Pathophysiologic Vasodilation in Cardiogenic Shock and Its Impact on Mortality.

Background: Cardiogenic shock (CS) mortality remains near 40%. In addition to inadequate cardiac output, patients with severe CS may exhibit vasodilation. We aimed to examine the prevalence and consequences of vasodilation in CS.

Methods: We analyzed all patients hospitalized at a CS referral center who were diagnosed with CS stages B to E and did not have concurrent sepsis or recent cardiac surgery. Vasodilation was defined by lower systemic vascular resistance (SVR), higher norepinephrine equivalent dose, or a blunted SVR response to pressors. Threshold SVR values were determined by their relation to 14-day mortality in spline models. The primary outcome was death within 14 days of CS onset in multivariable-adjusted Cox models.

Results: This study included 713 patients with a mean age of 60 years and 27% females; 14-day mortality was 28%, and 38% were vasodilated. The median SVR was 1308 dynes•s•cm^-5 (interquartile range, 870-1652), median norepinephrine equivalent was 0.11 µg/kg per minute (interquartile range, 0-0.2), and 28% had a blunted pressor response. Each 100-dynes•s•cm^-5 decrease in SVR below 800 was associated with 20% higher mortality (adjusted hazard ratio, 1.23; P=0.004). Each 0.1-µg/kg per minute increase in norepinephrine equivalent dose was associated with 15% higher mortality (adjusted hazard ratio, 1.12; P<0.001). A blunted pressor response was associated with a nearly 2-fold mortality increase (adjusted hazard ratio, 1.74; P=0.003).

Conclusions: Pathophysiologic vasodilation is prevalent in CS and independently associated with an increased risk of death. CS vasodilation can be identified by SVR <800 dynes•s•cm^-5, high doses of pressors, or a blunted SVR response to pressors. Additional studies exploring mechanisms and treatments for CS vasodilation are needed.