Response to letter-to-the-editor by Torres et al

We would like to thank the readers for their interest in our article.

The purpose of our study was not to compare echocardiographic assessment of left-sided filling pressures to right heart catheterization. We agree with Torres that invasive assessment of filling pressures is the best gold standard for cardiac hemodynamics. However, the aim of our study was quite different: We sought to determine whether it was possible to reproduce the clinical judgment of a heart failure specialist in community settings where such an individual would not be present. When patients are referred to specialized heart failure clinics, it is the clinical assessment of volume status by the heart failure specialist that routinely determines management rather than right heart catheterization (which is invasive and not always readily available). Of note, the clinical assessment of volume status, when performed by a heart failure specialist, has been shown from a recent analysis of the ESCAPE (Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness) trial to accurately reflect pulmonary capillary wedge pressure.1 In this analysis, a jugular venous pressure estimated at <8 mm Hg by the heart failure specialist corresponded to a similar measured central venous pressure 82% of the time. Conversely, a jugular venous pressure >12 mm Hg was accurate in 70% of the cases. From the history and physical examination, estimated right atrial pressure ≥12 mm Hg and orthopnea ≥2 pillows were associated with a pulmonary capillary wedge pressure ≥30 mm Hg (odds ratio 4.6, P < .001; odds ratio 3.6, P < .05, respectively).

Studies comparing echocardiography with right heart catheterization have been performed, and diastolic patterns have been shown to correlate with left-sided filling pressures.2 We did not intend to reproduce these studies but rather to evaluate whether these echocardiographic indices could be used in combination as a quick surrogate for volume status. Therefore, clinical assessment, in the right hands, can act as an acceptable gold standard to identify left-sided filling pressure. If an echocardiogram performed quickly and portably can easily be taught to minimally trained personnel, the handheld device could have potential in the point-of-care diagnosis of congestion in the community.

Other modalities such as brain natriuretic peptide (BNP) and bioimpedance monitoring can also help in the evaluation of volume status. BNP can sort out the etiology of undifferentiated dyspnea (pulmonary vs cardiac pathology) in the emergency room. In established heart failure however, without a baseline level, it may be difficult to know what the patient's volume status is compared to his or her usual state because patients with heart failure can run chronically elevated levels of BNP. Moreover, studies are still ongoing regarding the use of serial BNP levels in guiding fluid management in the ambulatory heart failure clinic. Bioimpedance monitoring, which measures electrical pulses across the thoracic cavity, assesses fluid levels in the chest. A recent study showed that when included in an implantable electronic device, it can identify the early stages of cardiac decompensation before symptoms appear.3 It is unclear at this point how the large quantity of information derived from this device should be dealt with and whether treating preclinical fluid accumulation aggressively prevents overt decompensation. Our study focused on clinical fluid accumulation and how to differentiate it from a euvolemic state. Although an abnormal relaxation pattern by echocardiography can sometimes reflect borderline elevated left-sided filling pressure,4 it is often not high enough to cause symptoms of congestion or be obvious on clinical examination. Therefore, in our study, we chose to classify patients with this filling pattern as euvolemic.

In conclusion, we have demonstrated that our algorithm, performed easily and portably with handheld echocardiography, is at least as good as the clinical evaluation by a heart failure specialist in the assessment of volume status. We agree that future studies need to be performed to evaluate its impact on morbidity and to assess whether it can be applied to heart failure with preserved systolic function.