Prognostic Value of High Dose Dobutamine Stress Magnetic Resonance Imaging

Overview

High-dose dobutamine/atropine stress cardiac magnetic resonance imaging (DS-MRI) has been incorporated in daily clinical practice for the detection of ischemic heart disease. Thus, wall motion abnormalities (WMA) during stress, precede the development of ST-segment depression on ECG and of anginal symptoms and aid in the detection of anatomically significant coronary artery disease (CAD). DS-MRI offers the possibility to integrate myocardial perfusion and wall motion analysis in a single examination. In this regard, recent data suggest that the assessment of myocardial wall motion and perfusion during a single session may enhance the sensitivity of the technique for the diagnosis of CAD. However, to date limited data is available on the prognostic value of high-dose DS-MRI in large patient cohorts, treated according to current guidelines. Assessment of long-term outcome of DS-MRI is important because this test may identify both high-risk patients, who would benefit from invasive diagnostic and therapy, and lower-risk patients in whom additional procedures and intensive medical follow-up are not required. In the present study we aim to determine the value of wall motion and perfusion assessment during high-dose dobutamine/atropine MRI in predicting cardiac events. In addition, the incremental value of the MR-stress testing results was assessed (inducible wall motion, perfusion abnormalities and the combination of both) after the consideration of traditional clinical risk factors and baseline ejection fraction.

Background: High-dose dobutamine stress cardiac magnetic resonance imaging (DS-MRI) is incorporated in daily clinical practice for the detection of coronary artery disease (CAD). Purpose: To determine the value of wall motion and perfusion assessment during DS-MRI for the prediction of cardiac events in a large patient cohort. Methods: Cardiovascular MR-Examination. Patients are examined in a clinical 1.5-T whole-body MR-scanner Achieva system (Philips Medical Systems, Best, The Netherlands) using a 5-element cardiac phased-array receiver coil. Cardiovascular MR-images were acquired at rest and during a standardized high-dose dobutamine/atropine protocol involving short breath holds, and using a vector electrocardiogram for R-wave triggering11. Electrocardiographic rhythm and symptoms were monitored continuously, and blood pressure was measured every 3 minutes. Follow-up Data. Personnel unaware of the stress testing results contacts each subject or an immediate family member and the date of this contact was used for calculating the follow-up time duration. Outcome data iscollected from a standardized questionnaire and determined from patient interviews at the outpatient clinic or by telephone interviews. Reported clinical events are confirmed by review of the corresponding medical records in our electronic Hospital Information System (HIS), contact with the general practitioner, referring cardiologist or the treating hospital. Cardiac death and nonfatal myocardial infarction are registered as major cardiac events. Cardiac death is defined as death from any cardiac cause (lethal arrhythmia, myocardial infarction, or congestive heart failure) or sudden unexpected death occurring without another explanation. Myocardial infarction is defined by angina of \>30 minutes duration and either ST segment elevation of ≥2mm in 2 consecutive ECG leads or a rise in troponin T of ≥0.03µg/l. Other events include clinically indicated coronary arterial revascularization by percutaneous coronary angioplasty (PCI) or coronary artery bypass graft (CABG). In case of 2 simultaneous cardiac events, the worst event was selected (cardiac death\>non-fatal myocardial infarction\>revascularization).