^1,2Associate Professor, ³Junior Resident III, Department of General Medicine, Government Medical College, Latur, Maharashtra, INDIA.

Email: vivek.ambhore@gmail.com

RESULTS

A total number of 100 patients were studied. In our study 68% were males and 32% were females. Majority of patients were in the age group between 51-60 years followed by age group between 61-70 years.

                                                                                         Table 1: Type of MI

Majority of the patients had (55%) anterior wall infarction, followed by inferior wall infarction (24%). Out of 100 patients with AMI 76 having arrhythmias. Out of 76 patients 55 were males and 21 were females. 80.88% of males having arrhythmia while 65.62% of females having arrhythmia.

Table 2: Specific arrhythmia

Sinus tachycardia was the most common arrhythmia. Sinus bradycardia was the second most common arrhythmia. However, VPCs occurred in isolation in 9% of patients but it also occurred along with other arrhythmia like first degree heart block, right bundle branch block, sinus tachycardia, and sinus bradycardia.

Table 3: Arrhythmia Vs Type of Myocardial Infarction

Sinus tachycardia (75%) found in majority of patients with anterior wall MI. Sinus bradycardia (92.3%) found in majority of patients with inferior wall MI. VPCs found in isolation (85.7%) in combination with sinus tachycardia (80%) of patients with anterior wall MI. Almost 100% mortality seen in patients develops ventricular tachycardia, ventricular fibrillation and complete heart block during the course of AMI. Less mortality seen in patients with VPCs.

DISCUSSION

Studying arrhythmias in hospitalized cases of acute myocardial infarction is an indirect estimate of mortality and assumes significance because true mortality due to acute myocardial infarction is difficult to ascertain in the community due to inadequate reporting and low autopsy rates. Indians show a higher incidence of mortality than other ethnic groups.¹ The risk factors namely age; sex, hypertension, diabetes mellitus, smoking, tobacco chewing, and alcohol were also evaluated in these patients. This study showed myocardial infarction was more common among elderly in accordance to the American Heart Association observation.⁶ This study showed a male preponderance as was observed in the Framingham Heart Study,⁷ is also the same with Boucher et al.⁸ The maximum incidence of AMI as seen in this study was in the age group of 51-60 years (38%), followed by 61-70 years (25%), only 11% of cases were below the age group of 40 year age and 16% above the age of 70 years incidence of this study almost compares well with incidence being 85% between 35 and 75 years of age as reported by Martin TC et al.⁹ In present study incidence of AMI in males was 68% and in females was 32% which compares well again with the study done by Martin TC et al⁹ where the incidence was 72% in males and 28% in females. Siddique MB et al,¹⁰ also observed males (67%) predominance over the females (33%); Rajkumar C et al¹¹ also observed males (68%) predominance over the females (32%); Marangmei L et al¹² also observed males (69%) predominance over the females (31%); Mhatre MA et al¹³ also observed males (74%) predominance over the females (26%). The age distribution in this present study ranged from 27 years to 90 years with a maximum number of patients in the age group of 51 to 60 years. There were 38% of patients in this age group. This is comparable with the findings of author Muthuraju N et al;¹⁴ Kumar V et al,¹⁵ which is 31% and 44% respectively. In the present study, 52% of patients were smokers. It correlated with the study conducted by Abidov et al,¹⁶ where 43-47% patients were smokers; Smoking correlated well with the study by Marangmei L et al¹² and Patil PR et al¹⁷ where (47% and 52.9%) were smoker respectively.  The Framingham study demonstrated that smokers have a 2-3fold increase in sudden cardiac death in each decade of life at entry between 30 and 50 years and significantly increases the risk of CAD in this high-risk patients.⁷ In our study, highly statistically significant association was found between smoking and the occurrence of arrhythmia. In our study, 33% were diabetic and in the study conducted by Abidov et al¹⁶ 20-24% were diabetic whereas Agrawal S et al¹⁸ and Patil PR et al¹⁷ where (35% and 36%) were diabetic respectively which correlate with our study. In the present study, 39% of patients consumed alcohol of which 87.18% had an arrhythmia. In a study by Djousse L et al¹⁹ it was concluded that there was little association between long-term occasional alcohol consumption and the risk of AF, but a significantly increased in risk of AF among subjects consuming >36 g/day. It is also correlated with the study conducted by Patil PR et al¹⁷ where 39.2% were alcoholic and developed arrhythmia in patients of AMI. In the present study, smoking and alcohol were the major risk factors in accordance with Deshpande JD et al study.²⁰ It was observed that, 56% of patients were hypertensive of which 82.14% had an arrhythmia. However, in our study no statistically significant association was found between hypertension and the occurrence of arrhythmia. Yildirir A et al²¹ concluded that the increased incidence of ventricular premature beats, complex ventricular arrhythmias and the presence of LVH are the major predictors of mortality in hypertensive patients.

Table 4: Comparison of studies for percent of arrhythmia during MI

This study is well comparable with Marangmei L et al¹² and Kumar V et al.¹⁵ In the present study, arrhythmia was detected in 76% of the patients. In a study by Aufderheide TP et al,² 90% of patients with acute myocardial infarction have some cardiac rhythm abnormality during the first 24 hours following infarct onset. The present study showed majority of arrhythmias occurred during the first hour of hospitalization. In the study by Aufderheide TP et al,² approximately 25% have cardiac conduction disturbance within 24 hours following infarct onset. In the present study, sinus tachycardia occurred in 21.05% of the patients, in a study by Irwin JM (1988)120, sinus tachycardia was observed in up to 30% of the patients. Sinus tachycardia was more frequent in anterior wall MI (75%) when compared to inferior wall MI (6%). It is also correlated well with the study by Marangmei L et al¹² and Muthuraju N et al¹⁴ where (21% and 30%) sinus tachycardia was found respectively. In the present study, sinus bradycardia was observed in 17.10% of the patients. It is correlated well with the study by Agarwal S et al¹⁸ Marangmei L et al¹² and Muthuraju N et al¹⁴ where (17%; 15% and 15%) sinus bradycardia was found respectively. In the present study, VPCs were observed in 9.21% of the patients when they occurred alone. However, they also occurred in some patients along with other (28.9%) arrhythmias like heart blocks, tachyarrhythmia, and bradyarrhythmia. In a study by Volpi A et al,²² approximately 36% of patients with acute myocardial infarction presented with less than one premature ventricular beat per hour in Holter, whereas almost 20% of patients showed frequent (more than 10 premature ventricular beats per hour). In the present study, VPCs were observed in 28.9% of the patients when they occurred alone and long with other arrhythmia. It is correlated well with the study by Marangmei L et al¹² and Muthuraju N et al¹⁴ where (23% and 20%) VPCs were found respectively. The study done by AV Ghuran and AJ Cann²³ it shows VPC are usually asymptomatic and their presence in the preinfarction period, regardless of frequency and complexity (bigeminy, multiformity etc.) bears no relation to the mortality. AIVR is usually benign and has no adverse effect on mortality. The present study also highlights this aspect. In the present study, 3.9% of patients developed ventricular tachycardia, 2.6% developed ventricular fibrillation 100% mortality seen during the first 48 hours of hospitalization. It is correlated well with the study by Marangmei L et al¹² and Muthuraju N et al¹⁴ where (7% and 5%) VT was found respectively. In the present study, ventricular fibrillation occurred in 2.6% of the patients. It is correlated well with the study by Kumar V et al,¹⁵ Muthuraju N et al¹⁴ and Agarwal S et al¹⁸ where (2.5%, 3%, and 5%) VF was found respectively. In the present study, patients with ventricular fibrillation found to have 100% mortality.  In the present study, total of 4% of patients had supraventricular tachyarrhythmias with AF being 2.6%, and atrial tachycardia in 1.3% case. The incidence of atrial fibrillation very well correlates with the study done by Novaro GM et al (2008)128 It is correlated well with the study by Muthuraju N et al,¹⁴ Mhatre MA et al¹³ and Agarwal S et al¹⁸ where (2%, 2%, and 1%) AF was found respectively. In the present study 50% mortality was seen in cases with AF.  In the present study, first degree heart block along with sinus bradycardia was observed in 1.3%, second degree heart block in 2.6% of the patients, complete heart block present alone in 2.6% of the patients, CHB along with first degree heart block was seen in 1.3% of the patients and associated with first degree heart block and VPC in 3.9%. Sinus bradycardia with first-degree heart block in 1.3%, RBBB, and VPC in 2.6% and LBBB in 7.8% of patients. Archbold RA et al²⁴ observed that LBBB and RBBB occurred in 2.4% and 3.6% of the patients respectively and bifascicular block occurred in 2.9%. A study by Goldberg RJ et al,²⁵ showed that in-hospital mortality is significantly higher with anterior wall infarction with complete heart block than with inferior wall myocardial infarction and that complete heart block is twice as common with inferior or posterior wall infarction as with anterior wall involvement. In the present study there is 100% mortality noted in patients with complete heart block and complete heart block plus first degree AV block. In the present study, the majority of patients did not have any arrhythmia during thrombolysis. The commonest arrhythmia during thrombolysis was VPC, followed by sinus bradycardia. In a study by Solimene et al,²⁶ reperfusion arrhythmias were observed in 75% patients and consisted of ventricular arrhythmias and/or sinus bradycardia.  In the present study, 81.5% of patients with LV dysfunction had arrhythmias. In a study by Ale jandro Macchia et al,²⁷ compared to patients with EF >50%, systolic dysfunction patients had higher mortality and sudden death rates. In a study by Yee Guan Yap et al,²⁸ in high-risk post-MI patients with LVEF < 40% or frequent VPCs, the risk of arrhythmic deaths was higher than that of non-arrhythmic deaths for up to 2 years.

CONCLUSION

Arrhythmia following AMI is an important cause of mortality and also important prognostic factor in deciding the outcome of the patient and hospital stay. Arrhythmia is very common during the first week of MI, particularly during the first few hours, tachyarrhythmias being more common than bradyarrhythmias. Age, sex, addiction and other co-morbid conditions is an important predictor of arrhythmia. It is more prevalent in the age group for more than 50 years, being more common in males than females with co-morbid conditions like hypertension, diabetes mellitus and addictions like smoking and alcohol.

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