Discussion
To the best of our knowledge, this study may be the first to
comprehensively assess RV function in patients with non-acute coronary
syndrome angina undergoing PCI using 3D-STE. The findings of this study
revealed impaired RV function in this patient population, which showed
improvement within 12 months post-PCI. Specifically, parameters
including TAPSE, S’, RVFAC, RVFWLS, RVGLS, RVSV and RVEF increased from
1 week to 6 months post-PCI. From 6 to 12 months post-PCI, RVFAC, RVGLS,
RVSV, and RVEF remained stable, while TAPSE, S’, and RVFWLS continued to
increase significantly. However, at 12 months post-PCI, s’, RVFAC,
RVFWLS, RVGLS, and RVEF were lower compared to the healthy control group
(P < 0.05). Subgroup analysis based on LVEF
demonstrated significant improvement in RV function in both groups;
however, patients with LVEF ≤ 50% exhibited lower RVFWLS at 12 months
post-PCI compared to those with LVEF > 50% (P < 0.05).
TAPSE and S’ are commonly utilized to assess RV longitudinal systolic
function. Modin et al. [11] demonstrated that a
decrease in TAPSE signifies impaired RV systolic function, and this
parameter decline is associated with the occurrence of coronary heart
disease in the general population. Previous
studies[12] have also shown that TAPSE decreases
in patients with acute myocardial infarction or chronic ischemic
coronary artery disease, with improvement observed post-PCI. Consistent
with prior research, our study found sustained improvement in RV
longitudinal systolic function within one year post-PCI in patients with
non-acute coronary syndrome angina.
RVFAC and RVEF are commonly used to evaluate overall RV systolic
function. Our study revealed an increase in RVFAC and RVEF from 1 week
to 6 months post-PCI (P < 0.05); however, there was no
significant change from 6 to 12 months post-PCI (P >
0.05). This suggests a relatively rapid recovery of overall right
ventricular systolic function in patients with non-acute coronary
syndrome angina post-PCI. In conditions of reduced myocardial blood flow
in the coronary arteries, the right ventricle may exhibit systolic
dysfunction, a phenomenon referred to as ”hibernating,” which is induced
by chronic low perfusion [13]. Following PCI,
restoration of ischemic coronary artery blood supply, regardless of the
obstructed coronary artery branch, leads to improvement in RV overall
systolic function due to collateral circulation influence.
RV possesses unique anatomical and physiological characteristics, and
conventional echocardiographic parameters may not suffice for
comprehensive analysis of its structure and function. Chronic myocardial
ischemia may lead only to local myocardial hibernation without
necessarily causing overall ventricular dysfunction. Such subclinical,
localized functional impairments can be observed through strain analysis
using 3D-STE. Previous studies have found decreased RVFWLS in patients
with non-acute coronary syndrome angina, suggesting that even mild
coronary artery ischemia can result in reduced right ventricular strain[14]. In this study, RV strain exhibited a
stronger capability in detecting RV systolic dysfunction in patients
with non-acute coronary syndrome angina compared to other conventional
echocardiographic parameters, indicating its sensitivity in capturing
right ventricular functional impairment. Improvement in RV strain
parameters was observed one year post-PCI, consistent with prior
research. Blessing et al. [15] found reduced RV
function in patients with chronic total occlusion of the right coronary
artery, which significantly improved following successful
revascularization of the right coronary artery. At 12 months post-PCI,
RVGLS showed no significant difference from that of healthy individuals,
but RVFWLS remained lower than RVGLS in the healthy control group. RVGLS
reflects strain in the interventricular septum and may be influenced by
left ventricular systolic function, while RVFWLS, representing local
strain of the right ventricular free wall, is less affected by left
ventricular influence.
Right ventricular function may be influenced by the left ventricle, as a
decrease in LVEF can affect right ventricular systolic function[16]. Therefore, we conducted subgroup analysis
based on LVEF, revealing significant improvement in both groups of RV
function parameters. Compared to patients with LVEF > 50%,
those with LVEF ≤ 50% exhibited lower RVFWLS at 12 months post-PCI
(19.1±3.696% vs. 20.66±2.659%, P = 0.009). Our study suggests
that irrespective of left ventricular function impairment, restoration
of blood supply to diseased vessels leads to a certain degree of
improvement in RV function. In a previous
study[17], patients with acute myocardial
infarction exhibited subclinical right ventricular dysfunction
regardless of infarction location (anterior or inferior wall), but these
patients had impaired left ventricular systolic function at baseline,
which may have influenced the observation of right ventricular function.
In contrast, our focus was on patients with non-acute coronary syndrome
angina and relatively preserved left ventricular systolic function. The
results indicate that although the right ventricle has thinner
myocardium and richer collateral circulation, it is still affected by
chronic ischemia. RVFWLS can more accurately assess subclinical RV
functional impairment in these patients following PCI treatment.
In this study, measurement of RVFWLS using 3D-STE appears to provide
more information regarding right ventricular function improvement. RV
strain measurement may have advantages over traditional
echocardiographic parameters in detecting subtle myocardial functional
impairments, which is consistent with previous studies[18-20]. While CMR remains the gold standard for
non-invasive assessment of RV size and function, it is time-consuming,
costly, and not widely available. Previous research has also shown a
high level of agreement between ultrasound and CMR in detecting
myocardial strain [21]. Therefore, RV strain, as a
non-invasive parameter for quantifying RV systolic function, may play a
crucial role in evaluating RV function in patients with non-acute
coronary syndrome angina after PCI, facilitating comprehensive
assessment of RV function in routine clinical practice.