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Utility of E/e′ Ratio During Low-Level Exercise to Diagnose HFpEF
Quick Takes
- Obtaining an E/e’ ratio during low-level (20-W) exercise is more feasible than at peak exercise and, if normal, has high predictive accuracy for normal E/e’peak (<15).
- E/e’20W has moderate predictive accuracy for normal PCWP during exercise right heart catheterization (<25 mm Hg).
- E/e’20W may have some value in ruling out HFpEF in patients with exertional dyspnea.
Study Questions:
Can the E/e’ ratio during low-level (20-W) exercise predict noninvasive and invasive parameters of elevated filling pressures during exercise? And, can it be used to exclude a diagnosis of heart failure with preserved ejection fraction (HFpEF)?
Methods:
This was a retrospective study looking at 528 consecutive patients with exertional dyspnea referred for supine bicycle stress echocardiography. Exclusion criteria included: ages <20 years, ejection fraction <50%, significant left-sided valvular disease (> moderate regurgitation and > mild stenosis), hypertrophic cardiomyopathy, and inability to reach the 40-W exercise stage, resting E/e’ ratio >15, elevated B-type natriuretic peptide (BNP) (>80 pg/mL in sinus rhythm or >240 pg/mL in atrial fibrillation), or no BNP data available.
Protocol 1 investigated the diagnostic ability of E/e’20W to predict a normal E/e’ ratio during peak exercise, defined as E/e’peak ≤15. Supine bicycle stress echocardiography was performed according to usual guidelines, with a 5-minute first stage at 20-W followed by graded 20-W increments up to patient-reported exhaustion. Mitral inflow velocity € and tissue Doppler at the septal annulus (e’) were acquired 30 seconds after the initiation of each stage. Protocol 2 investigated the diagnostic performance of E/e’20W in predicting PCWP <25 mm Hg in the subset of patients who had been brought back within several weeks for exercise right heart catheterization after bicycle stress echocardiography. The probability of HFpEF was determined using the HFA-PEFF diagnostic algorithm from the European Society of Cardiology.
Results:
Of the 528 dyspneic patients referred for exercise echocardiography, 215 patients were included in Protocol 1. Average age was 68 ± 12 years, 52% were female, body mass index (BMI) was 24 kg/m2 ± 6, 69% had hypertension, and 24% had atrial fibrillation. The feasibility of obtaining the E/e’ ratio decreased from 100% at rest to 96.3% during 20-W exercise and 74.9% during peak exercise, due to E-A wave fusion. E/e’ 20W had excellent predictive accuracy for E/e’peak ≤15, with an area under the curve (AUC) of 0.91 and an optimal cutoff value of ≤12.4, demonstrating both high specificity (94%) and sensitivity (77%).
The protocol 2 subset included 45 patients, with an average age of 71 ± 10 years, 76% were female, BMI was 23 kg/m2 ± 4, 82% had hypertension, and 7% had atrial fibrillation. At a cutoff of 12.4, E/e’20W had high specificity (83%) and moderate sensitivity (75%) in predicting normal pulmonary capillary wedge pressure (PCWP) during exercise (<25 mm Hg) with an AUC of 0.77. While E/e’peak had a higher AUC (0.81), its feasibility was only 66.7% vs. 86.7% for E/e’20W.
Conclusions:
Obtaining an E/e’ ratio during low-level exercise (20-W) is more feasible than at peak exercise due to the frequency of E-A fusion at high heart rate. E/e’20W has excellent predictive accuracy for E/e’peak (AUC 0.91), with an optimal cutoff of 12.4 in this study. E/e’20W has less overall predictive accuracy for normal PCWP during exercise, but has high specificity at the same cutoff of 12.4. The predictive accuracy of E/e’20W for the diagnosis of HFpEF was not directly evaluated in this study.
Perspective:
In the 2016 American Society of Echocardiography and European Association of Cardiovascular Imaging guidelines on evaluation of diastolic function, diastolic stress testing is recommended for patients with stage 1 diastolic dysfunction (i.e., delayed myocardial relaxation, but normal left atrial pressure) who have symptomatic and unexplained dyspnea with exertion. This test is considered normal when E/e’ ratio is <10 and tricuspid regurgitation velocity is <2.8 m/s with peak exercise. However, obtaining these values at peak exercise can be challenging due to E-A wave fusion at high heart rate.
This retrospective study evaluates the feasibility of using the E/e’ ratio at a lower level of exercise (20-W) and its ability to predict normal E/e’ ratio during peak exercise and normal PCWP on exercise right heart catheterization. Unfortunately, the study seems to overstate its findings, extrapolating the predictive accuracy of E/e’20W to the diagnosis of HFpEF, which is never directly evaluated. Moreover, the relatively low BMIs, lack of obstructive sleep apnea, and exclusion of patients unable to exercise to a level of 40-W are all likely to skew the study population away from a typical cohort of HFpEF patients in North America.
Clinical Topics: Arrhythmias and Clinical EP, Diabetes and Cardiometabolic Disease, Geriatric Cardiology, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Prevention, Valvular Heart Disease, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure, Heart Failure and Cardiac Biomarkers, Echocardiography/Ultrasound, Exercise, Hypertension
Keywords: Atrial Fibrillation, Body Mass Index, Diagnostic Imaging, Dyspnea, Echocardiography, Exercise, Exercise Test, Geriatrics, Heart Failure, Heart Valve Diseases, Hypertension, Natriuretic Peptide, Brain, Pulmonary Wedge Pressure, Stroke Volume
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