Clinical value of cardiovascular magnetic resonance in patients with MR-conditional pacemakers

Assessment of Tricuspid Regurgitation by Cardiac Magnetic Resonance Imaging: Current Role and Future Applications

Tricuspid regurgitation (TR) is a prevalent valvular disease with a significant mortality rate. The evaluation of TR severity and associated right heart remodeling and dysfunction is crucial to determine the optimal therapeutic strategy and to improve prognosis. While echocardiography remains the first-line imaging technique to evaluate TR, it has many limitations, both operator- and patient-related. Cardiovascular magnetic resonance imaging (CMR) has emerged as an innovative and comprehensive non-invasive cardiac imaging technique with additional value beyond routine echocardiographic assessment. Besides its established role as the gold standard for the evaluation of cardiac volumes, CMR can add important insights with regard to valvular anatomy and function. Accurate quantification of TR severity, including calculation of regurgitant volume and fraction, can be performed using either the well-known indirect volumetric method or novel 4D flow imaging. In addition, CMR can be used to assess the impact on the right heart, including right heart remodeling, function and tissue characterization. Several CMR-derived parameters have been associated with outcome, highlighting the importance of multi-modality imaging in patients with TR. The aim of this review is to provide an overview of the current role of CMR in the assessment and management of patients with TR and its future applications.

Cardiovascular Magnetic Resonance in Patients with Cardiac Electronic Devices: Evidence from a Multicenter Study

BACKGROUND

Most recent cardiac implantable electronic devices (CIEDs) can safely undergo a cardiovascular magnetic resonance (CMR) scan under certain conditions, but metal artifacts may degrade image quality. The aim of this study was to assess the overall diagnostic yield of CMR and the extent of metal artifacts in a multicenter, multivendor study on CIED patients referred for CMR.

METHODS

We analyzed 309 CMR scans from 292 patients (age 57 ± 16 years, 219 male) with an MR-conditional pacemaker (n = 122), defibrillator (n = 149), or loop recorder (n = 38); CMR scans were performed in 10 centers from 2012 to 2020; MR-unsafe implants were excluded. Clinical and device parameters were recorded before and after the CMR scan. A visual analysis of metal artifacts was performed for each sequence on a segmental basis, based on a 5-point artifact score.

RESULTS

The vast majority of CMR scans (n = 255, 83%) were completely performed, while only 32 (10%) were interrupted soon after the first sequences and 22 (7%) were only partly acquired; CMR quality was non-diagnostic in 34 (11%) scans, poor (<1/3 sequences were diagnostic) in 25 (8%), or acceptable (1/3 to 2/3 sequences were diagnostic) in 40 (13%), while most scans (n = 201, 68%) were of overall good quality. No adverse event or device malfunctioning occurred, and only nonsignificant changes in device parameters were recorded. The most affected sequences were SSFP (median score 0.32 [interquartile range 0.07-0.91]), followed by GRE (0.18 [0.02-0.59]) and LGE (0.14 [0.02-0.55]). ICDs induced more artifacts (median score in SSFP images 0.87 [0.50-1.46]) than PMs (0.11 [0.03-0.28]) or ILRs (0.11 [0.00-0.56]). Moreover, most artifacts were located in the anterior, anteroseptal, anterolateral, and apical segments of the LV and in the outflow tract of the RV.

CONCLUSIONS

CMR is a versatile imaging technique, with a high safety profile and overall good image quality even in patients with MR-conditional CIEDs. Several strategies are now available to optimize image quality, substantially enhancing overall diagnostic yield.

Reducing cardiac implantable electronic device-induced artefacts in cardiac magnetic resonance imaging

OBJECTIVES

Cardiac implantable electronic device (CIED)-induced metal artefacts possibly significantly diminish the diagnostic value of magnetic resonance imaging (MRI), particularly cardiac MR (CMR). Right-sided generator implantation, wideband late-gadolinium enhancement (LGE) technique and raising the ipsilateral arm to the generator during CMR scanning may reduce the CIED-induced image artefacts. We assessed the impact of generator location and the arm-raised imaging position on the CIED-induced artefacts in CMR.

METHODS

We included all clinically indicated CMRs performed on patients with normal cardiac anatomy and a permanent CIED with endocardial pacing leads between November 2011 and October 2019 in our institution (n = 171). We analysed cine and LGE sequences using the American Heart Association 17-segment model for the presence of artefacts.

RESULTS

Right-sided generator implantation and arm-raised imaging associated with a significantly increased number of artefact-free segments. In patients with a right-sided pacemaker, the median percentage of artefact-free segments in short-axis balanced steady-state free precession LGE was 93.8% (IQR 9.4%, n = 53) compared with 78.1% (IQR 20.3%, n = 58) for left-sided pacemaker (p < 0.001). In patients with a left-sided implantable cardioverter-defibrillator, the median percentage of artefact-free segments reached 87.5% (IQR 6.3%, n = 9) using arm-raised imaging, which fell to 62.5% (IQR 34.4%, n = 9) using arm-down imaging in spoiled gradient echo short-axis cine (p = 0.02).

CONCLUSIONS

Arm-raised imaging represents a straightforward method to reduce CMR artefacts in patients with left-sided generators and can be used alongside other image quality improvement methods. Right-sided generator implantation could be considered in CIED patients requiring subsequent CMR imaging to ensure sufficient image quality.

KEY POINTS

• Cardiac implantable electronic device (CIED)-induced metal artefacts may significantly diminish the diagnostic value of an MRI, particularly in cardiac MRIs. • Raising the ipsilateral arm relative to the CIED generator is a cost-free, straightforward method to significantly reduce CIED-induced artefacts on cardiac MRIs in patients with a left-sided generator. • Right-sided generator implantation reduces artefacts compared with left-sided implantation and could be considered in CIED patients requiring subsequent cardiac MRIs to ensure adequate image quality in the future.

Safety, feasibility, and prognostic value of stress perfusion CMR in patients with MR-conditional pacemaker

AIMS

To assess the safety, feasibility, and prognostic value of stress cardiovascular magnetic resonance (CMR) in patients with pacemaker (PM).

METHODS AND RESULTS

Between 2008 and 2021, we conducted a bi-centre longitudinal study with all consecutive patients with MR-conditional PM referred for vasodilator stress CMR at 1.5 T in the Institut Cardiovasculaire Paris Sud and Lariboisiere University Hospital. They were followed for the occurrence of major adverse cardiovascular events (MACE) defined as cardiac death or non-fatal myocardial infarction. Cox regression analyses were performed to determine the prognostic value of CMR parameters. The quality of CMR was rated by two observers blinded to clinical details. Of 304 patients who completed the CMR protocol, 273 patients (70% male, mean age 71 ± 9 years) completed the follow-up (median [interquartile range], 7.1 [5.4-7.5] years). Among those, 32 experienced a MACE (11.7%). Stress CMR was well tolerated with no significant change in lead thresholds or pacing parameters. Overall, the image quality was rated good or excellent in 84.9% of segments. Ischaemia and late gadolinium enhancement (LGE) were significantly associated with the occurrence of MACE (hazard ratio, HR: 11.71 [95% CI: 4.60-28.2]; and HR: 5.62 [95% CI: 2.02-16.21], both P < 0.001). After adjustment for traditional risk factors, ischaemia and LGE were independent predictors of MACE (HR: 5.08 [95% CI: 2.58-14.0]; and HR: 2.28 [95% CI: 2.05-3.76]; both P < 0.001).

CONCLUSION

Stress CMR is safe, feasible and has a good discriminative prognostic value in consecutive patients with PM.

Impact of wideband cardiac magnetic resonance on diagnosis, decision-making and outcomes in patients with implantable cardioverter defibrillators

AIMS

Although myocardial scar assessment using late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) imaging is frequently indicated for patients with implantable cardioverter defibrillators (ICDs), metal artefact can degrade image quality. With the new wideband technique designed to mitigate device related artefact, CMR is increasingly used in this population. However, the common clinical indications for CMR referral and impact on clinical decision-making and prognosis are not well defined. Our study was designed to address these knowledge gaps.

METHODS AND RESULTS

One hundred seventy-nine consecutive patients with an ICD (age 59 ± 13 years, 75% male) underwent CMR using cine and wideband pulse sequences for LGE imaging. Electronic medical records were reviewed to determine the reason for CMR referral, whether there was a change in clinical decision-making, and occurrence of major adverse cardiac events (MACEs). Referral indication was the most common evaluation of ventricular tachycardia (VT) substrate (n = 114, 64%), followed by cardiomyopathy (n = 53, 30%). Overall, CMR resulted in a new or changed diagnosis in 64 (36%) patients and impacted clinical management in 51 (28%). The effect on management change was highest in patients presenting with VT. A total of 77 patients (43%) experienced MACE during the follow-up period (median 1.7 years), including 65 in patients with evidence of LGE. Kaplan-Meier analysis showed that ICD patients with LGE had worse outcomes than those without LGE (P = 0.006).

CONCLUSION

The clinical yield from LGE CMR is high and provides management changing and meaningful prognostic information in a significant proportion of patients with ICDs.

Evidence to support magnetic resonance conditional labelling of all pacemaker and defibrillator leads in patients with cardiac implantable electronic devices

AIMS

Many cardiac pacemakers and defibrillators are not approved by regulators for magnetic resonance imaging (MRI). Even following generator exchange to an approved magnetic resonance (MR)-conditional model, many systems remain classified 'non-MR conditional' due to the leads. This classification makes patient access to MRI challenging, but there is no evidence of increased clinical risk. We compared the effect of MRI on non-MR conditional and MR-conditional pacemaker and defibrillator leads.

METHODS AND RESULTS

Patients undergoing clinical 1.5T MRI with pacemakers and defibrillators in three centres over 5 years were included. Magnetic resonance imaging protocols were similar for MR-conditional and non-MR conditional systems. Devices were interrogated pre- and immediately post-scan, and at follow-up, and adverse clinical events recorded. Lead parameter changes peri-scan were stratified by MR-conditional labelling. A total of 1148 MRI examinations were performed in 970 patients (54% non-MR conditional systems, 39% defibrillators, 15% pacing-dependent) with 2268 leads. There were no lead-related adverse clinical events, and no clinically significant immediate or late lead parameter changes following MRI in either MR-conditional or non-MR conditional leads. Small reductions in atrial and right ventricular sensed amplitudes and impedances were similar between groups, with no difference in the proportion of leads with parameter changes greater than pre-defined thresholds (7.1%, 95% confidence interval: 6.1-8.3).

CONCLUSIONS

There was no increased risk of MRI in patients with non-MR conditional pacemaker or defibrillator leads when following recommended protocols. Standardizing MR conditions for all leads would significantly improve access to MRI by enabling patients to be scanned in non-specialist centres, with no discernible incremental risk.

Free-breathing BLADE acquisition method improves T2-weighted cardiac MR image quality compared with conventional breath-hold turbo spin-echo cartesian acquisition

BACKGROUND

Cardiac magnetic resonance (MR) has become an essential diagnostic imaging modality in cardiovascular disease. However, the insufficient image quality of traditional breath-hold (BH) T2-weighted (T2W) imaging may compromise its diagnostic accuracy.

PURPOSE

To assess the efficacy of the BLADE technique to reduce motion artifacts and improve the image quality.

MATERIAL AND METHODS

Free-breathing TSE-T2W imaging sequence with cartesian and BLADE k-space trajectory were acquired in 20 patients. Thirty patients underwent conventional BH turbo spin-echo (TSE) T2W imaging and free-breathing BLADE T2W (FB BLADE-T2W) imaging. Twenty-one patients who had a signal loss of myocardium in BH short-axis T2W turbo inversion recovery (TSE-T2W-TIR) were scanned using free-breathing BLADE T2W turbo inversion recovery (BLADE TSE-T2W-TIR). The overall image quality, blood nulling, and visualization of the heart were scored on a 5-point Likert scale. The signal loss of myocardium, incomplete fat suppression near the myocardium, and the streaking or ghosting artifacts were noted in T2W-TIR sequences additionally.

RESULTS

The overall imaging quality, blood nulling, and the visualization of heart structure of FB BLADE-T2W imaging sequence were significantly better than those of FB T2W imaging with Cartesian k-space trajectory and BH TSE-T2W imaging sequence (P<0.01). The FB BLADE TSE-T2W-TIR reduces the myocardium signal dropout (P<0.05), incomplete fat suppression near myocardium (P<0.05), and the streaking and ghosting artifacts (P<0.05) in comparison with the BH TSE-T2W-TIR.

CONCLUSIONS

FB BLADE T2W imaging provides improved myocardial visibility, less motion sensitivity, and better image quality. It may be applied in patients who have poor breath-holding capability.

Cardiovascular magnetic resonance: What clinicians should know about safety and contraindications

Cardiovascular magnetic resonance (MR) is a multiparametric, non-ionizing, non-invasive imaging technique, which represents the imaging gold standard to study cardiac anatomy, function and tissue characterization. Faced with a wide range of clinical application, in this review we aim to provide a comprehensive guide for clinicians about MR safety, contraindications and image quality. Starting from the physical interactions of the static magnetic fields, gradients and radiofrequencies with the human body, we will describe the most common metal and electronic devices which are allowed (MR-safe), allowed under limited conditions (MR-conditional) or contraindicated (MR-unsafe). Moreover, some conditions potentially affecting image quality and patient comfort will be mentioned, including arrhythmias, claustrophobia, and poor breath-hold capacity. Finally, we will discuss the pharmacodynamics and pharmacokinetics of current gadolinium-based contrast agents, their contraindications and their potential acute and chronic adverse effects, as well as the safety issue concerning the use of vasodilating/inotropic agents in stress cardiac MR.

Cardiac magnetic resonance in patients with cardiac resynchronization therapy: is it time to scan with resynchronization on?

Cardiac resynchronization therapy (CRT) is recommended in international guidelines for patients with heart failure due to important left ventricular systolic dysfunction (or heart failure with reduced ejection fraction) and ventricular conduction tissue disease. Cardiac magnetic resonance (CMR) represents the most powerful imaging tool for dynamic assessment of the volumes and function of cardiac chambers but is rarely utilized in patients with CRT due to limitations on the device, programming and scanning. In this review, we explore the known utility of CMR in this cohort with discussion of the risks and potential benefits of scanning whilst CRT is active, including a practical strategy for conducting high quality scans safely. Our contention is that imaging in patients with CRT could be improved further by keeping resynchronization therapy active with resultant benefits on research and also patient outcomes.

3.0 T magnetic resonance imaging scanning on different body regions in patients with pacemakers

PURPOSE

Magnetic resonance imaging (MRI) at 3.0 T is becoming more common, but there is a lack of sufficient evidence on the safety of a 3.0 T scan in patients with pacemakers. This study aimed to investigate the safety and practical concerns of 3.0 T scans for patients with MR-conditional pacemakers.

METHODS

Twenty consecutive patients were enrolled. A standardized protocol was developed by cardiologists, pacemaker engineers, and radiologists. Pacemaker interrogation was performed immediately before and after the scan. Scan-related adverse events were documented, and imaging quality was graded as level 1 to 4 by radiologists.

RESULTS

Twenty-three MRI scans of different body regions (brain = 13, lumbar spine = 4, cervical spine = 2, and heart = 4) were performed, and the average time of a scan was 25 ± 11 min. No significant changes in sensing amplitude (atrial 3.1 ± 1.1 mV vs. 2.9 ± 1.2 mV, P = 0.71; ventricular 9.3 ± 3.5 mV vs. 10.2 ± 3.4 mV, P = 0.46), lead impedances (atrial 647 ± 146 Ω vs. 627 ± 151 Ω, P = 0.7; ventricular: 780 ± 247 Ω vs.711 ± 226 Ω, P = 0.36), or pacing threshold (atrial 0.6 ± 0.2 V/0.4 ms vs. 0.6 ± 0.2 V/0.4 ms, P = 0.71; ventricular 0.7 ± 0.3 V/0.4 ms vs. 0.7 ± 0.2 V/0.4 ms, P = 0.85) were observed pre- and postscan. No adverse events were detected. Image quality review showed grade 1 quality in 16 patients and grade 2 quality in 4 patients with artifacts of pulse generators and leads in cardiac MRI scan and no impact on diagnostic value.

CONCLUSION

Our initial data indicated that 3.0 T scanning might be feasible under a standardized protocol with good diagnostic imaging quality irrespective of body region in patients with MR-conditional pacemakers.

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).

An eight-year prospective controlled study about the safety and diagnostic value of cardiac and non-cardiac 1.5-T MRI in patients with a conventional pacemaker or a conventional implantable cardioverter defibrillator

OBJECTIVES

To investigate safety and diagnostic value of 1.5-T MRI in carriers of conventional pacemaker (cPM) or conventional implantable defibrillator (cICD).

METHODS

We prospectively compared cPM/cICD-carriers undergoing MRI (study group, SG), excluding those device-dependent or implanted <6 weeks before enrolment or prior to 01/01/2000, with cPM/cICD-carriers undergoing chest x-ray, CT or follow-up (reference group, RG).

RESULTS

142 MRI (55 cardiac) were performed in 120 patients with cPM (n=71) or cICD (n=71). In the RG 98 measurements were performed in 95 patients with cPM (n=40) or cICD (n=58). No adverse events were observed. No MRI prolonged/interrupted. All cPM/cICD were correctly reprogrammed after MRI without malfunctions. One temporary communication failure was observed in one cPM-carrier. Immediately after MRI, 12/14 device interrogation parameters did not change significantly (clinically negligible changes of battery voltage and cICD charging time), without significant variations for SG versus RG. Three-12 months after MRI, 9/11 device interrogation parameters did not change significantly (clinically negligible changes of battery impedance/voltage). Non-significant changes of three markers of myocardial necrosis. Non-cardiac MRI: 82/87 diagnostic without artefacts; 4/87 diagnostic with artefacts; 1/87 partially diagnostic. Cardiac MRI: in cPM-carriers, 14/15 diagnostic with artefacts, 1/15 partially diagnostic; in cICD-carriers, 9/40 diagnostic with artefacts, 22 partially diagnostic, nine non-diagnostic.

CONCLUSIONS

A favourable risk-benefit ratio of 1.5-T MRI in cPM/cICD carriers was reported.

KEY POINTS

• Cooperation between radiologists and cardiac electrophysiologists allowed safe 1.5-T MRI in cPM/cICD-carriers. • No adverse events for 142 MRI in 71 cPM-carriers and 71 cICD-carriers. • Ninety-nine per cent (86/87) of non-cardiac MRI in cPM/cICD-carriers were diagnostic. • All cPM-carrier cardiac MRIs had artefacts, 14 examinations diagnostic, 1 partially diagnostic. • Twenty-three per cent (9/40) of cardiac MRI in cICD-carriers were non-diagnostic.

Intra-cardiac distribution of late gadolinium enhancement in cardiac sarcoidosis and dilated cardiomyopathy

Cardiac involvement of sarcoid lesions is diagnosed by myocardial biopsy which is frequently false-negative, and patients with cardiac sarcoidosis (CS) who have impaired left ventricular (LV) systolic function are sometimes diagnosed with dilated cardiomyopathy (DCM). Late gadolinium enhancement (LE) in magnetic resonance imaging is now a critical finding in diagnosing CS, and the novel Japanese guideline considers myocardial LE to be a major criterion of CS. This article describes the value of LE in patients with CS who have impaired LV systolic function, particularly the diagnostic and clinical significance of LE distribution in comparison with DCM. LE existed at all LV segments and myocardial layers in patients with CS, whereas it was localized predominantly in the midwall of basal to mid septum in those with DCM. Transmural (nodular), circumferential, and subepicardial and subendocardial LE distribution were highly specific in patients with CS, whereas the prevalence of striated midwall LE were high both in patients with CS and with DCM. Since sarcoidosis patients with LE have higher incidences of heart failure symptoms, ventricular tachyarrhythmia and sudden cardiac death, the analyses of extent and distribution of LE are crucial in early diagnosis and therapeutic approach for patients with CS.