Kerala Heart Journal -Sharadha

Original article

Kerala Heart J  2016; 6(2):xx-xx.  


Clinical profile of patients with recanalised infarct related coronary artery after thrombolytic therapy

M.Chokkalingam, S.Saradha, Pradeep.G.Nayar, L.Tamil selvi.



Corresponding autho
r


Dr.S.Saradha, Assisstant Professor,
Department of Pharmacology,
Chettinad Hospital and Research Institute,
Kelambakkam, Tamilnadu, India.
Mobile: 9842936511. Email: saradhachoks@gmail.com



Abstract:

Background & Objective:

Thrombolytic therapy plays a major role in the management of acute myocardial infarction (AMI). The main goal in the treatment of AMI is early restoration of complete infarct artery perfusion. This study is aimed to analyze the clinical profile of patients who had complete recanalistaion of coronary artery after thrombolytic therapy, found by coronary angiogram.

Methodology:

A Retrospective Study conducted in the Cardiology department of Chettinad Hospital and Research Institute, Chennai. 50 patients with acute ST elevation Myocardial Infarction who underwent coronary angiogram and reported as recanalised coronary artery were included. Baseline characteristics like age, sex, clinical history, conventional risk factors, duration of symptoms, type of thrombolytic agent used and coronary angiogram results were analyzed in detail.

Results:

52% of subjects were above 40 years of age. Only 36% of diabetic, 46% of hypertensive and 16% of dyslipidaemic patients had complete recanalisation. 76% of patients reached the hospital within the window period. 94% of patients had thrombolysis with streptokinase. 56% of patients with Anterior Wall MI (AWMI) and 20 % of patients with Inferior Wall MI (IWMI) had completely recanalised artery.

Conclusion:

Male sex was predominant in the study population. Risk factors like advancing age, dyslipidemia, diabetes, hypertension and alcoholism decrease the chances of complete recanalistaion. The chance of recanalistaion was more when the patient reached hospital within the window period. Recanalisation was more complete when there is Left Anterior Descending artery(LAD) involvement.

Key words: Coronary artery disease, thrombolysis, recanalisation, streptokinase.

 

 Introduction:

        Thrombolytic therapy plays a major role in the management of acute myocardial infarction (AMI). The main goal in the treatment of AMI is early restoration of complete infarct artery perfusion. Thrombolytic therapy lyses infarct artery thrombi and enhance reperfusion, thereby reducing infarct size, preserving left ventricular function, and improving survival. In less than 50% of patients only, the most effective thrombolytic regimens achieve angiographic epicardial infarct related artery patency within 90 minutes(1).This study is aimed to analyze the clinical profile of patients who had complete or near complete recanalistaion of infarct related coronary artery after thrombolytic therapy ,found by coronary angiogram.

            Ischemic heart disease will be the most important cause of mortality worldwide in near future despite tremendous improvement in healthcare. Coronary artery diseases have been gaining importance in India because of increasing incidence of the disease. It is the most common of 5 causes of deaths in Indian population (2).AMI as the first manifestation of ischemic heart disease is very high and is approximately 70% and is a common cause for hospital admission. Despite this increasing incidence, the data regarding risk factors, profile and outcome of the patients presenting with ST-elevated MI (STEMI) who are treated by thrombolysis in India is lacking.

Objectives:

To analyze the clinical profile of patients who had complete or near complete recanalistaion of infarct related coronary artery after thrombolytic therapy, found by coronary angiogram.

Materials and Methods:


Study design: A Retrospective Study conducted in the Cardiology department, Chettinad Hospital and Research Institute.

Sample size: 50 patients.


Inclusion criteria:

1. Patients with acute ST elevation Myocardial Infarction(STEMI) with ST elevation of 1 mm or more in two contiguous leads or presence of new onset Left Bundle Branch Block (LBBB) or true posterior wall STEMI who underwent coronary angiogram and reported as recanalised coronary artery.

2. Typical rise of cardiac biomarkers either in the form of Creatine Kinase-MB (CKMB) or Troponin.

Exclusion criteria:

1. STEMI mimetics including Prinzmetal angina, myocarditis, pericarditis, preexisting LBBB, Left ventricular hypertrophy, hyperkalemia, hypercalcemia, Brugada syndrome.

 

Baseline characteristics like age, sex, clinical history, conventional risk factors, duration of symptoms, type of thrombolytic agent used and coronary angiogram results were analyzed in detail.

Results:

In this study we observed that 90% of the patients were males. 30% subjects were in the age group 31-40years. 28% subjects were between 41-50years. 24% subjects were above 50years. 18% participants were less than 30years. This implies that the chances of complete recanalistaion decreases as the age advances.

Analyzing the conventional risk factors, only 36% (18 patients) were having Diabetes mellitus (DM). So presence of diabetes decreases the chance of complete recanalistaion. Only 16% of patients had Dyslipidemia (DLP). This shows that the chances of complete recanalistaion is very less if the patient has dyslipidemia. 46% patients had Hypertension (HTN). Presence of HTN reduces the chances of complete recanalistaion.

20 patients had history of smoking out of which 18 patients who presented early (< 5 hours) had recanalised coronary artery. Smokers who present early are having high chances of complete opening of infarct related artery. 42% of the patients were known alcoholics which also decreases the chance of complete recanalistaion.76% patients reached hospital with in the window period of, < or = 5 hours, and the remaining 24% patients reached hospital > 5 hours from the onset of chest pain. Majority (94%) of patients had thrombolysis with streptokinase as per their wish.

56% of patients with Anterior Wall MI (AWMI) and 20 % of patients with Inferior Wall MI (IWMI) had completely recanalised artery which showed Left Anterior Descending (LAD) involvement has more probability for recanalisation. Our study revealed that common arteries which are recanalised are LAD -35 patients and Right Coronary Artery ( RCA) -13 patients.

 Patient Demography:-

Figure 1: Sex distribution

 

Figure 2: Age distribution

 

Figure 3: Smoking

 

            

Count

%

HTN

Absent

27

54.00

Present

23

46.00

DM

Absent

32

64.00

Present

18

36.00

DLP

Absent

42

84.00

Present

8

16.00

Smoking

Absent

30

60.00

Present

20

40.00

Window Period

≤ 5 Hours

38

76.00

> 5 Hours

12

24.00

Table 1: Risk factors

HTN-Hypertension, DM-Diabetes mellitus, DLP-Dyslipidaemia.

 

 

Figure 4: Hypertension

 

Figure 5: Diabetes mellitus

 

 

 

Window Period

 

≤ 5 Hours

> 5 Hours

Mann Whitney

Absent

Present

Absent

Present

U Test

Count

%

Count

%

Count

%

Count

%

U Value

Sig.

HTN

20

52.63

18

47.37

7

58.33

5

41.67

215.000

0.732

DM

27

71.05

11

28.95

5

41.67

7

58.33

161.000

0.067

DLP

31

81.58

7

18.42

11

91.67

1

8.33

205.000

0.411

Smoking

20

52.63

18

47.37

10

83.33

2

16.67

158.000

0.061

Alcohol

20

52.63

18

47.37

9

75.00

3

25.00

177.000

0.175

Table 2: Window period

 

 

 

         

Count

%

 

 

MI

 

 

ALMI

4

8.00

ASMI

2

4.00

AW+IWMI

1

2.00

AWMI

28

56.00

ILMI

3

6.00

IW+PWMI

1

2.00

IWMI

10

20.00

PWMI

1

2.00

LV  function

Normal

7

14.00

Adequate

12

24.00

Mild

16

32.00

Moderate

10

20.00

Severe

5

10.00

Angio finding

LAD

35

70.00

LCX

1

2.00

OM

1

2.00

RCA

13

26.00

Table 3: Clinical features

ALMI- AnteroLateral MI, ASMI-AnteroSeptal MI, IWMI-Inferior Wall MI, AWMI-Anterior Wall MI, PWMI-Posterior Wall MI, LV function - Left Ventricular function, LAD-Left Anterior Descending artery, LCX-Left Circumflex Artery, OM-Obtuse Marginal artery, RCA-Right Coronary Artery.

 

Figure 6: Thrombolytic agent

SK-Streptokinase, RETE-Reteplase, TNK-Tenecteplase.

 

           

Discussion:

 

Fibrinolytic therapy is an effective treatment in ST-segment elevation myocardial infarction (STEMI) for which American Heart Association/American College of Cardiology has clear cut guidelines regarding eligibility of patients.

 Rupture of the plaque with subsequent thrombosis is the leading cause of myocardial infarction in patients with coronary artery disease (3,4,5,6). It has been recognized that 1 to 12% of patients may suffer from a myocardial infarction with angiographically normal coronary arteries (MINCA)(7). Young people are more likely to suffer an MINC than older people(8,9).Our study also clearly showed the incidence is more common in patients less than 40 years and also 18% patients were less than 30 years.

The etiology of this disease is not clearly known. The proposed mechanisms include coronary spasm(8) and thrombosis,(9,10)platelet dysfunction.

Coronary vasospasm can produce myocardial ischaemia, but it is not certain that arterial spasm alone can cause myocardial necrosis. Syndrome X is angina with normal coronary arteries on angiography. Although dysfunction of vascular endothelium is thought to be a mechanism in both syndrome X and MINCA, there are important differences between the two groups. Most patients with MINCA do not have angina. Syndrome X patients tend to be young women. Syndrome X involves the coronary microvasculature, whereas MINCA is associated with epicardial vessels.(11)

 Cigarette smoking is a major risk factor in young patients with normal coronary arteries suffering myocardial infarction.(12,13,14)It has been shown that there is increased platelet consumption in young smokers without clinical evidence of coronary artery disease(15). This relation is presumably related to the mechanism of enhanced platelet aggregation and adhesion seen after smoking cigarettes (16,17) that would be expected to increase the thrombotic risk in smokers with normal coronary arteries. Our study also showed that nearly 40% of patients are smokers.

The most common mechanism of acute myocardial infarction is a plaque rupture with a thin fibrous cap overlying a large lipid core (18). It is well known that such vulnerable plaques can be present in vessels that appear angiographically normal (19). Another proposed mechanism of acute thrombosis is erosion and denudation of endothelial cells over the surface of plaques rich in proteoglycans, and smooth muscle cells (20). This mechanism of thrombosis is more common in younger patients and in women (21).

The angiographic definition of normal coronary arteries relies on axial contrast angiograms of the vessel lumen. This can underestimate the amount of atherosclerotic plaque (22). Atherosclerosis is associated with medial atrophy and vessel wall dilatation resulting in diffusely diseased arteries appearing to have an angiographically normal lumen. So there is limited information about the true prevalence of plaques in patients with myocardial infarction and normal coronary arteries. Intravascular ultrasound and Optical coherence tomography can overcome the limitations of angiography with tomography images and can provide accurate plaque burden.

Conclusion:

To summarize male sex was predominant in the study population. Majority of patients preferred thrombolysis with Streptokinase. Risk factors like advancing age, dyslipidemia, diabetes, hypertension, smoking & alcoholism decrease the chances of complete recanalistaion. The chance of recanalistaion was more when the patient reached hospital within the window period. Recanalisation was more complete when there is Left anterior descending artery involvement. .

Acknowledgement: All the authors are thankful to Chettinad Hospital and Research Institute.

 

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