Microvascular Dysfunction Is Associated With Impaired Myocardial Work in Obstructive and Nonobstructive Hypertrophic Cardiomyopathy: A Multimodality Study

Abstract

Background Two‐dimensional speckle tracking echocardiography has been shown to correlate with microvascular dysfunction, a hallmark of hypertrophic cardiomyopathy (HCM). We hypothesized that there is an association between myocardial work and left ventricular ischemia, with incremental value to global longitudinal strain, in patients with HCM. Methods and Results We performed a prospective assessment of patients with HCM, undergoing 2‐dimensional speckle tracking echocardiography and stress perfusion cardiac magnetic resonance. Results were stratified according to obstructive or nonobstructive HCM and the presence of significant replacement fibrosis (late gadolinium enhancement ≥15% of left ventricular mass). Seventy‐five patients with HCM (63% men, age 55±15 years) were evaluated, 28% with obstructive HCM (mean gradient 89±60 mm Hg). Perfusion defects were found in 90.7%, involving 22.5±16.9% of left ventricular mass, and 38.7% had late gadolinium enhancement ≥15%. In a multivariable analysis, a lower global work index ( r =−0.519, β‐estimate −10.822; P =0.001), lower global work efficiency ( r =−0.379, β‐estimate −0.123; P =0.041), and impaired global constructive work ( r =−0.532, β‐estimate −13.788; P <0.001) significantly correlated with ischemia. A segmental analysis supported these findings, albeit with lower correlation coefficients. A global work index cutoff ≤1755 mm Hg% was associated with hypoperfusion with a sensitivity of 88% and a specificity of 71%, while the best cutoff for global longitudinal strain (>−15.5%) had a sensitivity of 64% and a specificity of 57%. The association between myocardial work and perfusion defects was significant independently of late gadolinium enhancement ≥15% and obstructive HCM. Conclusions Impaired myocardial work was significantly correlated with the extent of ischemia in cardiac magnetic resonance, independently of the degree of left ventricular hypertrophy or fibrosis, with a higher predictive power than global longitudinal strain.

Systemic Vascular Resistance and Myocardial Work Analysis in Hypertrophic Cardiomyopathy and Transthyretin Cardiac Amyloidosis with Preserved Left Ventricular Ejection Fraction

“…Class D, another intermediate class due to high SVR c . Vertical dashed lines indicate the cut-off values by previous studies for impaired myocardial perfusion and late gadolinium enhancement (LGE) in HCM patients [ 21 ], and major cardiovascular events (MACE) in ATTR patients [ 22 ]. Tabulation below the graphics refers to some clinical findings from the patients belonging to different Classes (see also Table 3 ).…”

“…In Figure 2 , three more cut-off values for GWI are represented in the diagram according to other studies. The value of GWI < 1517 mm Hg% was found in HCM patients with myocardial perfusion defects at stress-perfusion cardiac magnetic resonance, and the value of <1363 mm Hg% also discriminated the presence of late gadolinium enhancement > 15% of myocardial mass at cardiac magnetic resonance imaging [ 21 ]. The interrupted line indicating the risk of “MACE” at the cut-off value of GWI <1043 mm Hg% was previously found as an all-cause mortality risk factor in amyloid patients (61% wildtype ATTR) [ 22 ].…”

“…According to Garcia Brás at al. [ 21 ], 18 patients of the HCM group (60%) also presented GWI values suggestive of impaired myocardial perfusion, and in 13 cases (43%), with possible late gadolinium enhancement > 15%.…”

Interventricular Septal Involvement Is Associated with More Impaired Ventricular Function and Mechanics in Apical Hypertrophic Cardiomyopathy

“…This was not accounted for in the pressure–strain loop assessment and may have meant that myocardial work was underestimated. While some investigators suggest adding the peak or mean dynamic pressure gradient to the brachial cuff pressure used in myocardial work estimation, others have shown good accuracy and predictive value without accounting for the additional afterload, and this remains unsettled in the published literature [ 29 , 30 ]. Fifth, cardiac magnetic resonance imaging was not routinely performed or available for review, which is a modality important in HCM for myocardial tissue characterization and the assessment of late gadolinium enhancement.…”

Systemic Vascular Resistance and Myocardial Work Analysis in Hypertrophic Cardiomyopathy and Transthyretin Cardiac Amyloidosis with Preserved Left Ventricular Ejection Fraction

“…Class D, another intermediate class due to high SVRc. Vertical dashed lines indicate the cut-off values by previous studies for impaired myocardial perfusion and late gadolinium enhancement (LGE) in HCM patients[21], and major cardiovascular events (MACE) in ATTR patients[22]. Tabulation below the graphics refers to some clinical findings from the patients belonging to different Classes (see also Table3).…”