麻豆传媒

Left ventricular ejection fraction (LVEF) and symptoms aren't the only tools that can help determine when to intervene in patients with aortic stenosis (AS), a registry study suggested.

LV global longitudinal strain (GLS) varied in asymptomatic but severe AS at the same degree of LVEF, reported Jeroen Bax, MD, PhD, of Leiden University Medical Center in the Netherlands, and colleagues in their study published online in .

That measure of strain was impaired in patients with asymptomatic severe AS versus controls without structural heart disease (average -17.9% versus -19.6%, P<0.001).

GLS measures the degree of longitudinal shortening in myocardial fibers, making it able to capture early LV systolic dysfunction, before any irreversible myocardial damage has occurred.

Of the 68.2% of patients who had a second transthoracic echocardiogram available, LV GLS deteriorated from -18.0% to -16.3% (P<0.001) over median 12 months' follow-up whereas LVEF stayed the same. These patients were roughly split between those who stayed asymptomatic and others who developed symptoms, but both groups showed no change in LVEF.

Compared to those with preserved LV GLS, individuals with GLS values less negative than -18.2% were at higher risk of becoming symptomatic (59% versus 45% at 2 years; 91% versus 79% at 5 years; log-rank P=0.02) and undergoing an aortic valve intervention (66% versus 57% at 2 years; 96% versus 82% at 5 years; log-rank P=0.03).

"This study shows that LV GLS is often impaired in asymptomatic severe AS and will further deteriorate if left untreated, while LVEF remains unchanged. This suggests that patients with impaired LV GLS at baseline have subclinical myocardial dysfunction that is probably secondary to diffuse fibrosis, which is not detected by the conventional echocardiographic parameters of LV systolic function," Bax's group wrote.

"Therefore, the evaluation of LV GLS and consideration of objective signs of AS-related cardiac damage in patients with asymptomatic severe AS with preserved LVEF (as recently suggested in a new AS staging classification) may help to define the optimal timing for aortic valve replacement (before symptom development and irreversible myocardial damage occur)," they suggested.

The retrospective analysis was based on the pooling of three institutional registries (Leiden University Medical Center, Belgium's Heart Valve Clinic, and Institut Universitaire de Cardiologie et de Pneumologie de Québec).

The dataset included 220 asymptomatic severe AS patients with preserved LVEF who had baseline echocardiographic data available with speckle tracking imaging for LV GLS analysis measured on a variety of software platforms. The study population comprised 57% men and had an average age of 68.

"It is tempting to make the connection that patients with asymptomatic AS with lower GLS should be considered for undergoing early intervention, but before coming to that conclusion, a few points should be considered," according to an accompanying editorial by James Thomas, MD, of Bluhm Cardiovascular Institute at Northwestern University in Chicago.

For one, the study did not show an adverse association of low GLS with outcomes and mortality, unlike others in the literature. "Despite having more symptom development and aortic valve replacements, there is no evidence that the outcomes were adversely affected by low GLS," Thomas noted, adding that symptom development is itself hard to define and interpret.

"Perhaps exercise echocardiography, which was popularized by these investigators, could have better defined the differences in functional capacity," he suggested.

The investigators also pointed out that their retrospective study design left room for potential selection bias and that, as participating centers were tertiary referral hospitals for aortic valve replacement, referral bias for treatment was also possible.

It may be time for a randomized trial of GLS-guided treatment in asymptomatic severe AS, Thomas suggested. "Out of necessity, it would be a large trial with a long follow-up, as it may be years before surgery is indicated after one or more AS echo indices has crossed into the severe range," he acknowledged.