Deactivation vs. asynchronous pacing - prospective evaluation of a protocol for rhythm management in patients with magnetic resonance conditional pacemakers undergoing adenosine stress cardiovascular magnetic resonance imaging.

BACKGROUND: Cardiovascular Magnetic Resonance (CMR) imaging with adenosine stress is an important diagnostic tool in patients with known or suspected coronary artery disease (CAD). However, the method is not yet established for CAD patients with pacemakers (PM) in clinical practice. A possible reason is that no recommendations exist for PM setting (paused pacing or asynchronous mode) during adenosine stress. We elaborated a protocol for rhythm management in clinical routine for PM patients that considers heart rate changes under adenosine using a test infusion of adenosine in selected patients. METHODS: 47 consecutive patients (mean age 72.3 ± 10,0 years) with MR conditional PM and known or suspected CAD who underwent CMR in clinical routine were studied in this prospective observational study. PM indications were sinus node dysfunction (SND, n = 19; 40,4%), atrioventricular (AV) block (n = 26; 55.3%) and bradyarrhythmia in permanent atrial fibrillation (AF, n = 2; 4.3%). In patients with SND, normal AV-conduction and resting HR >45 bpm at the time of CMR and in AF the PM was deactivated for the scan. In intermittent AV-block a test infusion of adenosine was given prior to the scan. All patients with permanent higher degree sinuatrial or AV-block or deterioration of AV-conduction in the adenosine test were paced asynchronously during CMR, in patients with preserved AV-conduction under adenosine the pacemaker was deactivated. CMR protocol included cine imaging, adenosine stress perfusion and late gadolinium enhancement. RESULTS: The adenosine test was able to differentiate between mandatory PM stimulation during CMR and safe deactivation of the device. In patients with permanent sinuatrial or AV-block (n = 11; 23.4%) or deterioration of AV conduction in the adenosine test (n = 5, 10.6%) asynchronous pacing above resting heart rate did not interfere with intrinsic rhythm, no competitive stimulation was seen during the scan. 10 of 15 (66,7%) patients with intermittent AV-block showed preserved AV-conduction under adenosine. As in SND and AF deactivation of the PM showed to be safe during CMR, no bradycardia was observed. CONCLUSION: Our protocol for rhythm management during adenosine stress CMR showed to be feasible and safe and may be recommended for pacemaker patients undergoing routine CMR.

Cardiovascular magnetic resonance in patients with magnetic resonance conditional pacemaker systems at 1.5 T: influence of pacemaker related artifacts on image quality including first pass perfusion, aortic and mitral valve assessment, flow measurement, short tau inversion recovery and T1-weighted imaging.

There are only limited data on the impact of device-related artifacts on image quality in cardiovascular magnetic resonance imaging (CMR) in patients with pacemakers (PM). Adenosine stress perfusion, T1-weighted imaging and flow measurement as well as valve characterization have not been evaluated previously concerning artifact burden. We aimed to assess image quality in all routinely used CMR sequences. We analyzed 2623 myocardial segments in CMR scans of 61 patients with MR conditional PM (mean age 72.1 ± 11.5 years), 23 (37.7%) with right sided, 38 (62.3%) with left-sided devices. There were no relevant artifacts in patients with right-sided devices irrespective of the imaging sequence. In left-sided implants no PM-induced artifacts were found in first pass perfusion sequence, flow analysis and T1 weighted imaging. Only few patients with left-sided devices showed significant PM-artifacts in aortic (3/38, 7.9%)/mitral (n = 2/38, 5.3%) valve imaging and STIR (n = 3/35, 8.6%). In STIR only 14/805 (1.7%) segments were involved. In left-sided PM SSFP cine sequences had more artifact burden than LGE with 377/1505 (25.0%) vs. 162/1505 (10.8%) myocardial segments involved by relevant artifacts respectively (p < 0.001). Apart from cine and LGE imaging in anterior myocardial segments with left-sided implants presence of MRI conditional pacemakers does not affect CMR image quality in multimodal CMR examinations to a significant extent. Our data supports evidence that reduced image quality does not need to be a major concern in PM patients undergoing CMR.

A novel cross-sector telemedical approach to detect arrhythmia in primary care patients with palpitations using a patient-activated event recorder.

BACKGROUND: Patient-activated event recorders (ER) can facilitate diagnosis in unclear palpi-tations, however impact of ER screening on further treatment in clinical routine is unknown. We investigated the feasibility and clinical value of a network-based telemetric monitoring using a patient activated ER. METHODS: The network consisted of 12 general practitioners (GP) and a department of car-diology (DC). GP-patients sent electrocardiograms (ECGs) twice daily and in case of palpitations. ECGs were transferred by email to GP and DC and analyzed independently by both. The therapeutic strategy was discussed between GP and DC. The monitoring period ended after 4 weeks or in case of detected arrhythmia. RESULTS: A group of 184 consecutive patients were retrospectively analyzed. Mean age was 57.5 ± 14.4 years (range 17-82), 104 (56.5%) were female. Significant arrhythmia occurred in 71 (38.5%) patients: Recurrence of known paroxysmal atrial fibrillation (AF; n = 27, 14.7%), de novo AF (n = 19, 10.3%), premature complexes/bigeminus (n = 13, 7.1%), sinus tachycar-dia (n = 7, 3.8%), atrioventricular nodal reentrant tachycardia (n = 3, 1.6%), and ventricular tachycardia (n = 2, 1.1%). A therapeutic consequence resulted in 63 (88.7%) patients with de-tected arrhythmia: new oral anticoagulation (n = 29, 40.8%), new antiarrhythmic medication (n = 27, 38.0%), behavioral intervention (n = 19, 26.8%), electrophysiology-study/catheter ablation (n = 4, 5.6%), cardioversion (n = 2, 2.8%), implantable cardioverter-defibrillator- -implantation (n = 1, 1.4%), and left atrial appendage occluder (n = 1, 1.4%). CONCLUSIONS: The investigated cross-sector telemetric network is a feasible approach to detect arrhythmia in patients with palpitations and may have high impact on further treatment, notably in those at risk for stroke due to AF.

Feasibility and safety of adenosine cardiovascular magnetic resonance in patients with MR conditional pacemaker systems at 1.5 Tesla.

BACKGROUND: Cardiovascular 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. METHODS: We 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. RESULTS: Pacemaker 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. CONCLUSION: Adenosine 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.