Conclusion
Although the overall incidence of cardiac toxicities is very low, dual HER-2 targeted therapy in breast cancer significantly increase the risk of developing LVEF and CHF when compared to anti-HER-2 alone. Sub-group analysis that addition of dual HER-2 blockade to adjuvant treatment in breast cancer increased the risk of developing cardiac toxicities but not for neoadjuvant or metastatic settings. Concomitant treatment with dual HER2 blockade would increase the risk of developing cardiac toxicities. Physicians should be aware of this risk and provide close monitoring during the administration of dual HER-2 targeted therapy.