Pattern of sudden cardiac deaths

Abstract

Background and objective

Sudden cardiac death can be defined as a sudden, unexpected death caused by loss of heart function. Notwithstanding major developments in the diagnosis and treatment of heart disease, it remains the major contributing factor for deaths. This considers the pattern of sudden cardiac deaths.

Methodology: This prospective study was conducted on all cases subjected to medico-legal autopsy in the forensic medicine department at a tertiary care hospital for a period of 18 months. All sudden cardiac deaths satisfying the WHO criteria were included. Unknown cases and bodies in advanced stage of decomposition were excluded.

Results

Sudden cardiac deaths accounted for 55% (82 cases) of 149 cases of sudden natural deaths and 6.5% of total autopsies conducted. The age group most commonly affected by sudden cardiac death ranged from 31 to 50 years. The majority of the cadavers had 90–95% degree of stenosis of left anterior descending artery, 70–80% of right coronary artery and 60–70% left circumflex artery. Coronary insufficiency was the major cause for sudden cardiac deaths with a total of 53 (64.63%) cases.

Conclusion

Sudden cardiac deaths accounted for 6.5% of all the autopsies conducted and males outnumbered females with M:F ratio of 10.7:1, with mean age of 44.5 ± 12.63 years. The largest number – 60.97% – were aged between 31 and 50 years. Coronary insufficiency accounted for 64.63% of sudden cardiac deaths.

Keywords

Study sudden cardiac deaths analysis predisposing factors ratio of sexes age groups

Introduction

Incidence of sudden cardiac deaths (SCDs) is increasing globally, with the first autopsy report of this condition ascribed to Leonardo da Vinci in the 15th century.¹ Since then, despite improvements in treatment and diagnosis, SCDs are the major cause of morbidity and mortality globally.

In this study, the definition for an SCD applied is: “Sudden cardiac death describes the unexpected natural death from a cardiac cause within a short time period, generally ≤1 hour from the onset of symptoms, in a person without any prior condition that would appear fatal.”²

The incidence of SCDs is increasing, so the main aim of the present study is to analyse sex dominancy, any common age groups involved, mean age and risk factors.

Results

The total number of autopsies conducted was 1260, out of which 82 (6.5%) cases were SCDs. There were 75 (91.4%) males and 7 (8.5%) females with M:F ratio of 10.7:1. The age range of cases was 21–80 years, with a mean age of 44.5 ± 12.63 years. Most (60.97%, 50 cases) were in the age group of 31–50 years as shown in Table 2.

In our study, coronary insufficiency was the major cause of death (n = 53), followed by myocardial infarction (MI) (n = 21). Frequency distribution of cause of death in the study is shown in Table 1. Two-thirds of cases from MI (n = 14) were due to superimposed thrombus in proximal part of coronary arteries. Calcification was well appreciated on gross and histopathological examination of coronaries in all cases of MI. The degree of coronary obstruction as seen in the study is shown in Table 3, and the left anterior descending artery (LAD) was most effective vessel among others which had 68.2% of obstruction in majority of cases. The only case of cardiomyopathy was in a marathon runner whose heart weighed about 500 g.

Table 1.

Distribution of cardiac deaths with sex frequency.

Cause of death	Males	Female	Total
Coronary insufficiency	49 (65.33%)	4 (57.14%)	53 (64.63%)
Myocardial infarction	19 (25.33%)	2 (28.57%)	21 (25.60%)
Cardiac tamponade	4 (5.33%)	0	4 (4.87%)
Aortic dissection	2 (2.66%)	1 (14.28%)	3 (3.65%)
Cardiomyopathy	1 (1.33%)	0	1 (1.21%)
Total	75 (100%)	7 (100%)	82 (100%)

Table 2.

Distribution of cardiac deaths with age range, mean age and SD.

COD	Age range	Mean	SD
Coronary insufficiency	21–80 years	43.04	6.31
Myocardial infarction	21–70 years	45.97	9.68
Cardiac tamponade	31–70 years	50.5	24.15
Aortic dissection	31–70 years	45.5	30.82
Cardiomyopathy	61–70	–	–

COD: Cause of death.

Table 3.

Different grades of coronary atherosclerosis (n = 82).

Grade	No. of cases	Percentage (%)
I	3	3.6
II	7	8.5
III	16	19.5
IV	56	68.2

Parameters such as alcohol, smoking, stress, diet and any previous cardiovascular system-associated illnesses were also taken into consideration. A total of 63 cases were alcohol-related, 58 cases were smokers and 50 cases were non-vegetarian.

The impact of diet on the cardiovascular system was evaluated through relative risk.

We found that those who consumed alcohol have 3.31 times more risk of SCD compared to non-drinkers, whereas the risk of cardiovascular deaths is 2.41 times higher in smokers than non-smokers. Non-vegetarians’ risk of SCD was 1.56 times greater than vegetarians.

Material and methods

A prospective study was conducted in the southern part of India for 18 months in the Department of Forensic Medicine in a tertiary care hospital. Ethical approval was obtained from the Institutional Ethical Committee prior to the study.

A total of 1260 autopsies were performed, out of which 82 cases were from SCD, as per WHO definition: “Sudden cardiac death which occurs immediately or within 24 hours of the onset of the terminal symptoms.” Detailed history of any illnesses of the deceased and their dietary habits was obtained from the investigating officers, family members and friends/eye witnesses. Standard dissection techniques were followed, and degree of coronaries obstruction were noted by gross and histopathological examination. Histopathological examination was performed following standard procedure with use of haematoxylin, eosin and reticulin stains, and results were noted. The findings were graded according to the histopathology grades of atherosclerosis as given by American Heart Association classification. The details were entered in a structured pro forma and results were tabulated and analysed. All quantitative variables were analysed and summarised using descriptive statistics, i.e. mean, standard deviation (SD). Cause of deaths for males and females were analysed for different age groups by using chi-square test of significance. The impact of diet on the cardiovascular system was evaluated through relative risk analysis.

Discussion

SCD is a major cause for morbidity and mortality worldwide, with the most common cause being coronary heart disease (CAD). Other common causes are MI, cardiomyopathy, valvular disease,³ etc. As per the WHO latest update, 17.9 million people die each year from cardiovascular deaths: an estimated 31% of all deaths worldwide.⁴

In our study, a total of 1260 autopsies were conducted, out of which 82 (6.5%) deaths were due to SCDs, with most due to coronary insufficiency (CAD), 53 (64.6%) cases (Figure 2, Case A), followed by MI, 21 (25.6%) cases (Figure 2, Case C), cardiac tamponade (CT) (Figure 2, Case D), aortic dissection (AD) (Figure 2, Case B) and hypertrophic cardiomyopathy were observed in the rest of the cases. A similar trend was seen in most studies conducted in Asia. However, our findings differ from those studies carried out in western countries. This may be due to variation in geographical conditions and diet, see Basso et al.⁵

In our study, SCDs were primarily due to coronary insufficiency as seen in 53 (64.6%) cases. The major vessel involved was the LAD with more than 75% obstruction followed by the right coronary artery (RCA) and the fewest cases were observed with involvement of the left circumflex artery (LCX).

Similarly, in the present study, SCDs from MI were in 14 out of 21 cases of MI (66.6%) due to superimposed thrombus in proximal part of arteries; a very similar trend was seen in a study conducted by Ahmad et al.⁶

In the present study, the ages ranged from 21 to 80 years (Figure 1), with mean age of 44.5 ± 12.63 years. Most, 60.97% (50 cases), were within the age group of 31–50 years which is the key age group for any country, and similar results were observed in a study conducted by Sonawane et al.⁷

Figure 1.

Distribution of cardiac deaths in different age groups.

Figure 2.

Case study photographs of some of the sudden cardiac deaths. (a) A 32-year-old male who complained of epigastric pain and vomiting was brought dead to the hospital. At autopsy, left anterior descending artery showed complete occlusion and microscopic photo also showed complete luminal occlusion by complicated atheroma with calcification. (b) A 48-year-old male complained of sweating and chest pain before collapsing. At autopsy: Gross and microscopy show aortic (longitudinal section) dissection and haemorrhage in the wall (double barrel aorta). (c) A 42-year-old male who complained of epigastric pain was brought dead to the hospital. At autopsy: Gross findings showed area of haemorrhage and microscopic photo shows myocardial fibres with necrosis with neutrophilic infiltrate, 400× H&E staining (acute myocardial infarction). (d) A 37-year-old male found unconscious at his workplace was brought dead at hospital. At autopsy: Pericardium showed 250 ml of blood clot (cardiac tamponade) with vertical tear (dissection) at the root of aorta.

The age range in the present study for SCDs due to coronary insufficiency was 21–80 years and mean age was 43.04 ± 6.3. Age range for MI was 21–70 years and mean age noted was 45.97 ± 9.68; mean age for CT and AD was 50.5 ± 24.15 and 45.5 ± 30.82, respectively. A study conducted by Srivatsa et al.⁸ in 2010–2011 noted the mean age was 55 + 10 years. This shows that within six years there were changes in mean age due to SCDs.

Our findings showed that in terms of sex distribution males greatly outnumbered females for SCDs with 75 male (91.4%) cases and seven female (8.5%) cases, out of the total with the M:F ratio of 10.7:1. A study was conducted by Rao et al. between 2008 and 2011 in Kingston, Jamaica and Bangalore.⁹ Despite the difference in geography and sample size, the M:F ratio was found to be the same as in our study. The probable reason is that males are primary bread winners and suffer more stress compared to females, and the reason for the lower female figures could be that in the study the majority of cases belonged to the younger age group when females have more oestrogen which has some cardioprotective property.

In our study, correlation of consumption of alcohol and smoking with SCDs was also evaluated. It was observed that users of alcohol had 3.31 times more risk of sudden cardiac deaths than non-drinkers. Similar correlation was noted between smokers and non-smokers, with the risk of SCDs being 2.41 times higher in smokers than non-smokers, a similar risk shown in the study conducted by Aune et al.¹⁰

Diet and stress also play a major role in SCDs. The risk is 1.56 times higher in non-vegetarians than in vegetarians. When our results were compared to similar studies undertaken in developing nations, similar observations were made.^11,12 However, contradictory results were obtained when compared with studies carried out by developed nations. This variation in such results with developed nations is due to quality and quantity of consumption of alcohol, smoking and diet.

Conclusion

SCDs accounted for 6.5% of total autopsies conducted. In the present study, males outnumbered females with M:F ratio of 10.7:1, with mean age of 44.5 ± 12.63 years. Most cases (60.97%) were aged between 31 and 50 years. Coronary insufficiency accounted for causing 64.63% of SCDs.

Footnotes

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

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