Transthoracic bioimpedance and brain natriuretic peptide levels accurately indicate additional diastolic dysfunction in patients with chronic advanced systolic heart failure

Abstract

Diastolic dysfunction in patients with heart failure has prognostic relevance, possibly because of its relationship with worsening haemodynamic status. In the quest for simpler indexes of haemodynamic status in patients, brain natriuretic peptide (BNP) levels have been proposed as a surrogate of diastolic function. To date, the value of combining BNP levels with non-invasive haemodynamic monitoring by transthoracic electric bioimpedance (TEB) for the prediction of diastolic function has not been evaluated. We compared left ventricular diastolic function measured by tissue Doppler imaging (TDI) with TEB results and BNP levels in 120 patients with chronic advanced systolic heart failure on optimal treatment (70 +/- 9 years, NYHA 2.4 +/- 0.8, ejection fraction 31 +/- 5%). Of the TEB variables measured, we only considered thoracic fluid content (TFC). To describe diastolic function, we used the TDI of the velocity of displacement of the mitral annulus (E') and the ratio E/E'. In all patients, E/E' was significantly related to TFC and to BNP levels (P < 0.001). Moreover, the combination of BNP > or = 350 pg/mL and TFC > or = 35/kOmega identified patients with diastolic dysfunction (defined as E/E' > or = 15) with high sensitivity and specificity (95 and 94%, respectively). The combination of transthoracic bioimpedance monitoring and BNP measurement accurately indicated the presence of diastolic dysfunction in most patients. These user-friendly and operator-independent tools may be useful as a screening assessment for diastolic dysfunction, and consequently abnormal central haemodynamic status, either in ambulatory patients or when an adequate echocardiographic evaluation is not readily available.