REN and endothelial dysfunction: The differences between the LVRR and non-LVRR clusters in terms of right ventricular end-diastolic volume and left atrial end-diastolic volume show that blocking the sympathetic nervous system and the renin–angiotensin–aldosterone system could reverse pulmonary vascular resistance, including pulmonary microvascular remodeling, vasoconstriction, and endothelial dysfunction; thus, reduction in the right ventricular end-diastolic volume and left atrial end-diastolic capacity could increase expulsion fraction, thereby improving the left ventricular ejection function.