Discussion
In patients with CS, a higher RAVI/LAVI was significantly associated
with adverse clinical outcomes. When stratified into quartiles, there
was nearly a 2-fold and 3-fold increase in death and LVAD implantation
in the third and fourth quartiles respectively when comparted to the
first and second quartiles.
CS is a grave complication of HF with very high mortality [9].
Determinants of outcomes among patients with CS are poorly understood
because of paucity of studies as well as a heterogeneity in patient
characteristics [10]. Even less understood are the determinants of
outcomes among patients with CS in the setting of “acute on chronic”
decompensated HF [11]. Chronic HF is a progressive disease that is
associated with structural remodeling due to neurohormonal and
hemodynamic changes. Among these patients, the integrity of the right
ventricular function determines clinical outcomes [12,13,14]. A
compromised RV is associated with worse outcomes [15,16].
Unfortunately, the routine evaluation of the RV function on
transthoracic echocardiogram had been neglected until recently. It has
been shown that RAVI/LAVI, a novel index that reflects important
inter-atrial interactions and RV dysfunction is associated with poor
outcomes in patients with pulmonary hypertension [6]. In present
study, we have also shown that RAVI/LAVI is also associated with adverse
outcomes in CS. Prior studies have established that RA dilatation is a
key indicator of the integrity of the RV functional status [17].
The RA is a thin walled chamber with a limited capacitance for the
increased pressure load. Sustained pressure load on the RA leads to
chamber dilatation rather than hypertrophy based on the law of Laplace.
A dilated RA leads to leftward bowing of the interatrial septum thereby
constraining the left atrium (LA).
In advanced stages of HFrEF with adverse remodeling, concurrent RV
dysfunction occurs in up to 65% of patients with HFrEF [14,18]. As
noted in this study, CS patients with higher RAVI/LAVI had significantly
higher levels of BNP reflecting a structural milieu of adverse
remodeling due to persistently elevated filling pressures. Thus,
RAVI/LAVI is an index that constitutively integrates multiple
hemodynamic variables between the left and right sides of the heart, and
more specifically the pressure-volume interactions with inter-atrial
structural remodeling. These results not only highlight the important
interactions between left and right heart systems but also underscore
the importance of identifying RA/LA structural remodeling in patients
with HFrEF presenting with CS. CS is a lethal condition which requires
timely initiation of advanced HF therapies in order to mitigate the
downward trajectory of end organ function that ultimately leads to
death. As we demonstrate, there were no differences in baseline patient
characteristics between the RAVI/LAVI groups suggesting that patient
co-morbidities, alone, are insufficient in prognostication in CS
patients. Thus the utility of a non-invasive parameter such as RAVI/LAVI
is a clinically readily available tool that can help risk stratify CS
patients and guide management in a time sensitive manner. Indeed the
identification of patients likely to suffer imminent adverse outcomes in
HFrEF with CS is critical to the timely adjudication of the need for
advanced HF therapies.