The major findings of our study are: (1) the incidence of hospital-acquired HF was 21% in adult hospitalized patients with no previous history of cardiac dysfunction who had a positive cumulative IV fluid balanced of > 4L in 3 days; (2) most of the hospital-acquired HF patients had HF with preserved LVEF and reported high in-hospital mortality and low HF-related mortality; and (3) targeted fluid minimization and IV furosemide at the mean dose of 60 mg did not reduce either hospital-acquired HF rates, in-hospital mortality, or the need for mechanical ventilators. Patients managed by the intervention protocol did have a shorter length of stay and less frequent ICU admission rates.
Data on incidence of hospital-acquired HF among medical hospitalized patients with no preexisting cardiac disorders is currently limited. Previous study reported a 1% incidence of hospital-acquired HF in medical, oncology, surgical, and orthopedic wards. 5 The median IV fluid volume administered 1 day and 2 days before the onset of HF was 2758 and 2000 mL, respectively. The authors demonstrated that administration of > 2 L of IV fluid on the day before the onset of HF was associated with hospital-acquired HF (OR 3.5, 95% CI 1.2–9.8).5 The 21% incidence of hospital-acquired HF in our cohort was higher than the Plant et al study. 5 In our study, about 70% of patients aged over 60 years old and had anemia. Recent studies have shown that anemia is common in patients with HF and is associated with worsening natural course of HF, increased HF admission, and increased mortalities. 8,9 These factors may influence the divergence of outcomes between studies. Patel et al. reported that 7% of acute HF hospitalizations in patients with the age over 55 had post-admission onset of acute HF or hospital-acquired HF. 4 However, they did not examine the association between fluid volume and hospital-acquired HF. Branan et al. studied the hidden fluid administration, including IV medication, line flushes, blood products, and enteral nutrition, and the development of fluid overload, defined as a positive accumulative fluid balance producing weight gain over 10% from baseline, in 219 ICU patients. 2 They found that the volume of hidden fluid was associated with fluid overload. The incidence of fluid overload in the high hidden fluid volume group (> 4.4 L) was 25% which was comparable to the HF rate in our study. The study did not report the rate of HF among those with fluid overload which would have allowed for better comparison. Pathophysiology involving hospital-acquired HF may include: 1) tachycardia or afterload mismatch in preexisting diastolic dysfunction or hypertensive heart disease, 2) myocardial ischemia due to an imbalance between the coronary blood supply and demand in hospitalized conditions, or 3) stress-induced cardiomyopathy.
We found that hospital-acquired HF in our patients was associated with adverse outcomes. Previous studies have shown that hospital-acquired HF carried high morbidity and in-hospital mortality. 1,2,4−6 Patel et al. demonstrated that short-term mortality in hospital-acquired HF was 3 times the rate of preadmission HF.4 Patients with hospital-acquired HF had a worse short-term prognosis compared with those with preadmission HF. The authors reported in-hospital mortality of 16%. Similarly, Plant et al found that length of stay and mortality in patients with hospital-acquired HF were significantly higher than those in the age-gender matched control group. 5 They reported a mortality rate of 13% in the hospital-acquired HF group. Taylor et al. also found that patients with hospital-acquired HF significantly had a higher death rate (26%) compared with the community group (6%). 6 In this study, the mortality in the hospital-acquired HF group was 48%. This is significantly higher than those reported by other studies. The possible explanation for the high mortality in our study may include a higher proportion of elderly patients with cancer, pneumonia, and pulmonary disease, a higher prevalence of concomitant anemia, and a higher rate of mechanical ventilator usage. These higher rates of subsequent ICU transfer and mechanical ventilator usage is in concordance with results from previous studies. 4,5
Previous studies have shown that IV fluid volume is associated with hospital-acquired HF, fluid overload, and adverse outcomes 1–6. Plant et al. found that failure to restart regular diuresis was common in the hospital-acquired HF group. 5 We developed an intervention protocol comprised of minimizing fluid administration and administering of IV diuretics to patients who were at risk of fluid overload and HF. We found that the use of this protocol in hospitalized patients with no pre-existing cardiovascular diseases who received a positive cumulative fluid balance greater than 4 L for 3 days was not associated with lower occurrence of hospital-acquired HF or reduced mortality compared to our control group who received standard care. Delivery of the intervention protocol was associated with less frequent ICU admission and shorter length of hospital stay. The possible reasons for the neutral effect of the protocol on hospital-acquired HF and in-hospital mortality may include: (1) the causes of death mostly did not relate to hospital-acquired HF, but rather to other underlying disease and comorbidities; (2) adherence to IV diuretics reached 85% of the interventional group; (3) volume of fluid minimization and diuretic dose in the protocol may be suboptimal; and (4) afterload optimization was not included and examined in the present study. Notably, a higher positive fluid balance or a need for large volume fluid in medical patients may be an indirect marker of more critically ill patients.
First, we did not investigate the natriuretic peptide or left ventricular ejection fraction in all patients. Second, we could not identify and exclude patients that may have concealed cardiac dysfunction. Third, the proportion of male, body weight, and BSA were different between groups. Lastly, this study is limited to patients with no preexisting cardiac conditions who were hospitalized in medical wards. Further study with a larger study population and improvement of the intervention protocol is required.