Response of the ECG to short-term diuresis in patients with heart failure

Background: Increase in the amplitude of electrocardiogram (ECG) QRS complexes has been observed in patients treated for heart failure (HF), but the underlying mechanism has not been delineated. Also, correlation of augmentation of the QRS potentials with loss of weight has been noted in patients recovering from anasarca of varying etiology, or after hemodialysis. We assessed the effect of diuresis-based fluid loss in patients treated for HF on the amplitude of ECG QRS complexes. Methods: This is a cohort study based on ECG and other data from a previously published investigation of patients with HF conducted at a university affiliated hospital, which used new measurements and analysis, performed by a totally blinded investigator based at another institution. Twenty-one patients (10 men) aged 70.5 ± 12.7 years, 13 with ischemic, and 8 with nonischemic cardiomyopathy, were admitted to the hospital for management of exacerbated HF and were observed for 48 hours. The patients received diuresis, and had routine laboratory testing, documentation of the net fluid lost, and recording of ECGs prior to the initiation of therapy and at 24 and 48 hours. Percent change (%Δ) over the course of observation in the sums of the amplitude of QRS complexes from 12 leads (∑QRS₁₂), 6-limb leads (∑QRS₆), and leads 1 + 2 (∑QRS₂) in mm of standard ECGs were correlated with net fluid loss corrected for admission weight in mL/kg. Results: Fluid loss amounted to 3204.9 ± 1399.5 mL in the course of 40 ± 23 hours of diuresis. ∑QRS₁₂ was 160.9 ± 42.3 mm before and 170.0 ± 50.7 mm after diuresis (P = 0.024). Percent change in ∑QRS₁₂, ∑QRS₆, and ∑QRS ₂ correlated well with the net fluid loss (r = -0.70, -0.82, -0.61, and P = 0.002, 0.0005, 0.001) correspondingly. Conclusion: Changes in sums of the amplitude of QRS complexes of the standard ECG correlates well with net fluid loss in response to short-term diuresis in patients with HF. Change in the ∑QRS₁₂, ∑QRS₆, and ∑QRS₂ from ECGs before and after diuresis can be used as an easily obtainable and universally available bedside index of the net fluid loss experienced by bedridden patients with HF undergoing therapy.