Objective: Acute myocardial infarction is one of the leading causes of all acute emergencies and is becoming an important public health problem in developing countries. Non-ST elevation myocardial infarction (NSTEMI) is more heterogeneous in its presentation and may be poorly characterized in clinical practice, leading to greater variation in diagnosis and treatment. Patients with diabetes and hypertension who develop an NSTEMI are at increased risk for poor hospital outcomes. This study aims to assess the differences between hypertensive diabetic and hypertensive non-diabetic patients with NSTEMI and to evaluate the prognostic impact of selected clinical and laboratory parameters on the occurrence of hospital complications.

Methods: This was a cross-sectional analytical study. All the adult hypertensive patients of newly diagnosed NSTEMI with or without diabetes mellitus admitted to Ibrahim Cardiac Hospital & Research Institute, Dhaka who fulfilled the inclusion and exclusion criteria were enrolled. The study population comprised 100 hypertensive patients with their first NSTEMI and were divided into two groups according to the presence of type 2 diabetes mellitus. Group I (n = 40) patients were diabetic and Group II (n = 60) were non-diabetic. The hospital outcome of the study population was recorded. The incidence of in-hospital adverse clinical events in the two groups was compared by using the odds ratio of the two binomial proportion analyses.

Results: Among 100 hypertensive NSTEMI patients, 40% were diabetic (Group I) and 60% were non-diabetic (Group II). The mean age was 58.1±10.2 years in the case of the diabetic group (Group I) and 56.3±10.5 years in the non-diabetic group (Group II) ranging from 30-70 years. Male patients (66%) were predominant in the study. The most common clinical presentation was chest pain which was 77.5% in Group I and 83.3 % in Group II followed by sweating (12.5% and 16.7%), dyspnea (10.0% and 11.7%), syncope (5.0% and 6.7%) and atypical chest pain (2.5% and 3.3%) respectively. Smoking was the commonest risk factor which was 62.5% in Group I and 75% in Group II followed by dyslipidemia (32.5% and 36.7%), family history of IHD (30% and 23.3%) and obesity (22.5% and 13.3%) respectively. Diabetic hypertensive patients had significantly higher heart rates, hypertensive peaks, and more episodes of asymptomatic ST segment depression. The most common in-hospital complications were heart failure (30% and 16.7%), arrhythmias (22.5% and 6.7%), renal failure (10% and 5.0%), cerebral ischemia (7.5% and 1.7%), death (7.5% and 3.3%) and cardiogenic shock (5.0% and 3.3%) in Group I and Group II respectively.

Conclusion: In-hospital adverse clinical events were more frequent in diabetic hypertensive individuals compared to non-diabetics. 

Coronary artery disease (CAD) is one of the common causes of death and disability in developed countries, responsible for about one in every five deaths [1]. It is rapidly becoming a pandemic within the developing world as well where it involves a relatively younger population [2]. Being one of the leading causes of all acute emergencies, acute myocardial infarction has become an important public health problem in developing countries [3]. Non-ST-segment elevation myocardial infarction (NSTEMI) is more heterogeneous in its presentation and may be poorly characterized in clinical practice, leading to greater variation in diagnosis and treatment [4]. Diabetes mellitus (DM) and hypertension frequently coexist in the same patient. This association has a negative impact on prognosis by strongly predisposing the individual patient to the development of an accelerated atherosclerotic cardiovascular disease. Consequently, diabetic hypertensive subjects have a higher incidence of coronary artery disease than patients with diabetes or hypertension alone.5 Patients with diabetes who develop an NSTEMI are at increased risk for each hospital outcome including heart failure, renal failure, cardiogenic shock, and death [6]. 

It is observed that the incidence rates (per 100,000) of STEMI declined appreciably (121 to 77), whereas the incidence rates of NSTEMI increased slightly (126 to 132) [7]. The annual incidence of NSTEMI varies significantly between countries, with a mean global annual incidence of about 3 per 1000 population [8]. Diabetes mellitus is becoming a pandemic worldwide. The worldwide number of people with DM is expected to double in thirty years, increasing from 171 million in 2000 to 366 million in 2030. The highest percentages of increases in disease prevalence are likely to be in developing nations. The prevalence of DM in the rural population of Bangladesh is 7.2%.9 The incidence of DM in patients hospitalized with MI ranges between 10-20% and approximately 40% have impaired glucose levels [10]. Diabetic patients have a higher prevalence of coronary artery disease with an increased number of fatal coronary events due to a higher incidence of plaque rupture and superimposed thrombosis in diffusely diseased coronary arteries [11]. The increased risk of atherosclerosis in patients with DM is caused by endothelial dysfunction, abnormal platelet reactivity, and coagulation fibrinolysis balance disorders [12]. Diabetic patients develop complications more frequently after MI and have doubled the in-hospital and long-term mortality compared to non-diabetic patients. Cardiogenic shock, heart failure, renal failure, arrhythmia, re-infarction, and cerebral infarction are serious complications in diabetics [11]. 

In Bangladesh, few studies have been undertaken in the past regarding the association of DM with adverse cardiovascular events but no study has been done describing the presenting characteristics, management, and outcomes of hypertensive diabetic and hypertensive nondiabetic patients with NSTEMI. This study aimed to describe hospital outcomes of hypertensive diabetic and hypertensive nondiabetic groups with all clinical presentations of NSTEMI.

This cross-sectional analytical study was conducted at the Department of Cardiology, Ibrahim Cardiac Hospital & Research Institute, Dhaka between August 2017 and January 2018. A total of 100 newly diagnosed NSTEMI patients within 24 hours of symptom onset and having hypertension with or without Diabetes Mellitus aged ⋝30 years and < 70 years were admitted to the Department of Cardiology, ICHRI within the study period fulfilling the inclusion and exclusion criteria were included in this study by convenient purposive sampling. Study subjects having the presence of ST-segment elevation on the presenting 12-lead electrocardiogram, clinical or laboratory evidence of any previous coronary event of any kind, or suffering from secondary hypertension, renal insufficiency, clinically significant liver disease, chronic obstructive lung disease, chronic alcoholism, and severe anemia, hypertensive emergency or crisis and unwilling to take part in the study were excluded from the study. The study patients (n=100) were divided into 2 groups: Group I (Diabetic group): NSTEMI patients having Hypertension and diabetes (n=40) and Group II (Non-diabetic group): NSTEMI patients having Hypertension and had no history of diabetes (n=60). Detailed clinical history and examination were carried out and recorded in preformed case record form. Blood was collected for glucose level and serum biochemical marker for myocardial necrosis. Other necessary laboratory investigations and imaging studies were done and recorded. Finally, hospital outcomes were observed and compared between the two groups. The comparison was done by using the odds ratio.

A total of one hundred patients with NSTEMI and hypertension admitted to the Department of Cardiology, ICHRI fulfilling the inclusion and exclusion criteria were included in this study from August 2017 to January 2018. The patients were classified into two groups based on the presence or absence of DM. The patients with NSTEMI having hypertension and diabetes were assigned as Group I and those with NSTEMI having hypertension and no diabetes were assigned as Group II.

Figure 1: The pie chart shows the distribution of patients according to the presence of diabetes (n=100)

In our study, it was observed that the majority (42.5%) of patients belonged to the age group 61-70 years in the diabetic NSTEMI group (Group I) and (36.6%) in non-diabetic NSTEMI (Group II). The mean age was 58.1±10.2 years in Group I and 56.2±10.5 years in Group II. There was no significant difference in age distribution between the two groups.

Table I: Distribution of the study population by age (n=100)

ns = not significant, P value reached from Student’s t-test

Group I - Hypertensive Diabetic NSTEMI patients

Group II - Hypertensive Non-diabetic NSTEMI patients. 

Group I: Hypertensive Diabetic NSTEMI patients, Group II: Hypertensive Non-Diabetic NSTEMI patients.

The majority (60%) of patients were male in Group I and 70% in Group II. There was no significant difference in gender distribution between the two groups.

Table II: Sex distribution of patients (n=100)

ns=not significant, P value reached from chi-square test

Group I - Hypertensive Diabetic NSTEMI patients

Group II - Hypertensive Non-diabetic NSTEMI patients.

Among study subjects, the most common clinical presentation was chest pain in both Group I (77.5%) and Group II (83.3%), Other common symptoms were sweating (12.5% and 16.7% in Group I and Group II respectively), dyspnea (10.0% and 11.7% in Group I and Group II respectively), syncope (5.0% and 6.7% in Group I and Group II respectively) and atypical chest pain was least common in both groups (2.5% and 3.3% in Group I and Group II respectively). There was no statistically significant difference in symptoms between the two groups.

Table III: Clinical presentation of patients

ns=not significant, P value reached from chi-square test

Group I - Hypertensive Diabetic NSTEMI patients

Group II - Hypertensive Non-diabetic NSTEMI patients. 

Smoking was the commonest risk factor which was 62.5% in hypertensive diabetic NSTEMI patients and 75% in hypertensive non-diabetic NSTEMI patients. Other risk factors were dyslipidemia (37.5% and 30%), family history of IHD (30% and 23.3%), and obesity (22.5% and 13.3%) in group I and group II respectively. No statistically significant difference was noted between groups concerning risk factors of MI (p>0.05). 

Table IV: Distribution of the study patients by risk factors (n=100)

ns = not significant, P value is measured by Chi-square test

Group I – Hypertensive Diabetic NSTEMI patients

Group II – Hypertensive Non-diabetic NSTEMI patients. 

NSTEMI diabetic patients (60%) developed more complications than non-diabetic NSTEMI patients (33%) which were statistically significant (p lessthan 0.05).

Table V: In-hospital outcome of study participants (n = 100)

ns= non-significant, s= significant, P value calculated by Chi-square test

Group I - Hypertensive Diabetic NSTEMI patients

Group II – Hypertensive Non-diabetic NSTEMI patients.

The most common complication was heart failure (30% in Group I and 16.7% in Group II). Other complications were renal failure (10% and 5.0%), cerebral ischemia (7.5% and 1.7%), death (7.5% and 3.3%), and cardiogenic shock (5.0% and 3.3%) respectively in diabetic and non-diabetic hypertensive patients with NSTEMI. Proportion of arrhythmia and cerebral ischemia was statistically significantly higher among diabetic patients than that of non-diabetic patients (p lessthan 0.05). Other complications were also higher in the diabetic group but the difference with non-diabetic patients was not statistically significant.

Table VI: Distribution of patients according to complications (n = 100)

s= significant, ns=not significant, P value calculated by Chi-square test

Group I – Hypertensive Diabetic NSTEMI patients

Group II – Hypertensive Non-diabetic NSTEMI patients.

Univariate logistic regression analysis shows that diabetic NSTEMI patients had significantly higher odds of developing arrhythmia (OR 4.06, 95%CI 1.16 – 14.28; p lessthan 0.05).

Table VII: Univariate logistic regression analysis showing the odds ratio of developing different complications in hypertensive diabetic NSTEMI patients (n = 100)

s= significant, ns=not significant, p-value determined by logistic regression analysis

Group I – Hypertensive Diabetic NSTEMI patients

Group II – Hypertensive Non-diabetic NSTEMI patients.

Cardiovascular disease is the leading cause of morbidity and mortality in people with diabetes mellitus. Patients with DM have a 2-to-4-fold increase in risk of developing cardiovascular disease than those without DM.13 Morbidity, mortality, and re-infarction rate are higher following NSTEMI in diabetic than non-diabetic subjects, with one-year mortality in this population as high as 50% [14]. 

This study was carried out to compare the in-hospital outcomes of hypertensive diabetic and hypertensive non-diabetic patients with NSTEMI. A total of 100 patients were included in the study. Forty diabetic hypertensive NSTEMI patients were included in Group I and 60 non-diabetic hypertensive NSTEMI patients were included in Group II. 

The mean age was found to be 58.1±10.2 years in Group I and 56.2±10.5 years in Group II. No statistically significant (p>0.05) difference was observed between the two groups. This is consistent with the study conducted by Colivicchi et al. (2008) where the mean age of diabetic patients was 54±2 years and of non-diabetic patients was 56±5 years [5]. The present observation is also similar to a study done in Bangladesh by Salim et al. (2015) which revealed that mean age was 58.7 ± 10.7 years in diabetic patients and 57.3 ± 13.2 years in non-diabetic patients with no statistically significant difference [15].

In the present study, the majority of patients were in the 7th decade of life in Group I and Group II (42.5% and 36.6% respectively). In concordance with this study, Franklin et al. (2004) observed that a higher incidence of MI was in the 65-74 age group in both diabetic and non-diabetic patients [6]. 

NSTEMI was predominant in male patients in both diabetic and non-diabetic groups (respectively, 60% and 70%). Franklin et al. (2004) showed almost similar results, where males were 60.9% in the diabetic group and 69.2% in the non-diabetic group. There was no statistically significant difference between the two groups in terms of sex distribution [6]. Kyto et al. (2015) have shown that men have a 2.4-fold overall risk for NSTEMI compared with women, which explains the higher prevalence of males in these studies [16]. 

The most common clinical presentation was chest pain in both diabetic and non-diabetic groups, which were 77.5% in Group I and 83.3 % in Group II. Dyspnoea was found in 10% and 11.7% of cases respectively. Similarly, Cader et al. (2017) noted that 74.2% of patients with NSTEMI were admitted with chest pain in their study and 42.3% of patients had dyspnoea.17 Other common symptoms at presentation were sweating, syncope, and atypical chest pain in both groups.  There was a statistically insignificant difference in clinical presentation between the two groups. Similar observations were also described by Dabek et al. (2016) where NSTEMI patients usually presented with chest pain (78.8%), dyspnoea (10.6%), syncope (3.5%), and atypical chest pain (2.2%) [12].

In the present study, smoking was the most common risk factor which was 62.5% in diabetic hypertensive and 75% in non-diabetic hypertensive patients with NSTEMI. Other risk factors were dyslipidemia (32.5% and 36.7%), family history of IHD (30% and 23.3%), and obesity (22.5% and 13.3%) in Group I and Group II respectively. The difference between the groups was not statistically significant regarding risk factors. A similar proportion was found in a previous study by Salim et al. (2015) which enlisted that tobacco users were 65.4% and 76.9%, dyslipidemia was present in 32.7% and 40.4%, family history of IHD was present in 30.8% and 23.1% and obesity was found in 19.2% and 5.8% in diabetic and non-diabetic patients respectively [15]. The most common risk factor of NSTEMI reported by Dabek et al. (2016) was smoking (44%).12 Franklin et al. (2004) also stated that smoking was the most common risk factor of NSTEMI in both diabetic and non-diabetic patients, which was found in 49.5% and 60.6% of patients respectively in their study [6]. 

In this study, diabetic patients developed significantly more complications than non-diabetic patients (p lessthan 0.05). The most common complication was heart failure in both groups of patients (30% and 16.7% respectively for Group I and Group II patients). Other complications were renal failure (10% and 5.0%), arrhythmia (22.5% and 6.7%), cerebral ischemia (7.5% and 1.7%), and cardiogenic shock (5.0% and 3.3%) in Group I and Group II respectively. Among them, arrhythmia and cerebral ischemia occurred at a significantly higher proportion in diabetic patients than in non-diabetic patients (p lessthan 0.05). In hospital mortality for Group I and Group II, patients were 7.5% and 3.3% patients respectively. Colivicchi et al. (2008) found a significantly higher proportion of in-hospital events as well as heart failure in diabetic patients than those of non-diabetic patients [5]. Franklin et al. (2004) revealed that the most common hospital outcomes were heart failure (28.9% and 16.5%), renal failure (8.4% and 4.5%), death (6.3% and 5.1%) and cardiogenic shock (4.8% and 4.1%) respectively in diabetic hypertensive and non-diabetic hypertensive patients with NSTEMI [6]. Cader et al. (2017) also reported that about 4.9% of NSTEMI patients had a cardiogenic shock, 12.5% had heart failure, 6.6% had acute kidney injury and 8.3% had death [17].

Logistic regression analysis showed that the odds ratio of diabetic patients developing heart failure was 2.14, renal failure was 2.11, arrhythmia was 4.06, cerebral ischemia was 4.78, cardiogenic shock was 1.53 and death was 2.35. Iqbal et al. (2011) reported that the OR of NSTEMI patients with DM developing heart failure was 2.5, (p less than 0.05), and cardiogenic shock was 1.9, (p lessthan 0.05) [3].

In a systematic review by Johansson and colleagues (2017), MI survivors remain at higher risk of dying in the first year than the general population, particularly when additional risk factors such as diabetes, hypertension, or older age are present.18 Therefore, it is pertinent to emphasize on control of diabetes and hypertension in the secondary prophylaxis of patients with myocardial infarction.

NSTEMI in diabetic hypertensive patients is significantly associated with more in-hospital complications and worse outcomes in comparison to non-diabetic hypertensive patients particularly cardiac arrhythmia and cerebral ischemia. There were no statistically significant differences in terms of presentation and risk factors for coronary artery disease among diabetic versus non-diabetic patients with hypertension presenting with NSTEMI.

Although the result of this study supports the hypothesis, there are some facts to be considered which might have affected the result of the current study. It was a single-center study. The number of the study population was relatively small. The sampling method was non-randomized, so there was a risk of selection bias. Long-term follow-up was not possible.

In this study, it was observed that most diabetic hypertensive patients with NSTEMI come at the late stage, making treatment options difficult and so more complications have already developed. However, if the limitations of this study are considered, this is a hospital-based prospective study that may not represent the total scenario of our community or country. So, further study can be done with a community-based large sample size at the national level.