Feasibility of Echocardiographic Techniques to Detect Subclinical Cancer Therapeutics-Related Cardiac Dysfunction among High-Dose Patients When Compared with Cardiac Magnetic Resonance Imaging.

BACKGROUND: Cardiac magnetic resonance imaging (CMR) is the gold standard for the quantification of global and regional myocardial function and can detect subclinical myocardial dysfunction in anthracycline-induced cardiomyopathy. The aim of this study was to ascertain reliable echocardiographic parameters that can be used for the early identification of cancer therapeutics-related cardiac dysfunction, compared with CMR. METHODS: Fifty-seven pediatric cancer survivors, 10 to 42 years of age, with cumulative anthracycline doses ≥ 200 mg/m(2), were studied with transthoracic echocardiography and CMR 2.4 to 26.9 years after chemotherapy. RESULTS: Three-dimensional echocardiography had the highest sensitivity in identifying subjects with CMR-derived ejection fractions < 55%. Subjects with end-systolic volume index values > 29 mL/m(2) were more likely to have CMR-derived ejection fractions < 55%. Three-dimensional speckle-tracking echocardiographic peak global longitudinal strain magnitude < -17.5% best identified subjects with abnormal peak midwall longitudinal strain magnitude by CMR. A decrease in early atrial myocardial velocity of <10 cm/sec at the interventricular septum also identified subjects with lower average peak midwall longitudinal strain and peak midwall circumferential strain magnitudes by CMR. CONCLUSIONS: Three-dimensional echocardiographic ejection fraction < 55%, end-systolic volume index > 29 mL/m(2), three-dimensional speckle-tracking echocardiographic peak global longitudinal strain magnitude < -17.5%, and a decrease in early atrial myocardial velocity at the interventricular septum of <10 cm/sec by Doppler tissue imaging are the most sensitive transthoracic echocardiographic parameters to identify subjects with subclinical myocardial dysfunction by CMR.

Effect of myocardial dysfunction in cardiac morbidity and all cause mortality in childhood cancer subjects treated with anthracycline therapy.

BACKGROUND: Subacute cardiotoxicity, consisting of acute myocyte damage and associated left ventricular dysfunction, occurs early during anthracycline therapy. We investigated the impact of myocardial dysfunction, defined herein by a shortening fraction (SF) < 29 % at any time during or after anthracycline therapy, on late onset cardiomyopathy and all-cause mortality, among childhood cancer survivors exposed to anthracyclines. In addition, we sought to identify subpopulations of subjects at highest risk for cardiomyopathy and death from all causes. METHODS: Five hundred thirty-one childhood cancer survivors exposed to anthracyclines were enrolled and studied on average 10 (1.4-27.3) years following their initial exposure. The medical records were reviewed to identify known risk factors associated with cardiotoxicity, including cumulative anthracycline dose, length of post-therapy interval, administration of other cardiotoxic medications (vinca alkaloids), previous heart disease, radiation dose to the heart, history of bone marrow transplantation, age at treatment, gender, systolic dysfunction, and history of congestive heart failure during anthracycline therapy. RESULTS: Ninety subjects (16.9 %) developed SF < 29 % and 71 patients (13.4 %) died on average 10 years after initial exposure (range 1.4-27.3 years). Total cumulative dose (OR 3.27, 95 % CI 1.94, 5.49, p < 0.001) and bone marrow transplantation (OR 2.57, 95 % CI 1.24, 5.30, p = 0.01) were found to be statistically significant risk factors for development of myocardial dysfunction. There was a 3-fold increase in the odds of having a SF < 29 % at any point during or following cancer therapy if a subject underwent bone marrow transplantation or had a total cumulative dose anthracycline therapy ≥ 240 mg/m2. The all-cause mortality ratio was almost seven-fold higher (95 % CI, 2.40-fold to 17.81-fold higher) if a subject developed systolic dysfunction, defined by a previous SF < 29 % anytime during or after anthracycline therapy. Nine deaths (12.7 %) were attributed to cardiovascular disease. The risk of dying as a result of cardiac disease also was significantly higher in individuals who had a SF < 29 % at any time during or after therapy. CONCLUSIONS: This study demonstrates an almost seven-fold increase in all cause mortality in pediatric cancer survivors with a history of anthracycline induced myocardial dysfunction defined as SF < 29 %.

Occult cardiotoxicity in childhood cancer survivors exposed to anthracycline therapy.

BACKGROUND: More than 50% of >270 000 childhood cancer survivors in the United States have been treated with anthracyclines and are therefore at risk of developing cardiotoxicity. Cardiac magnetic resonance (CMR) has demonstrated utility to detect diffuse interstitial fibrosis and changes in regional myocardial function. We hypothesized that CMR would identify occult cardiotoxicity characterized by structural and functional myocardial abnormalities in a cohort of asymptomatic pediatric cancer survivors with normal global systolic function. METHODS AND RESULTS: Forty-six long-term childhood cancer survivors with a cumulative anthracycline dose ≥200 mg/m(2) and normal systolic function were studied 2.5 to 26.9 years after anthracycline exposure. Subjects underwent transthoracic echocardiography, CMR with routine cine acquisition, tissue characterization, and left ventricular strain analysis using a modified 16-segment model. Extracellular volume was measured in 27 subjects, all of whom were late gadolinium enhancement negative. End-systolic fiber stress was elevated in 45 of 46 subjects. Low average circumferential strain magnitude (εcc) -14.9±1.4; P<0.001, longitudinal strain magnitude (εll) -13.5±1.9; P<0.001, and regional peak circumferential strain were seen in multiple myocardial segments, despite normal global systolic function by transthoracic echocardiography and CMR. The mean T1 values of the myocardium were significantly lower than that of control subjects at 20 minutes (458±69 versus 487±44 milliseconds; P=0.01). Higher mean extracellular volume was observed in female subjects (0.34 versus 0.22; P=0.01). CONCLUSIONS: Asymptomatic postchemotherapy pediatric patients have abnormal myocardial characteristics and strain parameters by CMR despite normal global cardiac function by standard transthoracic echocardiography and CMR measures.