A STUDYOF SERUM MAGNESIUM LEVELS AND ITS RELATION TO ARRHYTHMIAS IN ACUTE MYOCARDIAL INFARCTION

the relationship between serum magnesium levels and arrhythmias in patients with acute myocardial infarction.


Inclusion Criteria for Patients
Those patients presenting to the hospital within 12 hours of onset of symptoms were taken.Patients were considered to have acutemyocardial infarction, only if they had 2 of the followingcriteria: 1. History of chest discomfort. 2. ECG changes of acute myocardial infarction. 3. Rise of cardiacenzymes.

Methodology:-
Cases selected were subjected to a detailed history and thorough physical examination, routine investigation like haemoglobin, blood count, urine examination, blood sugar, blood urea, serum creatinine, serumelectrolytes,fasting lipidprofile,cardiacenzymesandechocardiography was performed in all cases.Serum magnesium level were estimated on day-1 andday-5.

Method of Serum Magnesium Estimation Method
Colorimetric end pointtest

Principle
At alkaline pH, magnesium reacts with xylidyl blue and produces a chelating red colored compound. The red increasing (or) the blue decreasing color are proportional to magnesium concentration.

Specimen
Non-haemolyzed serum should be analyzed since the magnesium concentration inside erythrocytes is 10 times greater than that in the ECF, haemolysis should be avoided and serum should be separated from the cells as soon as possible.
Serum magnesium 1.6 -2.4mg/dl. In this study group of 50 cases, 42 were males and 8 were female patients with a male-female ratio of 5.25:1.

Observations and Results:-
The maximum Incidence of acute myocardial infarction was seen in the 4th and 5th decades, followed by 6th and 7th decades. 28% patients were in the age group of 4th and 5th decade, 22werein the age group of60-70.

Serum magnesium in Acute Myocardial Infarction in Relation to Arrhythmia
In this cross sectional study of 50 patients, the mean serum magnesium level on day-1 in all 50 patients was 1.86±0.39 and the mean serummagnesium level on day-5 was 2.26±0.5.

Mean serum magnesium level in the group with Arrhythmia on Day-1 andDay-5
In the present study, out of 50 patients, 25 patients had significant ventricular premature contractions/ ventricular tachycardia/ ventricular fibrillation during their 5-days course in the hospital.   The above table shows that serum magnesium in patient with arrhythmia on Day-5 is 1.98±0.25, those without arrhythmia is 2.48±0.52. There is a significant difference between these two (p<0.001).

Mortality
In the above study of 50 patients, 7 patients died during their 5-dayhospital course. 5 patients died of ventricular tachycardia or ventricular fibrillation, 2 patients died of cardiogenic shock. Mortality percentage was 14%.

Discussion:-
Magnesium ion has emerged as a premier cardiovascular cation during the decade. It has been implicated in the pathogenesis of acute myocardial infarction and complication like arrhythmias. Magnesium is essential for activation of ATP, which maintains the sodium-potassium pump and also because of calcium blocking action, magnesium has been implicated in relation to arrhythmias after acute myocardialinfarction.
In the study group of 50 patients, 42 were males and 8 were females with a male-female ratio of 5.25:1. The maximum incidence of acute myocardial infarction was seen in the 4th and 5thdecades.
In the present study of 50 patients, the mean serum magnesium level on day-1 in all 50 patients was 1.86±0.39 and the mean serum magnesium level on day-5 was2.26±0.5. In the present study, the serum magnesium level on day-1 was significantly lower in patients with arrhythmias than those without arrhythmia (p<0.001). There was an increase in serum magnesium from Day-1 to Day-5 in both those with arrhythmias and those withoutarrhythmias.
Ceremuzynski et al 7 assigned 48 patients with acute myocardial infarction over 24 hour infusion of magnesium or placebo. The incidence of ventricular tachycardia (3 or more consecutive premature ventricular contraction at a rate faster than 120/ min) recorded by Holter monitoring was significantly reduced (p<0.001), but the incidence of other ventricular arrhythmias was not statisticallydifferent.
Raismusen et al 8 randomized 273 patients with suspected acute myocardial infarction to intravenous magnesium or placebo. There is a significant decrease in the ventricular arrhythmia in the magnesium group compared to placebo(p<0.05).
Shecter et al 9 randomized 103 patients with documented acute myocardial infarction to 48 hour infusion of magnesium or placebo. There is a significant decrease in mortality (p<0.01). There was also a non-significant decrease in the number of tachyarrhythmias requiring treatment (10/50) in the magnesium group compared to control(24/53).
Smith et al 10 randomized 400 patients with suspected AMI to a 24 hour infusion of magnesium sulphate or placebo. Two hundred patients had confirmed acute myocardial infarction. The difference in mortality and incidence of ventricular arrhythmias requiring treatment between magnesium and placebo groups were not statistically significant.