Prognostic Impact of Mild Hypokalemia in Terms of Death and Stroke in the General Population—A Prospective Population Study - 22/11/17

Doi : 10.1016/j.amjmed.2017.09.026

Nick Mattsson, MD ^a,^* , Olav Wendelboe Nielsen, MD, PhD, DMSc ^a, Linda Johnson, MD, PhD ^b, Eva Prescott, MD, DMSc ^a,^c, Peter Schnohr, MD, DMSc ^c, Gorm Boje Jensen, MD, DMSc ^c, Lars Køber, MD DMSc ^d, Ahmad Sajadieh, MD, DMSc ^a
^a Department of Cardiology, Copenhagen University Hospital of Bispebjerg, Denmark
^b Department of Clinical Sciences, Skåne University Hospital, Lund University, Malmö, Sweden
^c Copenhagen City Heart Study, Copenhagen University Hospital of Frederiksberg, Denmark
^d Department of Cardiology, Copenhagen University Hospital of Rigshospitalet, Denmark

^*Requests for reprints should be addressed to Nick Mattsson, MD, Copenhagen University Hospital of Bispebjerg, Department of Cardiology, Bispebjerg Bakke 23, Copenhagen, NV 2400, Denmark.Copenhagen University Hospital of BispebjergDepartment of CardiologyBispebjerg Bakke 23Copenhagen,NV2400Denmark

Sous presse. Épreuves corrigées par l'auteur. Disponible en ligne depuis le Wednesday 22 November 2017

Abstract

Background

Potassium supplementation reduces the risk of cardiovascular mortality and stroke in population studies; however, the prognostic impact of mild hypokalemia in the general population has not been thoroughly investigated. We aimed to investigate associations between mild hypokalemia and endpoints in the general population.

Methods

Participants (aged 48-76 years) from the general population study “Copenhagen City Heart Study” (n = 5916) were studied. Participants were divided into groups according to baseline values of plasma potassium (potassium): hypokalemia (<3.7 mmol/L, n = 758), normokalemia (3.7-4.5 mmol/L, n = 4973), and high potassium (>4.5 mmol/L, n = 185). Hypokalemia was further divided as potassium <3.4 mmol/L and 3.4-3.6 mmol/L. The primary endpoints were all-cause mortality and nonfatal validated ischemic stroke. The secondary endpoint was acute myocardial infarction (AMI). We adjusted for conventional risk factors, diuretics, and atrial fibrillation at baseline.

Results

Mean potassium in the hypokalemic group was 3.5 mmol/L (range, 2.6-3.6 mmol/L) and was associated (P < 0.05) with increased systolic blood pressure, higher CHA₂DS₂-VASc score, and increased use of diuretics as compared with normokalemia. Baseline atrial fibrillation was equally frequent across groups. Median follow-up-time was 11.9 years (Q1-Q3: 11.4-12.5 years). Hypokalemia was borderline associated with increased stroke risk in a multivariable Cox model (including adjustment for competing risk) as compared with normokalemia (hazard ratio [HR] 1.40; 95% confidence interval [CI], 1.00-1.98). The subgroup with potassium <3.4 mmol/L had higher stroke risk (HR 2.10; 95% CI, 1.19-3.73) and mortality risk (HR 1.32; 95% CI, 1.01-1.74) as compared with normokalemia. Hypokalemia was not associated with AMI, and no increased risk of mortality was seen with concomitant AMI and hypokalemia. No associations were seen with high potassium.

Conclusion

In a general population mild hypokalemia is associated with increased stroke risk and, to a lesser degree, increased mortality risk.

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Keywords : Epidemiology, Hypokalemia, Longitudinal population based cohorts, Mortality, Stroke

Plan

	Funding: The Copenhagen City Heart Study was supported by grants from the Danish Heart Foundation. All authors declare their independence from the funding source.
	Conflict of Interest: None.
	Authorship: All authors had full access to all of the data in the study and have contributed substantially to the writing of the manuscript.