Prolonged total isovolumic time is related to reduced long-axis functional recovery following valve replacement surgery for severe aortic stenosis

BACKGROUND

The left ventricular (LV) long axis (Lax) function is very sensitive in documenting myocardial abnormalities in aortic stenosis (AS). We hypothesized that Lax recovery after aortic valve replacement (AVR) is related to the extent of cavity dyssynchrony measured by total isovolumic time (t-IVT).

METHODS

A consecutive 107 patients (aged 70 ± 7 years, 70 male) with severe AS and Lax impairment were studied. T-IVT was measured before and after AVR. Reduced Lax function and its post-operative recovery were defined as mitral annular plane systolic excursion (MAPSE) ≦10 mm and an increase of MAPSE >10%, respectively.

RESULTS

LV function improved (EF: 43 ± 8 to 48 ± 10%; MAPSE: 7.9 ± 1.0 to 11.0 ± 2.4 mm) and t-IVT shortened (9.7 ± 3.7 to 7.0 ± 2.8s/min, p<0.01 for all) after AVR. Sixty-five (61%) patients had Lax recovery after a median of 32-month follow-up. Univariate predictors were LV size, LA dimensions, the presence of restrictive LV filling and prolonged t-IVT. Only LV end-systolic dimension, restrictive filling and t-IVT (OR 0.61, 95% CI 0.47-0.79, p<0.01) were independent predictors. A pre-operative t-IVT ≦ 9.3s/min was 81% sensitive and 63% specific in predicting Lax recovery (AUC 0.81, p<0.001). The prevalence of CAD or concomitant CABG were similar in 2 patient groups with different t-IVT.

CONCLUSIONS

Lax recovery was evident in the majority of AS patients after AVR. The lower prevalence of Lax recovery seen in patients with prolonged t-IVT suggests that dyssynchrony may play an important role in the process of adverse LV remodeling.

Importance of dynamic dyssynchrony in the occurrence of hypertensive heart failure with normal ejection fraction

AIMS

The impact of haemodynamic stress on left ventricular (LV) dyssynchrony in heart failure with normal ejection fraction (HFNEF) remains unknown. We sought to evaluate the relationship and predictive value of dynamic changes of LV dyssynchrony on hypertensive HFNEF.

METHODS AND RESULTS

A total of 131 subjects including 47 hypertensive HFNEF patients, 34 hypertensive patients with left ventricular hypertrophy (LVH) without HFNEF, and 50 normal controls were studied by dobutamine stress echocardiography with tissue Doppler imaging. Systolic and diastolic dyssynchrony were assessed using the LV six-basal-six-mid-segment model and cut-off values were derived from normal controls. The mean basal segments longitudinal systolic (mean Sm) and early diastolic (mean Em) velocities were measured. In normal controls, systolic and diastolic dyssynchrony did not develop during stress. The prevalence of resting systolic (36.2% vs. 38.2%, P = 0.85) and diastolic (34.0% vs. 29.4%, P = 0.66) dyssynchrony was similar in HFNEF and LVH groups. During stress, the prevalence of systolic and diastolic dyssynchrony increased dramatically to 85.1% and 87.2%, respectively, in HFNEF group, but only 52.9% and 58.8% in LVH group (P < 0.005). In HFNEF group, stress-induced increase in mean Sm was significantly blunted (2.8 ± 2.0 vs. 4.2 ± 2.4 cm/s, P = 0.004), and the increase was abolished for mean Em (-0.3 ± 2.5 vs. 2.4 ± 3.4 cm/s, P < 0.001). On multivariate analysis, stress-induced changes in mean Em (OR = 0.69, P = 0.004) and mean Sm (OR = 0.56, P = 0.004), and diastolic (OR = 4.6, P = 0.005) and systolic dyssynchrony during stress (OR = 4.3, P = 0.038) were independent determinants for occurrence of HFNEF.

CONCLUSION

Dynamic dyssynchrony during stress and impaired myocardial longitudinal function reserve are characteristics of HFNEF.

Cardiac resynchronization therapy for low-flow, low-gradient aortic stenosis

Low-flow, low-gradient aortic stenosis is a heterogeneous entity that encompasses truly severe aortic stenosis as well as mild-to-moderate aortic stenosis in which aortic valve orifice area is severely reduced primarily due to left ventricular (LV) contractile dysfunction. Under such circumstances the capacity of the LV to generate stroke-work is severely compromised. In this case report, we describe a patient with severe LV dysfunction and ventricular dyssynchrony due to right ventricular pacing who presented with decompensated heart failure in the setting of low-flow, low-gradient aortic stenosis. We discuss the management of this high-operative-risk patient, who ultimately underwent upgrading of his dual chamber pacemaker to a biventricular pacemaker with significant echocardiographic, haemodynamic, and clinical improvement.