October 13, 2017Circulation168 citationsOpen Access
View Full PaperLong-Term Potassium Monitoring and Dynamics in Heart Failure and Risk of Mortality
Key Result
Hypokalemia (HR 2.35; 95% CI 1.40-3.93) and hyperkalemia (HR 1.55; 95% CI 1.11-2.16) were associated with a higher risk of all-cause mortality compared to normokalemia in heart failure patients.
Study Design
Type
Cohort (n=2,164)
Structured PICO
Do abnormal serum potassium levels (hypokalemia or hyperkalemia) increase the risk of all-cause mortality in patients with heart failure?
P
Population
2,164 patients discharged from a previous acute heart failure admission, followed for a median of 2.8 years.
E
Exposure
Abnormal serum potassium levels (hypokalemia <3.5 mEq/L and hyperkalemia >5 mEq/L)
C
Comparator
Normokalemia (3.5-5.0 mEq/L)
O
Outcome
All-cause mortalityhard clinical
Both hypokalemia and hyperkalemia during long-term monitoring are independently associated with increased all-cause mortality in heart failure patients.
Main Result
Hazard Ratio: 2.35 (95% CI 1.4–3.93)
p-value: p=0.001
Abstract
Background: The prognostic value of long-term potassium monitoring and dynamics in heart failure has not been characterized completely. We sought to determine the association between serum potassium values collected at follow-up with all-cause mortality in a prospective and consecutive cohort of patients discharged from a previous acute heart failure admission. Methods: Serum potassium was measured at every physician-patient encounter, including hospital admissions and ambulatory settings. The multivariable-adjusted association of serum potassium with mortality was assessed by using comprehensive state-of-the-art regression methods that can accommodate time-dependent exposure modeling. Results: The study sample included 2164 patients with a total of 16 116 potassium observations. Mean potassium at discharge was 4.3±0.48 mEq/L. Hypokalemia (5 mEq/L) were observed at the index admission in 77 (3.6%), 1965 (90.8%), and 122 (5.6%) patients, respectively. At a median follow-up of 2.8 years (range, 0.03–12.8 years), 1090 patients died (50.4%). On a continuous scale, the multivariable-adjusted association of potassium values and mortality revealed a nonlinear association (U-shaped) with higher risk at both ends of its distribution (omnibus P =0.001). Likewise, the adjusted hazard ratios for hypokalemia and hyperkalemia, normokalemia as reference, were 2.35 (95% confidence interval, 1.40–3.93; P =0.001) and 1.55 (95% confidence interval, 1.11–2.16; P =0.011), respectively (omnibus P =0.0003). Furthermore, dynamic changes in potassium were independently associated with substantial differences in mortality risk. Potassium normalization was independently associated with lower mortality risk ( P =0.001). Conclusions: Either modeled continuously or categorically, serum potassium levels during long-term monitoring were independently associated with mortality in patients with heart failure. Likewise, persistence of abnormal potassium levels was linked to a higher risk of death in comparison with patients who maintained or returned to normal values.