RESUMO
BACKGROUND: Hyperkalemia (HK) is a life-threatening condition that is frequently evaluated by electrocardiogram (ECG). ECG changes in severe HK (≥ 6.3 mEq/L) are not well-characterized. This study sought to compare and correlate ECG metrics in severe HK to baseline normokalemic ECGs and serum potassium. METHODS: A retrospective analysis of 340 severe HK encounters with corresponding normokalemic ECGs was performed. RESULTS: Various ECG metrics were analyzed. P wave amplitude in lead II, QRS duration, T wave slope, ratio of T wave amplitude: duration, and ratios of T wave: QRS amplitudes were significantly different between normokalemic and HK ECGs. P wave amplitude attenuation in lead II correlated better with serum potassium than in V1. T wave metrics that incorporated both T wave and QRS amplitudes correlated better than metrics utilizing T wave metrics alone. CONCLUSION: Multiple statistically significant and quantifiable differences among ECG metrics were observed between normokalemic and HK ECGs and correlated with increasing degrees of serum potassium and along the continuum of serum potassium. When incorporated into a logistic regression model, the ability to distinguish HK versus normokalemia on ECG improved significantly. These findings could be integrated into an ECG acquisition system that can more accurately identify severe HK.
RESUMO
BACKGROUND: The incidence and prevalence of arrhythmia-induced cardiomyopathy (AIC) are unclear but likely underrecognized. LV dysfunction is common among patients with atrial fibrillation (AF), atrial flutter (AFL), and frequent premature ventricular contractions (PVC). The hallmark of AIC is the improvement of left ventricular ejection fraction (LVEF) following arrhythmia treatment. Changes in echocardiographic parameters and their effect on outcomes after rhythm control for AIC are not well understood. We aimed to study echocardiographic parameters and outcomes following rhythm control for AIC. METHODS: A multicenter, retrospective study was conducted at 4 different medical centers involving patients with AIC. Clinical, echocardiographic, and outcome (mortality and heart failure hospitalizations [HFH]) parameters were extracted from the medical record. RESULTS: Two hundred fifty-five patients (age 66 ± 11 years, 73% male) with AIC caused by AF (51%), atrial tachycardia/AFL (20%), and PVCs (29%) were included and followed for a median period of 6 months after successful rhythm control. Significant improvements in left ventricular (LV) ejection fraction (P < 0.0001), LV end-systolic volume (ml) (90 ± 48 to 58 ± 30; P < 0.0001), LV internal diameter end diastole (cm) (5.5 ± 0.78 to 5.3 ± 0.64; P = 0.0001) and end systole (4.7 ± 0.95 to 4.3 ± 1.02; P < 0.0001), right atrial pressure (mmHg) (11.3 ± 5.0 to 7.4 ± 3.2; P = 0.0001), and right ventricular function (n (%)) (42 (44) to 9 (11); P < 0.0001) were noted following arrhythmia treatment. No deaths occurred during follow-up. HFH occurred in 7 patients. Arrhythmia recurrence rate was 50.5%. Neither echocardiographic parameters nor recurrence of arrhythmia correlated with HFH. CONCLUSION: Arrhythmia treatment significantly improved echocardiographic LV dimensions, LVEF, and RAP in this multicenter AIC cohort, underscoring the need for early recognition and aggressive rhythm control in suspected AIC patients. The event rate was too low to assess for outcome predictors.