A comparative evaluation of plasma glycerol and free fatty acids in patients with ischaemic heart diseaseVS Singh, Anjana Sharma, Yeshowardhana, TN Mehrotra, GP Elhence
Departments of Biochemistry and Medicine, L.L,R.M. Medical College, Meerut, India
Plasma glycerol concentration was determined in 158 patients admitted to the hospital with acute chest pain. The patients were retrospectively divided into five groups according to their diagnosis, taking into account the presence or absence of myocardial infarction and complicating arrythmias, The plasma glycerol concentration was significantly higher in the group with complicating arrhythmias, irrespective of whether infarction was present or not. Therefore it is proposed that elevation of plasma glycerol may provide an important clue to determine those myocardial ischaemia cases who may develop cardiac arrythmias at a later stage.
Serum concentrations of free fatty acids (FFA) have been shown to be high in patients with acute myocardial infarction.  A positive relation has been found by some workers between the serum FFA levels, complicating arrythmias and death due to myocardial infarction. Recently, Carlstrom and Christensson  observed that patients of myocardial infarction complicated by arrythmias had higher glycerol concentrations than those cases of myocardial infarction not having this complication.
The present study was undertaken to evaluate plasma glycerol levels in patients of myocardial ischaemia with reference to the occurrance of arrythmias.
The present study was carried out on patients admitted to the intensive coronary care unit at the L.L.R.M. Medical College and Associated Hospitals, Meerut, with a history of acute pain in the chest. Patients suffering from diabetes mellitus and pulmonary embolism were excluded. None of the patients were given either Theophylline, sympathomimetic drugs, beta blocking agents or heparin. The diagnosis of myocardial infarction was based on the clinical and conventional typical electrocardiographic changes (Q waves and/or sequential changes in the ST segments and T waves; W.H.O., 1959).
Continuous monitoring was done during the patients' stay in the ward. Arrhythmias were defined as: atrial flutter or fibrillation, presence of more than 5 ectopics per minute, ventricular tachycardia and ventricular fibrillation and atrioventricular block. On the basis of clinical, electrocardiographic, and laboratory findings, the patients were retrospectively divided into following five groups:
28 patients (17 males and 11 females) with ages ranging from 35 to 85 years (mean 52 years) with a history of chest pain without any evidence of cardiac disease.
35 patients (22 males and 13 females) with ages ranging from 40 to 76 years (mean 54 years) with ischaemic heart disease without either arrhythmias or any evidence of myocardial infarction.
24 patients (16 males and 8 females) with ages ranging from 45 to 79 years (mean 68 years) with ischaemic heart disease accompanied by arrhythmias but no evidence of myocardial infarction. In this group, 2 patients had atrio ventricular block, 12 had atrial flutter or fibrillation and 10 had ventricular extra-systoles.
37 patients (26 males and 11 females) of varying age ranging from 50 to 85 years (mean 53 years) with acute myocardial infarction but without arrhythmias.
34 patients (22 males and 12 females) of varying age from 49 to 83 years) (mean 58 years) with acute myocardial infarction complicated by arrhythmias. 10 had atrial flutter or fibrillation, 20 had venticular extrasystoles, 2 had ventricular fibrillation and the remaining 2 had atrioventricular block.
Plasma glycerol (Randroup, 1960) serum enzyme creatine phosphokinase (Duma and Siegel, 1965) and free fatty acids (Trout et al, 1960) were estimated photometrically in all the patients. The normal range in our laboratory for FFA and glycerol in the fasting state are 0.45 to 0.9 m.Eq. /L and 35-65 µmol/L respectively. The range for,CPK is 11-72 I.U. / Litre.
[Figure 1] reveals the plasma glycerol and free fatty acid levels in the five groups.
There was no significant difference between the plasma free fatty acid concentrations in any of the group (p>0.5). Patients who had arrhythmias complicating either angina or myocardial infarction (Groups III and V) had a significantly higher plasma glycerol level (p < 0.001), as compared to patients of myocardial infarction or angina without arrythmias (Groups II and IV). There was no significant difference (p > 0.5) between plasma glycerol levels in patients of groups III and V and Groups II and. IV respectively. None of the non-cardiac cases had a plasma glycerol concentration above 150 µmol./L., whereas in the other groups the rise in plasma glycerol concentration above 150 µmol/L was found in 15 per cent, 61 per cent, 10 per cent and 63 per cent of the cases of Groups II to V respectively.
Serum CPK was elevated only in patients with acute myocardial infarction.
The breakdown of triglycerides into fatty acids and glycerol is controlled by a hormone sensitive lipase, activated by several hormones, of which catecholamines appear to be most essential. The fatty acids formed may either leave adipose tissue or be re-used within it, whereas glycerol cannot be reutilized in adipose tissue or in the muscle, , and is therefore released into the circulating plasma. There is evidence that lipid mobilization as well as cardiac arrhythmias in myocardial ischaemia are both direct effects of the rise of the plasma catecholamine levels.  The reutilization of a part of the fatty acids released might be responsible for the divergent results obtained by different workers concerning the corelation between plasma FFA levels and arrhythmias occurring in myocardial infarction. , Thus plasma glycerol concentration is a better index of the rate of lipolysis and also of catecholamine activity, than the plasma free fatty acid concentration.
In the present study the patients with angina and myocardial infarction complicated by arrhythmias were found to have significantly higher levels of plasma glycerol than the patients of angina and infarction not having arrhythmias.
Thus, irrespective of whether an infarction was present or not, the plasma glycerol was raised if there was a complicating arrhythmia. The plasma glycerol concentration may be of value in predicting the development of arrhythmias in patients of myocardial ischaemia whereas plasma fatty acids were not found to have any such relationship in the present study.