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.