Stress Echo 2030: the Novel ABCDE-(FGLPR) Protocol to Define the Future of Imaging

Each laboratory will adopt the preferred Echo stress among physical pharmacologic or pacing stress according to guidelines recommendations. Pharmacologic testing will be with dobutamine or vasodilators (dipyridamole, adenosine or regadenoson) according to physician preferences, patients' contraindications, local availability and cost. Pacing stress can be performed with transesophageal or with external permanent pacemaker. A standardized format with the ABCDE protocol will be followedl. Step D is easy with vasodilator, less easy with dobutamine, not easy and less feasible - impossible with (peak or post) treadmill exercise. Our recommendation is to use semi-supine exercise, capturing coronary flow signal in early or intermediate stages when most flow increases and feasibility is still high. When treadmill is used, step D is skipped; if information is deemed important, a vasodilator test can be performed at 30' after the end of exercise focused on CFVR and heart rate response.

The diastolic assessment should be included into all exercise SE tests by measuring standard Doppler-derived mitral inflow velocity, pulsed Tissue Doppler of mitral annulus, and retrograde tricuspid gradient of tricuspid regurgitation, at intermediate load of exercise and/or 1- 2 min after the end of the exercise. We will also assess, at baseline, intermediate load (50 watts) and peak-post stress: end-diastolic left ventricular volume index; end-systolic left ventricular volume index; ejection fraction and both stroke volume and cardiac output (to assess conventional contractile reserve); mitral regurgitation and left ventricular outflow tract obstruction; pulmonary artery systolic pressure; B-lines; right ventricular free wall strain to assess the presence of right ventricular dysfunction; left atrial volume index; peak atrial longitudinal strain; and mitral inflow E velocity and mitral annulus e' tissue Doppler velocity; global longitudinal strain (GLS).

Right ventricular function will be assessed at baseline and peak stress with variations of tricuspid annular plane systolic excursion, an index of right ventricular longitudinal function, and right ventricular fractional area change (a load-dependent index of right ventricular inlet function). To distinguish between genuine right ventricular dysfunction and/or pathological increases in pulmonary vascular load, we will combine systolic pulmonary artery pressure and right ventricular end-systolic area to calculate right ventricular end-systolic pressure-area relation. Peak systolic tricuspid annulus velocity and conventional indices of left ventricular systolic and diastolic function will also be measured at baseline and peak stress according to the standard ABCDE-FGLPR protocol. Right ventricular free wall strain combined with interventricular septum strain will be assessed. Left ventricular function, wall motion score index and E/e' at baseline and peak stress.

The examination of the heart starts with a resting transthoracic echocardiography. Exclusion criteria are: resting wall motion score index\>1.0; ejection fraction \<45%; diastolic dysfunction of grade 2 or more; hemodynamically significant (moderate or higher) valve regurgitation or stenosis; severe left ventricular hypertrophy (left ventricular mass index \>175 g/m2). A pharmacological SE with dipyridamole (0.84 mg/kg over 6 minutes) is recommended. The diagnostic end-points are stress-induced RWMA and abnormalities in global LVCR. All images will be analyzed as per guidelines similarly to the other projects, with emphasis on wall motion score index and LVCR based on ejection fraction and force. The hearts excluded from donation for RWMA or abnormal LVCR could however be collected for heart valve preparation and evaluated by coronary angiography and by pathological examination according to local facilities.