UK licence currently reads
All candidates for treatment with Herceptin, but especially those with prior anthracycline and cyclophosphamide (AC) exposure, should undergo baseline cardiac assessment including history and physical examination, ECG, echocardiogram, and/or MUGA scan. A careful risk-benefit assessment should be made before deciding to treat with Herceptin. Cardiac function should be further monitored during treatment (e.g. every three months). Monitoring may help to identify patients who develop cardiac dysfunction. Patients who develop asymptomatic cardiac dysfunction may benefit from more frequent monitoring (e.g. every 6-8 weeks). If patients have a continued decrease in left ventricular function, but remain asymptomatic, the physician should consider discontinuing therapy if no clinical benefit of Herceptin therapy has been seen. Caution should be exercised in treating patients with symptomatic heart failure, a history of hypertension or documented coronary artery disease.
http://www.emc.medicines.org.uk/
I've had 3 monthly echos (finished a years course of herceptin yesterday). Luckily for me LVEF has remained unchanged throughout