Table of Contents  
ORIGINAL ARTICLE
Year : 2016  |  Volume : 9  |  Issue : 5  |  Page : 609-612  

Prognostic significance of mitral regurgitation after myocardial infarction: An echocardiography-based study


Department of Medicine, Dr. V. M. Government Medical College, Solapur, Maharashtra, India

Date of Web Publication13-Oct-2016

Correspondence Address:
Vijaykumar V Ingle
Department of Medicine, Dr. V. M. Government Medical College, Solapur - 413 001, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0975-2870.192159

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  Abstract 


Background: Mitral regurgitation (MR) after acute myocardial infarction is common and often silent. Therefore, it should be specifically sought with careful physical examination and Doppler echocardiography. It also denotes an adverse prognosis. Materials and Methods: In this prospective study, we studied 52 patients of ST elevation acute myocardial infarction. The patients of ST elevation acute myocardial infarction whose admission electrocardiogram showed ST elevation of more than 0.1 mv (1 mm) in two or more limb leads or more than 0.2 mv (2 mm) in two or more chest leads were included in the study. Detailed echocardiographic analysis was done in all patients within 48 h of admission. MR jet was systematically evaluated using color Doppler as a primary tool. MR was classified as mild or moderate to severe depending on the recorded values. Results: Ischemic MR was detected in 22 patients. There were 12 patients with mild MR and 10 with moderate-to-severe MR. Thus, we had two groups of patients. One who had echocardiographically detected MR and other group without echocardiographically detected MR. Percentage of smokers was higher in the group of patients with MR than those without MR (72% and 60%, respectively). In addition, patients in the group with MR were with higher body mass index and were likely to present with higher Killip class on admission. Percentage of patients presenting with left ventricular (LV) enlargement was higher in the group of patients presenting with MR than those without MR (60% and 20%, respectively). In addition, LV dysfunction (both systolic as well as diastolic) was more prevalent in the group of patients presenting with MR than those without MR. Mortality percentage was higher in the group of patients presenting with MR than those without MR (22% and 10%, respectively). However, this difference was not statistically significant (P = 0.2597). Conclusion: Clinical or echocardiographic detection of MR derives its prognostic significance from an integration of multiple clinical, radiographic, electrocardiographic, and other echocardiographic characteristics.

Keywords: Acute myocardial infarction, echocardiogram, mitral regurgitation, mortality


How to cite this article:
Ingle VV. Prognostic significance of mitral regurgitation after myocardial infarction: An echocardiography-based study. Med J DY Patil Univ 2016;9:609-12

How to cite this URL:
Ingle VV. Prognostic significance of mitral regurgitation after myocardial infarction: An echocardiography-based study. Med J DY Patil Univ [serial online] 2016 [cited 2024 Mar 28];9:609-12. Available from: https://journals.lww.com/mjdy/pages/default.aspx/text.asp?2016/9/5/609/192159




  Introduction Top


Mitral regurgitation (MR) after myocardial infarction is the result of multifactorial processes involving local and global left ventricular (LV) remodeling. The prevalence of MR varies. Published studies differ greatly in design, inclusion criteria, duration of follow-up, and technique of MR assessment. However, they consistently indicate that MR after myocardial infarction carries adverse prognosis with an increased risk of death and heart failure. MR is often clinically silent; therefore, it should be systematically evaluated by echocardiography. Standard color Doppler imaging is a highly sensitive method to detect even mild degrees of ischemic MR. One unique advantage of echocardiography is that it accurately quantifies the severity of MR by measuring various Doppler parameters.[1]

In severe MR secondary to acute myocardial infarction, pulmonary edema, hypotension, and frank cardiogenic shock may develop. It is essential to determine the cause of MR, which includes ruptured papillary muscle, annular dilatation from severe LV dilatation, and papillary muscle displacement with leaflet tethering.[2]

Ischemic MR results from geometric changes in LV shape. Regional remodeling after myocardial infarction displaces papillary muscles and causes tethering of the mitral valve leaflet, which results in incomplete leaflet coaptation. Malcoaptation is aggravated further by dilatation of the mitral valve annulus, hence MR ensues. This mechanism is somewhat verified by the observation that mitral leaflet tethering causes tenting of leaflet toward apex that increases during exercise and stress. Exercise- and stress-induced geometric LV change increases regurgitant orifice area and volume and may result in dyspnea; it is also associated with a history of pulmonary edema. Ischemic MR cannot develop in the setting of regional wall motion abnormality alone because conformational change of LV shape is necessary for the development of functional MR. The severity of MR is related more to the extent of geometric change than to the severity of LV disease and systolic dysfunction.[3]


  Materials and Methods Top


This is a prospective study of consecutive patients of acute myocardial infarction. Patients of acute myocardial infarction whose admission electrocardiogram (ECG) showed ST elevation of more than 0.1 mv (1 mm) in two or more limb leads or more than 0.2 mv (2 mm) in two or more chest leads were included in the study.[4]

All patients presented with either chest pain or breathlessness, which was new in onset. Cardiac troponin testing was done in all cases.

Following patients were excluded from the study:

  • Previous h/o myocardial infarction.
  • Heart failure.
  • Organic mitral valve disease.
  • Previous mitral valve surgery.
  • The patients' demographic information, risk factors, Killip class on admission, ECG abnormalities, treatment, in-hospital complications, and mortality were recorded.


Full clinical data sheet is available for all patients.

Echocardiographic analysis

Echocardiogram was recorded using Imagic Agile color Doppler serial number 301178 with adult probe by an experienced echocardiographer within 48 h of hospital admission. Sizes of left ventricle and left atrium were measured in parasternal long axis view. LV ejection fraction was calculated in apical 4 chamber view by Simpson's method. Regional wall motion abnormalities were recorded, as predominant arterial territory was involved.[5]

MR jet was systematically evaluated using color Doppler as a primary tool. MR was classified as mild or moderate to severe depending on the following recorded values:[6],[7]

  • MR jet (% left atrium).


    • <15 as mild MR and.
    • 15 as moderate to severe MR.


  • Vena contracta.


    • <3 mm mild MR, and
    • >3 mm as moderate to severe MR.


  • Regurgitant volume.


    • <30 ml mild, and
    • >30 ml as moderate to severe MR.


  • Spectral Doppler density.


    • Faint mild MR, and
    • Dense as moderate to severe MR.




Statistical analysis

Baseline characteristics of patients of ST elevation acute myocardial infarction and echocardiographic values of patients are presented as mean and standard deviation. For comparing mortality difference between two groups of patients, Fisher's exact test is used.


  Results Top


Fifty-two patients of ST elevation acute myocardial infarction who fulfilled the entry criteria were included in the study. Echocardiography was performed in all patients within 48 h of hospital admission. Ischemic MR was detected in 22 patients. There were 12 patients with mild MR and 10 with moderate-to-severe MR. Thus, we had two groups of patients. One who had echocardiographically detected MR and other group without echocardiographically detected MR. Clinical characteristics, echocardiographic findings, and survival data are presented in the following tables.

[Table 1] depicts the results of a comparison between the above-mentioned two groups to baseline characteristics and risk factors.
Table 1: Baseline characteristics in patients with and without mitral regurgitation

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As shown in [Table 1], baseline variables were comparable between two groups. There were no differences between with and without MR with regard to mean age at presentation, gender, risk factors such as hypertension, diabetes mellitus, and hyperlipidemia. However, percentage of smokers was higher in the group of patients with MR than those without MR (72% and 60%, respectively). In addition, patients in the group with MR were with higher body mass index (BMI) and were likely to present with higher Killip class on admission. There was no much difference as far as location of myocardial infarction is concerned.

[Table 2] shows the echocardiographic analysis of patients with regard to LV dimensions, systolic, and diastolic functions.
Table 2: Echocardiographic in patients with and without mitral regurgitation

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From [Table 2], it can be inferred that the percentage of patients presenting with LV enlargement was higher in the group of patients presenting with MR than those without MR (60% and 20%, respectively). In addition, LV dysfunction (both systolic as well as diastolic) was more prevalent in the group of patients presenting with MR than those without MR.

[Table 3] shows the outcome of 52 patients within 7 days of Intensive Care Unit (ICU) stay. The characteristic, i.e., mortality is compared between the two groups of patients.
Table 3: Outcome of 52 patients

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As shown in [Table 3], 5 patients out of 22 died in the group of patients presenting with MR. Mortality percentage in the group of patients presenting with MR was 22% whereas in the other group, i.e., in the group of patients presenting without MR, the mortality percentage was 10% (3 out of 30 patients).

Thus, mortality percentage was higher in the group of patients presenting with MR than those without MR (22% and 10%, respectively). However, this difference was not statistically significant (P = 0.2597).


  Discussion Top


We conducted this study to find out the prevalence of ischemic MR in patients with ST elevation acute myocardial infarction and association of ischemic MR with outcome within 7 days of ICU stay to predict the prognostic value of the same in relation to short-term mortality.

We found that incidence of MR in our 52 patients studied was 43%, i.e., 22 out of 52 patients had some degree of MR. Similarly, Bursi et al. in their study found that out of 773 subjects studied, MR was detected in 386 patients, i.e., overall incidence was 50%. Although we found similar trend in the detection of new cases of MR, reported incidence varies from <20% in angiography studies to 50% in echocardiography studies.[8],[9],[10]

The clinical characteristics in our study indicate that for any degree of MR, patients are likely to be smokers and with higher BMI. Furthermore, they are likely to present with higher Killip class.

Echocardiographic characteristics of patients indicated that those acute myocardial infarction patients with MR had lower ejection fraction, larger LV size, and greater degree of diastolic dysfunction. Dudzinski and Hung in their study observed that LV ejection fraction was 37-41% in acute myocardial infarction patients with MR as compared to 55-70% in those without MR. They also observed that MR severity was directly related to LV dilatation. Hence, our echocardiographic inferences in acute myocardial infarction patients are valid.

In addition, mortality in those patients with any degree of MR was higher than those without MR (22% and 10%, respectively).

However, this association was not statistically significant (P = 0.2597). Barzilai et al. in their clinical study (the MILLIS study group) concluded that MR as an independent variable does not contribute as prognostic indicator to predict short-term mortality.[11],[12]


  Conclusion Top


We conclude that in patients with acute myocardial infarction, early detection of mitral regurgitation by echocardiography denotes adverse prognosis. But for comprehensive risk stratification after AMI integration of multiple variables like clinical characteristics, radiographic, electrocardiographic and other echocardiographic parameters along with mitral regurgitation is required. Relatively small sample size was a limitation of our study.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Bursi F, Enriquez-Sarano M, Jacobsen SJ, Roger VL. Mitral regurgitation after myocardial infarction: A review. Am J Med 2006;119:103-12.  Back to cited text no. 1
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2.
Bonow RO, Mann DL, Zipes DP, Libby P, editors. Braunwalds Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Published by Saunders an Imprint of Elsevier Inc. Philadelphia. PA. 2012. p. 1509.  Back to cited text no. 2
    
3.
Salukhe TV, Henein MY, Sutton R. Ischemic mitral regurgitation and its related risk after myocardial infarction. Circulation 2005;111:254-6.  Back to cited text no. 3
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4.
Apple FS, Wu AH. Myocardial infarction redefined: Role of cardiac troponin testing. Clin Chem 2001;47:377-9.  Back to cited text no. 4
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5.
Cheitlin MD, Alpert JS, Armstrong WF, Aurigemma GP, Beller GA, Bierman FZ, et al. ACC/AHA Guidelines for the Clinical Application of Echocardiography. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Clinical Application of Echocardiography). Developed in collaboration with the American Society of Echocardiography. Circulation 1997;95:1686-744.  Back to cited text no. 5
    
6.
Ascah KJ, Stewart WJ, Jiang L, Guerrero JL, Newell JB, Gillam LD, et al. A Doppler-two-dimensional echocardiographic method for quantitation of mitral regurgitation. Circulation 1985;72:377-83.  Back to cited text no. 6
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7.
Armstrong WF, Ryan T, editors. Feigenbaums Echocardiography. Seventh Edition. Published by Wolter Kluwer (India) pvt. ltd., New Delhi. 2010. p. 310-35.  Back to cited text no. 7
    
8.
Bursi F, Enriquez-Sarano M, Nkomo VT, Jacobsen SJ, Weston SA, Meverden RA, et al. Heart failure and death after myocardial infarction in the community: The emerging role of mitral regurgitation. Circulation 2005;111:295-301.  Back to cited text no. 8
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9.
Lamas GA, Mitchell GF, Flacker GC, Smith SC Jr, Gersh BJ, Basta L. et al. For the Survival and Ventricular Enlargement (SAVE) Group Investigators. Clinical significance of mitral regurgitation after myocardial infarction. Circulation 1997;96:827-33.  Back to cited text no. 9
    
10.
Barzilai B, Gessler C Jr., Pérez JE, Schaab C, Jaffe AS. Significance of Doppler-detected mitral regurgitation in acute myocardial infarction. Am J Cardiol 1988;61:220-3.  Back to cited text no. 10
    
11.
Dudzinski DM, Hung J. Echocardiographic assessment of ischemic mitral regurgitation. Cardiovasc Ultrasound 2014;12:46.  Back to cited text no. 11
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12.
Barzilai B, Davis VG, Stone PH, Jaffe AS. Prognostic significance of mitral regurgitation in acute myocardial infarction. The MILIS Study Group. Am J Cardiol 1990;65:1169-75.  Back to cited text no. 12
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    Tables

  [Table 1], [Table 2], [Table 3]



 

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