Pulmonary Hypertension in Non-Cardiac Surgery – a mandate for the multidisciplinary team!

Pulmonary Hypertension (PH) is due to a variety of conditions, some of which are common, i.e. PH associated with left heart disease and PH associated with lung disease, and others that are extremely rare, i.e. idiopathic and heritable PH. Today, there are more patients with PH undergoing non-cardiac surgery (NCS) than previous, for several reasons. First, echocardiographic detection of PH has improved on a population-based level. Second, PH as a comorbidity of left heart disease and lung disease is common, increasingly recognized and diagnosed. Third, more patients survive precapillary PH and age with the condition acquiring comorbid left heart and lung disease. Because of increased PH incidence, and because PH increases mortality of NCS significantly, a scientific statement intended to provide guidance on the evaluation and management of PH in patients undergoing NCS, is meaningful and needed. In patients with severe pulmonary arterial hypertension (PAH), peri-operative mortality has been reported in the range of 2-7% for elective and up to 15% for emergency NCS procedures ¹. In Europe, the recent 2022 ESC Guidelines on cardiovascular assessment and management of patients undergoing non-cardiac surgery ² have embraced the topic PH and NCS in one of their chapters, and the ESC Guidelines on Cardiovascular Diseases during Pregnancy have last addressed and analysed pregnancy in detail in 2018 ³. Authors of the AHA Scientific Statement on Pulmonary Hypertension in Non-Cardiac Surgery should be commended on their initiative to provide an inclusive update.

Authors propose to proceed in five simple steps: 1) Classification of PH group to define the underlying pathology; 2) Preoperative risk assessment that will guide surgical decision-making; 3) PH optimization before surgery to reduce perioperative risk, including transient use of a parenteral prostacyclin; 4) Intraoperative management of pulmonary hypertension to avoid right ventricular dysfunction and maintain cardiac output; and 5) Postoperative management of PH to ensure safe recovery from surgery over at least 24 h.

As an introduction, authors provide an elegant summary of the 2022 ESC/ERS Guidelines in the diagnosis and treatment of PH, emphasizing that current chronic treatments of PH are focused on the right ventricle. While much of the theory of right ventricular failure is known, data on occurrence, treatments and fatality in PH with right ventricular failure are scarce, and therefore currently subject of a European Reference Network project.

Authors succeed in pointing out the dilemma of contemporary PH which is the difficulty to understand and treat PH as comorbid disease, versus to understand and treat PH with comorbid disease. All of today‘s hemodynamic threshold metrics are derived from large databases including patients with PH of mixed etiologies, e.g. mainly heart failure and chronic obstructive pulmonary disease ^{4 5}. The simultaneous presence of two or more diseases or medical conditions in a patient defines a comorbidity. The crux remains to tease out which is the underlying condition, and which is the secondary condition or accompanying comorbidity. PH as comorbid disease should not be treated, but rather the underlying condition, e.g. heart failure or lung disease. By contrast, PH with comorbid disease remains pulmonary vascular disease and has to be treated with drugs approved for PH. Pre-existing chronic therapy for PH in the peri-operative phase of NCS must be continued. Authors offer the available risk scores for PAH, heart disease and lung disease, whichever is the leading condition, and point out that none of them has been validated for risk stratification prior to NCS, an area of unmet needs yet to be explored by future research. The correct definition of PH in the setting of NCS is based on a meticulous pre-operative diagnostic work-up and should include assessment of detailed medical history, functional status, severity of disease, and timing of first occurrence of comorbidities. Echocardiography and right heart catheterization (if clinically indicated, and including post-capillary PH) are key components in the pre-operative work-up. The morbidity and mortality associated with PH in NCS derive from the haemodynamic response of the right ventricle to acute increases in afterload ⁶, therefore best assessment of right ventricular function is mandatory and, apart from echocardiography, may include preoperative cardiac magnetic resonance imaging. As illustrated in the guidelines there is a great value in bedside echocardiogram that immediately informs about right ventricular function by looking at right ventricular metrics, the pulmonary artery and the vena cava ⁷. In addition, the type of NCS must be detailed. Authors also touch upon pregnancy in their scientific statement, which does share some features with NCS, particularly around delivery, but is of course a separate entity deserving a dedicated scientific statement.

Elective NCS can be meticulously planned over weeks with increasing doses of vasodilators and their combinations. However, in the acute non-elective setting the optimization of right ventricular performance is challenging. The right ventricle follows different timelines than the left ventricle, and requires weeks to remodel. Therefore, acute RV relief in severe PH is limited to diuretics, avoidance of pain, and use of ECMO. Acute initiation of systemic vasodilation may be detrimental in this setting.

A recurrent recommendation of the Scientific Statement is that patients scheduled for NCS should be discussed by a multidisciplinary team (MDT) ⁷ including a cardiologist, pneumologist, radiologist, thoracic surgeon, perfusionist, and anaesthesiologist ⁸, and other experts. The MDT is central for difficult decisions regarding diagnosis, initial treatments, management steps, and timings which as so important for PH in NCS. MDTs are part of any modern cardiovascular guidelines, and appear as heart teams, chronic thromboembolic pulmonary hypertension (CTEPH) teams, pregnancy heart teams, PH teams, or pulmonary embolism response teams (PERTs). MDTs are the hopes for best care in the future, coping with increasingly complex patients and increasingly complex treatments.