and corrected QT dispersion during haemodialysis. Postgrad Med J 2002;78:273-5.  Back to cited text no. 15
[PUBMED]    
16.Malhis M, Al-Bitar S, Farhood S, Zaiat KA. Changes in QT interval in patients with End-Stage Renal Disease Before and After Hemodialysis. Saudi J Kidney Dis Transpl 2010;21: 460-5.  Back to cited text no. 16
[PUBMED]  Medknow Journal  
17.Näppi SE, Virtanen VK, Saha HH, Mustonen JT, Pasternack A. QTc dispersion increased during hemodialysis with low-calcium dialysat. Kidney Int 2000;57:2117-22.   Back to cited text no. 17
    
18.Gafter U, Battler A, Eldar M, Zevin D, Neufeld HN, Levi J. Effect of hyperparathyroidism on cardiac function in patients with end stage renal disease. Nephron 1985;41:30-3.  Back to cited text no. 18
    
19.Higham PD, Campbell RW. QT dispersion. Br Heart J 1994;71:508-9.  Back to cited text no. 19
    

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Correspondence Address:
Dina Oktavia
Department of Internal Medicine, Faculty of Medicine, University of Indonesia-Cipto Mangunkusumo National General Hospital, Jakarta
Indonesia
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DOI: 10.4103/1319-2442.109571

PMID: 23538349

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