The Scottish Coronary Revascularisation Register

Time trends 1997-2003

Prepared by Jill Pell Rachel Slack Greater Glasgow NHS Board on behalf of the Scottish Coronary Revascularisation Register Steering Groups

The Scottish Coronary Revascularisation Register

Time trends 1997-2003

Prepared by Jill Pell Rachel Slack Greater Glasgow NHS Board on behalf of the Scottish Coronary Revascularisation Register Steering Groups

Published by Greater Glasgow NHS Board Dalian House

350 St Vincent Street Glasgow G3 8YU

Copyright 2004 GGNHSB

Printed in Scotland by Image and Print Group

All right reserved. No part of this publication may be reproduced, stored in a retrieval

system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of GGNHSB.

A catalogue for this publication is available from the British Library

ISBN 0 948310 44 8

1

Coronary artery disease is a major cause of ill-health and death in Scotland. Coronary revascularisation provides an effective means of treating symptoms, improving quality of life and, in some cases, increasing life expectancy. Due to a number of technical and therapeutic developments, revascularisation has become increasingly safe and effective. As a result, the number of patients benefiting from revascularisation has increased. As with any procedure, it is important to ensure that the selection of patients is appropriate and the outcomes achieved meet acceptable standards. Since it was established seven years ago, the Scottish Coronary Revascularisation Register has been an invaluable resource in enabling cardiac surgeons and interventional cardiologists in Scotland to monitor their own practice and compare it with other hospitals both within Scotland and elsewhere. I am indebted to those involved in setting up and running the register, without whose hard-work and commitment the register would not exist.

Dr EM Armstrong Chief Medical Officer Scottish Executive

Foreword

2

page

Introduction 3

Methods 4

Hospitals where procedures undertaken 6

Number of procedures by year 7

Previous cardiac surgery 8

Use of coronary stents 9

Severity of cardiac disease 10

Urgency of procedures 11

Selected procedures 12

Age 12

Obesity 13

Diabetes 14

Hypertension 16

Left ventricular function 16

Risk of death and repeat revascularisation 17

Cardiac transplantation 19

Summary 20

Appendix A. Definitions and abbreviations 21

Appendix B. Members of the Scottish Coronary Revascularisation Steering Groups 22

Contents

3

Dr thods Narrowing of the coronary arteries can cause angina, increase the risk of a heart attack (myocardial infarction) and, in some patients, reduce life expectancy. In addition to treatment with drugs and preventative measures such as smoking cessation, coronary revascularisation can be used, in appropriate patients, to improve blood flow in the coronary arteries. This is achieved through either coronary artery bypass grafting, in which the narrowed section is bypassed using a graft made from either a vein or another artery, or by percutaneous coronary intervention, in which a catheter is fed into the coronary arteries via a vein in the groin and the coronary artery then forced open by expanding a small balloon or held open using a hollow stent. Over the past few decades there have been a number of significant technical and therapeutic advances in both procedures. These have reduced the risk of undergoing coronary revascularisation, improved long-term prognosis and increased the number of patients eligible for coronary revascularisation. These include: • increased use of arterial rather than venous grafts, • the development of less invasive methods of surgery, • the development of drugs that can be used in conjunction with revascularisation, • increased use of coronary stents, and • the development of coronary stents impregnated with drugs that can reduce the

risk of the artery narrowing again. This report describes overall trends in coronary revascularisation in Scottish NHS hospitals between April 1997 and March 2003 in terms of the number and type of patients undergoing revascularisation, the type of revascularisation undertaken and outcome.

Dr Jill Pell Chairman Scottish Coronary Revascularisation Steering Groups

Introduction

4

The Scottish Coronary Revascularisation Register The Scottish Coronary Revascularisation Register was set up in April 1996. Since April 1996, data have been collected on all patients undergoing coronary artery bypass grafting in Scottish NHS hospitals. Since April 1997, data have also been collected on all patients undergoing percutaneous coronary interventions in Scottish NHS hospitals. The data are collected prospectively by clinical, nursing, audit and administrative staff located in the twelve NHS hospitals where these procedures are undertaken. The hospitals collect the same information using standard definitions (Appendix A). The information collected on each patient includes:

• demographic characteristics, • severity of cardiac disease, • drug therapy, • past medical and surgical history, • co-morbid conditions and other risk factors, and • in-hospital complications.

Follow-up Throughout Scotland, data are routinely collected on all acute hospital admissions via the Scottish Morbidity Record (SMR1). The General Registrar’s Office (GRO) collects data from death certificates on all deaths that occur in Scotland whether in hospital or in the community. Therefore SMR1 and GRO data can provide information on events following discharge even if they occur in the community or in a different hospital to the index procedure. The Scottish Coronary Revascularisation Register is linked annually to the SMR1 and GRO databases to provide follow-up information on:

• survival, • readmission to hospital, • acute myocardial infarction, • repeat coronary angiography, and • repeat coronary revascularisation

Steering Groups There are two steering groups for cardiac surgery and percutaneous coronary intervention respectively (Appendix B). The members of the steering groups are representatives of the participating hospitals. The steering group members are responsible for liaising with their colleagues, reviewing the results, validating data completeness and accuracy, and disseminating information and recommendations.

Methods

5

Developments There have been a number of recent developments: • Since 2000, data have been collected on coronary angiography. This is an

investigation undertaken prior to revascularisation by either coronary artery bypass grafting or percutaneous coronary intervention.

• The private hospitals in Scotland that undertake coronary revascularisation have

been approached in an attempt to expand coverage of the register to all hospitals rather than just NHS hospitals.

• We are grateful to the Scottish Coronary Intervention Network and Scottish

Executive for providing funding from 2003 to employ dedicated data collectors. Prior to this, data collection was dependent on the goodwill of existing members of staff. This development should improve data completeness and accuracy.

• In parallel, funding has been provided for some technical developments in the way

in which data are captured, transferred, collated and reported. Once completed, these should reduce delays to reporting.

Reporting The steering groups produce detailed annual reports containing information on individual hospitals. These are distributed to relevant clinicians, Medical Directors, Directors of Public Health and the Chief Medical Officer. In addition, we submit data to the Society of Cardiothoracic Surgeons and the European Association of Cardio-Thoracic Surgery so that Scottish Cardiac Surgeons can compare their own practice with that of surgeons across the United Kingdom and in other European countries. The current report is additional to the normal annual reports and has been written for a wider readership. This report therefore presents a general overview of the data collected since the establishment of the registers. In addition to presenting time trends in coronary artery bypass grafting and percutaneous coronary intervention between April 1997 and March 2003, we are grateful to Mr Andrew Murday, Consultant Cardiothoracic Surgeon in Glasgow Royal Infirmary, for providing information on trends in cardiac transplantation for inclusion in this report.

6

coronary

angiography

percutaneous

coronary intervention

coronary artery bypass surgery

cardiac

transplantation

Aberdeen Royal Infirmary

Ayr Hospital

Glasgow Royal Infirmary

Dumfries & Galloway Royal Infirmary

Golden Jubilee Hospital Glasgow

Hairmyres Hospital East Kilbride

Inverclyde Royal Infirmary Greenock

Ninewells Hospital Dundee

Raigmore Hospital Inverness

Royal Infirmary Edinburgh

Western General Hospital Edinburgh

Western Infirmary Glasgow

Hospitals where procedures undertaken

7

Between April 1997 and March 2003, 34,468 coronary revascularisation procedures have been undertaken in Scottish NHS hospitals. Overall 16,520 (48%) were performed as coronary artery bypass grafts and 17,948 (52%) were percutaneous coronary interventions. However, the relative contribution of the two procedures has changed over time. The number of coronary artery bypass grafts performed has remained relatively static over the past six years. By contrast, the number of percutaneous coronary interventions performed has doubled. As a result the overall number of coronary revascularisation procedures has increased by 51%, from 4,661 to 7,024 per annum. The percentage of revascularisation procedures performed by percutaneous coronary intervention has increased from 44% to 58%.

0

500

1000

1500

2000

2500

3000

3500

4000

4500

97/98 98/99 99/00 00/01 01/02 02/03

Year

CABGPCI

Overall, 24,822 (72%) coronary revascularisation procedures were undertaken on men and 9,646 (28%) on women. However, this varied according to the type of revascularisation performed. Men accounted for 75% of coronary artery bypass graft procedures but only 69% of percutaneous coronary interventions. There was no trend in sex breakdown over time.

Number of procedures by year

8

Patients are at increased risk if they had previous cardiac surgery because this increases the technical difficulties of performing revascularisation. Overall, 3% of patients undergoing coronary artery bypass had previous cardiac surgery, as had 11% of patients undergoing percutaneous intervention. Over the six year period, there was a small decline in the percentage of patients who had previous surgery. This may be due to a number of factors including a declining threshold for revascularisation, an increasing trend to use percutaneous intervention as the first procedure and improvements in outcome.

0

2

4

6

8

10

12

14

97/98 98/99 99/00 00/01 01/02 02/03

Year

Per

cent

age

of p

atie

nts

CABGPCI

Previous cardiac surgery

9

There has been a steep increase in the use of coronary stents as part of percutaneous coronary intervention. In 1997/1998 only 47% of patients undergoing percutaneous coronary intervention had one or more stents inserted. By 2002/2003 this figure had increased to 85%. Among patients in whom stents are inserted, the percentage receiving more than one stent has increased from 7% to 37%. This trend mirrors that observed in other countries and is consistent with increasing evidence from trials that use of stents increases the likelihood that the artery will remain open, and therefore reduces the need for repeat revascularisation in the future.

0102030405060708090

97/98 98/99 99/00 00/01 01/02 02/03Year

Per

cent

age

of P

CIs

invo

lvin

g st

ent i

nser

tion

Use of coronary stents

10

In general, the vast majority of coronary artery bypass grafts are performed for multi-vessel disease (ie. more than one narrowed artery). The percentage of coronary bypass grafts performed for multi-vessel disease has remained fairly constant over the past six years. With improvements in percutaneous coronary intervention, such as increased use of coronary stents, percutaneous coronary intervention has become an increasingly acceptable option for some patients with multi-vessel disease. As a result, the number of patients undergoing percutaneous intervention for multi-vessel disease has increased from 1,006 in 1997/1998 to 1,604 in 2002/2003. Among patients undergoing revascularisation for multi-vessel disease the percentage treated by percutaneous intervention has increased from 29% to 40% over the six years. The number of patients undergoing percutaneous intervention for single vessel disease has also increased. The increase exceeds that demonstrated for multi-vessel disease. Therefore, the percentage of patients undergoing percutaneous coronary intervention who have multi-vessel disease has, in fact, fallen from 55% to 43%. The increase in percutaneous intervention for single vessel disease suggests that the threshold for percutaneous coronary intervention has probably fallen over time. Some patients with single vessel disease who now undergo percutaneous coronary intervention would not have undergone revascularisation in previous years.

0

10

20

30

40

50

60

70

80

90

100

97/98 98/99 99/00 00/01 01/02 02/03

Year

Per

cent

age

with

mul

ti-ve

ssel

dis

ease

CABGPCI

Severity of cardiac disease

11

Overall, 20% of coronary artery bypass grafting is performed as an urgent or emergency procedure. This figure has remained relatively stable over the last six years. Percutaneous coronary intervention is more likely to be performed as an urgent or emergency procedure. Also the percentage of percutaneous interventions performed as urgent or emergency procedures has steadily increased from 38% to 52%. A number of studies have suggested that percutaneous coronary intervention can be an effective emergency treatment for myocardial infarction (heart attack) in some patients. It can remove the blockage in the artery before the heart muscle is damaged irreparably due to lack of oxygen and in some situations may be more effective than the current treatment of dissolving the clot with thrombolytic drugs. However, this requires that patients admitted with heart attacks have rapid access to catheter laboratories and interventional cardiologists irrespective of the hospital they attend or the time of day. In Scotland, primary angioplasty is used relatively infrequently and less often than in a number of other countries, such as the USA and Germany. It is likely that the percentage of percutaneous coronary interventions performed as non-elective procedures will increase further in the future.

0

10

20

30

40

50

60

97/98 98/99 99/00 00/01 01/02 02/03

Year

Per

cent

age

as u

rgen

t / e

mer

genc

y

CABGPCI

Urgency of procedures

12

Although some patients may be suitable candidates for either bypass grafting or percutaneous coronary intervention, some are only suitable for one or other procedure. Therefore, in order to be able to draw fairer comparisons between the two procedures, the following figures exclude: • urgent and emergency procedures, • procedures done during the same operation as another procedure

(eg. bypass surgery done during the same operation as valve replacement), and • patients who have undergone previous cardiac surgery Therefore the results are based on 18,081 coronary revascularisations, of which 11,369 (63%) were coronary artery bypass grafts and 6,712 (37%) percutaneous coronary interventions.

Because of the increase in overall life-expectancy and improved survival among patients with coronary artery disease, there are an increasing number of elderly patients with coronary artery disease in the general population. Cardiac surgery has become increasingly safe in elderly patients. In young patients suitable for both forms of revascularisation, percutaneous coronary intervention is increasingly considered the preferred option in order to postpone the need for cardiac surgery. Hence, over the past six years, the percentage of coronary artery bypass grafts performed on patients over 75 years of age has steadily increased from 4% to 7%. There has been no consistent trend in the age breakdown of patients undergoing percutaneous coronary intervention.

0

2

4

6

8

97/98 98/99 99/00 00/01 01/02 02/03

Year

Per

cent

age

>75

year

s

CABGPCI

Age

Selected Procedures

13

Within the general population, the percentage of people who are obese is steadily increasing. Obesity increases the risk of developing coronary artery disease and confers a worse prognosis in those who develop it. In line with the general population, the percentage of patients undergoing percutaneous coronary intervention who are obese (body mass index ≥30) has steadily increased from 24% to 30%. By contrast, the percentage of patients undergoing coronary artery bypass surgery who are obese has remained relatively stable. Obesity increases the risks associated with cardiac surgery. Therefore, this is likely to reflect patient and procedure selection.

05

10152025303540

97/98 98/99 99/00 00/01 01/02 02/03Year

Per

cent

age

who

are

obe

se

CABGPCI

Among obese patients undergoing revascularisation, the percentage undergoing percutaneous interventions has increased from 23% to 30%.

0

10

20

30

40

50

60

70

80

90

97/98 98/99 99/00 00/01 01/02 02/03

Year

Per

cent

age

unde

rgoi

ng p

roce

dure

CABGPCI

Obesity

14

The prevalence of diabetes mellitus in the general population is increasing. This is particularly true of type II diabetes which is associated with obesity. Diabetes mellitus increases the risk of developing coronary artery disease. It is also associated with a worse prognosis once coronary artery disease occurs. Patients with diabetes mellitus can be more difficult to revascularise because they tend to have more widespread disease including both large and small arteries. Overall, the percentage of patients with diabetes mellitus has increased from 14% to 18% among patients undergoing coronary artery bypass grafting and from 9% to 13% among patients undergoing percutaneous coronary intervention.

0

2

4

6

8

10

12

14

16

18

20

97/98 98/99 99/00 00/01 01/02 02/03

Year

Per

cent

age

with

dia

bete

s

CABGPCI

The increase in the percentage of patients with diabetes mellitus has been greater for percutaneous coronary intervention than coronary artery bypass grafting. As a result, among diabetic patients undergoing revascularisation the percentage treated by percutaneous intervention has increased from 22% to 33%.

Diabetes

15

Even when restricted to diabetic patients with multi-vessel disease, use of percutaneous intervention has increased from 14% to 21%. One research study has suggested that diabetic patients with multi-vessel disease may have a better prognosis following coronary artery bypass grafting than percutaneous coronary intervention. However this result has yet to be corroborated by randomised trials.

0102030405060708090

97/98 98/99 99/00 00/01 01/02 02/03

Year

Per

cent

age

unde

rgoi

ng

proc

edur

e

CABGPCI

16

Fig. 10 % hypertensive The percentage of patients who have hypertension has increased from 43% to 59% for coronary artery bypass grafting and from 30% to 46% for percutaneous coronary intervention.

0

10

20

30

40

50

60

70

97/98 98/99 99/00 00/01 01/02 02/03

Year

Per

cent

age

with

hyp

erte

nsio

n CABGPCI

Left ventricular function is a measure of how well the heart is performing as a pump. Patients with poor left ventricular function have a worse prognosis irrespective of how they are treated. Over the past six years, the percentage of patients undergoing percutaneous coronary intervention who have moderate or severe impairment of their left ventricular function has increased from 29% to 40%.

0

10

20

30

40

50

97/98 98/99 99/00 00/01 01/02 02/03

Year

Per

cent

age

with

poo

r LV

fu

nctio

n

CABGPCI

Hypertension

Left ventricular function

17

In general, coronary artery bypass grafting provides a more definitive treatment for narrowed or blocked arteries. Therefore, it tends to be longer after surgery before symptoms recur and a second procedure needs to be considered. However, this needs to be weighed against the fact that coronary artery bypass grafting is a major operation and therefore carries a higher risk of death and complications at the time of the procedure. Among patients undergoing a first elective revascularisation procedure, the risk of dying within 30 days was 0.3% for percutaneous intervention and 2% for coronary artery bypass grafting. The relative risks and benefits of the two procedures need to be considered by individual patients in consultation with their doctor, taking account of the extent of their cardiac disease, their symptoms and prognosis, and their surgical and anaesthetic risk. As shown in previous sections, patients undergoing coronary artery bypass surgery are now more likely to be elderly, diabetic and hypertensive. Therefore they are at greater overall risk from surgery as demonstrated by the increase in their Parsonnet score. Despite this, the percentage of patients dying during or immediately after bypass surgery has fallen over the past six years. This suggests that the decline in death rates is an underestimate of the increasing safety of surgery.

0

1

2

3

4

5

6

7

97/98 98/99 99/00 00/01 01/02 02/03

Year

Parsonnet score% died

Risk of death and repeat revascularisation

18

The improvements over time in early survival following coronary artery bypass grafting are maintained in the medium term. Therefore, patients are now more likely to be alive two years after surgery than they were four years ago.

Years

210

Sur

viva

l1.0

.9

.8

As mentioned in previous sections patients undergoing percutaneous coronary interventions are now more likely to have coronary stents inserted. As a result of this, and other developments, the risk of patients requiring a second revascularisation procedure following percutaneous coronary intervention has fallen over the past four years.

Years

210

Rep

eat r

evas

cula

risat

ion

.2

.1

0.0

1997/1998

1997/1998

2000/2001

2000/2001

19

Cardiac transplantation is undertaken at the Glasgow Royal Infirmary. The transplantation unit was temporarily closed during 2000/2001 due to staff shortages but re-opened in September 2001. Since then, the number of transplants performed each month has been fairly constant. Since, reopening the unit a total of 27 patients have undergone transplantation. Around 160 patients who have undergone transplantation are currently under long-term follow-up.

0

5

10

15

20

25

30

35

40

Jan-93 Jan-94 Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04

Num

ber o

f tra

nspl

ants

in p

revi

ous

12 m

onth

s

Half of the patients who undergo cardiac transplantation survive at least 10 years.

Years

1086420

Sur

viva

l

1.0

.9

.8

.7

.6

.5

.4

Cardiac transplantation

20

Cardiac transplantation Cardiac transplantation

Between April 1997 and March 2003, the overall number of coronary revascularisations performed each year has steadily increased. This is largely due to percutaneous coronary intervention being performed on patients with single vessel disease, some of whom would not previously have undergone revascularisation. These are a relatively low risk group of patients. However, in other respects the risk profile of patients undergoing revascularisation has got worse over time. There has been an increase in the percentage of patients who are elderly, diabetic, obese, hypertensive or have poor left ventricular function. Also, the number of percutaneous coronary interventions performed as emergencies for acute coronary syndromes (unstable angina or myocardial infarction/heart attack) has increased. The increase in the risk profile of patients has been more than offset by the benefits of a number of technical and therapeutic developments that have combined to improve prognosis in a number of regards. For example, the risk of dying during or immediately after surgery has fallen. This benefit is maintained over the longer term so that patients are now more likely to be alive two years after bypass surgery than they were six years ago. The percentage of percutaneous interventions that include insertion of coronary stents has doubled. As a result the need for repeat revascularisation procedures has fallen. Since the cardiac transplantation unit reopened in September 2001, 27 patients have undergone transplantation in Scotland. The long term results are good with more than half of patients surviving 10 or more years after transplantation. In conclusion, an increasing number of patients now have access to revascularisation and transplantation within Scotland and there is evidence that the outcome of these procedures is steadily improving.

Summary

21

CABG coronary artery bypass grafting

diabetes mellitus includes both type I and type II

emergency revascularisation performed within 24 hours of referral

GRO General Registrar’s Office hypertension systolic blood pressure ≥140mmHg,

diastolic blood pressure ≥90mmHg, or patient taking anti-hypertensive drug therapy

moderate left ejection fraction 30%-50% ventricular impairment severe left ejection fraction <30% ventricular impairment NHS National Health Service obese body mass index ≥ 30 PCI percutaneous coronary intervention

(includes coronary angioplasty and stenting) isolated excludes coronary artery bypass grafting

performed during the same operation as another surgical procedure, such as valve replacement.

multi-vessel disease more than one coronary artery with a significant

(≥70%) stenosis/narrowing Parsonnet score composite measure of a patient’s overall risk

from coronary artery bypass surgery SMR Scottish Morbidity Record urgent revascularisation performed during the same

admission as referral (because the patient was unfit to be discharged home)

Appendix A. Definitions and Abbreviations

22

Cardiac Surgery Steering Group

Geoff Berg Western Infirmary, Glasgow Ian Colquhoun Glasgow Royal Infirmary Kenneth Davidson Golden Jubilee National Hospital Hussein El-Shafei Aberdeen Royal Infirmary Alan Faichney Western Infirmary, Glasgow Mike Higgins Glasgow Royal Infirmary Bob Jeffrey (1996-2003) Aberdeen Royal Infirmary Pankaj Mankad (1996-2003) Royal Infirmary, Edinburgh Andrew Murday Glasgow Royal Infirmary Jill Pell (Chairman) Greater Glasgow NHS Board Rachel Slack Greater Glasgow NHS Board Vipin Zamvar Royal Infirmary, Edinburgh

Percutaneous Coronary Intervention / Coronary Angiography Steering Group

Steven Cross Raigmore Hospital, Inverness Andy Flapan Royal Infirmary, Edinburgh Hani Eteiba Glasgow Royal Infirmary John Gemmill (2000-2002) Ayr Hospital Stuart Hillis Western Infirmary, Glasgow Kerry Jane Hogg(1997-2003) Glasgow Royal Infirmary Kevin Jennings Aberdeen Royal Infirmary Helen Papaconstantinou Inverclyde Hospital, Greenock Alastair Pell Monklands Hospital, Airdrie Jill Pell (Chairman) Greater Glasgow NHS Board Stuart Pringle Ninewells Hospital, Dundee Rachel Slack Greater Glasgow NHS Board Ian Starkey Western General Hospital, Edinburgh Graham Tait Dumfries and Galloway Royal Infirmary Simon Woldman Ayr Hospital

IT support and Data Coordinators

Fiona Bett Western General Hospital, Edinburgh Jim Christie Western Infirmary, Glasgow Irene Crawford Golden Jubilee Hospital, Glasgow Heather Fitzpatrick Dumfries and Galloway Royal Infirmary Jackie Howlett Royal Infirmary, Edinburgh Margaret Kinnaird Western Infirmary, Glasgow Ann Mackintosh Ninewells Hospital, Dundee Alison McOuat Glasgow Royal Infirmary Hilary Milne Aberdeen Royal Infirmary Tanya Schofield Aberdeen Royal Infirmary Alison Smith Raigmore Hospital, Inverness Mark Watts Glasgow Royal Infirmary Jim Young Hairmyres Hospital, Airdrie John Zarecki Royal Infirmary, Edinburgh

Appendix B. Members of the Scottish Coronary Revascularisation Steering Groups

ISBN 0 948310 44 8