Newer echocardiographic techniques for aortic-valve imaging: Clinical aids today, clinical practice tomorrow

Table 1 Prevalence[8,9], prognosis[10] and percentage of patients undergoing surgery[8] for severe aortic stenosis and preserved ejection fraction

	High gradient (mean > 40 mmHg)	Low gradient (mean < 40 mmHg)
Normal flow (SV > 35 mL/m2)
Prevalence	30%-62.7%	15.3%-38%
Prognosis (2 yr survival rates)	44% ± 6%	83% ± 6% (best prognosis)
% Undergoing surgery	80% (highest rates of surgery)	53%
Low flow (SV < 35 mL/m2)
Prevalence	8%-13.2%	8.8%-24%
Prognosis (2 yr survival rates)	30% ± 12%	27% ± 13%-worst prognosis
% Undergoing surgery	68%	36%-lowest rates of surgery