Anthracycline cardiotoxicity: an update on mechanisms, monitoring and prevention

Anthracycline chemotherapy causes dose-related cardiomyocyte injury and death leading to left ventricular dysfunction. Clinical heart failure may ensue in up to 5% of high-risk patients. Improved cancer survival together with better awareness of the late effects of cardiotoxicity has led to growing recognition of the need for surveillance of anthracycline-treated cancer survivors with early intervention to treat or prevent heart failure. The main mechanism of anthracycline cardiotoxicity is now thought to be through inhibition of topoisomerase 2β resulting in activation of cell death pathways and inhibition of mitochondrial biogenesis. In addition to cumulative anthracycline dose, age and pre-existing cardiac disease are risk markers for cardiotoxicity. Genetic susceptibility factors will help identify susceptible patients in the future. Cardiac imaging with echocardiographic measurement of global longitudinal strain and cardiac troponin detect early myocardial injury prior to the development of left ventricular dysfunction. There is no consensus on how best to monitor anthracycline cardiotoxicity although guidelines advocate quantification of left ventricular ejection fraction before and after chemotherapy with additional scanning being justified in high-risk patients. Patients developing significant left ventricular dysfunction with or without clinical heart failure should be treated according to established guidelines. Liposomal encapsulation reduces anthracycline cardiotoxicity. Dexrazoxane administration with anthracycline interferes with binding to topoisomerase 2β and reduces both cardiotoxicity and subsequent heart failure in high-risk patients. Angiotensin inhibition and β-blockade are also protective and appear to prevent the development of left ventricular dysfunction when given prior or during chemotherapy in patients exhibiting early signs of cardiotoxicity.

High-Sensitivity Troponin T and NT-proBNP Kinetics in Breast Cancer Chemotherapy

BACKGROUND/AIMS

Doxorubicin (DOX) and trastuzumab (TRA) are associated with cardiac dysfunction.

METHOD

High-sensitivity troponin T (hs-TnT) and brain natriuretic peptide attached to the amino acid N-terminal fragment in the prohormone (NT-proBNP) were measured before and on days +1, +2, +3, and +7 during cycles 1 and 2 of therapy with DOX or TRA in breast cancer patients.

RESULTS

Five of eleven DOX-treated women, compared with 2/11 TRA-treated women, had undetectable baseline hs-TnT. By day +1 of cycle 2, all the DOX-treated women (p = 0.03) but only 7/11 TRA-treated women (p = ns) had detectible hs-TnT. Time to peak was 1-2 days for both groups. In the DOX-treated women, hs-TnT showed significant peaks from precycle baseline, increases in precycle 1 to precycle 2 levels, and a cycle 1 to cycle 2 peak and area under the curve (AUC). hs-TnT increased from precycle (1, 4.6 ± 6.3 pg/mL) to a cycle 2 peak of 16.1 ± 15.0 pg/mL (p < 0.002). No increases were seen with the TRA treatment. Transient posttreatment increases in NT-proBNP were seen after both therapies.

CONCLUSION

DOX was associated with increased pretreatment baseline, peak, and AUC hs-TnT levels. Both DOX and TRA acutely perturb NT-proBNP. Assessment of pre- and posttreatment hs-TnT could be a means of quantifying cumulative myocardial injury in the course of chemotherapy.

Sudden death risk stratification in non-ischemic dilated cardiomyopathy using old and new tools: a clinical challenge

INTRODUCTION

Risk stratification for sudden cardiac death in non-ischemic dilated cardiomyopathy (NIDCM) remains a clinical challenge. Areas covered: Currently, left ventricular ejection fraction (LVEF), severity of heart failure symptoms according to NYHA classification, and morphology and duration of the QRS complex guide device management in these patients with implantation of a cardioverter defibrillator (ICD) and/or cardiac resynchronization therapy (CRT) devices. Recently, the results of a randomized trial stirred some controversy regarding the utility of ICD in NIDCM patients, however, a subsequent meta-analysis confirmed prior findings of the survival-prolonging benefit of device therapy. Newer risk markers, like late gadolinium enhancement in cardiac magnetic resonance imaging (CMR) detecting myocardial fibrosis, are encouraging in improving risk stratification in these patients. Furthermore, resurgence of an old tool, the electrophysiology study (EPS), and technical advances in genetics in identifying high-risk familial NIDCM, appear promising in this direction. Expert commentary: Based on old and new tools, a more individualized approach may be applied in NIDCM patients, whereby CMR, EPS and genetics may provide further guidance, particularly in patients with LVEF>35%. These issues are herein reviewed and a practical algorithm is proposed for risk stratification and device implantation in NIDCM patients with LVEF below and above 35%.