P798 Right atrial phasic function and correlation with right ventricular function in patients with reduced left ventricular ejection fraction and no pulmonary hypertension:insights from 3D echocardiography

Background

The right atrium (RA) is a highly dynamic chamber with 3 mechanical functions (reservoir, conduit, booster pump) and prognostic implications in heart failure (HF) and pulmonary hypertension (PH). However, RA function and its interplay with the right ventricular (RV) performance in patients (pts) with reduced left ventricular ejection fraction (LVEF) and without PH remain to be clarified.

Methods

We used three-dimensional echocardiography to study 55 pts (61 ± 14 years, 43 men) with LVEF < 40% no more than mild tricuspid regurgitation (TR), and maximum velocity of the TR jet < 3 m/s. We measured the three-dimensional RA total, passive, active ejection volumes (EV) and the respective emptying fractions (EF). In addition, we compared RV volumes and ejection fraction (RVEF) between patients with normal and abnormal RA function.

Results

Mean LVEF was 30 ± 7%. Mean echo-derived pulmonary vascular resistance was 1.64 ± 0.54 Wood units. 28 pts (51%) had reduced RA reservoir function (total EF = 34 ± 9%), 34 pts (62%) had reduced RA conduit function (passive EF = 15 ± 4%), and 10 pts (18%) had reduced RA pump function (active EF = 11 ± 3%). Pts with reduced RA reservoir function showed larger RV end-systolic volume (RVESV 124 ± 48ml vs. 90 ± 32ml; p = 0.004) and lower RVEF (38 ± 8% vs. 46 ± 6%; p < 0.001) than pts with normal RA function. Pts with reduced RA conduit function showed smaller RV stroke volume (RVSV 65 ± 19 ml vs. 80 ± 22ml; p = 0.009). Pts with impaired RA pump function showed larger RVESV (142 ± 45ml vs. 99 ± 41ml; p = 0.02) and lower RVEF (36 ± 6% vs. 43 ± 8%; p = 0.006).

RVESV was positively correlated with total (r2 = 0.47, p < 0.001), passive (r2 = 0.29, p = 0.03) and active (r2 = 0.39, p = 0.003) RAEV, while it was negatively correlated with total (r2=-0.41, p = 0.002), passive (r2=-0.34, p = 0.01) and active (r2=-0.31, p = 0.02) RAEF. RVSV showed a positive correlation with both total (r2 = 0.4, p = 0.002) and passive (r2 = 0.41, p = 0.002) RAEV. Finally, RVEF was positively correlated with total (r2 = 0.51, p < 0.001), passive (r2 = 0.47, p < 0.001), and active (r2 = 0.36, p = 0.007) RAEF.

Conclusions

RA dysfunction is not uncommon in pts with reduced LVEF, even in the absence of PH. In these pts, RA function is associated with significant changes in RV function. The RA acts as a dynamic modulator of RV pump function by redistributing RV filling and ejection force among reservoir, conduit and pump functions in the setting of altered hemodynamics. The clinical and prognostic significance of RA function in pts with reduced LVEF warrant further studies.

P669 Functional remodeling of the left atrium after first acute ST-elevation myocardial infarction: a 3D echocardiography study

Background

Left atrium (LA) is a dynamic structure which is functionally coupled with the left ventricle and modulates its function in many cardiac conditions. The geometric and functional remodeling of the LA occurring early after myocardial infarction are poorly understood.

Purpose

We sought to evaluate the early changes in LA geometry and function occurring in survivors of a first acute ST-elevation myocardial infarction (STEMI), using three-dimensional echocardiography (3DE).

Methods

LA phasic volumes and strain (both longitudinal and circumferential) were measured using a dedicated automated software package in 54 patients at pre-discharge after STEMI, and in 54 age- and sex-matched healthy volunteers (controls), (figure 1).

Results

In STEMI patients, both maximal (LAV max) and minimal (LAV min) LA volumes were significantly larger than in controls 63 ± 15 vs. 53 ±11 ml; p = 0,002 and 38 ± 15 ml vs. 25 ± 6; p <0.0001 (respectively). Moreover, when compared to controls (Table 1). Both longitudinal (LASr) and circumferential strain reservoirs showed a significant negative correlation with peak cardiac troponin I values (r=-0.344; p = 0.007 and r=-0.357; p = 0.005, respectively) as an estimate of the extent of myocardial damage.

Conclusion

STEMI was associated to significant geometrical and functional remodeling of the LA which was correlated with the extent of myocardial damage.

Table 1 Controls STEMI patients P-value Longitudinal% LASr 21.8 ± 8.4 13.72 ± 8.27 <0.0001 LAScd -12.8 ± 8.48 -6.43 ± 4.74 <0.0001 LASct -9.73 ± 6.04 -7.26 ± 5.87 0.05 Circumferential % LASr-c 27.31 ± 8.07 18.92 ± 9.16 <0.0001 LAScd-c -11.2 ± 5.93 -6.46 ± 5.68 0.0002 LASct-c -16.22 ± 6.33 -12.41 ± 5.94 0.004 LASr longitudinal strain reservoir, LAScd: longitudinal strain conduit, LAScd: longitudinal strain contraction, LASr-c: circumferential strain reservoir, LAScd-c: circumferential strain conduit , LASct-c:circumferential strain contraction

Abstract P669 Figure 1