Evaluation of mitral annular plane systolic excursion derived ejection fraction to determine left ventricular systolic function

Master of Health Sciences in Clinical Technology (Cardiology) (M_HSCT)

Introduction Left ventricular ejection fraction (LVEF) is an essential measurement in echocardiography used to diagnose, treat, and manage patients. Two dimensional (2D) echocardiography is the most common imaging modality used to determine LVEF. Mitral annular plane systolic excursion (MAPSE) is considered a useful surrogate of 2D longitudinal function and can be converted to an ejection fraction through the formula MAPSE EF = (4.8 x MAPSE) + 5.8. MAPSE EF has been proven to be a valid method to determine ejection fraction in adult males with impaired LV systolic function. Currently, no research has been conducted to determine if this equation could be used in the daily setting. Therefore, the aim of the study was to evaluate mitral annular plane systolic excursion formula for determining ejection fraction in daily practice. MethodsThis prospective descriptive-analytical study was conducted in central South Africa, including 475 male or female adult participants aged 18 and above. Ethical approval (Appendix A) and informed consent (Appendix C) were obtained, and participants were provided with an information guide (Appendix D). The patients were further subdivided according to their primary clinical condition: systemic hypertension, diabetes mellitus type 2, congestive cardiac failure, and ischemic heart disease. Systolic parameters were measured by transthoracic echocardiography. MAPSE was measured and converted to MAPSE EF and correlated with Teichholz EF, modified Simpson’s apical four chamber (AP4CH) and apical two chamber (AP2CH) EF, global longitudinal strain-derived EF, systolic (S’) tissue Doppler imaging of the medial and lateral mitral valve annuli, and LV myocardial performance index (MPI). A correlation value of ≥0.70 was considered a strong clinical correlation. Participants were excluded if they had had aortic-and/or mitral valve replacement surgeries, had mitral valve annular dysfunction, pericardial diseases, tachyarrhythmias, malignant- or uncontrolled hypertension, new or uncontrolled diabetes mellitus type 2, acute ischemic events, or inadequate imaging views. Results Patients presented at a mean age of 61±14.9 years with no gender dominance. Most of the patients were from the Bethlehem region, since the private practice where the study was conducted is situated in Bethlehem (Appendix E). Futhermore,70% of the patients had mild symptoms and were in New York Heart Association (NYHA) class 1 and 2 at presentation (Appendix F). Normal to mildly impaired systolic measurements were noted in the total population with a mean EF:50.2±0.3% (Appendix G). A noteworthy impairment of all systolic parameters was present in the congestive cardiac failure (CCF) group (EF < 30%). Normal to mild impairment was noted in the ischemic group, while normal systolic parameters were found in the hypertension and diabetes mellitus groups. Correlation coefficients for the total study group are illustrated in Appendix H1. Overall, a strong positive correlation was observed between MAPSE EF and all the other systolic parameters (r:>0.82), while LV MPI had a strong negative correlation with MAPSE EF (r:-0.74). MAPSE EF also correlated strongly with the systolic parameters in both genders (r: >±0.73) (Appendix H2 and H3). MAPSE EF and the systolic parameters correlated the best (r:>0.80) in the congestive cardiac failure group. Similarly, in both genders, a strong close correlation was noted between MAPSE EF and the systolic parameters (r:>±0.70), with only LV MPI in the female group, which had low clinical correlation (r:-0.65) (Appendix H4 and H5). In the diabetes mellitus type 2, hypertension, and ischemic heart disease groups, no clinical correlation was noted between MAPSE EF and the systolic parameters. However, a low correlation (r:<0.62) was noted between MAPSE EF and S’ in the hypertension group, and S’ was the only systolic parameter which had a strong, positive correlation (r:>0.74) with MAPSE EF in the ischemic heart disease group. Patients with grade one diastolic dysfunction also demonstrated poor correlations between MAPSE EF and all the systolic parameters (Appendix H6). This improved in grade two diastolic dysfunction (Appendix H7), while patients with grade three diastolic dysfunction had an excellent correlation (r:>±0.84) between MAPSE EF and the other systolic parameters (Appendix H8). Strain-derived EF had a strong, positive correlation (r:>0.81) with modified Simpson’s AP4CH EF in the total population, as well as in all the subgroups (Appendix H9). Strong, negative correlation (r:>-0.76) was observed between LV MPI and Simpson’s AP4CH EF in the total population, while low to weak clinical correlation between these two systolic variables was noted in the subgroups (Appendix H10). Discussion Our patients presented at a mean age of 61±14.9 years with normal or minimally impaired systolic echocardiographic parameters. However, in patients with congestive cardiac failure, echocardiographic parameters were exclusively impaired. Although strong correlations were noted in the total population, subgroup analyses demonstrated several differences between MAPSE EF, and the other methods used to determine systolic LV function. In the congestive cardiac failure group, MAPSE EF correlated superbly with all the systolic parameters, irrespective of gender. It should be noted that this is the first time that MAPSE EF in both genders with CCF was determined. In the hypertension, diabetes mellitus, and ischemic heart disease groups, less favourable correlations were observed between MAPSE EF and the other systolic parameters. MAPSE EF correlated moderately only with S’ in the hypertension group, and strongly in the ischemic heart disease group. We predict that basal segment function was most likely preserved in our patient population study since MAPSE and S' were normal, although left ventriculography was not obtained. Conclusion Results demonstrated that MAPSE EF is a valid method to determine ejection fraction in patients with significantly impaired systolic function, irrespective of gender.

Promoter: Ms J Mofokeng (M. HS Clinical Technology-Cardiology) Co-promoter: Prof. SC Brown (D. Med, M. Med FCP, DCH, UFS)