P802 Delayed time to peak left ventricular outflow tract velocity is associated with symptomatic status in patients with hypertrophic obstructive cardiomyopathy

Funding Acknowledgements None. The presence and magnitude of left ventricular outflow tract (LVOT) obstruction in hypertrophic obstructive cardiomyopathy (HOCM) patients is weakly associated with presence of symptoms. The factors underlying this are not well understood. We hypothesize that time to peak velocity (TPV) of LVOT flow is associated with symptomatic status. We included 136 HOCM patients (58% men, mean age 55 ± 14 years) with peak gradients ≥30 mmHg at rest or during Valsalva without aortic valve stenosis. At rest and during Valsalva, continuous wave Doppler tracings from 3 consecutive beats were used to assess peak velocity (PV), left ventricular ejection time (LVET) and TPV, which was defined as the time interval between the onset of flow over the LVOT and the moment of PV. Differences were compared between asymptomatic and symptomatic patients (defined as New York Heart Association class I vs. II-IV). The relation between symptom status and TPV was investigated using logistic regression models. A random sample of 20 patients was examined by 2 observers and reproducibility was assessed using the intraclass correlation coefficient (ICC). Symptomatic patients were more often female (table) and had significantly higher mean TPV values (figure). In multivariable logistic regression models, TPV was an independent predictor of symptomatic status after correction for PV, LVOT diameter, heart rate and age (odds ratio 1.02 per 1 ms, p < 0.001). The ICC was 0.99 with a mean difference of 0.28 ± 8.5 ms. Delayed TPV is associated with symptomatic status in HOCM patients, after adjustment for heart rate, peak velocity, LVOT diameter and age, and is an easily measured echocardiographic variable with excellent inter-reader reproducibility. The clinical implications of delayed TPV, particularly in the context risk prediction and clinical decision making, remain to be determined. Characteristics per group Asymptomatic HOCM patients n = 47 Symptomatic HOCM patients n = 89 p value Age, y 55 ± 14 55 ± 14 0.99 Male gender 34 (72%) 45 (51%) 0.01 Body mass index, kg/m² 27 ± 5 28 ± 5 0.08 Left atrial diameter, mm 46 ± 7 47 ± 7 0.64 Septal wall thickness, mm 18 ± 4 19 ± 5 0.58 LV outflow tract diameter, mm 22 ± 3 21 ± 3 0.001 Peak velocity, cm/s 403 ± 86 434 ± 79 0.03 LV ejection time, ms 316 ± 44 340 ± 42 0.002 Time to peak velocity, ms 157 ± 32 178 ± 32 <0.001 HOCM = hypertrophic obstructive cardiomyopathy, LV = left ventricular. Abstract P802 Figure. Time to peak velocity per NYHA class