Left ventricular ejection fraction (LVEF) identifies reduced cardiac function in symptomatic patients. However, alternative metrics are needed to detect subclinical dysfunction before cardiac remodeling results in systemic damage. Fast-SENC segmental intramyocardial strain (fSENC) is a unique cardiac magnetic resonance imaging (CMR) modality that measures myocardial contraction in 1 heartbeat per image plane. This prospective registry compares fSENC and LVEF in patients with varying degrees of progressive dysfunction.
A single center, prospective registry of MRI scans acquired with a 1.5T scanner were evaluated for conventional CMR diagnostics including LVEF, LV-Volumes, LV-Mass, LV-T1/T2 mapping, and Late Gadolinium Enhancement (LGE). In addition, fSENC scans were acquired and processed with the MyoStrain software to quantify intramyocardial strain. Three short axis scans (basal, midventricular, & apical) were used to calculate strain in 16 longitudinal segments while three long axis scans (2-chamber, 3-chamber, & 4-chamber) were used to calculate 21 circumferential segments. fSENC and CMR LVEF were compared based on a modified ACC/AHA Heart Failure Stage ranking that separated stages B and C each into two levels of structural heart disease based on complete CMR evaluation including T1/T2 mapping and LGE analysis.
A total of 792 scans in 619 patients were included in the study. Patients had an average (± stdev) age of 54 (17) yrs and BMI of 26 (5) kg/m2; 45% had arterial hypertension, 12% diabetes mellitus, 30% valvular heart disease, 27% cancer, 7% atrial fibrillation, and 22% coronary artery disease.
Figure 1 shows the relationship between ACC/AHA Heart Failure stage in the x-axis versus A) the amount of normal myocardium (strain < -17%) and B) CMR LVEF in the y-axis respectively.
fSENC shows a more linear response across all stages of heart failure. The ability to separate HF stage with a quantitative metric enables detection of subclinical dysfunction before symptoms or clinical change in global CMR measurements such as LVEF, volumes, mass, etc. Even in patients with normal LVEF, fSENC quantified the progression of structural heart diseases.