The incidence of cardiotoxicity during cancer therapy is underestimated due to limitations of current diagnostic tests. Current biomarkers (BNP, NT-pro-BNP, hs-Troponin, etc.) and imaging calculations (e.g. echocardiography) such as left ventricular ejection fraction (LVEF) are currently included in the guidelines to designate cardiotoxicity during cancer therapy. Unfortunately, these diagnostics identify systemic damage in symptomatic patients after the heart is unable to compensate for regional dysfunction. Fast-SENC segmental intramyocardial strain (fSENC) is a unique cardiac magnetic resonance imaging (CMR) test that regionally detects subclinical intramyocardial dysfunction in 1 heartbeat.
This single center, prospective Prefect Study was used to evaluate cardiotoxicity and the impact of cardioprotective therapy in Breast Cancer and Lymphoma patients (NCT03543228). fSENC was acquired with a 1.5T MRI and processed with the software to quantify intramyocardial strain. Segmental strain was measured in three short axis scans (basal, midventricular, apical) with 16 LV / 6 RV longitudinal segments & three long axis scans (2-, 3-, 4-chamber) with 21 LV / 5 RV circumferential segments. fSENC CMR was performed before chemotherapy, during and after anthracycline/taxane therapy, at 1 year follow-up, and as needed in between designated follow-up periods. Cardioprotective therapy was offered to patients meeting the definition of cardiotoxicity by the ESC Guidelines on Cardiotoxicity and/or ESMO Clinical Practice Guidelines or those observing a substantial decline in cardiac function.
Two hundred eight (208) CMRs were performed in fifty-two (52) patients (44 female). Patients had an average (± stdev) age of 53 (15) yrs, BMI of 26 (5) kg/m2; 77% had breast cancer, 23% had Lymphoma. fSENC CMRs required 11 (2) min total exam time. The % of normal fSENC (segmental stain < -17%) with a threshold of 65% showed a sensitivity of 87% and specificity of 89% in detecting cardiotoxicity while echocardiography GLS with a threshold of -17% observed a sensitivity of 20% and specificity of 88%. Figure 1 shows receiver operating characteristic curves for fSENC based on the percent of normal myocardium, and echocardiography global longitudinal strain (GLS) respectively. Global fSENC had substantially lower sensitivity than segmental fSENC despite having higher accuracy than the other global metrics.
Segmental fSENC intramyocardial strain detects subclinical dysfunction due to cardiotoxic response of chemotherapy before other biomarkers and imaging modalities. The ability to detect the subclinical cardiotoxicity of chemotherapy agents, or other pharmacological agents that cause or worsen heart failure, enables proactive prescription of cardioprotective medications to avoid tissue remodeling that precedes systemic cardiac dysfunction and worsening of global measures such as LVEF and current biomarkers.