Myocardial Work Analysis Research Articles

Non-invasive myocardial work: an echocardiographic measure of post-infarct scar on contrast-enhanced cardiac magnetic resonance imaging

Abstract Background Late gadolinium contrast enhanced cardiac magnetic resonance (LGE CMR) imaging accurately quantifies the extent of fibrosis and transmurality in chronically infarcted left ventricular (LV) segments, and identifies viability. Moreover, CMR characterizes the remote, non-infarcted zone, which is an emerging region of interest following ST-segment elevation myocardial infarction (STEMI). Non-invasive myocardial work is a novel LV function parameter - calculated from speckle-tracking strain echocardiography and sphygmomanometrically-determined blood pressure, which has shown excellent correlation with invasively measured myocardial work. Purpose To explore the relation of non-invasively estimated parameters of LV myocardial work to post-infarct scar on LGE CMR, and to compare myocardial work indices between the infarct core and remote zone in STEMI patients who were treated with primary percutaneous coronary intervention (PCI). Methods Patients with a STEMI who underwent primary PCI and LGE CMR, in addition to echocardiographic studies where non-invasive myocardial work analysis was feasible, were included. The LV was subdivided into non-infarcted, non-transmural and transmurally infarcted segments. The remote zone was defined as the non-infarcted myocardial segment diametrically opposed to the infarct core, without any evidence of LGE. Myocardial work indices were compared with linear mixed models, ANOVA and Wilcoxon signed rank tests. Results 53 patients (89% male, age 58±9 years) and 689 segments were analysed. The mean scar burden comprised 14±7% of the total LV mass and 76 (11%) segments showed transmural LGE. The following non-invasive myocardial work indices: myocardial work index (MWI), constructive work (CW) and myocardial work efficiency (MWE) showed a significant inverse relationship with infarct transmurality (p<0.05 for all comparisons) while a positive trend was observed for wasted work (WW) (p=0.086) (Figure 1). The core zone demonstrated lesser MWI (1237±568 vs. 1514±518 mmHg%; p=0.010), CW (1331±627 vs. 1827±537 mmHg%; p<0.001) and MWE (92 (84–98) vs. 98 (95–99) %; p<0.001) as well as greater WW when compared to the remote zone (107 (26–196) vs. 26 (10–90) mmHg%; p=0.001). Conclusions In STEMI patients who underwent primary PCI, MWI, CW and MWE were significantly related to the extent of transmural infarction, while WW demonstrated a trend. MWI, CW and MWE were significantly lower, and WW higher, in the core zone compared to the remote zone. Non-invasive myocardial work indices may provide an echocardiographic method for determining post-infarct viability, as well as characterization of the remote zone. MW and scar transmurality on LGE CMR Funding Acknowledgement Type of funding source: None

Myocardial work - correlation patterns and reference values from the population-based STAAB cohort study.

BackgroundRecently, myocardial work analysis as an echocardiographic tool to non-invasively determine LV work has been introduced and validated against invasive measurements. Based on systolic blood pressure and speckle-tracking derived longitudinal strain (GLS) during systole and isovolumic relaxation, it is considered less load-dependent than LV ejection fraction (LVEF) or GLS and to integrate information on LV active systolic and diastolic work.ObjectivesWe aimed to establish reference values for global constructive (GCW) and global wasted work (GWW) as well as of global work index (GWI) and global work efficiency (GWE) across a wide age range and to assess the association with standard echocardiography parameters to estimate the potential additional information provided by myocardial work (MyW).MethodsThe Characteristics and Course of Heart Failure STAges A/B and Determinants of Progression (STAAB) cohort study carefully characterized a representative sample of the population of the City of Würzburg, Germany, aged 30–79 years. We performed myocardial work analysis using the standardized, quality-controlled transthoracic echocardiograms of all individuals lacking any cardiovascular risk factor.ResultsOut of 4965 participants, 779 (49±10 years, 59% women) were eligible for the present analysis. Levels of GCW, GWW, and GWE were independent of sex and body mass index, and were stable until the age of 45 years. Thereafter, we observed an upward shift to further stable values of GCW and a linear increase of GWW with advancing age, resulting in lower GWE. Age-adjusted percentiles for GCW, GWW, GWI, and GWE were derived. Higher levels of blood pressure or LV mass were associated with higher GCW, GWI, and GWW, resulting in lower GWE; higher LVEF correlated with higher GCW and GWI, but lower GWW. Higher E/e´ correlated with higher GWW, higher e´ with lower GWW.ConclusionsDerived from a large sample of apparently healthy individuals from a population based-cohort, we provide age-adjusted reference values for myocardial work indices, applicable for either sex. Weak correlations with common echocardiographic parameters suggest MyW indices to potentially provide additional information, which has to be evaluated in diseased patient cohorts.

P1537 Myocardial work in patients with aortic stenosis before and short term after transcatheter aortic valve replacement

Abstract Objective The newly introduced noninvasive myocardial work analysis could potentially be beneficial in predicting the best timing for aortic valve replacement as well as clinical outcomes in patients with high grade aortic valve stenosis (AS), which is the leading valvular disease in the modern aging society. However, to date there is little data on the applicability of the method in the setting of extremely increased left ventricular (LV) afterload. Purpose In this pilot study, we aimed to apply myocardial work analysis in patients with increased LV afterload due to severe AS and to investigate the differences of myocardial work parameters in patients with different AS entities. In addition, we analyzed the early changes of myocardial work after the afterload reduction by transcatheter aortic valve replacement (TAVR). Methods We retrospectively studied echocardiographic data of 28 consecutive patients with severe AS before and 7 days after TAVR. Global Work Index (GWI), Global Constructive Work (GCW), Global Wasted Work (GWW) and Global Work Efficiency (GWE) were calculated using commercially available software based on noninvasive pressure-strain loops. In order to correct for underestimation of intraventricular pressure, we added the mean aortic valve pressure gradient to the peripheral systolic blood pressure used by the software. Results From the included patients (mean age 76 ± 10 years) 13 were classified as having normal flow (NF) severe AS, 8 had low flow low gradient (LFLG) and 7 paradoxical low flow low gradient (PLFLG) AS. GWI and GCW were significantly lower in patients with LFLG AS compared to patients with NF or PLFLG AS (936 ± 528 mmHg% vs. 2493 ± 485 mmHg% vs. 1959 ± 469 mmHg% [p < 0.005] and 1132 ± 477 mmHg% vs. 2770 ± 507 mmHg% vs. 2189 ± 603 mmHg%, [p < 0.005], respectively). 7 days after TAVR, GCW and GWI decreased significantly in patients with NF AS. In other AS entities, a trend towards increased GWI and GCW was observed, but the difference did not reach statistical significance. GWI and GCW remained significantly lower in LFLG AS group when compared to NF and PLFLG groups (1069 ± 378 mmHg% vs. 1919 ± 310 mmHg% vs. 2064 ± 842 mmHg% [p < 0.005] and 1286 ± 346 mmHg% vs. 2107 ± 258 mmHg% vs. 2227 ± 949 mmHg% [p < 0.005]) early after TAVR. GWE and GWW did not differ between the groups and were not influenced by TAVR. Conclusion In this pilot study we applied the adapted myocardial work analysis in patients with increased afterload due to severe AS. We have shown that GCW and GWI are significantly higher in patients with NF AS when compared to LFLG and PLFLG AS. The differences between the groups persisted early after TAVR in spite of significant reduction of GWI and GWC in patients with NF AS. The clinical and prognostic importance of these findings are still to be investigated in a bigger cohort study.

P1513 Myocardial work analysis is a potential novel tool to diagnose subclinical cardiac dysfunction in cirrhotic cardiomyopathy

Abstract Funding Acknowledgements This work was supported by a grant of Ministery of Research and Innovation, CNCS-UEFISCDI, project number PN-III-P1-1-TE-2016-0669, within PNCDI III Background Cirrhotic cardiomyopathy (CCM) is defined as systolic and/or diastolic cardiac dysfunction, associated with high preload and low afterload. Thus, assessment of cardiac dysfunction in these circumstances is still debatable. Left ventricular (LV) deformation is still load-dependent, and does not reflect directly myocardial energy consumption. Since myocardial work (MW)incorporates both deformation and afterload, it might be a better alternative for the assessment of LV function in CCM. Methods 80 subjects were assessed by 2D conventional and speckle tracking echocardiography (STE): 40 patients with liver cirrhosis (LC) (58 ± 8 years, 23 males), free of any cardiovascular disease or diabetes, and 40 age and gender matched normal, control subjects. Left ventricular ejection fraction (LVEF) and systolic/diastolic blood pressure (SBP/DBP) were measured. A new approach was used to evaluate myocardial work by 2DSTE: global constructive work (GCW), as the "positive" work of the heart; global wasted work (GWW), as the "negative" work of the heart; global work efficiency (GWE), as the GCW/(GCW + GWW) in %; and global work index (GWI), as the GCW added to GWW. E/E’ ratio, left atrial volume index (LAVi), and systolic pulmonary arterial pressure (sPAP) were also assessed. Results Patients with LC had significantly lower SBP/DBP than controls, with similar LVEF (Table). GCW and GWI were decreased in patients with LC, probably due to decrease in afterload, which shifts LV work to a lower level of energy. GWE and GWW were similar to controls. By segmental analysis (18 segments model), apical and mid antero-lateral segments were the first affected in terms of myocardial work, with higher WW, low WE, but without a compensatory increase in CW in other segments, suggesting a regional myocardial dysfunction. All patients with LC presented significantly elevated E/E’ ratio, LAVi, and sPAP, compared to controls (Table). Conclusion Myocardial global constructive work and global work index decrease in LC patients, compared to normal individuals, probably due to augmented peripheral vasodilatation. Apical and mid antero-lateral segments are the first affected. Assessment of global and regional MW might be a potential new tool to assess CCM, and to understand the relationship between LV remodeling and increased filling pressure under different loading conditions. Comparative myocardial work indices group SBP (mmHg) DBP LVEF (%) E/E’ LAVI sPAP GWI GWE (% ) GCW (mmHg % ) GWW (mmHg %) LC (40) 111 ±14 69 ± 12 59 ± 7 8.5 ± 2.5 45.9 ± 14.5 26 ± 9 1927 ± 379 95 ± 2 2068 ± 386 90.1 ± 49 Controls (40) 126 ± 14 76 ± 8 61 ± 7 7.5 ± 2.2 31.8 ± 6.8 21 ± 8 2123 ± 353 95± 2 2302 ± 335 94.4 ± 49 P value 0.001 0.004 0.3 0.05 0.001 0.009 0.01 0.9 0.005 0.7 Abstract P1513 Figure. Myocardial Work Cirrhotic Cardiomyopathy

P4380Echocardiographically determined myocardial work An emerging bioassay for clinical studies Results from the STAAB cohort study

Abstract Introduction A novel echocardiographic method to non-invasively determine myocardial work based on speckle-tracking derived longitudinal strain and blood pressure has recently been validated and offers new opportunities to study the mechanistic associations. Heart failure patients with prolonged electrical conduction (ie, left bundle branch block) exhibit reduced myocardial global work efficiency (GWE) due to an increase in global wasted work (GWW), which could be improved by biventricular pacing. We here investigated the association of ETI and myocardial work in a non-diseased population. Methods The Characteristics and Course of Heart Failure STAges A/B and Determinants of Progression (STAAB) cohort study carefully characterized a representative sample of the population of a medium-sized town in Germany, aged 30–79 years and free from heart failure. Off-line analysis of the standardized, quality-controlled transthoracic echocardiograms regarding myocardial work yields the following parameters: global constructive work (GCW): work performed during shortening in systole and adding negative work during lengthening in isovolumic relaxation; global wasted work (GWW): negative work performed during lengthening in systole adding work performed during shortening in isovolumic relaxation; and global work efficiency (GWE): GCW/(GCW+GWW). Results We performed myocardial work analysis in 935 individuals from the sample of the first planned STAAB interim analysis who were in sinus rhythm, had preserved left ventricular ejection fraction and were free from significant valvular disease (51% female, 53±12 years). In linear regression including age, sex, heart rate, and ETI, we found increasing heart rate (64±10 bpm), QRS width (95±12 ms), QT interval (414±28 ms), and PQ interval (164±28 ms) associated with lower GWE (−0.11, −0.02, −0.03, and −0.001, respectively; all p<0.05) and higher GWW (+2.64, +0.29, +0.79, +0.16 mmHg%, respectively; all p<0.05). Conclusion In subjects free of overt cardiac disease, GWE strongly associated with ETI. Prolonged atrio-ventricular and intra-ventricular coupling and repolarization was associated with an increase in wasted work, while constructive work was not affected. These findings not only suggest a positive effect on myocardial energetics by reducing the heart rate, but also advocate the concept of myocardial work as a bioassay that is responsive to subtle changes. Myocardial work holds promise to be further studied in diseased patient groups. Acknowledgement/Funding German Ministry of Research and Education within the Comprehensive Heart Failure Centre Würzburg (BMBF 01EO1004 and 01EO1504)