Systolic-dicrotic notch pressure difference can identify tachycardic patients with septic shock at risk of cardiovascular decompensation following pharmacological heart rate reduction

Background: During sepsis, heart rate (HR) reduction could be a therapeutic target, but identification of responders (non-compensatory tachycardia) and non-responders (compensatory for 'fixed' stroke volume [SV]) is challenging. We tested the ability of the difference between systolic and dicrotic pressure (SDPdifference), which reflects the coupling between myocardial contractility and a given afterload, in discriminating the origin of tachycardia. Methods: In this post hoc analysis of 45 patients with septic shock with persistent tachycardia, we characterised features of haemodynamic response focusing on SDPdifference, classifying patients according to variations in arterial dP/dt(max) after 4 h of esmolol administration to maintain HR <95 beats min(-1). A cut-off value of 0.9 mm Hg ms(-1) was used for group allocation. Results: After reducing HR, arterial dP/dt(max) remained above the cut-off in 23 patients, whereas it decreased below the cut-off in 22 patients (from 0.99 [0.37] to 0.63 [0.16] mmHg ms(-1); mean [SD], P<0.001). At baseline, patients with decreased dP/dt(max) after esmolol had lower SDPdifference than those with higher dP/dt(max) (40 [19] vs 53 [16] mm Hg, respectively; P=0.01). The SDPdifference remained unchanged after esmolol in the higher dP/dt(max) group (49 [16] mm Hg), whereas it decreased significantly in patients with lower dP/dt(max) (29 [11] mmHg; P<0.001). In the latter, the HR reduction resulted in a significant cardiac output reduction with unchanged SV, whereas in patients with higher dP/dt(max) SV increased (from 48 [12] to 67 [14] ml; P<0.001) with maintained cardiac output. Conclusions: A decrease in SDPdifference could discriminate between compensatory and non-compensatory tachycardia, revealing a covert loss of myocardial contractility not detected by conventional echocardiographic parameters and deteriorating after HR reduction with esmolol.