Should beta-blockers be used in portal hypertension?
Can be a double-edged blade too dangerous to wield
BY MARWAN S. GHABRIL, MD, AGAF
Nonselective beta-blockers (NSBB) are a cornerstone in the primary and secondary prophylaxis of variceal bleeding in patients with cirrhosis and clinically significant portal hypertension (CSPH), defined as a hepatic venous pressure gradient (HVPG) of at least 10 mm Hg. In the absence of routine HVPG measurement in most clinical practices, NSBB therapy is targeted to a 25% heart rate reduction or target heart rate of 55-60 beats per minute. There is ample evidence supporting this indication for NSBB as summarized in the Baveno VI consensus recommendations in a wide range of liver disease severity, encompassing patients with low-risk small esophageal varices to those with large varices, stigmata, and advanced Child-Pugh class. Tasked with the contrarian perspective on NSBB use, the argument for caution hinges on observations that disease progression can shift the balance of risk and reward to NSBB minimization or avoidance. Understanding the hyperdynamic circulation in worsening portal hypertension of cirrhosis is paramount to these considerations.
The pathophysiology of portal hypertension
Portal hypertension arises as a result of both increased portal venous inflow and increased hepatic sinusoidal resistance and is characterized by splanchnic and systemic vasodilation and reduced effective systemic arterial volume. Compensatory mechanisms include systemic neurohormonal activation, increased heart rate and cardiac output, sodium and water retention (increased plasma volume), and vasoconstrictor system activation. These mechanisms suffice in restoring effective arterial volume initially but also contribute to increased splanchnic/portal inflow and portal hypertension. In advanced decompensation the cardiovascular reserve is overwhelmed with progressive systemic vasodilation, worsening sodium and water retention, vasoconstriction of vital organ vascular beds and an ineffective hyperdynamic state (tachycardia, inadequate cardiac output, and systemic hypotension). This pathophysiological state is heralded clinically by the development of worsening or refractory ascites, and belies the development of other complications of advanced cirrhosis including hyponatremia and hepatorenal syndrome.
The beneficial effects of NSBB in decreasing portal hypertension are mediated by inhibition of splanchnic vasodilation and cardiac effects (reduced heart rate and cardiac output) leading to reduced portal inflow. However, these cardiac effects can be deleterious to systemic hemodynamics in more advanced disease, particularly with acute insults that exacerbate arterial hypovolemia such as bleeding or infection. As such, blunting of sympathetic drive by NSBB carries different degrees of tolerance and risk depending on the hemodynamic reserve in the hyperdynamic state.
Reported clinical experiences
The controversy over NSBB use in advanced cirrhosis arises out of heterogeneous, commonly retrospective datasets and nonrandomized cohorts, with conflicting reports of positive, negative, or neutral effects on mortality and acute kidney injury. Not surprisingly, studies describing detrimental effects of NSBB are based on patients with strictly defined refractory ascites or those with spontaneous bacterial peritonitis.1,2 Importantly, these studies also describe significantly lower blood pressure in at-risk NSBB treated patients, This baseline hemodynamic difference is either not observed,or not explicitly compared in studies/subcohorts with decreased or unaffected mortality with NSBB use in advanced cirrhosis.2
In the largest prospective study of NSBB in cirrhosis with ascites (which used data from three randomized satavaptan trials), NSBB users and nonusers were more closely matched for baseline mean arterial pressure.3 There was no effect of NSBB on mortality but there was a 29% rate of NSBB discontinuation (i.e., intolerance) during the year of follow-up. Predictors of NSBB discontinuation were hospitalization, variceal bleeding, infection, hepatorenal syndrome, Child-Pugh class C, and refractory ascites. Furthermore, NSBB discontinuation was associated with a notable increase in mortality. Similarly, clinically driven discontinuation of NSBB was observed in half of hospitalized patients with acute-on-chronic liver failure in the prospective CANONIC study, and was also associated with significantly higher short-term mortality.
It is possible that NSBB tolerance may select patients with adequate hemodynamic reserve despite the severity of other liver decompensations. Conversely, intolerance of therapeutic NSBB may signify evolving inadequacy of hemodynamic reserve, giving rise to two distinctly different risk/benefit profiles. This double-edged blade perspective is supported by findings of impaired cardiac output in patients with refractory ascites with impaired renal perfusion, and increased wait-list mortality with NSBB use in patients with compromised global cardiac function.4,5
When is caution due?
Rather than a “therapeutic window” that is either wide open or suddenly shut, in nonhospitalized patients risk is on a continuum and there are no agreed upon liver-specific parameters that define strict barriers to NSBB treatment. Refractory ascites may not absolutely define the closure of this window but should put clinicians on notice for a patient’s vulnerability. The Baveno VI recommendations echo the need for caution, with NSBB in refractory ascites with close monitoring of blood pressure, serum sodium, and creatinine. Treatment cessation, reduction or temporary withholding, and careful reintroduction (with reversible insults) are advised in patients with systolic blood pressure <90 mm Hg, serum Na <130 mEq/L, or those with acute kidney injury.
In the absence of randomized trials that account for cirrhotic cardiomyopathy and cardiac reserve, the risks and putative nonvariceal benefits of NSBB (e.g., reducing gut bacterial translocation) are not truly defined in this patient population. We lack HVPG-based or surrogate assessments in routine practice to determine which patients are hemodynamically benefiting from NSBB therapy, or reliable indicators of imminent NSBB intolerance or risk. While the indications for NSBB may expand to prevention of decompensation, serious questions about their safety are being asked in advanced decompensation. Poor tolerance of therapeutic NSBB dosing and unquantified, but likely negative, impact on quality of life raise additional questions. In a shared decision-making partnership, the patient’s perspective on the utility, tolerance, and monitoring of NSBB therapy in preventing variceal bleeding is vital, particularly when there are endoscopic or earlier shunting alternatives. “Primum non nocere” is not a gladiatorial cry, and in the wrong patients NSBB can be a double-edged blade too dangerous to wield.
References
1. Serste T et al. Hepatology. 2010;52:1017-22.
2. Mandorfer M et al. Gastroenterology. 2014;146:1680-90 e1.
3. Bossen L et al. Hepatology. 2016;63:1968-76.
4. Giannelli V et al. J Hepatol. 2020;72:463-71.
5. Tellez L et al. J Hepatol. 2020 May 20. doi: 10.1016/j.jhep.2020.05.011.
Dr. Ghabril is a gastroenterologist with the Indiana University, Indianapolis. He has no conflicts.
