|Year : 2014 | Volume
| Issue : 3 | Page : 175-179
Profile of cardiac arrhythmia in acute myocardial infarction patients within 48 hours of admission: A hospital based study at RIMS Imphal
Linda Marangmei, Salam Kenny Singh, Konsam Biona Devi, Sambhaji Shivaji Raut, Dhanaraj Singh Chongtham, Ksh Birendra Singh
Department of Medicine, Regional Institute of Medical Sciences, Imphal, Manipur, India
|Date of Web Publication||5-Jan-2015|
Department of Medicine, Regional Institute of Medical Sciences, Imphal - 795 001, Manipur
Source of Support: None, Conflict of Interest: None
Background: Acute myocardial infarction (AMI) is a major cause of death worldwide with arrhythmia being the most common determinant in the post-infarction period. Objective: To study prevalence of cardiac arrhythmia in AMI patients within 48 hours of admission and to correlate between type of arrhythmia with site of myocardial infarction. Materials and Methods: Descriptive analytic study carried out in Medicine Department, RIMS, Imphal over a period of 2 years. Results and Observations: Hundred AMI patients were studied, of which 76% developed arrhythmia. Most common conduction abnormality was ventricular premature complex (VPC; 23%) followed by sinus tachycardia (21%). Heart block was present in 15%, bundle branch block in 11%, and ventricular tachycardia in 7% of the patients. In inferior wall myocardial infarction (IWMI), sinus bradycardia was more common, so also was heart block more common showing 28.95% against 6.55% in anterior wall myocardial infarction (AWMI). On the other hand, AWMI patients had sinus tachycardia more frequently than IWMI (31% versus 7.8%) and ventricular tachycardia likewise was also more common in them. It was associated with high mortality, six of seven patients who developed ventricular tachycardia died within 48 hours of hospitalization (P-value <0.01). Conclusion: Arrhythmia is common in post-infarction period seen in 76% of AMI patients. It is also a major cause of mortality in them with higher mortality seen in those with later hospital presentation.
Keywords: Acute myocardial infarction, Heart block, Ventricular premature complex, Ventricular tachycardia
|How to cite this article:|
Marangmei L, Singh SK, Devi KB, Raut SS, Chongtham DS, Singh KB. Profile of cardiac arrhythmia in acute myocardial infarction patients within 48 hours of admission: A hospital based study at RIMS Imphal. J Med Soc 2014;28:175-9
|How to cite this URL:|
Marangmei L, Singh SK, Devi KB, Raut SS, Chongtham DS, Singh KB. Profile of cardiac arrhythmia in acute myocardial infarction patients within 48 hours of admission: A hospital based study at RIMS Imphal. J Med Soc [serial online] 2014 [cited 2020 Oct 27];28:175-9. Available from: https://www.jmedsoc.org/text.asp?2014/28/3/175/148514
| Introduction|| |
0Acute myocardial infarction (AMI) is myocardial necrosis in a clinical setting consistent with acute myocardial ischemia and detection of elevated values of cardiac biomarkers (CK-MB/troponin-I) above the 99 th centile of the upper reference limit 4 hours after starting of symptom.  Complication includes arrhythmic, mechanical, inflammatory sequel, about 90% develops some form of cardiac arrhythmia. In 25% patients, such rhythm abnormalities manifest within first 24 hours and risk of ventricular fibrillation is maximum in the 1 st hour and declines thereafter. 
Major mechanisms of arrhythmias in the acute phase of coronary occlusion are reentry caused by inhomogeneity of the electrical characteristics of ischemic myocardium and cellular electrophysiological mechanism for reperfusion arrhythmia appears to include washout of various ions such as lactate, potassium, and toxic metabolic substances that have accumulated in the ischemic zone.  Peri-infarction arrhythmias are related with in-and out-hospital outcome of the patients, there is no available data of arrhythmia in AMI patients of Manipur in the last 5 years. This study was to document prevalence of arrhythmias in AMI and to study the correlation between types of arrhythmia with site of myocardial infarction among the regional population of Manipur.
| Materials And Methods|| |
0The present study entitled "Profile of cardiac arrhythmias in acute myocardial infarction within 48 hours of admission - A hospital-based study at RIMS, Imphal" was carried out in the Department of Medicine, Regional Institute of Medical Sciences (RIMS), Imphal, Manipur over a period of 24 months from September 2010 to August 2012.
Hundred patients more than 18 years irrespective of sex, socioeconomic status admitted in the intensive coronary care unit (ICCU) with diagnosis of AMI were studied. Those with documented arrhythmia before the episode of AMI and those with defined causes like thyroid disorders and dilated cardiomyopathy (DCM) were excluded.
Tools and procedure
A detailed history with particular emphasis on the risk factors were noted and general physical along with thorough systemic examination was done. The patients were followed for the first 48 hours in the ICCU for development of arrhythmia, with baseline electrocardiography (ECG) at admission and daily ECG thereafter, and any abnormal rhythm observed in the cardiac monitor was supplemented with the 12-lead ECG recording. Likewise CK-MB titers at admission and 48 hours later were done. For estimation of CK-MB titer, Thermo Scientific method was used utilizing an immunoinhibition principle. Patients also underwent all routine investigations including lipid profile and echocardiography. The type of AMI, age, and sex was correlated with type of cardiac arrhythmia. For statistical analyses of data, Statistical Package for Social Sciences (SPSS 16.0 version) was used. Prevalence was calculated and results were expressed as percentages. Data was collected and scrutinized for completeness and chi-square test was applied for comparison analysis.
| Results|| |
0The present study included 100 patients, age group 40-50 years were 36%, 50-60 years and 60-70 years were 24% each, and those more than 70 years were only 14%. Genderwise 31% were females, while 69% were males. Risk factor profile of the AMI patients show diabetes mellitus in 22%, hypertension in 26%, past history of acute coronary syndrome (ACS) in 6%, past history of cerebrovascular accident in 4%, obesity in 15%, smokers were 47%, and patients consuming alcohol were 64%.
Mean of duration between onset of symptoms and hospitalization is 16.11 hours, with only 11% patients reaching the hospital within 2 hours of onset of symptoms.
Majority of the patients had anterior wall myocardial infarction (AWMI) 61% (anterior wall, anteroseptal, anterolateral), 38% patients had inferior wall myocardial infarction (IWMI; inferolateral, inferior wall, inferoposterior, inferior +right ventricle). One patient had antero-IWMI. Seventy-six percent of the patients with AMI had arrhythmia within 48 hours of hospitalization, 22% at the time of hospitalization, and 27% patients within 1 st hour of hospitalization. Progressively arrhythmia occurrence decreased with time. Only 2% patients had new arrhythmia after 24 hours of hospitalization [Table 1]. Graphical representation is shown in [Figure 1]. Twenty-four patients presented with palpitation, out of which 22 developed arrhythmia; which is statistically significant (P-value 0.039). Rhythm was reverted to normal in 52 of 76 patients. The occurrence of arrhythmia in the various group of MI patients show 77% in diabetics, while it was 24% in nondiabetics, 76% in hypertensive and 74% in nonhypertensive, 86% in alcoholics and 70% in nonalcoholic; but none of the above findings met statistical significance, except for the arrhythmia difference in smokers 85% and 67% in nonsmokers, which was statistically significant (P-value 0.045).
Arrhythmia was more with IWMI patients (79%) than in AWMI patients (69%), but was not statistically significant. The conduction abnormality seen are as follows; ventricular premature complex (VPC) was most common (23%) followed by sinus tachycardia in 21% [Figure 2], heart block (first, second, and third degree) was present in 15% [Figure 3] and [Figure 4] [Figure 5], bundle branch block (right and left bundle branch block) was present in 11%, and ventricular tachycardia in 7% of the patients [Table 2] and [Table 3]. Graphical representation is shown in [Figure 6]. Comparing the various conduction abnormalities with the site of infarction show VPC in 21% with AWMI and 24% with IWMI, heart block in 6% with AWMI and 29% with IWMI, and bundle branch block in 13% with AWMI and 8% with IWMI. There was no statistical significant difference between the above conduction abnormality and site of infarction. However, sinus bradycardia was seen in 8% with AWMI compared to 24% with IWMI, so it was more common in the later with P-value of 0.05 showing statistical significance.
|Figure 6: Prevalence of different types of arrhythmias VPC = Ventricular premature complex|
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Five of 61 patients with AWMI and two of 38 patients with IWMI developed ventricular tachycardia. Ventricular tachycardia was more common when anterior and IWMI was associated with lateral wall involvement; P-value was 0.005 and was statistically significant. Six of 7 patients who developed ventricular tachycardia succumbed to death within 48 hours of hospitalization. This finding was also statistically significant with P-value <0.01. Thirteen percentpatients expired during first 48 hours of hospitalization.
Thirty-two patients have more than one conduction abnormality and 44 patients had only one conduction abnormality.
| Discussion|| |
In the present study, 84% of the patients were in the age group of 41-70 years, 14% were more than 70 years of age, and 2% were below 40 years. It compares well with study by Martin.  Gender wise females were 31%, while males were 69%. It showed male preponderance as was observed in Framingham Heart Study,  and is the same with Boucher et al.,  study with69.6 males. Present study had 22% diabetic, 26% hypertensive, and 47% patients were smokers. It correlated with the study conducted by Abidov et al.,  where 43-47% patients were smokers and 20-24% had diabetes mellitus; however, hypertensive patients in our study was lower. Framingham Heart Study  concluded that smokers have two to three times increase in sudden cardiac death in each decade at point of entry between 30 and 50 years of age. In our study, there was higher mortality among smokers (19%) than nonsmokers (7.5%), so it is well comparable with Framingham Heart Study. This increase may be due to increase in arrhythmia among smokers which is statistically significant in this study.
In the study by McNamara et al.,  in-hospital mortality was lower with shorter door-to-needle times. This relationship was particularly pronounced in those presenting within 1 st hour of symptom onset to presentation time (P for trend <0.001). This is comparable to our study as higher mortality was seen in those patients who reached the hospital after 6 hours of onset of the symptoms as against earlier within 6 hours presentation; 15.5 vs 6.9%. In present study, 76% of the patients had arrhythmia during first 48 hours of hospitalization, which is less than study by Aufderheide,  but not statistically significant. The 3% atrial fibrillation within 48 hours of hospitalization is comparable to the DIAMOND study by Schmiegelow et al.  In present study, 26% patients developed conduction abnormality in the form of either heart block or bundle branch block. Heart Block was seen in 15%, which is well comparable with study of Shirafkan et al.,  and bundle branch block was seen in 11% patients. Mortality in these patients within 48 hours was 13.3%, which is lower than study by Lim et al.,  this may be related to short duration of follow-up in present study. In present study, 7% patients developed ventricular tachycardia, of which 85% patients died during first 48 hours of hospitalization. Mortality was higher in patients with ventricular tachycardia as studied by Goldberg et al. 
Conduction disturbances were mostly atrioventricular in IWMI and mostly intraventricular in anterior MI. In present study, heart block was common in patients with IWMI (28.95%) compared to 6.55% with AWMI. Bundle branch block was more common in patients with AWMI (13%) than patients with IWMI (8%). This finding is comparable with both studies done by Escosteguy et al.,  and Majumder et al. 
| Conclusion|| |
The study showed high prevalence of peri-infarction arrhythmia; ventricular tachycardia in particular being a common cause of mortality in AMI patients within 48 hours of hospitalization. Higher mortality was seen in those with later hospital presentation bringing out the importance of recognizing myocardial infarction, its associated complications, and the need for early presentation to the hospital for better patient outcome.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3]