Serum magnesium and phosphorus values are lower among patients with paroxysmal atrial fibrillation: insights from the PLACEBO study

Abstract

Background

Magnesium and phosphorus comprise micronutrients in circulating blood, while associated disorders have been linked with increased risk of cardiovascular disease (CVD). Low serum magnesium has been connected to atrial fibrillation (AF) development among individuals without CVD, as patients with higher serum phosphorus levels, without chronic kidney disease (CKD), demonstrate an increased risk of AF plus higher rates of cardiovascular morbidity. Patients with paroxysmal atrial fibrillation (PAF) seem to hold the same cardiovascular risk as patients with permanent AF. The exact connection between serum magnesium and phosphorus levels and PAF has not been adequately explored.

Purpose

We aimed to investigate the potential relationship between serum magnesium and phosphorus levels and the number of AF paroxysms during the past 6 months from enrollment.

Methods

We analyzed preliminary data from the Ergospirometry in Paroxysmal Atrial Fibrillation Prognosis (PLACEBO) trial (NCT05246423), an observational, prospective, single-center cohort study aiming to examine the prognostic role of cardiopulmonary exercise testing variables in the future paroxysms of AF. We included 53 patients diagnosed with PAF, without CKD, and 30 healthy individuals. Normality was assessed with the Shapiro-Wilk test. Normally distributed variables are presented as mean±SD and significance was investigated with T-test while non-normally variables were distributed as median (IQR) and investigated with the Mann-Whitney U test. A p-value <0.05 was considered statistically significant.

Results

The study cohort comprised 54 patients with PAF, without CKD, and 30 healthy individuals. Baseline demographics are presented in the relevant table. Patients with PAF were older than controls and they had more comorbidities, as expected. Serum magnesium and phosphorus levels were significantly lower among patients with PAF compared to controls [1.9±0.22 versus 2.13±0.26 mg/dl and 3.95 (0.75) versus 3.3 (0.65) respectively (p>0.001)]. Higher serum phosphorus levels were associated with lowest frequency of AF paroxysms within the previous 6 months (R=-0.293, p=0.039).

Conclusions

Patients with PAF demonstrate lower serum magnesium and phosphorus levels compared to healthy individuals. This might be in part explained by the fact that serum phosphorus is known to be inversely associated with BMI; in our cohort, BMI was higher among patients with PAF. The lowest the frequency of AF episodes, the highest the serum phosphorus levels, a finding that comes in contrary with previous reports pointing towards an increased risk of AF development and higher cardiovascular mortality among individuals with higher serum phosphorus levels. Our findings may highlight novel potential therapeutic strategies targeting serum magnesium and phosphorus in patients with PAF, with an eye to minimize the number of AF paroxysms.

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Author notes

Funding Acknowledgements: None.