en Original Research Original Research <span style="font-size:13pt"><span style="text-justify:kashida"><span style="text-kashida:0%"><span style="text-autospace:none"><span new="" roman="" style="font-family:" times=""><span style="font-style:italic"><b><span style="font-size:9.0pt"><span style="font-style:normal">Background: </span></span></b><span style="font-size:9.0pt"><span style="font-style:normal">St-elevation myocardial infarction (STEMI) is a serious condition that occurs when the blood flow to one or more coronary arteries is blocked, leading to damage or death of the heart muscle (myocardial injury or necrosis). The present study aimed to compare QTc and QTd intervals in patients with STEMI before and 90 minutes after treatment in Booali Sina Hospital, Qazvin, Iran.</span></span></span></span></span></span></span></span><br> <span style="font-size:13pt"><span style="text-justify:kashida"><span style="text-kashida:0%"><span style="text-autospace:none"><span new="" roman="" style="font-family:" times=""><span style="font-style:italic"><span style="font-size:9.0pt"><span style="font-style:normal">&nbsp;&nbsp; <b>Methods:</b> The present study is an analytical cross-sectional study. Between March 2021 and 2022, 107 patients administered to Booali Sina Hospital, Qazvin, Iran, due to STEMI who underwent primary PCI were enrolled in the study. Data including age, sex, height and weight, disease history, QTc interval before and 90 minutes after treatment, QTd before and 90 minutes after treatment and Ejection fraction values were extracted from the patient&#39;s files. Then, the relationship between change in QT and QTd after treatment with response to treatment based on ST Resolution was evaluated. SPSS 20.0 statistical program was used for the statistical analysis. All values are given as mean&plusmn; standard deviation (SD). A p-value of less than 0.05 was considered as significant.</span></span></span></span></span></span></span></span><br> <span style="font-size:13pt"><span style="text-justify:kashida"><span style="text-kashida:0%"><span style="text-autospace:none"><span new="" roman="" style="font-family:" times=""><span style="font-style:italic"><span style="font-size:9.0pt"><span style="font-style:normal">&nbsp;&nbsp; <b>Results:</b> The observed mean difference in investigated variables of patients, including age, height, weight, and BMI, was not statistically significant between the two groups (response to treatment and non-response to treatment (</span></span><span style="font-size:9.0pt">P</span><span style="font-size:9.0pt"><span style="font-style:normal"> > 0.05). Findings demonstrated that the mean QTd 1 in the response to the treatment group was higher compared to the non-response to the treatment group, and this difference was not statistically significant (</span></span><span style="font-size:9.0pt">P</span><span style="font-size:9.0pt"><span style="font-style:normal"> = 0.337). It is remarkable that the mean QTd 2 in the response to treatment group was statistically significantly lower than the non-response to treatment group (</span></span><span style="font-size:9.0pt">P</span><span style="font-size:9.0pt"><span style="font-style:normal"> = 0.002).</span></span></span></span></span></span></span></span><br> <span style="font-size:13pt"><span style="text-justify:kashida"><span style="text-kashida:0%"><span style="text-autospace:none"><span new="" roman="" style="font-family:" times=""><span style="font-style:italic"><span style="font-size:9.0pt"><span style="font-style:normal">&nbsp;&nbsp; <b>Conclusion:</b> We showed that QTd in the studied patients after primary angioplasty reduced significantly compared to the QTd before the treatment, so the QTd can be considered as a noninvasive measure of the response to the treatment in patients with STEMI.</span></span></span></span></span></span></span></span><br> <span style="font-size:13pt"><span style="text-justify:kashida"><span style="text-kashida:0%"><span style="text-autospace:none"><span new="" roman="" style="font-family:" times=""><span style="font-style:italic"><span style="font-size:9.0pt"><span style="font-style:normal"></span></span></span></span></span></span></span></span><br> &nbsp; Acute coronary syndrome, ST-segment elevation, Primary percutaneous coronary intervention, QT dispersion 691 696 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-8334-2&slc_lang=en&sid=1 Mir Mohammad Sadra Ghods Hosseini dr.sadraghods@gmail.com 200319475328460089511 200319475328460089511 No Clinical Research Development Unit, Qods Hospital, Qazvin University of Medical Sciences, Qazvin, Iran Samira Dodangeh sdodangeh@ymail.com 200319475328460089512 200319475328460089512 No Clinical Research Development Unit, Booalisina Hospital, Qazvin University of Medical Sciences, Qazvin, Iran Hamid Reza Javadi javadi.hr@gmail.com 200319475328460089513 200319475328460089513 No Clinical Research Development Unit, Booalisina Hospital, Qazvin University of Medical Sciences, Qazvin, Iran Alireza Razaghi razzaghi.alireza1@gmail.com 200319475328460089514 200319475328460089514 No Social Determinants of Health Research Center, Research Institute for Prevention of Non-Communicable Diseases, Qazvin University of Medical Sciences, Qazvin, Iran Majid Haji Karimi m.hajikarimi@qums.ac.ir 200319475328460089515 200319475328460089515 Yes Clinical Research Development Unit, Booalisina Hospital, Qazvin University of Medical Sciences, Qazvin, Iran