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  IN THIS Article
 ::  Abstract
 ::  Introduction
 ::  Material and Methods
 ::  Results
 ::  Discussion
 ::  References
 ::  Article Tables

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ARTICLE
Year : 1977  |  Volume : 23  |  Issue : 3  |  Page : 101-105

An evaluation of the prognostic indices in acute myocardial infarction


Intensive Coronary Care Unit, Medical Research Centre, Bombay Hospital Trust, Bombay Hospital, Marine Lines. Bombay-400 020, India

Correspondence Address:
S J Mishra
Intensive Coronary Care Unit, Medical Research Centre, Bombay Hospital Trust, Bombay Hospital, Marine Lines. Bombay-400 020
India
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PMID: 614423

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 :: Abstract 

A prospective study of hundred patients of acute myocardial infarction admitted in the Intensive Cardiac Care Unit was carried out. The prognosis of each patient, immediate and delayed morta­lity, were assessed on admission by the coronary prognostic indices (C.P.I.) formulated by Peel, Norris and Chapman. The merits and drawbacks of each coronary prognostic index system are discussed. It is felt that the coronary prognostic index would be more accurate if a higher score is given to precursor, life threatening arrhy­thmias, and conduction defects, and the prognostic index is calculat­ed daily during the stay in the I.C.C.U.



How to cite this article:
Mishra S J, Sharma S C, Bandi S C, Periwal P K, Amin B M, Shah N J, Pinto I J. An evaluation of the prognostic indices in acute myocardial infarction. J Postgrad Med 1977;23:101-5

How to cite this URL:
Mishra S J, Sharma S C, Bandi S C, Periwal P K, Amin B M, Shah N J, Pinto I J. An evaluation of the prognostic indices in acute myocardial infarction. J Postgrad Med [serial online] 1977 [cited 2014 Oct 25];23:101-5. Available from: http://www.jpgmonline.com/text.asp?1977/23/3/101/42758



 :: Introduction Top


Assessment of prognosis in acute myocardial infarction is of utmost importance to a treating clinician as it helps to determine the period of stay in an Inten­sive Coronary Care Unit, the period of immobilization after the attack and plan of rehabilitation.

Patients with acute myocardial infarc­tion are now observed continuously in Intensive Coronary Care Units and it has become possible to assess more acu­curately the likely prognosis of an in­dividual patient. The coronary prog­nostic indices commonly used are those reported by Peel et al [12] Norris et al [9] and Chapman et al [4] and many clinicians have combined their criteria to calculate the mortality and assess the prognosis of an attack of acute myocardial infarction.

As the risk factors in acute myocardial infarction in India differ from those in Western countries [13] it is possible that the severity of the disease and clinical course and prognosis also differ. The purpose of this article is to compare the accuracy of the three commonly used coronary prognostic indices [4],[9],[12] in Indian patients with myocardial infarction.


 :: Material and Methods Top


One hundred consecutive patients with acute myocardial infarction admitted at the Intensive Coronary Care Unit of the Bombay Hospital were studied. There were 83 males and 17 females in the age range from 37 years to 76 years. A detailed medical history with special reference to age, symptomatology, pre­cipitating factor, previous history of in­farction, angina, hypertension or dia­betes was enquired and their family his­tory was noted. A detail physical exam­ination was performed and pulse, systolic blood pressure, presence of shock, cardiac failure and other complications were recorded on admission. Electro­cardiogram was taken to find out the extent of infarction, arrhythmias or con­duction defect. A portable X-ray chest was taken routinely on each patient to assess the heart size and the condition of lung fields. Fasting venous blood was collected at the time of admission for routine examination and for serum glu­tamic oxaloacetic transminase, lactic de­hydrogenase, sugar, urea and serum elec­trolytes. Enzyme studies were repeated after 24 hours and 48 hours.

All the patients were observed under continuous E.C.G. monitoring for 2-3 days with the help of heart rate monitor, audiovisual alarm system and arrhythmia monitor at the Central Nursing Station.

All patients were assessed on admis­sion for their likely prognosis by record­ing the score according to the indices of Peel et al , [12] Norris et al [9] and Chapman et al, [4] in a special protocol. Patients were kept under observation during the intermediate coronary stay. The fatal cases were analysed for their cause of death and their prognostic index scores were correlated.


 :: Results Top


A hundred patients of proved acute myocardial infarction were studied. Their electrocardiographic diagnosis is stated in [Table 1].

Thirteen patients out of hundred in­cluded in this study expired (13%). The prognostic index scores of these 100 patients are tabulated in [Table 2]. For the convenience they were classified in 3 groups-mild, moderate and severe with the comparable scores of 3 prognos­tic indices. The mortality rate was higher in the more severe forms of the disease.

Of the 13 cases which expired, cardio­genic shock was the causative factor for 6 of them accounting for 46.15%. 3 died of cardiac arrest, 2 following ventricular asystole and 1 due to ventricular fibrilla­tion, thus accounting for 23.0717 . 3 (23.07%) cases succumbed to left ven­tricular failure and pulmonary oedema and 1 case (7.68%) died as a result of pulmonary embolism.

Thus pump failure, (shock, left ven­tricular failure and pulmonary em­bolism) were responsible for 69.227c mortality.

It was observed that 7 patients who had very high scores in one or all three coronary prognostic indices have surviv­ed.


 :: Discussion Top


Mortality in case of acute myocardial infarction treated in a hospital intensive coronary care unit, varies widely accord­ing to the individual risk factors. Peel et al [12] constructed a coronary prognostic index (CPI) by addition of these risk factors viz. age and sex, past history of infarction, angina or other cardiovas­cular disease, presence of shock or failure and electrocardiographic findings.

The expected mortality in their indices was directly proportional to the scores. Their indices are based mostly on sub­jective criteria and have no consideration for the site of infarction. It has been observed by Beard et al [2] and Norris et al [9] that there is a significantly greater mortality from anterior wall infarction compared with posterior wall infarction. This has been observed in our series too [Table 1]. Failure to consider this factor may have caused a lower score in the fatal cases.

Norris et al [9] formulated coronary prognostic indices based on a prospective study of 57 patients of myocardial infarc­tion using mostly objective criteria con­sisting of age of the patient, site of infarc­tion, systolic blood pressure on admission, heart size, lung fields and history of pre­vious infarction. They claimed that theirs was an unbiased method of assess­ment of prognosis of acute myocardial infarction and was calculated immediately after admission. We have observe( in the present series that this index too does not correlate well with the mortality rate, as some patients having as love a score as 1.7 have died and those having as high a score as 4.8 have had an un­eventful recovery [Table 2] and [Table 3] On closer analysis it was noticed that it our series the patients with low Norris (CPI) score mostly died of ventricular fibrillation, pulmonary embolism or hear' block which had not been given an adequate score while constructing Norris's, C.P.I.

Analysis of most of the larger recorded series [5],[7],[10] has shown that during the first 2448 hours after acute myocardial infarction irritability is at its peak; 85. 90% of the patients in intensive coronary care unit developed one or more arrhythmias. These arrhythmias may be benign and short lasting but certain arrhythmias may be persistent and may lead to a fatal outcome. The recorded incidence shows that these fatal arrhythmias, especially ventricular tachycardia­ (13.4%), ventricular fibrillation (11% ) and complete heart block (6.4%) are not uncommon causes of death. Ventricular fibrillation is the commonest malignant arrhythmia accounting for about 60% of deaths that occur within 1-2 hours after acute myocardial infarction, mostly be­fore the admission to intensive coronary care unit. [11] Although cardiac arrest due to ventricular fibrillation is relative­ly common during first 24-48 hours after acute myocardial infarction, it can also occur later in the course of the disease even after transfer of the patient from intensive coronary care unit. [1] Ventri­cular fibrillation is a major cause of death and the importance of precursor arrhy­thmias has been completely ignored while formulating the Norris's prognostic index and that might explain its in­accuracy.

The assessment of likely prognosis of acute myocardial infarction when cal­culated and analysed by the coronary prognostic index scores constructed and reported by Chapman [4] shows that in mild cases (CPI scores 0-28) the morta­lity was 6.06% while in severe cases (CPI scores 57-83) the mortality was 58.33%. But it has been observed in our series that patients with scores as low as 4 had expired and on the other hand patients with scores as high as 80 had uneventful recovery.

In Chapman's coronary prognostic in­dex like in Norris's prognostic index, there is no score for arrhythmias as it is felt that in a well run intensive coronary care unit, all arrhythmias can be con­trolled. In addition, the known risk factors like previous history of infarction, age of patient, presence of heart failure have not been taken into account in con­structing this coronary prognostic index.

The occurrence of incipient left ventri­cular failure after acute myocardial in­farction is relatively common and may not worsen the prognosis, but occasional­ly acute pulmonary oedema may develop after 48 hours, with rapid rise in left ventricular and diastolic pressure lead­ing to rapid increase in pulmonary venous pressure. [8] If this occurs it will increase the mortality and this complica­tion has accounted for three of the deaths in the present series. The score given to left ventricular failure is therefore con­sidered low.

The presence or absence of arrhythmia and heart block has not been taken into account while compiling Chapman's coronary prognostic index. Complete A-V block is particularly hazardous and it may precipitate cardiac arrest. In the present series 23.07% of the mortality was due to cardiac arrest (due to ventri­cular fibrillation or ventricular asystole). Complete heart block develops relatively late with inferior wall infarction and does not have much effect on the prog­nosis [9] On the other hand with anterior wall infarction, complete A-V block deve­lops suddenly leading to high morta­lity. [3],[6]

Prediction of the eventual outcome of acute myocardial infarction is difficult as re-infarction cannot be predicted and may occur in cases which at the begin­ning are mild; further although the in­cidence of fatal complications is higher in severe cases, a certain number of mild cases may also develop fatal complica­tions later in the intermediate stage [14] as well as during the stay in intensive coro­nary care unit resulting in unpredictable deaths.

It would appear that a higher score should be given to life threatening and precursor arrhythmias and conduction defects and the scores must be assessed every day during the stay in intensive coronary care unit. This would combat the drawback of low admission score and enable us to give a more accurate prog­nosis.

 
 :: References Top

1.Aber, C. P., Portal, R. W. and Chopra, M. P.: Cardiac monitoring in a regional hospital, Brit. Med. J., 1: 209-212, 1969.  Back to cited text no. 1    
2.Beard, O. W., Hipp, H. R., Robins. M., Taylor, J. S., Ebert, R. V. and Beran, L. C.: Initial myocardial infarction among 503 veterans-Five year survival, Amer. J. Med., 28: 871-883, 1960.  Back to cited text no. 2    
3.Chamberlain, D. A., Leinbach, R. C., Vassaux, C. E., Kastor, J. A., Desanctis, R. W. and Sanders, C. A.: Sequential atrioventricular pacing in heart block complicating acute myocardial infarction, New England J. Med., 282: 577-582, 1970.  Back to cited text no. 3    
4.Chapman, B. L.: Correlation of mortality rate and serum enzymes in myocardial infarction. Test of efficiency of coronary care, Brit. Heart J., 33: 643-646, 1971.  Back to cited text no. 4    
5.Eddy, J. D. and Mackinnon, J.: A coro­nory care unit in a general medical ward, Brit. Heart J., 32: 733-737, 1970.  Back to cited text no. 5    
6.Lassers, B. W.., Anderton, J. L., George, M., Muir, A. L. and Julian, D. G.: Hae­modynamic effects of artificial pacing in complete heart block complicating acute myocardial infarction, Circulation, 38: 308-323, 1968.  Back to cited text no. 6    
7.Lawrie, D. M., Greenweed, T. W., God­dard, M., Harvey, A. C., Donald, K. W., Julian, D. G. and Oliver, M. F.: A coro­nary care unit in the routine management of acute myocardial infarction, Lancet, ii: 109-114, 1967.  Back to cited text no. 7    
8.Loeb, H. S., Gunnar, R. M., Pietras, R. J. and Tobin, J. R.: Relationship between central venous and left ventricular fill­ing pressures prior to and during treat­ment of shock, Amer. J. Cardiol., 23: 125, 1969.  Back to cited text no. 8    
9.Norris, R. M., Brandt, P. W. T., Caughey, D. E., Lee, A. J. and Scott, P. J.: A new coronary prognostic index, Lancet, is 274­2 . 78, 1969.  Back to cited text no. 9    
10.Norris, R.. M., Mercer, C. J. and Yeates, S. E.: Idioventricular rhythm complicat­ing acute myocardial infarction, Brit. Heart J., 32: 617-621, 1970.  Back to cited text no. 10    
11.Pantridge, J. F. and Geddes, J. S: A. mobile intensive care unit in the manage­ment of myocardial infarction, Lancet, 2: 271-273, 1967.  Back to cited text no. 11    
12.Peel, A. A. F., Semple T., Want, L., Lancaster, W. M. and Dall, J. L. G.: A coronary prognostic index for grading the severity of infarction, Brit. Heart J., 24: 745-760, 1962.  Back to cited text no. 12    
13.Pinto, 1. J., Peter, T., Colaso, F. and Datey, K. K.: Environmental and host factors in coronary heart disease includ­ing risk factors-An epidemiological view -the current development in India, Published in Springer-Verlag, New York, Heidelberg, Berlin, 1970.  Back to cited text no. 13    
14.Shah, N. J., Mishra, S. J., Bandi, S. C. and Sharma, K.: Intermediate period after acute myocardial infarction, under publication.  Back to cited text no. 14    



 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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