Introduction: Acute myocardial infarction (MI) is the leading cause of death in globally. Electrocardiogram (ECG) is a pivotal tool for risk stratification due to its affordability, non-invasiveness, and rapid results. The Tpeak-Tend interval shows how repolarization propagates throughout the myocardium and has been linked to dangerous ventricular arrhythmias and major adverse cardiac events (MACE) in patients with ST-segment elevation myocardial infarction (STEMI). Objective: To study the role of Tpeak-Tend/QT interval ratio as a predicator of in-hospital MACE in patients with STEMI. Methodology: This cross-sectional study was conducted at a tertiary care hospital between September 2022 and February 2024. A total of 87 patients were enrolled, of which 79 patients with STEMI presentation who met the inclusion criteria were included. Further the Tpeak-Tend/QT ratio was calculated, those with Tpeak-Tend/QT ratio < 0.3 were grouped as Group A (n=32), and those with ratio > 0.3 were in group B (n=47) Results: Out of 79 patients in this study, male gender was predominant, in group A, 23 of 32 patients and in group B, 32 of 47 patients were male. The most common age group noted in Group A was 60-70 years and in group B it was 50-60 years. Chest discomfort was the most common presenting symptom in 27 out of 32 patients in group A and 44 out of 47 patients in group B. Further in these patients the occurrence of in-hospital MACE was analysed, it was observed that the commonest MACE was heart failure, seen in 4 of 32 patients in group A and 16 of 47 patients in group B. Conclusion: The study showed a statistically significant correlation (P value = 0.03) between the incidence of in-hospital MACE in STEMI patients and a high Tpeak-Tend/QT ratio (>0.3). Hence Tpeak-Tend/QT ratio > 0.3 on a 12-lead ECG is a non-invasive and dependable predictor of MACE.
Ischemic heart disease is one of the main causes of death globally. In 2020, ischemic heart disease claimed 19 million lives worldwide [1]. Changes in the ECG directly impact acute myocardial infarction diagnosis and prognosis. Acute myocardial infarction has already eclipsed communicable diseases as India's leading cause of death, and the annual burden of STEMI alone is estimated to be more than three million [2].
Major adverse cardiac events include heart failure, pulmonary oedema, cardiogenic shock, and arrhythmias [3]. Estimating the probability of major adverse cardiovascular events and mortality in patients with acute myocardial infarction is essential for formulating initial and short-term treatment plans. An ECG can effectively determine a patient's risk for various cardiac morbidities and overall mortality, which is a useful diagnostic tool for acute myocardial infarction [4]. According to research, specific electrocardiographic characteristics can be used for clinical risk classification for significant adverse cardiac events [5].
Prognostic risk markers for cardiac events, such as arrhythmias and sudden cardiac death, have been established based on traditional ECG findings of aberrant ventricular repolarisation [6]. The Tpeak-Tend interval is the interval between the peak of T wave to end of T wave, this is thought to correlate with the dispersion of the repolarisation process. The QT interval is the interval between beginning of QRS complex to end of T wave, it represents the entire duration of ventricular depolarisation and repolarisation. The prolongation of Tpeak-Tend/QT interval ratio has been associated with mortality in several cardiovascular events [7]. We aimed to study the role of Tpeak-Tend/QT interval ratio as a predicator of in-hospital MACE in patients with STEMI.
This cross-sectional study was conducted from September 2022 to February 2024 in patients with STEMI who were admitted to Shri BM Patil Medical College Hospital and Research Centre, BLDE (Deemed to be University), Vijayapura. Institutional Ethics Committee clearance was obtained with the reference number (IEC/749/2022-23). Additionally, the study was registered with the Clinical Trials Registry-India (CTRI/2022/11/047690). The sample size was calculated based on a 95% confidence level and a 10% margin of error, considering an expected 22% mortality rate in STEMI patients showing an increased Tpeak-Tend/QT ratio. All patients with STEMI were included and all patients with bundle branch block, non-ST-segment elevation myocardial infarction (NSTEMI), temporary/permanent pacemaker and valvular heart disease were excluded.
Among 87 enrolled patients, 79 with STEMI met the inclusion criteria for the study, while eight patients were excluded based on the following criteria: four with NSTEMI, two with bundle branch block, and two with valvular heart disease. The diagnosis of STEMI was made in 79 of 87 patients based on the clinical history of chest pain, detailed clinical examination, ECG, and blood investigations like cardiac enzymes (Troponin I). Other investigations, such as complete hemogram, lipid profile, renal profile, echocardiography were done. A 12-lead ECG was used to calculate the Tpeak-Tend/QT ratio. The 'tangent' approach was used to measure Tpeak-Tend interval in ST-segment leads from the peak of T wave to end of T wave [8]. The corrected QT interval (QTc) was calculated using Bazett's formula (QT interval/ √ RR interval) [9]. The Tpeak-Tend/QT ratio was calculated using the Tpeak-Tend interval and QTc. The patients in group A had a Tpeak-Tend/QT ratio < 0.3, while patients in group B had a Tpeak-Tend/QT ratio > 0.3. These patients were also monitored for in-hospital MACE, such as cardiogenic shock, pulmonary oedema, and heart failure.
Statistical Analysis
The data was analysed using (SPSS) version 20 (IBM Corp, Armonk, NY) software and entered into an Excel sheet. Descriptive data was entered using percentages, mean, and standard deviation. A P-value of < 0.05 was considered statistically significant, and the categorical variables between the two groups were assessed using the Chi-square test. The data was represented in the form of tables and charts.
In the present study, out of 79 patients who were included, the common age group in group A was between 60 to 70 years, 16 of 32 patients belonged to this age group (n=16; 50%), group B the common age group was between 50-60 years, 22 of 47 patients belonged to this age group (n=22; 46.8%). Of 32 patients in group A, 23 were male and 9 were female. In group B out of 47 patients, 32 were male and 15 were female. The age and gender distribution among the patients in both groups is shown in (Table 1/ Fig 1).
Demographical data |
Group-A (n=32) |
Group-B (n=47) |
P value |
Chi-square |
||
Age group (in years) |
Male (n=23; %) |
Female (n=9; %) |
Male (n=32; %)
|
Female (n=15; %)
|
||
21-30 |
0 (0) |
0 (0) |
1 (3.1) |
0 (0) |
0.56 |
36.2 |
31-40 |
2 (8.6) |
1 (11.1) |
2 (6.2) |
1 (6.6) |
||
41-50 |
2 (8.6) |
1 (11.1) |
5 (15.6) |
2 (13.3) |
||
51-60 |
5 (21.7) |
2 (22.2) |
14 (43.7) |
8 (53.3) |
||
61-70 |
11 (47.8) |
5 (55.5) |
7 (21.8) |
3 (20) |
||
71-80 |
3 (13.3) |
1 (11.1) |
3 (9.3) |
1 (6.6) |
Table 1/ Fig 1: Age-Gender distribution of group A and group B patients.
The most common presenting complaint in both groups was chest pain, seen in 20 (86.9%) of 23 males and 7 (77.7%) out of 9 females in group A and in group B, 31 (96.8%) out of 32 male patients and 13 (86.6%) out of 15 female patients had chest pain, followed by dyspnoea and palpitation. In patients belonging to both groups, the commonest risk factor was hypertension with 16 (69.5%) out of 23 males and 7 (77.7%) out of 9 females in group A. In group B, 20 (62.5%) out of 32 males and 8 (53.3%) out of 15 females had hypertension, followed by other risk factors like diabetes, smoking and alcohol consumption (Table 2/ Fig 2). An overview of hemodynamic and lab data of 79 patients divided into group A and group B is tabulated in (Table 3/ Fig 3).
Clinical Data |
Group A (n=32) |
Group B (n=47) |
P value |
Chi-square |
||
Male (n=23; %) |
Female (n=9; %) |
Male (n=32; %)
|
Female (n=15; %)
|
|||
Chest pain |
20 (86.9) |
7 (77.7) |
31 (96.8) |
13 (86.6) |
*0.05 |
44.8 |
Dyspnoea |
16 (69.5) |
6 (66.6) |
23 (71.8) |
8 (53.3) |
0.35 |
19.2 |
Palpitation |
8 (34.7) |
4 (44.4) |
16 (50) |
7 (46.6) |
0.25 |
17.7 |
Risk factors |
||||||
Diabetes |
11 (47.8) |
5 (55.5) |
17 (53.1) |
8 (53.3) |
*0.05 |
48.2 |
Hypertension |
16 (69.5) |
7 (77.7) |
20 (62.5) |
8 (53.3) |
*0.05 |
17.2 |
Smoking |
11 (47.8) |
0 (0) |
16 (50) |
0 (0) |
*0.05 |
56.3 |
Alcohol |
13 (56.5) |
0 (0) |
12 (37.5) |
0 (0) |
0.52 |
35.6 |
Table 2/ Fig 2: Clinical Data and risk factors of group A and group B patients.
*P <0.05, statistically significant
Hemodynamic and laboratory data (Reference values) |
Group A (n=32) |
Group B (n=47) |
p- value |
Chi-square |
||
Mean |
SD |
Mean |
SD |
|||
Pulse rate (60-100 beats/minute) |
86.7 |
27.3 |
87.4 |
19.1 |
0.84 |
52.3 |
Systolic blood pressure (100-120 mm Hg) |
108.4 |
31.7 |
106.5 |
23.8 |
0.75 |
47.5 |
Haemoglobin (12-15gm%) |
13.3 |
2.4 |
13.4 |
2.5 |
0.48 |
26.8 |
White blood cells (4000-10000 cells/103L) |
12239.6 |
3493.6 |
12250 |
3505.5 |
0.15 |
14.6 |
Troponin I (<19 ng/dl) |
5449 |
7911 |
9888 |
58.41 |
*0.05 |
35.6 |
Creatinine (0.4-1.1mg/dl) |
1.12 |
0.38 |
0.89 |
0.3 |
0.09 |
17.3 |
Fasting blood sugar (70-100 mg/dl) |
160 |
82 |
180 |
88 |
0.37 |
27.8 |
Total cholesterol (<200 mg/dl) |
153 |
37 |
182 |
79 |
0.98 |
34.6 |
Triglycerides (<150 mg/dl) |
140 |
63 |
179 |
75 |
0.89 |
47.8 |
Table 3/ Fig 3: Hemodynamic and Lab Data of group A and group B patients.
*P <0.05, statistically significant
The incidence of in-hospital MACE and its association with Tpeak-Tend/QT ratio is depicted in (Table 4/ Fig 4). Heart failure was seen in 4 (12.5%) out of 32 patients in group A and 16 (34%) out of 47 patients in Group B. one (3.1%) out of 32 patients and 9 (19.1%) out of 47 patients in group B had pulmonary oedema. Cardiogenic shock was seen in 1 (3.1%) out of 32 patients in group A and 5 (10.6%) out of 47 patients in group B. There was statistically significant correlation with prolonged Tpeak-Tend/QT ratio (>0.3) and occurrence of MACE like cardiogenic shock, pulmonary oedema, and heart failure among group B patients.
Major Adverse Cardiac Events |
Group A (32) n (%) |
Group B (47) n (%) |
P value |
Chi-square |
Heart Failure (*LVEF <40%) |
4 (12.5) |
16 (34) |
*0.01 |
56.52 |
Pulmonary Oedema |
1 (3.1) |
9 (19.1) |
*0.01 |
42.34 |
Cardiogenic Shock |
1 (3.1) |
5 (10.6) |
*0.01 |
51.63 |
Table 4/ Fig 4: Distribution of Major Adverse Cardiac Events of group A and group B patients.
*P<0.05, statistically significant
*LVEF- Left ventricular ejection fraction
Out of the 79 patients in this study, the common age group was 60+/-10 years. In a similar study, done by Panikkath et al. on s associated with an increased risk of sudden cardiac death, at Oregon in 2011, most of the 353 patients who took part in a study was found to be between 50 and 70 years [10]. In another study in 2019 by Xue C et al they studied the predictive value of the Tpeak-Tend interval for ventricular arrhythmia and mortality in heart failure patients with an implantable cardioverter-defibrillator, in China found that the most common age group in 318 patients was between 60 and 70 years [11]. The study findings are consistent with previous study of a similar kind, suggesting that aging is significant risk factor for myocardial infarction. This study showed male predominance, where of the 79 patients, 54 (68.3%) were male and 25 (31.6%) were female. In another study by Zumhagen et al. in 2016 on patients with Brugada syndrome, a total of 178 patients were studied of which 124 (or 70%) were male and 54 (30%) were female [12]. In another study by Kazemi B in 2020 et al, they evaluated the role of Tpeak to end/QT and Tpeak to end/QTc ratios in patients with STEMI undergoing percutaneous intervention vs. thrombolytic therapy on 188 patients in Iran, 138 (73.96%) patients were men, and 50 (24.3%) patients were women [13]. This indicates that myocardial infarction is more common in men.
In all 79 individuals, this study examined risk factors such as alcohol intake, smoking, diabetes and hypertension. It was observed that hypertension and smoking were significant risk factors (p=0.05) associated with STEMI. It is consistent with study by candia JC et al titled Relationship of the T-wave Tpeak-Tend interval with conduction system disorders in arterial hypertension in Paraguay in 2019 on 67 patients showed that hypertension being an important risk factor (p=0.03) in development of STEMI [14].
The most common symptom among the 79 STEMI patients in this study was chest pain, which was followed by dyspnea and palpitations. In a study done by Usalp S titled Use of T-wave duration and Tpeak-Tend interval as new prognostic markers for patients treated with cardiac resynchronization therapy in 2017 in Poland with 67 ACS patients reported that chest pain was the most common symptom in 84% of patients [15].
Hemodynamic and laboratory data in this study showed a strong correlation between STEMI and elevated troponin I levels (p=0.05). In a study by Antzelevitch C titled Tpeak-Tend interval as a marker of arrhythmic risk in Pennsylvania in 2019 on 277 patients showed that in patients with STEMI with Tpeak-Tend/QT ratio > 0.3, there was significant increase in troponin I levels suggesting strong correlation between high troponin I levels and Tpeak-Tend/QT ratio (p=0.05) [16].
It was observed in this study that 35 of 47 patients (74.5%) belonging to group B with Tpeak-Tend/QT ratio >0.3 also had LVEF < 40%. In a study by Mugnai G et al titled Tpeak-to-Tend/QT is an independent predictor of early ventricular arrhythmias and arrhythmic death in anterior ST elevation myocardial infarction patients in Belgium in 2016 showed that 285 of 331 patients who had Tpeak-Tend/QT ratio more than 0.3 had LVEF less than 40% [17].
The study findings showed that a Tpeak-Tend/QT ratio greater than 0.3 was associated with a higher risk of MACE in STEMI patients. The MACE, namely heart failure (Group A= 4;12.5%, Group B=16;34%), pulmonary oedema (Group A=1;13.1%, Group B=9;19.1%), and cardiogenic shock (Group A=1;3.1%, Group B=5;10.6%). This study finding are similar to study by Alhamaydeh et al titled T peak-T end interval on the prehospital 12-lead ECG is a strong predictor of adverse cardiac events in patients with suspected acute coronary syndrome in United states in 2019 on 650 patients showed that 145(22.3) patients developed MACE like pulmonary oedema, heart failure, and cardiogenic shock. It said that in patients with STEMI [18], the Tpeak-Tend/QT ratio is a highly reliable and strong predictor of death.
Limitation
The study was conducted out using a small sample size with single center. It will take more multicentric studies with higher sample sizes to conclusively demonstrate how the Tpeak-Tend/QT ratio affects MACE prediction in STEMI patients.
The present study which predicted the role of Tpeak-Tend/QT interval ratio in patients with STEMI and MACE, showed that patients with Tpeak- Tend/QT ratio > 0.3 on ECG were found to have an increased risk of MACE, including pulmonary oedema, heart failure, and cardiogenic shock. ECG is a simple, bedside, quick to perform, inexpensive, non-invasive tool to diagnose STEMI, further the Tpeak-Tend/QT ratio which is calculated using ECG can be used as a predictor of in-hospital MACE in STEMI patients.
Acknowledgments
Authors acknowledges the immense co-operation received by the patients and the help received from the scholars whose articles are cited and included in references of this manuscript. The authors are also grateful to authors/editors/publishers of all those articles, journals, and books from where the literature for this article has been reviewed and discussed.
Conflict of interest: Nil
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