The Role of Cardiac Magnetic Resonance to Predict Response to Cardiac Resynchronization Therapy: A Systematic Review and Meta-analysis

Abstract

Cardiac resynchronization therapy (CRT) has revolutionized heart failure (HF) management, offering benefits in morbidity, mortality, and symptom alleviation. However, optimal response rates are not universally achieved, necessitating enhanced patient-selection strategies. Myocardial scar patterns, quantified by delayed-enhancement cardiac magnetic resonance (DE-CMR), have been implicated in CRT outcomes. We conducted a meta-analysis of observational studies assessing CRT responses by performing a systematic literature search using PubMed, Embase, Ovid MEDLINE, Scopus, the Cochrane Library, ScienceDirect, and the Web of Science. Scar burden, left ventricular ejection fraction (LVEF), left ventricular end-systolic volume (LVESV), and left ventricular end-diastolic volume (LVEDV) were evaluated. CRT response rates among ischemic and non-ischemic cardiomyopathy patients were also explored. This meta-analysis incorporated eight studies meeting the eligibility criteria. CRT responders exhibited a significantly lower scar burden (-11.7%; 95% confidence interval, 6.6%-16.8%) compared to non-responders, supporting the predictive value of scar quantification (I ² = 95.25%; P < .001). Responders demonstrated an increased mean LVEF (from 25.2% to 31.9%), while non-responders showed modest changes (from 23.3% to 24.4%). Responders experienced a decrease in mean LVESV from 158.8 to 132.8 mL, contrasting with a more stable mean LVESV value in non-responders (reduction from 160.9 to 157.6 mL). Responders experienced a reduced mean LVEDV from 219.4 to 196.7 mL, while non-responders showed more minimal changes (from 213.4 to 210.6 mL). Limited data suggested a CRT response rate of 34.7% in ischemic cardiomyopathy; non-ischemic data were insufficient. In conclusion, DE-CMR, assessing the scar burden, emerges as a valuable tool for predicting the CRT response. A lower scar burden correlates with improved responses, supporting the role of DE-CMR in refining patient selection for CRT. This meta-analysis contributes insights into personalized CRT strategies, emphasizing the potential of imaging modalities to enhance therapeutic outcomes in HF patients. Further research is warranted to solidify these findings and refine clinical applications.

Keywords: Cardiac magnetic resonance; cardiac resynchronization therapy; heart failure; meta-analysis; scar burden.

Figure 1:

Flow diagram according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, showing the identification of studies via a rigorous search of the database.

Figure 2:

Mean scar burden difference. A forest plot showing the mean scar burden difference between cardiac resynchronization therapy responders and non-responders. Abbreviation: CI, confidence interval.

Figure 3:

Mean ejection fraction in cardiac resynchronization therapy (CRT) responders. A forest plot showing the mean ejection fraction in CRT responders pre-CRT (upper) and post-CRT (lower). Abbreviation: CI, confidence interval.

Figure 4:

Mean left ventricular ejection fraction in cardiac resynchronization therapy (CRT) non-responders. A forest plot showing the mean ejection fraction in CRT responders pre-CRT (upper) and post-CRT (lower). Abbreviation: CI, confidence interval.

Figure 5:

Mean left ventricular end-systolic volume in cardiac resynchronization therapy (CRT) responders. A forest plot showing the mean ejection fraction in CRT responders pre-CRT (upper) and post-CRT (lower). Abbreviation: CI, confidence interval.

Figure 6:

Mean left ventricular end-systolic volume in cardiac resynchronization therapy (CRT) non-responders. A forest plot showing the mean ejection fraction in CRT non-responders pre-CRT (upper) and post-CRT (lower). Abbreviation: CI, confidence interval.

Figure 7:

Mean left ventricular end-diastolic volume in cardiac resynchronization therapy (CRT) responders. A forest plot showing the mean ejection fraction in CRT responders pre-CRT (upper) and post-CRT (lower). Abbreviation: CI, confidence interval.

Figure 8:

Mean left ventricular end-diastolic volume in cardiac resynchronization therapy (CRT) non-responders. A forest plot showing the mean ejection fraction in CRT non-responders pre-CRT (upper) and post-CRT (lower). Abbreviation: CI, confidence interval.

Figure 9:

A forest plot showing the average cardiac resynchronization therapy response rate in patients with ischemic cardiomyopathy. Abbreviations: CI, confidence interval; Ev/Trt, event/treated.