Beyond the Ejection Fraction: Multimodality Assessment of Left Ventricular Function in Coronary Artery Disease

TECHNICAL CONSIDERATIONS

These three echocardiographic approaches differ considerably in their execution requirements. The modified Simpson’s method necessitates clear visualization of endocardial borders in multiple views, is relatively time-intensive (2–3 min), and depends heavily on operator expertise. MAPSE measurement is technically straightforward, requiring only an M-mode through the lateral mitral annulus, can be performed in under 30 s, and has excellent reproducibility even among less experienced operators. GLS measurement requires specialized speckle-tracking software, takes 1–2 min, and demands moderate operator expertise. Importantly, both MAPSE and GLS can be obtained in patients with challenging acoustic windows where Simpson’s method may be impossible.

MAPSE is believed to be a better marker of myocardial energy kinetics instead of the current utility as a surrogate to ejection fraction (EF) in assessing left ventricular (LV) function. A recent review article proposed MAPSE as a straightforward and reliable echocardiographic parameter for assessing LV longitudinal function, highlighting its clinical utility in various cardiovascular conditions, its correlation with other cardiac function measures, and its prognostic value despite the adoption of more advanced imaging techniques.^[1] Artificial intelligence-based MAPSE estimation is proposed to guide clinical decisions in critical care echocardiography.^[2]

STUDY FINDINGS AND IMPLICATIONS

Baig et al. designed a methodologically sound study involving 300 participants: 100 patients with CAD and LVEF <50%, 100 with CAD and LVEF >50%, and 100 healthy controls.^[1] Their most striking finding was the concordance between all three methods in healthy controls and CAD patients with reduced LVEF (<50%). However, in patients with preserved LVEF (>50%) and CAD, significant discrepancies emerged between the modified Simpson’s method and both MAPSE and GLS, while MAPSE and GLS showed good correlation with each other.^[3]

These observations raise important questions about ventricular dysfunction in CAD patients with preserved LVEF. Do MAPSE and GLS detect subtle impairments in longitudinal function missed by the modified Simpson’s method? Could these measures identify a subset of patients with “preserved ejection fraction” who have meaningful cardiac dysfunction requiring closer monitoring?

EVIDENCE FROM ECHOCARDIOGRAPHIC STUDIES

A growing body of evidence supports the value of GLS and MAPSE in CAD patients with preserved LVEF. GLS detected subclinical LV dysfunction in CAD patients with preserved LVEF and was independently associated with adverse outcomes.^[1] Furthermore, layer-specific strain analysis could identify significant coronary disease despite normal LVEF values, with endocardial GLS being particularly sensitive.^[4] A GLS cutoff value of −17.4% had good sensitivity and specificity for predicting obstructive CAD in patients with normal LVEF.^[5]

MAPSE was significantly reduced in patients with CAD and preserved LVEF compared to controls and correlated with exercise capacity better than LVEF. MAPSE reduction correlated with CAD severity and provided independent prognostic information in CAD patients with preserved LVEF.^[6]

Direct comparison studies found that both GLS and MAPSE detected subclinical dysfunction in other disorders such as diastolic dysfunction and anthracycline cardiotoxicity apart from CAD. In all these subsets of patients, GLS showed a stronger correlation with disease severity and outcomes.^[7,8] This growing evidence base suggests that the findings by Baig et al. are consistent with a broader understanding that traditional LVEF assessment may miss important subclinical dysfunction in CAD patients.^[1]

INSIGHTS FROM ADVANCED IMAGING MODALITIES

Beyond echocardiography, other imaging modalities confirm the presence of subclinical dysfunction in CAD patients with preserved LVEF. Cardiac magnetic resonance imaging (MRI) studies have provided particularly compelling evidence. Cardiac MRI strain analysis demonstrated reduced myocardial strain values in CAD patients with preserved LVEF, with strain abnormalities correlating with perfusion defects.^[9] Late gadolinium enhancement could detect subclinical myocardial damage and was associated with a worse prognosis even when LVEF remained normal.^[10] Feature tracking MRI-derived GLS was reduced in CAD patients with preserved LVEF and correlated with the extent of myocardial fibrosis.^[11]

Multimodality comparative studies further strengthen this evidence. A high correlation between echocardiographic GLS and cardiac MRI feature tracking strain, with both identifying abnormalities in regions with perfusion defects on single photon emission computed tomography (SPECT).^[12] Furthermore, reduced longitudinal function measured by either echo GLS or MRI feature tracking occurred earlier than reductions in myocardial perfusion reserve on positron emission tomography.^[13] This consistent evidence across multiple imaging modalities reinforces the clinical significance of the findings by Baig et al. and suggests that subclinical longitudinal dysfunction in CAD patients with preserved LVEF is a real phenomenon with important clinical implications.^[1]

CLINICAL IMPLICATIONS

The findings of this study, supported by broader literature, have several implications for practice.

First, they validate MAPSE as a simple surrogate for LVEF assessment in healthy individuals and those with clearly reduced LVEF – particularly valuable when image quality is suboptimal or rapid assessment is needed.

Second, the discordance between methods in CAD patients with preserved LVEF suggests that a multi-parametric approach might provide more comprehensive evaluation in this population. Rather than relying solely on LVEF, integrating MAPSE and GLS could enhance the detection of subtle dysfunction and improve risk stratification.

Third, these findings highlight the importance of considering ventricular function beyond EF. Longitudinal function, as assessed by MAPSE and GLS, may be preferentially affected in CAD, potentially preceding global systolic dysfunction. This is consistent with the anatomical arrangement of myocardial fibers, where subendocardial longitudinal fibers are most vulnerable to ischemia.

FUTURE DIRECTIONS

Future research should address several important questions. Longitudinal studies are needed to evaluate the prognostic significance of discordance between these measurements. Investigation of how these parameters correlate with functional capacity, biomarkers, and long-term outcomes would further enhance their clinical utility. In addition, integration of artificial intelligence and machine learning approaches might improve the accuracy and reproducibility of these measurements.

Most importantly, interventional studies are needed to determine whether targeting therapy based on subclinical dysfunction detected by MAPSE or GLS in CAD patients with preserved LVEF improves outcomes. This would move these parameters from diagnostic tools to therapeutic guides.

CONCLUSION

The study by supported evidence from multiple imaging modalities, represents an important contribution to our understanding of LV function assessment in CAD. Their findings suggest that while the modified Simpson’s method remains valuable, complementary approaches such as MAPSE and GLS provide additional insights, particularly in CAD patients with preserved LVEF. A more holistic approach to ventricular function assessment incorporating multiple parameters may enhance our ability to detect subtle dysfunction, guide therapy, and improve outcomes.