CODES.AND.STUFF

The rules for applying ICD-10 codes for Myocardial Infarction as detailed in the ICD- 10 Clinical Coding Instruction Manual (Version 2.0) page IX-9 remains a current national standard. Due to a number of queries received by the National Clinical Classifications Helpdesk on MI coding the following guidance is published to reinforce the existing rule and to provide additional examples for assistance.

The guidance on page XXI-14 of the ICD-10 Clinical Coding Instruction Manual (Version 2.0) states that when a patient is transferred from one hospital Trust to another for the treatment or rehabilitation of a condition, then the original condition will continue to be the primary diagnosis following transfer. However, the coding of an acute MI, when a patient moves from one hospital Trust to another is an exception to this rule. This rule was introduced due to the over reporting of acute MI’s and inflation of national statistics in England. This was agreed through collaborative work between the Department of Health, national clinical groups and NHS Classifications Service.

It is a common occurrence for a patient who has suffered an MI to be either transferred to another hospital within the same Trust or discharged to another Trust for rehabilitation or further treatment.

If the patient is discharged from the first Trust this will end the first hospital provider spell and the admission to the second Trust will generate a new hospital provider spell.

The Hospital Episodes Statistics team at the NHS Information Centre for health and social care has confirmed that there is no easy way to identify those instances when a patient who has been admitted to one Trust following discharge from another Trust. Consequently, the coding of an MI (I21.- Acute myocardial infarction – I22.- Subsequent myocardial infarction) on all associated hospital provider spells will lead to multiple counting, thus inflating the national figures for the incidence of MI in England.

A hospital spell may consist of multiple consultant episodes, and it is therefore possible for an MI to be recorded on more than one episode. However, in order to accurately monitor the number of acute MIs in England, it is essential that an MI is only coded on the first hospital provider spell in which it occurs.

Codes from the ICD-10 category I24.- Other acute ischaemic heart diseases, classify ischaemic heart disease that is acute, or with a stated duration of four weeks or less. Therefore, on a successive hospital provider spell where the diagnostic statement is an MI, the most appropriate ICD-10 code is I24.8 Other forms of acute ischaemic heart disease. For example:

Example 1:

A patient with severe chest pain is admitted to Trust A under the care of Dr Brown. Dr Brown makes a diagnosis of acute MI. This is the patient’s first MI, and the patient is transferred to the care of Dr White (a consultant cardiologist), thereby generating a second consultant episode of care within one hospital spell.

First Consultant Episode – Dr Brown (Trust A):

I21.9    Acute myocardial infarction, unspecified

Second Consultant Episode – Dr White (Trust A):

I21.9    Acute myocardial infarction, unspecified

Rationale: The two episodes have both occurred within the first hospital spell. This is the only time a code from category I21.- Acute myocardial infarction can be assigned twice, as per guidance published on page IX-9 of the ICD-10 Clinical Coding Instruction Manual, Version 2.0.

Example 2:

A patient is admitted to Trust A with an acute MI. This is the patient’s first MI: however, the patient is known to have Coronary Artery Disease (CAD) and is (where appropriate) awaiting a coronary angioplasty and stent. A clinical decision is made that the patient urgently requires this procedure. Trust A does not have the facilities to perform the angioplasty, and the patient is discharged from Trust A and admitted directly to Trust B for the angioplasty and stent, thereby generating a second hospital provider spell.

The patient is discharged from Trust B the day after the procedure and readmitted directly to Trust A for cardiac rehabilitation, thereby generating a third hospital provider spell.

First Hospital Provider Spell (Trust A):

I21.9    Acute myocardial infarction, unspecified

I25.1    Atherosclerotic heart disease

Second Hospital Provider Spell (Trust B):

I25.1    Atherosclerotic heart disease

(The main condition treated at Trust B is the coronary artery disease)

I24.8    Other forms of acute ischaemic heart disease

Third Hospital Provider Spell (Trust A):

I24.8    Other forms of acute ischaemic heart disease

I25.1    Atherosclerotic heart disease

Z50.0 Cardiac rehabilitation

Z95.5 Presence of coronary angioplasty implant and graft

Rationale: The acute MI code (I21.- Acute myocardial infarction) must only be assigned on the first hospital provider spell.

Example 3:

A patient with osteoarthritis of the knee is admitted to Trust A, an orthopaedic specialist hospital, for a total knee replacement. One day post surgery, the patient suffers an acute myocardial infarction and is discharged from Trust A and admitted directly to Trust B, an acute hospital trust, thereby generating a second hospital provider spell.

First Hospital Provider Spell (Trust A):

M17.9 Gonarthrosis, unspecified

I21.9    Acute myocardial infarction, unspecified

Second Hospital Provider Spell (Trust B):

I24.8    Other forms of acute ischaemic heart disease

Z96.6 Presence of orthopaedic joint implants

Rationale: The acute MI code (I21.- Acute myocardial infarction) must only be assigned on the first hospital provider spell. If the clinician confirms that the MI is due to the procedure, then code Y83.1 Surgical operation with implant of artificial internal device would also be assigned on the first hospital provider spell.

Example 4:

Patient is admitted to Trust A following an MI. The patient suffered his first MI five years ago. The patient is known to have coronary artery disease and is awaiting coronary artery bypass graft (CABG). The patient is discharged from Trust A and is admitted directly to Trust B for emergency CABG, generating a second hospital provider spell.

First Hospital Provider Spell (Trust A):

I22.9  Subsequent myocardial infarction of unspecified site

(A code from ICD-10 category I21.- Acute myocardial infarction can only ever be assigned once in a lifetime for a patient’s first MI, and as stated above the patient suffered an MI five years ago)

I25.1  Atherosclerotic heart disease

Second Hospital Provider Spell (Trust B):

I25.1    Atherosclerotic heart disease

(The main condition treated at Trust B is the coronary artery disease)

I24.8    Other forms of acute ischaemic heart disease

Rationale: The acute MI code (I21.- Acute myocardial infarction) must only be assigned on the first hospital provider spell. It is not appropriate to assign I22.- Subsequent myocardial infarction on the second provider spell as it would look as if the patient had suffered another MI and this would lead to double counting.

Example 5:

Patient admitted to Trust A with an MI whilst on holiday. Patient previously suffered an acute MI five years ago. Patient is discharged from Trust A and admitted directly to Trust B for cardiac rehabilitation, creating a second hospital provider spell. Whilst in Trust B, the patient suffers another acute MI.

First Hospital Provider Spell (Trust A):

I22.9    Subsequent myocardial infarction of unspecified site

Second Hospital Provider Spell (Trust B):

I22.9    Subsequent myocardial infarction of unspecified site

I24.8    Other forms of acute ischaemic heart disease

Z50.0   Cardiac rehabilitation

Rationale: As this is a separate MI to the one suffered during the first provider spell, it is appropriate to assign ICD-10 code I22.9 Subsequent myocardial infarction of unspecified site on this second provider spell, as this is when the MI occurred. As the MI will be the main condition treated during the provider spell, it will become the primary diagnosis.

If the patient has another subsequent MI in the same episode or any episode within the same spell, and this is confirmed as a definite new MI by the clinician, then another I22.- Subsequent myocardial infarction would be assigned for each subsequent MI. The ICD-10 CCIM page IX-10 does state that I22.- Subsequent myocardial infarction is assigned to the patient’s 2nd MI, 3rd MI, 4th MI etc. and therefore all subsequent MIs.

Further guidance regarding subsequent myocardial infarction can be found on page IX-10 of the ICD-10 Clinical Coding Instruction Manual (Version 2.0).

Coding Clinic, NHS Classifications Service

www.connectingforhealth.nhs.uk/codingclinic

Tags: cardiovascular, MI, myocardial infarction