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Clinical and prognostic significance of serum magnesium concentration in patients with severe chronic congestive heart failure : the PROMISE Study . OBJECTIVES The aim of this study was to determine the prognostic significance of alterations in serum magnesium in patients with moderate to severe congestive heart failure . BACKGROUND Reductions in serum magnesium have been postulated to play a role in promoting arrhythmias and to have an adverse impact on survival in congestive heart failure , although support for this postulate is lacking . METHODS Serum magnesium levels were measured in 1,068 patients enrolled in a survival study of class III or IV heart failure at the time of double-blind randomization to milrinone , a phosphodiesterase inhibitor , or placebo . All patients received conventional therapy with digoxin , diuretic drugs and a converting enzyme inhibitor throughout the trial . The median follow-up period was 6.1 months ( range 1 day to 20 months ) . RESULTS Patients with high serum magnesium ( defined as > or = 1.9 mEq/liter , n = 242 ) were less likely to survive than were patients with a normal magnesium level ( n = 627 ) ( p < 0.05 , risk ratio = 1.41 ) . Patients with a low magnesium level ( defined as < or = 1.5 mEq/liter , n = 199 ) had no difference in survival compared with the group with a normal magnesium level ( p = NS , risk ratio = 0.89 ) . At baseline , the patients in the high magnesium group were older and had more severe functional and renal impairment . An analysis after adjustment for these variables demonstrated no difference in survival comparing the low , normal and high magnesium groups . Although the three groups had no difference in frequency of ventricular tachycardia , length of longest run or frequency of ventricular premature beats on baseline Holter monitoring , the group with hypomagnesemia had more frequent ventricular couplets . CONCLUSIONS Serum magnesium does not appear to be an independent risk factor for either sudden death or death due to all causes in patients with moderate to severe heart failure . Hypomagnesemia is associated with an increase in the frequency of certain forms of ventricular ectopic activity , but this is not associated with an increase in clinical events . The higher mortality rate among the patients with hypermagnesemia is attributable to older age , more advanced heart failure and renal insufficiency .
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Intervention_Pharmacological
milrinone
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Intervention_Pharmacological
phosphodiesterase inhibitor
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Intervention_Control
placebo
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Intervention_Physical
conventional therapy with digoxin
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Intervention_Physical
diuretic drugs and a converting enzyme inhibitor
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Outcome_Physical
Serum magnesium levels were measured
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Outcome_Mortality
survive
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Outcome_Mortality
survival
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Outcome_Physical
functional and renal impairment
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Outcome_Mortality
survival
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Outcome_Physical
ventricular tachycardia
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Outcome_Physical
length of longest run or frequency of ventricular premature beats
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Outcome_Other
baseline Holter monitoring
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Outcome_Mortality
sudden death or death
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Outcome_Physical
ventricular ectopic activity
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Participant_Condition
severe chronic congestive heart failure
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Participant_Condition
moderate to severe congestive heart failure
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Participant_Condition
class III or IV heart failure