Right ventricular ejection fraction (RVEF) identifies reduced right-side cardiac function in symptomatic patients. However, alternative metrics are needed to detect subclinical RV dysfunction before cardiac remodeling results in systemic damage. Fast-SENC intramyocardial strain (fSENC) is a unique cardiac magnetic resonance imaging (CMR) modality that measures intramyocardial RV contraction in 1 heartbeat per image plane. This prospective registry compares fSENC and RVEF in patients with documented pulmonary disease.
A single center, prospective registry of MRI scans acquired with a 1.5T scanner were evaluated for conventional CMR diagnostics including RVEF. In addition, fSENC scans were acquired and processed with the MyoStrain software to quantify intramyocardial RV strain. Two short axis scans (basal & midventricular) were used to calculate strain in 6 longitudinal RV segments while two long axis scans (3-chamber & 4-chamber) were used to calculate 5 circumferential RV segments. Two additional planes (2-chamber long axis & apical short axis) were included to also evaluate LV intramyocardial strain producing a total of 6 planes (3 short axis & 3 long axis) with 16 longitudinal LV segments and 21 circumferential LV segments.
A total of 95 scans in 76 patients with pulmonary disease (42% COPD, 25% pulmonary hypertension, 26% asthma, 6% pneumonia) were included in the study. Patients had an average (± stdev) age of 46 (18) yrs and BMI of 26 (5) kg/m2 (65% arterial hypertension, 25% diabetes mellitus, 44% moderate or severe tricuspid valve regurgitation, 28% cancer, 13% atrial fibrillation, 33% coronary artery disease). Figure 1 shows the relationship between CMR RVEF in the y-axis versus RV GCS in the x-axis respectively. A polynomial fit curve showed a nonlinear decline in CMR RVEF after RV GCS worsened to greater than -17% (r = 0.75); the polynomial fit curve for RV GLS had an r = 0.56.
fSENC detects subclinical RV and LV dysfunction before changes in ejection fraction in patients with pulmonary disease. The ability to directly measure intramyocardial RV strain allows quantification of the impact of diseases, pharmacological therapies and device interventions on right ventricular function.