Clinical utility of cardiovascular magnetic resonance imaging in patients with implantable cardioverter defibrillators presenting with electrical instability or worsening heart failure symptoms.

BACKGROUND: Data on the usefulness of cardiovascular magnetic resonance (CMR) imaging for clinical decision making in patients with an implanted cardioverter defibrillator (ICD) are scarce. The present study determined the impact of CMR imaging on diagnostic stratification and treatment decisions in ICD patients presenting with electrical instability or progressive heart failure symptoms. METHODS: 212 consecutive ICD patients underwent 1.5 T CMR combining diagnostic imaging modules tailored to the individual clinical indication (ventricular function assessment, myocardial tissue characterization, adenosine stress-perfusion, 3D-contrast-enhanced angiography); four CMR examinations (4/212, 2%) were excluded due to non-diagnostic CMR image quality. The resultant change in diagnosis or clinical management was determined in the overall population and compared between ICD patients for primary (115/208, 55%) or secondary prevention (93/208, 45%). Referral indication consisted of documented ventricular tachycardia, inadequate device therapy or progressive heart failure symptoms. RESULTS: Overall, CMR imaging data changed diagnosis in 40% (83/208) with a significant difference between primary versus secondary prevention ICD patients (37/115, 32% versus 46/93, 49%, respectively; p = 0.01). The information gain from CMR led to an overall change in treatment in 21% (43/208) with a similar distribution in primary versus secondary prevention ICD patients (25/115,22% versus 18/93,19%, p = 0.67). The effect on treatment change was highest in patients initially scheduled for ventricular tachycardia ablation procedure (18/141, 13%) with revision of the treatment plan to medical therapy or coronary revascularization. CONCLUSIONS: CMR imaging in ICD patients presenting with electrical instability or worsening heart failure symptoms provided diagnostic or management-changing information in a considerable proportion (40% and 21%, respectively).

Characteristics of the ablation lesions in cardiac magnetic resonance imaging after radiofrequency ablation of ventricular arrhythmias in relation to the procedural success.

BACKGROUND: In human patients, studies about the cardiac magnetic resonance (CMR) appearance of the acute radiofrequency (RF) lesions in relation to the procedural outcomes after catheter ablation (CA) of ventricular arrhythmias (VA) are scarce. We aimed to investigate the RF lesions characteristics in relation to the procedural success. METHODS: Patients referred for ablation of VA received CMR (1.5 T) using gadolinium contrast before and after ablation. CA in left ventricle was performed using a 3.5-mm irrigated catheter. The volume and transmurality of the RF-induced lesions were measured in early gadolinium-enhanced postablation CMRs. Acute failure was defined as persistently inducible VA at the end of the CA. RESULTS: Twenty-five patients (60.7 ±â€¯9.8 years, 19 with sustained ventricular tachycardia) were studied. All RF lesions had nonenhanced core. The volume of the nonenhanced lesions showed positive correlation with the maximal RF power (r = 0.598, P = .002) and the impedance drop (r = 0.416, P = .038). Patients with transmural (≥75%) lesions had significantly larger impedance drop as compared to those with nontransmural lesions (<75%): 20.3 ±â€¯9.4 versus 13.5 ±â€¯4.3, P = .037. In the failures, the lesions volume was nonsignificantly larger: 3.86 ±â€¯3.3% versus 2.6 ±â€¯1.7%, P = .197; however, it was considerably deeper: 86 ±â€¯13% versus 62 ±â€¯26%, P = .03. CONCLUSIONS: CMR after VA ablation showed nonenhanced lesions resembling the no-reflow phenomenon in myocardial infarction. Although the size and the depth of the RF injury correlated with the ablation energy and impedance drop, they were not associated with acute ablation success.

Clinical workflow and applicability of electrophysiological cardiovascular magnetic resonance-guided radiofrequency ablation of isthmus-dependent atrial flutter.

Aims: To determine safety and efficacy of electrophysiological cardiovascular magnetic resonance (EP-CMR)-guided radiofrequency (RF) ablation in patients with typical right atrial flutter in a routine clinical setting. Methods and results: Thirty patients with typical right atrial flutter underwent clinically indicated EP-CMR-guided cavotricuspid isthmus ablation. EP-CMR protocols included pre- and post-ablation CMR imaging (whole heart, T2-weighted, and early-/late-gadolinium enhancement) together with electroanatomic mapping of the right atrium. Coronary sinus cannulation time and total ablation procedure duration were used as performance measures to determine the learning experience of the EP-CMR interventionalist and for comparison with conventional, fluoroscopy-guided atrial flutter ablation. Procedural safety and success rates were evaluated at 1 week and 3 months follow-up. Safety and success rates of EP-CMR were similar to conventional flutter ablations (primary success rate, 93% vs. 100%; recurrence rate, 0% vs. 3%, respectively). EP-CMR procedure duration indicated a learning experience (first vs. last six patients, 54.2 ± 23.1 vs. 29.7 ± 20.0 min) and the minimum number of procedures needed to achieve a level of competency was n = 12. An isthmus angle <110° and the presence of pouch-like isthmus anatomy were indicative of significantly prolonged EP-CMR procedure duration. CMR-defined ablation lesion size was not associated with total RF-ablation time or RF-induced maximum temperature. Conclusion: In a routine clinical setting, EP-CMR demonstrated its safety and high efficacy for the treatment of typical right atrial flutter with performance and outcome measures similar to conventional, fluoroscopy-guided flutter ablation. Hence, EP-CMR represents a valid alternative to conventional right atrial flutter ablation.

Cardiovascular magnetic resonance imaging in patients with cardiac implantable electronic devices: a device-dependent imaging strategy for improved image quality.

Aims: To prospectively determine evaluability of routine cardiovascular magnetic resonance (CMR) diagnostic modules in a referral population of implanted rhythm device all-comers, and to establish a device-dependent CMR imaging strategy to achieve optimal image quality. Methods and results: One hundred and twenty-eight patients with cardiac implantable electronic devices [insertable cardiac monitoring system, n = 14; implantable loop-recorder, n = 21; pacemaker, n = 31; implantable cardioverter-defibrillator (ICD), n = 50; and cardiac resynchronization therapy defibrillator (CRT-D), n = 12] underwent clinically indicated CMR at 1.5 T. CMR protocols were tailored to the clinical indication and consisted of cine, perfusion, T1-/T2-weighted, late-gadolinium enhancement (LGE), 3D angiographic, and post-contrast cine spoiled gradient echo (SGE) scans. Image quality was determined using a 4-grade visual score per myocardial segment. Segmental evaluability was strongly influenced by device type and location with the highest proportion of non-diagnostic images encountered in the presence of ICD/CRT-D systems. Cine steady-state free-precession (SSFP) imaging was found to be mostly non-diagnostic in ICD/CRT-D patients, but a significant improvement of image quality was demonstrated when using SGE sequences with a further incremental improvement post-contrast resulting in an overall four-fold higher likelihood of achieving good image quality. LGE scans were found to be non-diagnostic in about one-third of left-ventricular segments of ICD/CRT-D patients but were artefact-free in > 94% for all other device types. Conclusion: Device type and location constitute the main independent predictors of CMR image quality and thus, need to be considered during protocol adaptation. Most notably, post-contrast SGE cine imaging proved superior to conventionally used SSFP sequences. Thus, following the proposed device-dependent CMR imaging strategy, diagnostic image quality can be achieved in the majority of device patients.