Preoperative investigations in adult cardiac surgery patients Olivia Swingland Kunal Bhakhri Jon Anderson Abstract Preoperative investigations in cardiac surgery can be divided into diag- nostic and assessment of fitness for surgery. Diagnostic investigations are used to detect and evaluate coronary, valvular, myocardial and thoracic aortic disease. Knowledge of an individual patient’s co- morbidities is essential in determining the risk of postoperative morbidity and mortality, thus allowing for more accurate informed consent. Further- more, the results of preoperative investigations may predict the likely postoperative hospital stay and support required in order to maximize the chances of uneventful recovery. Additionally, the changing operative demographic, with an increased age and burden of co-morbidities frequently makes open-heart surgery challenging prompting a reliance on minimally invasive procedures that may not require cardiopulmonary bypass such as transcatheter aortic valve implantation (TAVI) and mitral valve repair. This article highlights the tests for preoperative diagnosis and assessment of fitness for surgery in adult cardiac patients. They should be used to guide clinicians in making appropriate management decisions, particularly with regard to elderly, frail or complex cardiac cases discussed in the setting of joint cardiology and cardiothoracic meetings. Keywords Cardiac; carotid; echocardiogram; investigations; preopera- tive; risk stratification Diagnostic investigations of adult cardiac disease Coronary heart disease The exercise tolerance test is a useful screening investigation in which a patient undergoes a standardized protocol of increasing exercise with continuous recording of 12-lead ECG and blood pressure monitoring. It is used for the diagnosis of ischaemic heart disease (ST segment depression >1 mm, fall in blood pressure or angina), and the assessment of asymptomatic valvular disease and exercise related arrhythmias. Its usefulness is limited in patients on beta-blockers, those with limited exercise tolerance due to co-morbidities and those with resting ECG abnormalities. Radionuclide perfusion imaging with thallium or technetium can also be used as a screening investigation for significant coronary artery disease. For patients that are unable to exercise, vasodilators such as adenosine may be used to stress the heart. Images are obtained at peak stress and at rest. Reversible perfusion defects indicate viable ischaemic myocardium; irre- versible defects indicate non-viable scar. Cardiac catheterization: a recent (within the previous 12 months) coronary angiogram is required for patients undergoing coronary artery bypass surgery. It is used to demonstrate coronary artery anatomy and to identify the location and severity of dis- ease; a stenosis >50% is considered significant. This guides se- lection of the target vessels to graft. A left ventriculogram shows left ventricular function and may detect mitral regurgitation. Stress echocardiography: echocardiography provides informa- tion on ejection fraction, left ventricular size and regional wall motion abnormalities. Stress echocardiograms are performed using dobutamine infusion to pharmacologically stress the heart by increasing cardiac work. It can identify hibernating myocar- dium and predicts the likely improvement in cardiac perfor- mance following revascularization. (Hibernating myocardium is defined as reversible left ventricular dysfunction caused by chronically insufficient myocardial perfusion.) Positron emission tomography (PET) scanning helps to differentiate stunned and hibernating myocardium from scarred myocardium in patients who do not complain of angina but present primarily with symptoms of heart failure or poor left ventricular function. FDG-PET additionally enables visualization of the metabolic activity in viable myocardial cells. Cardiac MRI can be used to further assess left ventricular function, myocardial perfusion and viability. Gadolinium contrast MRI discriminates between partial thickness and full thickness infarcts, and therefore is useful when evaluating pa- tients with poor left ventricular function who are doubtful can- didates for coronary revascularization. Coronary CT angiogram (CTA): advances in CT imaging tech- nology, including the introduction of multidetector (multi-slice) row systems with electrocardiographic gating, have made imag- ing of the heart and the coronary arteries feasible. Cardiac CTA can provide information about coronary anatomy and left ven- tricular function that can be used in the evaluation of patients with suspected or known CAD. It is also useful to visualize previous coronary grafts in patients planned for redo cardiac surgery. In most circumstances, a negative coronary CT angiogram rules out significant obstructive coronary disease with a very high degree of confidence, based on negative predictive value of 93% obtained in cohorts. Therefore it is useful for managing patients scheduled for non-coronary artery cardiac surgery particularly in the surgery of aortic root aneurysms where it may be difficult to engage the coronary ostia in angiography. On the contrary, the positive predictive values probabilities following a positive coronary CT angiogram are more variable, Olivia Swingland MBBChir MSc is a Clinical Fellow at the Royal Free Hospital, London, UK. Conflicts of interest: none declared. Kunal Bhakhri MRCS is a Cardiothoracic Registrar at The Hammersmith Hospital, London, UK. Conflicts of interest: none declared. Jon Anderson FRCS is a Cardiothoracic Consultant at the Hammersmith Hospital, London, UK. Conflicts of interest: none declared. CARDIOTHORACIC SURGERY I SURGERY 33:2 52 Ó 2014 Published by Elsevier Ltd.