Neither increase in mean pressure gradient (MPG) nor systolic pulmonary artery pressure (SPAP) at peak exercise predicts outcomes in patients with asymptomatic aortic stenosis (AS) according to a study published in JACC Cardiovascular Imaging.
Approximately 5% the population older than 70 years of age are affected by aortic stenosis. Patients with severe AS either symptomatic or with left ventricular systolic dysfunction should be referred for percutaneous or surgical aortic valve replacement according to current guidelines. On the other hand, management of asymptomatic severe AS is still in question.
If severe aortic stenosis is left untreated, there is a risk of sudden death without preceding symptoms and irreversible myocardial dysfunction. However, patients undergoing treatment have the risk of surgery and prosthetic valve complications.
Past literature has suggested that stress echocardiography may enhance the prognostic assessment of asymptomatic AS. The prognosis could be worse with an increase in the mean pressure gradient, lesser increase in left ventricular ejection fraction and higher systolic pulmonary artery pressure.
To examine this, Coppelia Goublaire, M.D., and colleagues evaluated 148 patients with moderate to severe asymptomatic AS with preserved ejection fraction and normal peak SPAP who underwent a symptom-limited exercise echocardiography. 36 of the 148 subjects developed symptoms during the exercise test and were referred for surgery. The remaining 112 patients with a normal exercise test results were managed conservatively. 38 of them had an increase in mean pressure gradient >20 mm Hg and a peak systolic pulmonary artery pressure >60 mm Hg. An AS-related event was observed in 30 patients during a mean follow-up of 14 ± 8 months. Aortic valve replacement or AS-related events were not predicted by exercise-induced increase in MPG >20 mm Hg (p=0.51) or peak SPAP >60 mm Hg (p=0.45). However, baseline MPG remained as an important predictor of these outcomes (p= 0.003).
“The findings of Goublaire et al. showed that many asymptomatic patients are not asymptomatic. They also confirm and extend our appreciation that findings of severe aortic stenosis at rest have prognostic meaning. Even in the absence of symptoms, patients with higher resting mean pressure gradients are more likely to experience problems.” – Dr. Michael S. Lauer
In the accompanying editorial, Dr. Michael S. Lauer stated, “The findings of Goublaire et al. offer an important contribution to the growing literature on asymptomatic aortic stenosis. They confirm that many asymptomatic patients are not asymptomatic.” He also added, “These results confirm and extend our appreciation that findings of severe aortic stenosis at rest have prognostic meaning. Even in the absence of symptoms, patients with higher resting mean pressure gradients are more likely to experience problems.”
In conclusion, the authors confirmed the importance of exercise testing regardless of the modality to unmask functional limitations. Moreover, neither the increase of mean pressure gradient nor the increase of systolic pulmonary hypertension during exercise was predictive of AS-related events. Since this is a relatively small, single-center study, future multicenter prospective studies are needed to confirm these findings but for now, these results do not support the use of these parameters in the risk-stratification and clinical management of asymptomatic AS patients.