Long-term response of the left ventricle to cardiac resynchronization therapy: insights from standard and strain echocardiography

Global longitudinal strain as a prognostic marker in cardiac resynchronisation therapy: A systematic review

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Left ventricular global longitudinal strain (LV GLS) is a sensitive parameter that correlates with myocardial scar burden and fibrosis with potential value in CRT candidates.

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First systematic review evaluating the existing evidence for the prognostic value of LV GLS in patients undergoing CRT implantation.

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Despite significantly abnormal baseline GLS at CRT implantation, there is still a significant association between incrementally worse LV GLS at CRT implantation and prognostic outcomes on long-term follow-up.

Purpose

Cardiac resynchronisation therapy (CRT) has proven mortality benefits for heart failure patients with moderate to severe systolic left ventricular dysfunction and evidence of a left bundle branch block. Determining responders to this therapy can be difficult due to the presence of myocardial fibrosis and scar. Left ventricular global longitudinal strain (LV GLS) is a robust and sensitive measure of myocardial function and fibrosis that has significant prognostic value for a plethora of cardiac pathologies. Our aim was to perform a systematic review of the value of LV GLS for predicting outcomes in patients undergoing CRT.

Methods

A systematic review of the literature was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) protocol for reporting on systematic reviews and meta-analyses. An electronic search of all English, adult publications in EMBASE, MEDLINE/PubMed and the Cochrane Database of Systematic reviews was undertaken.

Results

The search yielded, 9 studies that included 3,981 patients with symptomatic heart failure, undergoing CRT implantation with LV GLS utilised as a predictor of all-cause mortality, cardiovascular death, rehospitalisation, LVAD implantation/ heart transplantation or left ventricular reverse remodelling. Significant heterogeneity was observed in study outcome measures, included populations, LV-GLS cut-offs and follow-up definitions, resulting in the inability to reliably conduct a meta-analyses. Overall, pre-CRT LV GLS was found to be a predictor of outcome post CRT insertion.

Conclusions

In conclusion, all studies implied that incrementally abnormal baseline LV GLS pre-CRT implantation was associated with a long term poorer outcome.