Effect of Dynamic Potassium Change on In-Hospital Mortality, Ventricular Arrhythmias, and Long-Term Mortality in STEMI

Prognostic impact of potassium levels in patients with ventricular tachyarrhythmias

BACKGROUND

The study sought to assess the prognostic impact of potassium levels (K) in patients with ventricular tachyarrhythmias.

METHODS

A large retrospective registry was used including all consecutive patients presenting with ventricular tachyarrhythmias on admission from 2002 to 2016. Patients with hypokalemia (i.e., K < 3.3 mmol/L), normokalemia (i.e., K 3.3-4.5 mmol/L), and hyperkalemia (i.e., K > 4.5 mmol/L) were compared applying multi-variable Cox regression models and propensity-score matching for evaluation of the primary endpoint of all-cause mortality at 3 years. Secondary endpoints were early cardiac death at 24 h, in-hospital death, death at 30 days, as well as the composite endpoint of early cardiac death at 24 h, recurrences of ventricular tachyarrhythmias, and appropriate ICD therapies at 3 years.

RESULTS

In 1990 consecutive patients with ventricular tachyarrhythmias, 63% of the patients presented with normokalemia, 30% with hyperkalemia, and 7% with hypokalemia. After propensity matching, both hypokalemic (HR = 1.545; 95% CI 0.970-2.459; p = 0.067) and hyperkalemic patients (HR = 1.371; 95% CI 1.094-1.718; p = 0.006) were associated with the primary endpoint of all-cause mortality at 3 years compared to normokalemic patients. Hyperkalemia was associated with even worse prognosis directly compared to hypokalemia (HR = 1.496; 95% CI 1.002-2.233; p = 0.049). In contrast, potassium measurements were not associated with the composite endpoint at 3 years.

CONCLUSION

In patients presenting with ventricular tachyarrhythmias, normokalemia was associated with best short- and long-term survival, whereas hyperkalemia and hypokalemia were associated with increased mortality at 30 days and at 3 years.

Potassium Disturbances and Risk of Ventricular Fibrillation Among Patients With ST-Segment-Elevation Myocardial Infarction

Background Potassium disturbances per se increase the risk of ventricular fibrillation (VF). Whether potassium disturbances in the acute phase of ST-segment-elevation myocardial infarction (STEMI) are associated with VF before primary percutaneous coronary intervention (PPCI) is uncertain. Methods and Results All consecutive STEMI patients were identified in the Eastern Danish Heart Registry from 1999 to 2016. Comorbidities and medication use were assessed from Danish nationwide registries. Potassium levels were collected immediately before PPCI start. Multivariate logistic models were performed to determine the association between potassium and VF. The main analysis included 8624 STEMI patients of whom 822 (9.5%) had VF before PPCI. Compared with 6693 (77.6%) patients with normokalemia (3.5-5.0 mmol/L), 1797 (20.8%) patients with hypokalemia (<3.5 mmol/L) were often women with fewer comorbidities, whereas 134 (1.6%) patients with hyperkalemia (>5.0 mmol/L) were older with more comorbidities. After adjustment, patients with hypokalemia and hyperkalemia had a higher risk of VF before PPCI (odds ratio 1.90, 95% CI 1.57-2.30, P<0.001) and (odds ratio 3.36, 95% CI 1.95-5.77, P<0.001) compared with normokalemia, respectively. Since the association may reflect a post-resuscitation phenomenon, a sensitivity analysis was performed including 7929 STEMI patients without VF before PPCI of whom 127 (1.6%) had VF during PPCI. Compared with normokalemia, patients with hypokalemia had a significant association with VF during PPCI (odds ratio 1.68, 95% CI 1.01-2.77, P=0.045) after adjustment. Conclusions Hypokalemia and hyperkalemia are associated with increased risk of VF before PPCI during STEMI. For hypokalemia, the association may be independent of the measurement of potassium before or after VF.