Invasive assessment of fluid therapy in hypotensive patients of postinferior wall myocardial infarction complicated by right ventricular infarction

Abstract

Background: Management of such patients with inferior wall myocardial infarction (IWMI) complicated by right ventricular myocardial infarction (RVMI) requires volume replacement along with the standard therapy. However, the optimum amount of fluid needed to maintain systolic blood pressure (SBP) ≥90 mmHg in such patients has not been reported yet. This study evaluates the role of graded fluid infusion in improving the hemodynamic parameters in patients of IWMI with RVMI in hypotension or shock and also optimizes the amount of fluid needed to maintain SBP ≥ 90 mmHg. Materials and Methods: In this single-center, prospective observational study, patients with first episode of acute coronary syndrome diagnosed as IWMI complicated by RVMI and SBP <90 mmHg were included. The hemodynamic parameters such as heart rate, SBP, cardiac output, cardiac index, and pulmonary capillary wedge pressure (PCWP) were measured at the baseline and after each 500 ml normal saline over 15 min until SBP ≥ 90 mmHg was attained. The primary objective was to study the change in cardiac output, cardiac index, and PCWP with response to fluid. The amount of fluid needed for ≥ 10 rise in cardiac output and to maintain SBP ≥ 90 mmHg was also evaluated. The secondary objectives were to study the need for inotropic support, complications such as inhospital mortality, acute pulmonary edema, and local site bleeding. Further, the predictors of early responders (<2 L of fluid) were also evaluated. Results: Among all 16 patients, 3 (18.7%) were excluded and the rest received graded fluid therapy. Invasively monitored and graded fluid therapy resulted a significant rise in cardiac output (2.1 ± 0.7 L/min vs. 3.7 ± 0.7 L/min), cardiac index (1.3 ± 0.3 L/min/m2 vs. 2.4 ± 0.76 L/min/m2), and PCWP (8.4 ± 3.0 mmHg vs. 17.6 ± 1.5 mmHg) in comparison to baseline parameters. On an average, 865 ± 462 mL fluid infusion was required for 10% improvement in CO from baseline. However, 2192 ± 560 mL fluid was needed for consistent maintenance of SBP ≥ 90 mmHg. The effect of fluid therapy was not significantly correlated with baseline clinical and hemodynamic parameters. There were no procedure- and therapy-related complications reported during the study. Conclusions: Early response to fluid therapy within 2 L of normal saline occurred independently of baseline hemodynamic parameters. However, more studies with larger number of patients would be needed to confirm the same.