Abstract
BackgroundCardiovascular Magnetic Resonance (CMR) with adenosine stress is a valuable diagnostic tool in coronary artery disease (CAD). However, despite the development of MR conditional pacemakers CMR is not yet established in clinical routine for pacemaker patients with known or suspected CAD. A possible reason is that adenosine stress perfusion for ischemia detection in CMR has not been studied in patients with cardiac conduction disease requiring pacemaker therapy. Other than under resting conditions it is unclear whether MR safe pacing modes (paused pacing or asynchronous mode) can be applied safely because the effect of adenosine on heart rate is not precisely known in this entity of patients. We investigate for the first time feasibility and safety of adenosine stress CMR in pacemaker patients in clinical routine and evaluate a pacing protocol that considers heart rate changes under adenosine.MethodsWe retrospectively analyzed CMR scans of 24 consecutive patients with MR conditional pacemakers (mean age 72.1 ± 11.0 years) who underwent CMR in clinical routine for the evaluation of known or suspected CAD. MR protocol included cine imaging, adenosine stress perfusion and late gadolinium enhancement.ResultsPacemaker indications were sinus node dysfunction (n = 18) and second or third degree AV block (n = 6). Under a pacing protocol intended to avoid competitive pacing on the one hand and bradycardia due to AV block on the other no arrhythmia occurred. Pacemaker stimulation was paused to prevent competitive pacing in sinus node dysfunction with resting heart rate >45 bpm. Sympatho-excitatory effect of adenosine led to a significant acceleration of heart rate by 12.3 ± 8.3 bpm (p < 0.001), no bradycardia occurred. On the contrary in AV block heart rate remained constant; asynchronous pacing above resting heart rate did not interfere with intrinsic rhythm.ConclusionAdenosine stress CMR appears to be feasible and safe in patients with MR conditional pacemakers. Heart rate response to adenosine has to be considered for the choice of pacing modes during CMR.
Highlights
Cardiovascular Magnetic Resonance (CMR) with adenosine stress is a valuable diagnostic tool in coronary artery disease (CAD)
Pacemaker programming CMR was performed more than six weeks after PM implantation in all individuals according to European society of cardiology (ESC) guidelines [13]
The present study shows no complications of adenosine stress CMR related to the presence of a PM or the underlying cardiac conduction disorder
Summary
Cardiovascular Magnetic Resonance (CMR) with adenosine stress is a valuable diagnostic tool in coronary artery disease (CAD). Cardiovascular magnetic resonance (CMR) as a noninvasive imaging modality is firmly established in the clinical workup for patients with known or suspected CAD It has become the gold standard for chamber quantification and detection of left ventricular wall motion impairment in ischemic cardiomyopathy [1,2,3]. Post myocardial infarction (MI) complications such as negative remodeling, formation of aneurysms and intraventricular thrombi, pericardial effusion and ischemic mitral valve regurgitation can be detected precisely even in obese patients less suitable for echocardiographic assessment [4] It has become the most important technique for tissue characterization such as scar detection in MI [5], and a stand alone imaging modality in differential diagnosis in ischemic versus other cardiomyopathies such as myocarditis [1]. Hemodynamic relevance of stenoses in known CAD can be evaluated reliably [7]
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