The trigger factors included: Acute coronary syndrome 30 cases (36.1%), anemia 28 cases (33.7%), infection 22 cases (26.5%), hypertensive emergency 16 cases (19.3%), tachyarrhythmia 15 cases (18.1%), acute renal failure 8 cases (9.6%), COPD exacerbation 8 cases (9.6%).