Rapid early rise in heart rate on treadmill exercise in patients with asymptomatic moderate or severe aortic stenosis: a new prognostic marker?

OBJECTIVE: To examine the clinical significance and prognostic value of an early rapid rise in heart rate (RR-HR) in asymptomatic patients with moderate or severe aortic stenosis (AS). METHODS: We retrospectively assessed the prospectively collected data from 306 patients (age 65±12 years, 33% women) with moderate (n=204) or severe AS (n=102) with a median follow-up of 25 months (mean 34.9±34.6 months). All had echocardiography and modified Bruce exercise treadmill tests (ETT). RR-HR was defined as achieving 85% target HR or ≥50% increase from baseline in the first 6 min. The outcome measures were revealed symptoms during ETT, aortic valve replacement (AVR) and all-cause mortality. RESULTS: RR-HR occurred in 77 (25%) and 64% developed revealed symptoms (postive predictive value 64% and negative predictive value 84%). On univariate Cox regression analyses in patients with severe AS, RR-HR was associated with AVR (HR 3.32, 95% CI 2.03 to 5.45, p<0.001) but not with all-cause mortality (HR 0.04, 95% CI 0.13 to 9.21, p=0.798). In patients with moderate AS, RR-HR was associated with all-cause mortality (HR 2.67, 95% CI 1.09 to 6.56, p=0.032), but not with AVR (HR 1.35, 95% CI 0.92 to 1.98, p=0.127). These associations remained significant in multivariate Cox regression analyses after adjustment for age, sex, hypertension, coronary artery disease, abnormal blood pressure response, Doppler stroke volume and mean pressure gradient (both p<0.001). CONCLUSIONS: RR-HR was associated with the development of revealed symptoms. It predicted revealed symptoms on serial ETT, AVR in severe AS and all-cause mortality in moderate AS. RR-HR may be a useful new measure to define risk in AS.