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ORIGINAL ARTICLE Table of Contents  
Ahead of print publication
An observational study to evaluate the relation between infarction type, site, and the degree of conductive system damage


1 Department of General Medicine, Government Erode Medical College and Hospital, Erode, Tamil Nadu, India
2 Department of General Medicine, Government Erode Medical College, Erode, Tamil Nadu, India
3 Department of Physiology, Government Erode Medical College, Erode, Tamil Nadu, India

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Date of Submission24-Mar-2022
Date of Decision08-May-2022
Date of Acceptance13-May-2022
Date of Web Publication04-Aug-2022
 

  Abstract 


Background: Obesity, insulin resistance, and type 2 diabetes mellitus are all on the rise, and they are all significant risk factors for ischemic heart disease (IHD). The prevalence of risk factors for IHD is quickly growing in developing countries as a result of urbanization. Large rises in IHD are observed around the world, and IHD has overtaken cancer as the leading cause of death after 2020. Materials and Methods: This is a 6-month prospective observational research undertaken at a tertiary care hospital where the myocardial infarction (MI) patients admitted to the intensive coronary care unit were included in the study. Results: Atrioventricular (AV) block was absent in 178 of 200 patients with acute MI. AV block was found in 22 of the remaining cases. The following is the frequency of each form of AV block: 12 patients had type 1 AV block. In five of the cases, type 1, 3 transition was found. Type 2 AV block was found in two cases. In one case, there was a 2, 3 transition. Conclusion: Preventing conduction system block may require the effective management of hypertension and maintaining appropriate blood glucose levels.

Keywords: Conduction system of heart, coronary artery, ischemic heart disease, myocardial infarction


How to cite this URL:
Sangeetha K, Myilsamy S, Vijayakumar P, Periaswamy P. An observational study to evaluate the relation between infarction type, site, and the degree of conductive system damage. APIK J Int Med [Epub ahead of print] [cited 2022 Oct 6]. Available from: https://www.ajim.in/preprintarticle.asp?id=353263





  Introduction Top


Coronary artery disease (CAD) is one of the most common types of heart disease in those over 40 years of age. CAD is becoming a more widespread health problem as our society ages. Obesity, insulin resistance, and type 2 diabetes mellitus are all on the rise, and they are all significant risk factors for ischemic heart disease (IHD). The prevalence of risk factors for IHD is quickly growing in developing countries as a result of urbanization. Large rises in IHD are observed worldwide, and IHD has overtaken cancer as the leading cause of death after 2020.[1]

By 2020, cardiovascular disease (CVD) is expected to claim 25 million lives per year, and coronary heart disease (CHD) will overtake infectious illnesses as the leading cause of death and disability worldwide.[2] India is the home to one-sixth of the world's population, with about three-quarters of the country's population living in rural areas. There are no accurate nationwide data on cause-specific death. CVD is responsible for 24% of all deaths in India, with CHD accounting for more than half of all deaths.[3]

Many individuals with acute myocardial infarction (MI) are admitted with conduction blockages. As a result, the current research aims to determine the prevalence of conduction block in acute MI, as well as the varied types of conduction block in acute MI and the prognostic implications of conduction block in acute MI.


  Materials and Methods Top


This is a 6-month prospective observational research undertaken at a tertiary care hospital where the MI patients admitted to the intensive coronary care unit (ICCU) were included in the study. After taking the ethical committee clearance from the institution and informed consent from the study population, detailed history, clinical examination, and other required data were collected from the patients. All the patients who are managed in ICCU were included in the study. Patients those who are critically ill and those who do not agree to participate in the study are excluded from the study.

Clinicodemographic details such as age and sex were self-reported by the study participants. Anthropometric measurements such as height and weight were recorded from each participant at the beginning of data collection. Blood pressure was assessed on every participant using a manual sphygmomanometer after half an hour of completing the questionnaires. A resting paper electrocardiogram (ECG) was recorded and evaluated manually by the cardiologist available at our institute for specifying the conduction disorders. Atrioventricular (AV) disturbances were evaluated by assessing the relationship between the P waves and QRS complexes on the ECG at the time of admission. Cardiovascular comorbidities such as hypertension, diabetes, previous history of angina or MI, previous history of hear complaints, and family history of heart disease were gathered and recorded from each study participant. Habits such as cigarette smoking and alcohol consumption were assessed.

Statistical analysis

The data collected from the study participants were entered into Microsoft Excel and the representation of data in the form of tables has been done in the form of numbers and percentages. Continuous variables with a normal distribution are presented as means and were compared using unpaired two-tailed t-tests.


  Results Top


The number of female patients in this study of 200 patients with acute ST-elevation MI (STEMI) was 60 (30%), whereas the number of male patients was 140 (70%). As a result, the incidence of MI in males is higher than in females [Table 1].
Table 1: Sociodemographic details of study participants

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In a study of 200 patients with acute STEMI, 49 (24.5%) were hypertensive and 151 (75.5%) were not. In this study, the prevalence of hypertension in patients with MI was 24.5% [Table 2].
Table 2: Prevalence of hypertension among patients of myocardial infarction

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The prevalence of diabetes among MI patients was determined to be 61 (30.5%) individuals with diabetes and 139 (69.5%) without diabetes in this study, which included 200 patients. The percentage of people with diabetes who had MI was 30.5%, whereas the percentage of people who had MI but did not have diabetes was 69.5% [Table 2].

Serum cholesterol

The average number of individuals with MI who have high serum cholesterol is 60 (30%). The number of people who do not have high serum cholesterol is 140. Raised serum cholesterol accounts for 30% of MI patients (200), whereas those without high blood cholesterol accounts for 70%.

Smoking

With a total of 200 patients, 42 patients (21%) with acute MI had a smoking history and 158 patients were nonsmokers. Smoking was found to be present in 21% of MI patients. A total of 79% of 200 MI patients were nonsmokers.

Alcohol

There are 60 alcoholics (30%) and 140 nonalcoholics among 200 MI patients. Alcoholics accounted for 30% of acute MI patients, whereas nonalcoholics accounted for 70% of 200 MI patients.

Type of myocardial infarction

Among 200 patients who presented with MI, 19 (8.5%) had anterolateral MI, 81 (40.5%) had appendicular skeletal MI (the most common kind), 8 had anterior wall MI (AWMI), and 11 individuals had extensive anterior wall MI.

With inferior wall MI (IWMI), 35 people had only IW infarction, whereas 26 people had both IW and posterior wall MI.

IW + right ventricular MI was found in 19 cases, whereas IW + LWMI was present in one patient.

The majority of individuals with IWMI have only the IW involved [Table 3].
Table 3: Classification of myocardial infarction based on the anterior and inferior wall

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Anterior and inferior infarction

Anterior wall-related infarctions occur more frequently than inferior infarctions among 200 patients who have had an acute MI. Anterior infarction was found in 119 of the 200 (59.5%) MI patients, whereas IW infarction was found in 81. The percentage of MI related to the IW is 40.5%. Anterior wall-related MI accounts for 59.5% of all MIs. Both anterior and IWMI patients are included in the AWMI and IWMI studies. Sixteen patients (8%) with Intraventricular Conduction Delay (IVCD) were found among 200 MI patients. Nine of the 19 (47.4%) individuals with IVCD were positive for right bundle branch block (RBBB). Three of them have left bundle branch block (LBBB). Both RBBB and left anterior fascicular block (LAHB) were found in two individuals. Only LAHB was found in two of the individuals. In this study, RBBB is more common than LBBB.

Atrioventricular block

AV block was absent in 178 of 200 patients (89%) with acute MI. AV block was found in 22 (11%) of the remaining cases. The following is the frequency of each form of AV block: 12 (6%) patients had type 1 AV block. In five of the cases, type 1, 3 transition was found. Type 2 AV block was found in two cases (1%). In one case, there was a 2, 3 transition. Two (1%) of the patients had type 3 block. In six patients, the transition to Type 3 block has happened.


  Discussion Top


AV block is more likely in the right coronary artery (RCA) occlusion than the left coronary artery occlusion, according to a retrospective study of STEMI patients in Brittany from 2006 to 2013. Increased parasympathetic tone causes it to be transient, and the most common arrhythmia is sinus bradycardia.

Occlusion of the RCA AV block occurs in 5.9% of cases, compared to 1.5% in other artery infarctions.[4] About 2.6% of patients who were not reperfused had AV block, compared to 1.2% of patients who had a percutaneous coronary intervention and 0.5% of patients who were not thrombosed. The incidence of three-degree AV block in acute MI is 4%–5% according to the TRACE study.[5] The incidence of two-and three-degree AV blocks is 7%–10%, and it is particularly high in the first 48 h.[6],[7]

According to the Copenhagen City Heart Study (COPEN), RBBB is more than LBBB when it comes to bundle branch block.[8] The new BBB in Hirulog and Early Reperfusion or Occlusion (HERO)-2 trial is not prevalent in acute MI, but it has a bad prognosis. The risk of death in AWMI with AV conduction abnormalities is higher than in inferior MI.

The limitations of this study include that it was conducted in a population of one region of India; hence, the results could not be generalized to a bigger extent. Furthermore, the observational nature of this study does not facilitate in drawing conclusions regarding the causal relationship between the conduction damage and the observed cardiovascular risks.


  Conclusion Top


Damage to the conduction system has been connected to a number of established cardiovascular risk factors and illnesses. Preventing conduction system block may necessitate adequate hypertension control as well as maintaining proper blood glucose levels.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Selwyn Andrew P, Eugene B. Ischemic heart disease. In: Kasper DL, Braunwald E, Fauci AS, Hauser SL, Longo DL, Jameson JL, editors. Harrison's Principles of Internal Medicine. 16th ed. Blacklick, USA: McGraw Hill; 2005. p. 1434.  Back to cited text no. 1
    
2.
Gaziano Michael J. Global burden of cardiovascular disease. In: Zipes Douglas P, Peter L, Bonow Robert O, Eugene B, editors. Braunwald's Heart Disease. 7th ed. Amsterdam, Netherlands: Elsevier Saunders; 2005. p. 1-11.  Back to cited text no. 2
    
3.
Antman EM. ST-elevation myocardial infarction: Management. In: Zipes Douglas P, Peter L, Bonow Robert O, Eugene B, editors. Braunwald's Heart Disease. 7th ed. Amsterdam, Netherlands: Elsevier Saunders; 2005. p. 1195-212.  Back to cited text no. 3
    
4.
Podrid PJ. Arrhythmias after acute myocardial infarction. Evaluation and management of rhythm and conduction abnormalities. Postgrad Med 1997;102:125-8, 131-4, 137-9.  Back to cited text no. 4
    
5.
Goldberg RJ, Zevallos JC, Yarzebski J, Alpert JS, Gore JM, Chen Z, et al. Prognosis of acute myocardial infarction complicated by complete heart block (the Worcester Heart Attack Study). Am J Cardiol 1992;69:1135-41.  Back to cited text no. 5
    
6.
Bauer GE, Julian DG, Valentine PA. Bundle-branch block in acute myocardial infarction. Br Heart J 1965;27:724-30.  Back to cited text no. 6
    
7.
McNally EM, Benchimol A. Medical and physiological considerations in the use of artificial cardiac pacing. I. Am Heart J 1968;75:380-98.  Back to cited text no. 7
    
8.
Tunstall-Pedoe H, Kuulasmaa K, Amouyel P, Arveiler D, Rajakangas AM, Pajak A. Myocardial infarction and coronary deaths in the World Health Organization MONICA project. Registration procedures, event rates, and case-fatality rates in 38 populations from 21 countries in four continents. Circulation 1994;90:583-612.  Back to cited text no. 8
    

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Correspondence Address:
Panneerselvam Periaswamy,
Department of Physiology, Government Erode Medical College, Perundurai, Erode, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ajim.ajim_40_22




 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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    -  Sangeetha K
    -  Myilsamy S
    -  Vijayakumar P
    -  Periaswamy P


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