Rotational mechanics of the left ventricle (LV) play an important role in the function of the LV [1, 2, 3, 4, 5]. The LV base rotates in a clockwise direction, while the apex of the LV moves in a counterclockwise direction during systole resulting in their net difference called LV twist. The physiology of this movement is based on the subepicardial and subendocardial muscle fibers running perpendicular to each other, their contraction creates a characteristic form of LV motion responsible for up to 40% of the ejection [1, 2, 3, 4, 5]. Although its physiological importance is known, several studies have been conducted recently analyzing its clinical significance even under healthy circumstances. In addition, further investigations are required to confirm its prognostic value. Three-dimensional (3D) speckle-tracking echocardiography (STE) seems to be an optimal method to determine its significance in real clinical settings due to its non-invasive and easy-to-perform nature [6, 7, 8, 9]. Therefore, the aim of the present study was to examine the prognostic significance of 3D-STE-derived LV twist in healthy adults.

LV contractility represented by LV strains and LV rotational mechanics play a fundamental role in LV function [11, 12, 13, 14, 15]. In systole, the LV shortens in a longitudinal direction represented by LV longitudinal strain (LS), narrows in a circumferential direction represented by LV circumferential strain and thickens in a radial direction represented by LV radial strain [16]. In addition, the rotational mechanics of the LV play a significant role in optimizing its pumping function as well. This is due to the special LV myocardial architecture: there are two perpendicular left- and right-handed muscle bands in the subepicardium and subendocardium of the LV. The torque of the subepicardial one is larger, so its effect prevails. Accordingly, although the shortening of the LV muscle fibers during the heart cycle is about 15–20%, the LV ejection fraction (EF) is normally 60–65% [3].

Clinically, the prognostic impact of echocardiography-derived LV-EF and LV-GLS is well-documented, but the predictive value of LV rotational mechanics needs further investigation [17, 18, 19]. For instance, increased LV twist was predictive of non-sustained ventricular tachycardia in hypertrophic cardiomyopathy patients [17]. In another study, LV twist was found to be a predictor of preserved LV function after surgery in severe mitral regurgitation [18]. The presence of LV torsion independently predicted peak oxygen uptake during exercise and its impairment proved to be predictive of a reduced functional capacity [19]. LV twist was found to be a predictor of mortality in aortic valve stenosis as well [20]. Although in several scientific works, 2D-STE was used for the detection and calculation of LV rotational parameters [21], according to recent recommendations, 2D-STE is not recommended for measuring LV apical and basal rotations [22]. 3D-STE combines the advantage of STE and 3D echocardiography allowing visualization of the LV as a heart chamber with 3D features for simultaneous assessment of volumes, strains and rotational parameters using the same 3D virtual LV cast respecting the cardiac cycle [6, 7, 8, 9]. 3D-STE is an easy-to-learn and easy-to-implement technique, which is validated for the determination of LV twist [23, 24, 25], and normal reference values are also available [26].

The prognostic value of 3D-STE-derived LV twist on survival is a less examined phenomenon [20]. According to the presented findings, it could be stated that increased LV twist, mostly due to elevated LV basal rotation, shows associations with increased risk of cardiovascular events in a healthy population during a 12-year follow-up period. In subjects with cardiovascular events, not only was the LV-GLS, a known prognostic factor, reduced, but LV twist proved to be increased due to elevated LV basal rotation. Moreover, two-thirds of the events were present in subjects with increased LV twist. It should be emphasized that these associations were present in an apparently healthy population. One might rightly ask what could explain this. As we know, it is the subepicardial layer in the LV that determines the direction of LV rotation. In cases of abnormalities like ischaemia affecting the subendocardium, LV overrotation is expected to be detected [3]. Accordingly, this overrotation, which can be determined by 3D-STE, has a strong prognostic value. Moreover, in correspondence with the previous findings, LV-GLS and age showed associations with LV rotational mechanics as well [27, 28]. These results should be assessed in the light of the fact that no significant abnormalities could be demonstrated with routine examinations in the healthy individuals. However, it cannot be excluded with certainty that there was no latent pathology that required hospitalization and/or care later during the long-term follow-up, as confirmed by the results (invasive care, death). Further investigations are warranted in a larger healthy population to confirm the presented findings.

The most important limitations are listed below:

- The image quality is still a significant limitation of 3D-STE, which may have had significant effects on the results obtained.

- Only the prognostic impact of LV twist was analyzed, the predictive role of other 3D-STE-derived parameters on survival was not examined.

- The concept of healthiness was pronounced based on the results of routine examinations in individuals who claimed to be complaint-free. During follow-ups, significant cardiovascular events occurred in 9% of the cases, which can mean that some of the subjects could have had latent diseases.

- When evaluating the obtained results, it should be taken into account that the study design was retrospective. In addition, clinical and echocardiographic data of a relatively small number of healthy individuals were analysed using a relatively new imaging technology.

3D-STE is suitable for non-invasive evaluation of LV rotational mechanics. In cases of cardiovascular events, LV twist was increased as a consequence of increased LV basal rotation, which can be explained by abnormalities such as subendocardial ischaemia leading to LV overrotation. Based on the results of a prolonged follow-up, it can be said that 3D-STE-derived LV twist independently predicts future cardiovascular events in healthy adults.

This author takes responsibility for all aspects of the reliability and freedom from bias of the data presented and their discussed interpretation.

AN—Conceptualization, Writing – original draft, DLO—Investigation, Data curation, AA—Investigation, ZR—Conceptualization, Investigation, Writing – review & editing, NA—Conceptualization, Writing – review & editing, ÁK—Methodology, Investigation, Data curation. CL—Conceptualization, Investigation, Writing – review & editing. All authors contributed to editorial changes in the manuscript. All authors read and approved the final manuscript. All authors have participated sufficiently in the work and agreed to be accountable for all aspects of the work.

Institutional and Regional Human Biomedical Research Committee of University of Szeged, Hungary approved the study under the registration number of 71/2011 (prolonged on February 20, 2023). The study was conducted in accordance with the Declaration of Helsinki (revised in 2013) and all participants gave informed consent.

Not applicable.

This research received no external funding.

The authors declare no conflict of interest. Attila Nemes is serving as one of the Editorial Board members of this journal. We declare that Attila Nemes had no involvement in the peer review of this article and has no access to information regarding its peer review. Full responsibility for the editorial process for this article was delegated to Massimo Iacoviello.