Decision analysis for pre-operative interventions in cardiac patients for non-cardiac surgery

Severe valvular disease Severe valvular disease in patients presenting for noncardiac surgery is a major predictor of increased peri-operative cardiovascular risk, mandating intensive management that may result in delay or cancellation of, or pre-operative intervention before, surgery except in the case of emergency surgery [1]. Symptomatic stenotic lesions (aortic and mitral valve stenosis) are associated with a higher risk of peri-operative cardiac complications than symptomatic regurgitation (aortic or mitral valve insufficiency), which is usually better tolerated in the peri-operative setting or may even be stabilized pre-operatively with medical pretreatment [1]. The valvular disease with the highest risk for the non-cardiac surgical patient is severe aortic stenosis. Pre-operative evaluation In the natural history of aortic stenosis, a long latent period exists with increasing obstruction and pressure load on the myocardium while the patients remain asymptomatic. The chief manifestations are angina, syncope and heart failure. Once these symptoms become manifest, and if not treated adequately, the prognosis is poor [2]. Complete pre-operative assessment includes ECG, echocardiography and angiography. Pre-operative decision process Pre-operative management depends on the urgency of surgery and includes the following options: open surgical repair before the non-cardiac surgical procedure; balloon valvuloplasty before the non-cardiac surgical procedure; clearance for surgery without further pre-operative intervention; cancellation. In recently published guidelines [1], it is recommended that, if the aortic stenosis is severe and symptomatic, elective non-cardiac surgery should be postponed and aortic valve replacement performed before elective surgery. If the patient is not a candidate for valve replacement or surgery is semi-elective, balloon valvuloplasty may be performed. In patients without left ventricular failure, the mortality following aortic valve replacement ranges from 2% to 9% in most centres and may be as low as 1% in patients under the age of 70 years. Concomitant coronary artery disease and poor left ventricular (LV) function are the most important variables affecting overall survival rate [2,3]. Balloon valvuloplasty was first described by the Mayo Clinic Group and has been re-evaluated recently in our institution [4,5]. Out of eight patients who underwent the procedure, which was successful in all cases without mortality, one patient died before non-cardiac surgery with CHF; all other patients underwent non-cardiac surgery without complications. If the patients are not candidates for aortic valve replacement or balloon valvuloplasty, non-cardiac surgery may be performed without pre-operative intervention in a selected group of patients at an acceptably low risk, probably because peri-operative anaesthesiological and surgical management has improved substantially over the past decade [6,7]. In two recent studies, peri-operative mortality ranged from 1.9% to 7.1%. Peri-operative morbidity included pulmonary oedema in 17.3% of cases, which was effectively treated, and myocardial infarction in 1.9% [6,7]. There are currently no clear recommendations or algorithms available to assist the selection of the most suitable peri-operative approach for each patient. The decision depends on the severity of the cardiovascular disease, the risk and urgency of the planned surgical procedure and institutional-specific capabilities. Coronary artery disease The risk of peri-operative cardiac complications in patients with a cardiac risk undergoing non-cardiac surgery may be reduced by different strategies. One of these is to perform coronary revascularization before the patient undergoes the non-cardiac surgical procedure. Pre-operative coronary revascularization includes coronary artery bypass grafting (CABG) surgery, PTCA and coronary stent placement. Such interventions are only justified if the benefit is greater than the risk. In recent years, many studies have tried to clarify the pre-operative approach but, until now, no large prospective randomized trials have been available. In addition, it has been difficult to establish 'hard data' in a time of constant change: Anaesthetic and surgical techniques change. Peri-operative care has improved substantially. Coronary revascularization procedures have also undergone revolutionary changes with improved techniques. Currently, a rational approach is based on (a) mathematical meta-analysis models [8,9] and (b) task force recommendations and guidelines [1,10]. The pre-operative decision should be based on the following: Clinically stable patients undergoing low-risk procedures will not benefit from extensive pre-operative testing and intervention. A potential benefit will only exist for patients with advanced coronary artery disease if these patients undergo high-risk procedures. Indications for pre-operative revascularization (CABG and PTCA) do not differ from those given for non-surgical patients. Coronary stent placement is a novel, increasingly popular technology. A prospective evaluation in the peri-operative setting does not exist, and single reports do not at the moment justify this technique pre-operatively. Local factors including experience in different techniques and the outcome-orientated quality of work of the cardiological, anaesthesiological and surgical team contribute to the decision in an individual centre.