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Revista Uruguaya de Medicina Interna

Print version ISSN 2393-6797On-line version ISSN 2393-6797


SORIANO-MORENO, Anderson N.  and  FLORES-MALPARTIDA, Freddy. Comparison of four formulas to adjust the QT interval to the heart rate in a cardiac patient. Rev. Urug. Med. Int. [online]. 2019, vol.4, n.1, pp.16-22. ISSN 2393-6797.


The prolongation of the QT interval in the electrocardiogram is a well-known risk factor for developing cardiovascular events. In Latin America there is no much evidence about the epidemiology of electrocardiographic alterations. The objective of this study was to evaluate the prevalence of long corrected QT interval according to four formulas.


Retrospective descriptive study. A total of 156 electrocardiographic records of 12 referrals made to patients older than 40 years were review. The measurements were made manually and later the values ​​were adjusted to the heart rate by means of four existing validated formulas. The long QT interval was considered when the duration exceeded 470ms.


Of the 156 records analyzed, 55.7% of the records belonged to female patients and the mean age was 70.3 ± 9.7 years. 9.6% of the records were considered long using the Bazzet formula, 4.4% according to the Hodges formula, 3.8% according to the Fridericia formula and 3.2% according to the Framingham formula. The formula of Fridericia was found to be the most consistent to adjust the QT interval to the heart rate.


Depending on the formula used, the prevalence of the long QT interval varied significantly. The formula of Fridericia was the one that showed the best consistency.

Keywords : Long QT interval; Electrocardiograph; Arrhythmias.

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