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First-Phase Ejection Fraction Predicts Response to CRT
Quick Takes
- First-phase ejection fraction (EF1) measures systolic function from end-diastole to the peak transaortic valve flow velocity.
- EF1 is higher in individuals who have favorable response to CRT.
- Improvement in EF1 after EF1 is associated with lower rates of adverse cardiac outcomes.
Study Questions:
Can first-phase ejection fraction (EF1) identify patients who have greater response to cardiac resynchronization therapy (CRT)?
Methods:
EF1 was measured as the EF from end-diastole to the time of peak transaortic valve flow velocity on Doppler echocardiography. Favorable response to CRT was reduction in left ventricular end-systolic volume (LVESV) by ≥15%. A total of 197 subjects who underwent CRT were retrospectively identified, after excluding individuals with suboptimal images, moderate or severe valve disease, and loss to follow-up. Improvement in a composite clinical score was also assessed. A validation study was performed in a second hospital in 100 patients.
Results:
In the initial retrospective study, 113 of 197 subjects (57%) had improvement in LVESV and 147 (75%) had improvement in the composite clinical score. Demographics and standard echocardiographic parameters were similar between responders and nonresponders. However, EF1 was significantly lower for nonresponders than responders, after adjustment for age, sex, and baseline QRS duration (9.0% vs. 16.4%, p < 0.001). The highest tertile of EF had markedly higher response rates (92.3% vs. 12.1%, p < 0.001). Receiver-operating characteristic analysis for EF1 was 0.89 and greater than for other variables evaluated. In logistic regression analysis, each 1% increase in EF1 was associated with an increased odds of response of 1.47 (p < 0.001). After a median follow-up of 20.3 months, 42 patients had an adverse event (death or hospitalization for heart failure). Improvement of EF1 from baseline to 6 months was associated with fewer events (hazard ratio, 0.83; p < 0.001). Similar findings were found in the validation cohort.
Conclusions:
EF1 may be helpful to identify individuals likely to respond to CRT.
Perspective:
CRT is an important therapy for heart failure, which both improves symptoms and clinical outcomes. However, some patients do not experience symptomatic improvement or improvement in imaging or biomarkers. Given the cost and complexity of CRT, there is interest in improving recognition of these patients. EF1 certainly seems promising as such a marker. However, this metric has not been tested in a prospective randomized trial. Prior studies of promising electrocardiographic and imaging markers have largely been dead ends. Further, it is unclear if denial of CRT to those with lower likelihood of response will be seen as ethical or legally tenable. That said, greater information on likelihood of response will be helpful in counseling patients and enabling informed decision making.
Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure, Heart Failure and Cardiac Biomarkers, Echocardiography/Ultrasound
Keywords: Arrhythmias, Cardiac, Biomarkers, Cardiac Resynchronization Therapy, Diagnostic Imaging, Diastole, Echocardiography, Echocardiography, Doppler, Electrocardiography, Heart Failure, Stroke Volume
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