Abstract 14913: Relationship Between Serum Potassium Levels, Arrhythmias, and Mortality Following NSTEACS- Insights from the MERLIN-TIMI 36 Trial
BACKGROUND: Low serum potassium ([K+]) following ACS has been implicated in the genesis of ventricular tachycardia (VT). Although little data support the benefit of potassium repletion, current practice is to maintain levels at least ≥4.0 mEq/L. Recent data, however, suggest that higher [K+] (>4.0 mEq/L) might in fact be associated with worse outcomes.
METHODS: The MERLIN-TIMI 36 trial enrolled 6560 pts hospitalized with a NSTEACS. A 7-day continuous ECG was initiated at randomization and provides a unique opportunity to examine the relationship between arrhythmic events and baseline [K+] (available in 6312 pts, 96%). Median time from symptoms to randomization was 24hr. OR and HR adjusted for TIMI Risk Score and creatinine clearance.
RESULTS: Median [K+] was 4.2 mEq/L (IQR 3.9-4.5). The incidence of VT was lower in pts with higher levels of [K+], whereas the incidence of ventricular pauses >3 seconds was higher. There was a U-shaped relationship between [K+]and both cardiovascular death and overall mortality at 1 year, with the lowest rates in patients with a [K+] between 3.5-4.0 mEq/L. (Figure) A similar pattern was observed for CV death and mortality at 7 and 14 days. There was no relationship between [K+] and the incidence of supraventricular tachycardia or shorter runs of VT < 8 beats per minute. Nor was there a relationship with assignment to ranolazine.
CONCLUSIONS: In the setting of NSTEACS, higher serum [K+] are associated with lower rates of VT but higher rates of significant ventricular pauses, which may offer pathologic insight to explain why patients with a [K+] between 3.5-4.0 mEq/L are at the lowest risk of CV death. Further studies are needed to define the optimal strategies for managing electrolytes during hospitalizations for ACS.
- © 2012 by American Heart Association, Inc.