Non-contrast magnetic resonance imaging for guiding left ventricular lead position in cardiac resynchronization therapy

Comparative efficacy of image-guided techniques in cardiac resynchronization therapy: a meta-analysis

Background

Several studies have illustrated the use of echocardiography, magnetic resonance imaging, and nuclear imaging to optimize left ventricular (LV) lead placement to enhance the response of cardiac resynchronization therapy (CRT) in heart failure patients. We aimed to conduct a meta-analysis to determine the incremental efficacy of image-guided CRT over standard CRT.

Methods

We searched PubMed, Cochrane library, and EMBASE to identify relevant studies. The outcome measures of cardiac function and clinical outcomes were CRT response, concordance of the LV lead to the latest sites of contraction (concordance of LV), heart failure (HF) hospitalization, mortality rates, changes of left ventricular ejection fraction (LVEF), and left ventricular end-systolic volume (LVESV).

Results

The study population comprised 1075 patients from eight studies. 544 patients underwent image-guided CRT implantation and 531 underwent routine implantation without imaging guidance. The image-guided group had a significantly higher CRT response and more on-target LV lead placement than the control group (RR, 1.33 [95% CI, 1.21 to 1.47]; p < 0.01 and RR, 1.39 [95% CI, 1.01 to 1.92]; p < 0.05, respectively). The reduction of LVESV in the image-guided group was significantly greater than that in the control group (weighted mean difference, − 12.46 [95% CI, − 18.89 to − 6.03]; p < 0.01). The improvement in LVEF was significantly higher in the image-guided group (weighted mean difference, 3.25 [95% CI, 1.80 to 4.70]; p < 0.01). Pooled data demonstrated no significant difference in HF hospitalization and mortality rates between two groups (RR, 0.89 [95% CI, 0.16 to 5.08]; p = 0.90, RR, 0.69 [95% CI, 0.37 to 1.29]; p = 0.24, respectively).

Conclusions

This meta-analysis indicates that image-guided CRT is correlated with improved CRT volumetric response and cardiac function in heart failure patients but not with lower hospitalization or mortality rate.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02061-y.

Development and validation of an automatic method to detect the latest contracting viable left ventricular segments to assist guide CRT therapy from gated SPECT myocardial perfusion imaging

OBJECTIVES

The purpose of this study is to use ECG-gated SPECT MPI to detect the latest contracting viable left ventricular (LV) segments to help guide the LV probe placement used in CRT therapy and to validate segment selection against the visual integration method by experts.

METHODS

For each patient, the resting ECG-gated SPECT MPI short-axis images were sampled in 3D to generate a polar map of the perfusion distribution used to determine LV myocardial viability, and to measure LV synchronicity using our phase analysis tool. In the visual integration method, two experts visually interpreted the LV viability and mechanical dyssynchrony from the short-axis images and polar maps of viability and phase, to determine the latest contracting viable segments using the 17-segment model. In the automatic method, the apical segments, septal segments, and segments with more than 50% scar were excluded as these are not candidates for CRT LV probe placement. Amongst the remaining viable segments, the segments, whose phase angles were within 10° of the latest phase angle (the most delayed contracting segment), were identified for potential CRT LV probe placement and ranked based on the phase angles of the segments. Both methods were tested in 36 pre-CRT patients who underwent ECG-gated SPECT MPI. The accuracy was determined as the percent agreement between the visual integration and automatic methods. The automatic method was performed by a second independent operator to evaluate the inter-operator processing reproducibility.

RESULTS

In all the 36 patients, the LV lead positions of the 1st choices recommended by the automatic and visual integration methods were in the same segments in 35 patients, which achieved an agreement rate of 97.2%. In the inter-operator reproducibility test, the LV lead positions of the 1st choices recommended by the two operators were in the same segments in 25 patients, and were in the adjacent segments in 7 patients, which achieved an overall agreement of 88.8%.

CONCLUSIONS

An automatic method has been developed to detect the latest contracting viable LV segments to help guide the LV probe placement used in CRT therapy. The retrospective clinical study with 36 patients suggests that this method has high agreement against the visual integration method by experts and good inter-operator reproducibility. Consequently, this method is promising to be a clinical tool to recommend the CRT LV lead positions.

A Review of Image-guided Approaches for Cardiac Resynchronisation Therapy

Cardiac resynchronisation therapy (CRT) is a standard treatment for patients with heart failure; however, the low response rate significantly reduces its cost-effectiveness. A favourable CRT response primarily depends on whether implanters can identify the optimal left ventricular (LV) lead position and accurately place the lead at the recommended site. Myocardial imaging techniques, including echocardiography, cardiac magnetic resonance imaging and nuclear imaging, have been used to assess LV myocardial viability and mechanical dyssynchrony, and deduce the optimal LV lead position. The optimal position, presented as a segment of the myocardial wall, is then overlaid with images of the coronary veins from fluoroscopy to aid navigation of the LV lead to the target venous site. Once validated by large clinical trials, these image-guided techniques for CRT lead placement may have an impact on current clinical practice.

Nuclear Image-Guided Approaches for Cardiac Resynchronization Therapy (CRT)

Cardiac resynchronization therapy (CRT) is a standard treatment for patients with heart failure. However, 30-40 % of the patients having CRT do not respond to CRT with improved clinical symptom and cardiac functions. It is important for CRT response that left ventricular (LV) lead is placed away from scar and at or near the site of the latest mechanical activation. Nuclear image-guided approaches for CRT have shown significant clinical value to assess LV myocardial viability and mechanical dyssynchrony, recommend the optimal LV lead position, and navigate the LV lead to the target coronary venous site. All these techniques, once validated and implemented, should impact the current clinical practice.

Nuclear image-guided left ventricular pacing lead navigation feasibility of a new technique

PURPOSE

Current techniques for left ventricular (LV) lead implantation in patients with ischemic cardiomyopathy (ICM) typically underutilize information which is important for optimal lead location, including LV mechanical activation pattern and scar location. We sought to develop a technique in which this information, contained in single-photon emission computed tomographic (SPECT) images, could be integrated as to guide the electrophysiologist during the implantation procedure.

METHODS

Five ICM patients underwent SPECT as well as multidetector cardiac computed tomographic (MDCT) imaging prior to the LV lead implantation procedure. Images were merged to create a "fusion" image, in which the SPECT data were projected onto the anatomically accurate MDCT epicardial surface. The fusion image was registered to the operative field using the coronary veins, apparent on the MDCT image, as a fiducial system. After registration, LV lead implantation was guided by the fusion image using a commercial catheter navigation system.

RESULTS

Successful guidance was achieved in each patient, with minimal disturbance to standard workflow. Leads were implanted in late-activating, unscarred regions according to the fusion image, with locations corroborated by fluoroscopic and electrographic features. In regions where leads were contiguous to the phrenic nerve shown on the fusion image, pacing consistently demonstrated diaphragmatic stimulation.

CONCLUSIONS

In this technical report, the description and feasibility of a new technique for SPECT image-guided LV pacing lead navigation is demonstrated. Prospective study will be required to confirm image precision and registration/navigation accuracy, as well as to demonstrate value relative to standard implantation techniques.

Pre-Implant Assessment For Optimal LV Lead Placement In CRT: ECG, ECHO, or MRI?

Cardiac resynchronization therapy (CRT) improves cardiac function in many patients with ventricular dyssynchrony. The optimal use of imaging for pre-implantation assessment remains a subject of debate. Here, we review the literature to date on the utility of echocardiography and cardiac MR, as well as conventional ECG, in choosing the best site for LV lead implantation. Prior to the use of imaging for pre-implantation evaluation, LV leads were placed empirically, based on average responses from population-level studies. Subsequently, patient-specific approaches have been used to maximize response. Both echocardiography and cardiac MR allow determination of areas of latest mechanical activation. Some studies have found improved response when pacing is applied at or near the site of latest mechanical activation. Similarly, both echocardiography and cardiac MR provide information about the location of any myocardial scar, which should be avoided when placing the LV lead due to variable conduction and high capture thresholds. Alternative approaches include targeting the region of latest electrical activation via measurement of the QLV interval and methods based on intraoperative hemodynamic measurements. Each of these modalities offers complementary insights into LV lead placement, so future directions include multimodality pre-implantation evaluation, studies of which are ongoing. Emerging technologies such as leadless implantable pacemakers may free implanting electrophysiologists from the constraints of the coronary sinus, making this information more useful and making non-response to CRT increasingly rare.

3D fusion of LV venous anatomy on fluoroscopy venograms with epicardial surface on SPECT myocardial perfusion images for guiding CRT LV lead placement

OBJECTIVES

The aim of this study was to develop a 3-dimensional (3D) fusion tool kit to integrate left ventricular (LV) venous anatomy on fluoroscopy venograms with LV epicardial surface on single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) for guiding cardiac resynchronization therapy (CRT) LV lead placement.

BACKGROUND

LV lead position is important for CRT response. For LV lead placement into viable regions with late activation, it is important to visualize both LV venous anatomy and myocardium.

METHODS

Major LV veins were manually identified on fluoroscopic venograms and automatically reconstructed into a 3D anatomy. 3D LV epicardial surface was extracted from SPECT MPI. SPECT-vein fusion that consisted of geometric alignment, landmark-based registration, and vessel-surface overlay was developed to fuse the 3D venous anatomy with the epicardial surface. The accuracy of this tool was evaluated using computed tomography (CT) venograms. LV epicardial surfaces and veins were manually identified on the CT images and registered with the SPECT image by an independent operator. The locations of the fluoroscopic and CT veins on the SPECT epicardial surfaces were compared using absolute distances on SPECT short-axis slice and the 17-segment model.

RESULTS

Ten CRT patients were enrolled. The distance between the corresponding fluoroscopic and CT veins on the short-axis epicardial surfaces was 4.6 ± 3.6 mm (range 0 to 16.9 mm). The presence of the corresponding fluoroscopic and CT veins in the 17-segment model agreed well with a kappa value of 0.87 (95% confidence interval: 0.82 to 0.93). The tool kit was used to guide LV lead placement in a catheter laboratory and showed clinical feasibility and benefit to the patient.

CONCLUSIONS

A tool kit has been developed to reconstruct 3D LV venous anatomy from dual-view fluoroscopic venograms and to fuse it with LV epicardial surface on SPECT MPI. It is technically accurate for guiding LV lead placement by the 17-segment model and is feasible for clinical use in the catheterization laboratory.

Cardiac magnetic resonance-derived anatomy, scar, and dyssynchrony fused with fluoroscopy to guide LV lead placement in cardiac resynchronization therapy: a comparison with acute haemodynamic measures and echocardiographic reverse remodelling

AIMS

Left ventricular (LV) lead positioning for cardiac resynchronization therapy (CRT) is largely empirical and operator-dependent. Our aim was to determine whether cardiac magnetic resonance (CMR)-guided CRT may improve the acute and the chronic response.

METHODS AND RESULTS

CMR-derived anatomical models and dyssynchrony maps were created for 20 patients. The CMR targets (three latest activated segments with <50% scar) were overlaid on to live fluoroscopy. Acute haemodynamic response (AHR) to LV pacing was assessed using an intra-ventricular pressure wire. Chronic CRT response (end-systolic volume reduction ≥15%) was assessed 6 months post-implantation. All patients underwent successful CMR-guided LV lead placement. A CMR target segment was paced in 75% of patients. The mean change in LVdP/dtmax for the CMR target was +14.2 ± 12.5 vs. +18.7 ± 11.9% for the best AHR in any segment and +12.0 ± 13.8% for the segment based on coronary sinus (CS) venography. Using CMR guidance, the acute responder rate was 60 vs. 50% on the basis of venography. At 6 months 60% of patients were echocardiographic responders. Of the echocardiographic responders, 92% were successfully paced in a CMR target segment compared with only 50% of non-responders (P = 0.04).

CONCLUSION

CMR guidance compared well when validated against the AHR. Lead placement was possible in the CMR target region in most patients with an AHR comparable with the best achieved in any CS branch. The chronic response was significantly better in patients paced in a CMR target segment. These results suggest that CMR guidance may represent a clinically useful tool for CRT.

[Advances in cardiac pacing]

This article contains a review of the current status of remote monitoring and follow-up involving cardiac pacing devices and of the latest developments in cardiac resynchronization therapy. In addition, the most important articles published in the last year are discussed.