Code first the underlying cause, if known and applicable, such as:

acute kidney failure (N17.-)

acute myocarditis (I40.-)

cardiomyopathy (I42.-)

chronic kidney disease (CKD) (N18.-)

heart failure (I50.-)

hypertensive urgency (I16.0)

nonrheumatic aortic valve disorders (I35.-)

paroxysmal tachycardia (I47.-)

pulmonary embolism (I26.-)

pulmonary hypertension (I27.0, I27.2-)

sepsis (A41.-)

takotsubo syndrome (I51.81)