Clinical relevance of serum ionized magnesium concentration in dogs with myxomatous mitral valve disease.

Abstract

BACKGROUND: Hypomagnesemia is associated with a poor prognosis in humans with congestive heart failure (CHF), but studies in veterinary medicine are limited. HYPOTHESIS: Serum ionized magnesium concentration [iMg] would decrease as CHF progresses compared with the initial diagnostic levels and that lower [iMg] would be negatively associated with prognosis in dogs with CHF. ANIMALS: A total of 181 client-owned dogs with myxomatous mitral valve disease (MMVD) were included. They were classified into the preclinical stage (NO-CHF, n&#x2009;=&#x2009;108), stage C (n&#x2009;=&#x2009;42), and stage D (n&#x2009;=&#x2009;31) based on the American College of Veterinary Internal Medicine MMVD classification. METHODS: This is a retrospective study from 2 referral centers. The [iMg] was compared among the NO-CHF, stage C, and stage D groups. Kaplan-Meier curves and the log-rank test were used to compare the incidence of death between groups. Multivariable Cox regression analysis was used to estimate the association of hypomagnesemia with the death. RESULTS: In the stage D group, the [iMg] was lower than that in the NO-CHF (P&#x2009;<&#x2009;.0001) and stage C groups (P&#x2009;<&#x2009;.003). In the Kaplan-Meier survival analysis, the 1-year cumulative survival rate in hypomagnesemic dogs was 53% compared with 91.5% in normomagnesemic dogs (log-rank test, P&#x2009;<&#x2009;.0001). In the multivariable Cox analysis, lower concentration of [K] and [iMg], along with higher E, were associated with negative prognoses. Specifically, hypomagnesemia was associated with an approximately 4-fold increased risk of death (hazard ratio&#x2009;=&#x2009;4.015; 95% confidence interval, 1.537-10.488; P&#x2009;=&#x2009;.005). CONCLUSIONS AND CLINICAL IMPORTANCE: Assessing the [iMg] might serve as a potential marker for estimating the severity and prognosis indirectly in dogs with MMVD. Combining [iMg] measurement with other diagnostic methods, such as echocardiography, could improve the prognostic evaluation of MMVD in dogs.