Dynamic Assessment of Left Ventricular Coupling and Myocardial Reserve in Patients with Cardiogenic Shock

Abstract

Abstract Background Pulmonary artery catheter hemodynamics are associated with improved survival in cardiogenic shock (CS). We investigated aortic pulsatility index (API) and cardiac power output (CPO) as surrogates for left ventricular (LV) coupling and myocardial reserve, respectively, in patients with CS undergoing dynamic assessment after a milrinone bolus. Methods Patients with SCAI stage C CS underwent a milrinone drug study (50 mcg/kg bolus infused over 10 minutes) to assess inotropic response. Hemodynamic measurements were obtained at baseline and following the bolus. API and CPO were used to risk stratify patients with the incidence of LVAD, OHT or death at one year as the primary composite endpoint. Results 224 patients in SCAI stage C CS underwent hemodynamics prior to milrinone bolus, and 117 patients had low baseline API <1.45. Of the 117 patients, 88 had a final API <2.2 after milrinone load, consistent with LV decoupling, in which 73% met the composite endpoint. The remaining 29 patients had a final API ≥2.2 consistent with LV recoupling, and only 55% met the composite end point (P=0.046). Of the 117 patients, 40 patients had low myocardial reserve (final CPO <0.77 W), in which 78% met the composite endpoint. Of the 77 patients that demonstrated myocardial reserve (final CPO ≥0.77 W), only 64% met the composite endpoint (P=0.039). Conclusions The use of API and CPO in a dynamic assessment after provocative testing led to improved risk stratification in patients with SCAI stage C CS for clinical outcomes including LVAD, OHT, or death at one year. Clinical Perspective Our research study highlights improved risk stratification of patients in SCAI stage C cardiogenic shock when utilizing a dynamic assessment of hemodynamics with provocative maneuvers as opposed to only static measurements. Using aortic pulsatility index as a surrogate for left ventricular coupling and cardiac power output as a surrogate for myocardial reserve after milrinone bolus improved risk stratification for patients in cardiogenic shock. The clinical implications are to aid physicians in deciding which patients may need more upfront aggressive therapeutics, such as temporary mechanical circulatory support, more urgent evaluation for advanced therapies, or palliative discussions. Patients in cardiogenic shock that can demonstrate left ventricular coupling with myocardial reserve after milrinone bolus may have more time to be optimized medically whereas those with uncoupled left ventricles and poor myocardial reserve need urgent escalation of care.