ISO 9564-1 format 4: do I need an IV? ISO 9564-1 format 4 describes an extended PIN block format. Simply said, this standard can be used to encrypt 4-digit PIN codes in a secure way. 

The standard mentions (simplified) to add random values to the PIN, before encrypting it with a cipher that can be chosen by the implementer (we will go for AES-CTR). 

I wonder now, if we follow this standard, and append a cryptographically random value to the PIN before encryption, do we then still need an IV for the AES encryption?
ISO 9564-1 format 4 does not need a IV since it adds entropy to the plaintext PIN before encrypting.  There is no need to append a random value to the PIN.

The Format 4 PIN block algorithm is illustrated above.  The PIN and the PAN are both padded.  The padded values are called the plain text PIN field and the plain text PAN field.  The last $8$ bytes of the padded PIN field are random.  The plain text PAN has deterministic padding. The plain text PIN field is encrypted and then XORed with the plain text PAN field and the result is then encrypted again, yielding the encrypted PIN block.
Format 4 is typically used with a fixed AES key for each encryption operation on a particular device.  Since there are only $8$ bytes of mixed-in entropy for each PIN-PAN combination, Format 4 has the potential to be vulnerable to a chosen plaintext dictionary attack.  An attacker could capture an encrypted Format 4 PIN Block.  The attacker could then recover the PIN by repeatedly encrypting all possible PIN values until by chance the encrypted PIN block is the same as the encrypted PIN block the attacker is attempting to decode.
There are $64$ bits of random data in the plain text PIN Block. The PIN is between $4$ and $12$ decimal digits and thus adds at least $13$ bits of entropy.  Therefore above attack would require at least $2^{77}$ chosen plaintexts.
It would difficult to obtain $2^{77}$ chosen plaintexts from any single device.  Furthermore, the PCI PTS standard requires compliant devices to rate limit PIN encryption to $120$ PINs per hour.  As such, the above attack is not feasible.