A quick search of Medline brought up numerous references to the connection between magnesium deficiency and heart disease. Some excerpts from Medline Abstracts appear below.
A link between Mg deficiency and sudden death is suggested by a substantial number of studies published over the past three decades. Data come from epidemiologic, autopsy, clinical, and animal studies. They suggest that: (1) Sudden death is common in areas where community water supplies are Mg-deficient. (2) Myocardial Mg content is low in people who die of sudden death. (3) Cardiac arrhythmias and coronary artery vasospasm can be caused by Mg deficiency and (4) Intravenous Mg reduces the risk of arrhythmia and death immediately after acute myocardial infarction. Because of these data, Mg supplementation has been proposed as a possible method of reducing the risk of sudden death. Suggested ways of supplementing Mg include public education to change dietary habits, addition of Mg to community water supplies, fortification of foods, and oral supplementation. Despite the substantial number of studies linking Mg deficiency with sudden death, no prospective studies have yet investigated whether large-scale Mg supplementation is useful for the primary prevention of sudden death.
A pilot phase 6 month open trial of oral magnesium supplementation in nine ischaemic heart disease patients with low erythrocyte magnesium levels led to significant increases of erythrocyte magnesium in these patients, and to an impressive decrease of anginal attacks and nitrate consumption, as well as to a lesser degree of ST segment depression on surface ECG obtained at exercise testing in seven patients.
From January 1992 to January 1993 the incidence of sudden cardiac death among the population of the Media Valle del Serchio area (Tuscany, Italy), composed of a population of 35,000, was found to be twice that of the European average...
In the examined geographic area a high prevalence of coronary artery disease was verified through the records of the Public Health Service, which documents the main causes of mortality in Tuscany, and through the hospitalization data and the services provided for ischemic heart disease at the local coronary care unit compared with the national average. Moreover, research was accomplished on physical and chemical properties of drinking water in the same area, and this revealed a very low total hardness due to the paucity of calcium and magnesium salts.
By logistic regression, the following factors were independently, significantly, and inversely associated with coronary heart and vascular disease deaths and hospitalizations: alcohol intake, dietary riboflavin, dietary iron, serum magnesium, leisure time exercise, habitual physical activity, and female gender.
CONCLUSIONS: These associations emphasize the important role of modifiable dietary and behavioral characteristics in the causation and prevention of CHD.
Abnormal dietary deficiency in Mg as well as abnormalities in Mg metabolism appear to play important roles as risk factors for ischemic heart disease and acute myocardial infarction, namely in hypertensive vascular disease, diabetic vascular disease, insulin resistance, atherosclerosis and vasospasm. Experimental, epidemiological as well as clinical evidence that supports a role for Mg in these risk factors are reviewed.
...new findings...suggest that the ionized level of [Mg2+]o is an important determinant of vascular tone, contractility and reactivity.
Hemodynamic and 31P-NMR spectroscopic studies were performed on intact, perfused working rat hearts exposed to low (0.3 mM) extracellular Mg([Mg2+]o). Low [Mg2+]o perfusion resulted in rapid and significant falls in cardiac output, coronary flow, stroke volume, developed pressure and the rate-pressure product. Concomitant with this O2 consumption decreased and lactate production increased.
...These observations are consistent with the tenet that low [Mg2+]o can result in marked reduction in oxygen and substrate delivery to the cardiac myocytes, probably as a result of coronary vasoconstriction.
The oxidation states of intracellular myoglobin and cytochrome oxidase aa3 were monitored by reflectance spectrophotometry in isolated perfused rat hearts subjected to an acutely magnesium deficient environment.
Ferrylmyoglobin formation was found to be formed considerably before intracellular release of either creatine phosphokinase or lactic dehydrogenase. These studies may have wide implications as a new mechanism by which low extracellular Mg2+ can induce myocardial injury and subsequent cardiac failure.
CONCLUSION: The Core Study revealed a consistent adverse effect of high body mass index and excess salt intake on BP (blood pressure) and a beneficial effect of magnesium on BP.
It is well established that clinically significant changes in a number of electrolytes occur in patients with congestive heart failure (CHF). Magnesium ions are an essential requirement for many enzyme systems, and evidence is rapidly emerging that magnesium deficiency is a major risk factor for survival of CHF patients. In animal experiments, magnesium has been shown to be involved in several steps of the atherosclerotic process and, although in humans the situation is somewhat more complex, magnesium ions play an extremely important role in CHF and various cardiac arrhythmias. A number of drugs commonly used to treat CHF can significantly affect not only cellular magnesium ion homeostasis, but potassium as well. These include mercurial, thiazide, and loop diuretics. It has also been reported that hypomagnesemia is common in digitalis intoxication. In contrast, a number of agents have been shown to have either a magnesium-conserving effect (potassium-sparing diuretics) or not to affect magnesium ion balance (angiotensin-converting enzyme inhibitors). The clinical consequences of magnesium deficiency include the development of various cardiac arrhythmias, all of which respond well to magnesium treatment. Thus, it is more than apparent that magnesium ion homeostasis is of major importance in CHF. Future studies should address the complex role of magnesium ions in electrolyte imbalance, particularly in relation to heart failure.
Inotropic and lusitropic effects of the parathyroid hormone (PTH) upon the rat heart ventricle myocardium were studied in conditions of calcium and magnesium deficit in drinking water. The control rats revealed two phases of the hormone effect: the positive and negative ones, whereas the experimental rats only revealed the negative inotropic effect. Both the negative and positive inotropic effects were followed by an acceleration of the relaxation.
This page was first uploaded to The Magnesium Web Site on December 10, 1995