Hemodynamic basis of mitral E transmission in the left ventricular cavity and its relation to the left ventricular relaxation process

Myocardial contractile reserve on dobutamine echocardiography predicts late spontaneous improvement in cardiac function in patients with recent onset idiopathic dilated cardiomyopathy

OBJECTIVES

The purpose of this study was to determine whether identification of contractile reserve with dobutamine would predict recovery of myocardial function during follow-up in patients with recent onset idiopathic dilated cardiomyopathy (IDC).

BACKGROUND

The prognosis of patients presenting with new onset IDC is variable and difficult to predict.

METHODS

Twenty-two patients (17 men, 5 women, 46 +/- 14 years) with recently diagnosed IDC (4 +/- 3 months) underwent dobutamine echocardiography. Left ventricular ejection fraction (LVEF) and LV sphericity before and at peak dobutamine infusion (30 +/- 11 microg/kg/min) were determined. A follow-up echocardiographic assessment was done at 6 +/- 4 months.

RESULTS

The LVEF on dobutamine was directly related to baseline LV mass expressed as g/ml (Pearson r = 0.65, p = 0.0003). Baseline variables that were significantly predictive of follow-up LVEF were deceleration time (r = 0.69, p = 0.0006), wall motion score index (WMSI) (r = -0.63, p = 0.002), LV mass (r = 0.56, p = 0.008) and LVEF on dobutamine (r = 0.84, p = 0.0001). When either deceleration time or WMSI or LV mass was entered into a regression equation to predict follow-up LVEF, the LVEF on dobutamine added significantly to predictive power. However, if LVEF on dobutamine was entered first, none of the other three variables added significantly to prediction. Baseline LV sphericity at end diastole (ED) (r = 0.13, p = 0.6) did not correlate with follow-up LV sphericity in ED, whereas LV sphericity in ED on dobutamine (ED [r = 0.70, p = 0.0004]) correlated with LV sphericity in ED on follow up.

CONCLUSIONS

This study demonstrates that dobutamine-induced improvement in baseline LVEF and LV sphericity identifies patients with IDC who exhibit substantial improvement in LV function and geometry over time.

An integrated measure of left ventricular diastolic function based on relative rates of mitral E and A wave propagation

BACKGROUND AND OBJECTIVES

The mitral E wave propagation inside the left ventricle is slowed in patients with abnormal left ventricular (LV) relaxation with a prolongation of its transit time to the LV outflow tract (T(e)). On the contrary, the mitral A wave propagation is faster in those with elevated LV end-diastolic stiffness, resulting in a shortening of its transit time (T(a)). We hypothesized that the T(e)/T(a) ratio may serve an integrated measure of global LV diastolic function.

METHODS AND RESULTS

The T(e)/T(a) ratio was measured with Doppler echocardiography in 94 subjects: 25 normal subjects, 38 patients with LV hypertrophy (18 with secondary LV hypertrophy and 20 with hypertrophic cardiomyopathy), and 31 patients undergoing left heart catheterization for clinical indications. The T(e)/T(a) ratio was 1. 98 +/- 0.61 in the normal subjects, 3.32 +/- 0.93 in patients with secondary LV hypertrophy (P <.0001 vs normal), and 3.18 +/- 1.36 in patients with hypertrophic cardiomyopathy (P =.0003 vs normal). In the invasive group the T(e)/T(a) ratio (range 0.56 to 3.60) correlated significantly with Tau (r = 0.76, P <.0001), peak negative dP/dt (r = -0.46, P =.01), the LV late diastolic stiffness index (r = 0.57, P =.0013), LV pre-A wave pressure (r = 0.46, P =. 0096), LV end-diastolic pressure (r = 0.58, P =.0007), and the amount of LV pressure rise with atrial systole (r = 0.52, P =.0032) but not with the heart rate. Tau and LV stiffness were its sole determinants by stepwise multiple regression (R = 0.82).

CONCLUSIONS

The ratio of mitral E and A wave transit times inside the LV (T(e)/T(a) ratio) is closely related to LV relaxation, its late diastolic stiffness, and filling pressures and gives valuable insights into LV diastolic performance.