HRQoL after coronary artery bypass grafting and percutaneous coronary intervention for stable angina

Abstract

Objectives. To assess the health related quality of life (HRQoL) and the change in the NYHA class after coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI) in the management of stable coronary artery disease (CAD). The study was non-randomized. CABG group consisted of 240 patients and 229 patients were treated with PCI. HRQoL was measured prospectively by the 15D instrument. Results. Three-year survival was 95.0 and 95.6% (NS). The HRQoL improved statistically in both groups until 6 months after treatment but deteriorated towards the end of the follow-up of 36 months. Clinically evident improvement of the HRQoL and decrease of the NYHA class took place more frequently among CABG patients. Conclusions. Despite initially more serious preoperative state and more demanding procedure CABG patients achieve equal level of HRQoL when compared with PCI patients. CABG patients may also obtain better relief from symptoms in mid-term follow-up. HRQoL cannot be the only factor to determine outcome after invasive treatment of CAD but it has to be placed in the context of the overall situation.

• HRQoL
• CABG
• PCI
• 15D

The efficacy and relative benefits of coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) have been compared in several randomized and observational studies 1–5. When selecting mode of treatment for coronary revascularization, the technical outcome may not be the only consideration. Post procedural health status, including symptoms, functionality and quality of life is also an important end point 6–8. In the present prospective study, we aimed to assess the health related quality of life (HRQoL) and change in physical performance after CABG or PCI in the management of initially stable coronary artery disease (CAD) during 36-month follow-up.

Material and methods

A total of 1 330 patients were referred for coronary artery angiography and included in a prospective study on HRQoL between October, 2000 and January, 2003 (Figure 1). Patients with stable angina and with invasive treatment, CABG or PCI, were included the present survey. The Ethical Board approved the study. All patients provided informed consent before participation. The research nurse interviewed the patients before angiography in order to elicit basic HRQoL. Patients were assessed with follow-up questionnaires, which were mailed after 6 months and after 18 months and with a follow-up visit by the research nurse after 36 months. The option for treatment based on the findings of the coronary angiography. Lesions with stenosis of more than 50% of the luminal diameter in a coronary artery were considered significant on the diagnostic angiogram. A cardiologist usually opted for PCI whereas CABG was always discussed by cardiologists and cardiac surgeons. Thus the patient cohort represents a contemporary real-world sample. 240 patients were referred to CABG aiming at optimal coronary revascularization and 229 patients were treated with PCI intended to dilate the culprit lesion(s) of the coronary arteries. The primary outcome measure was determination of postprocedural HRQoL. Secondary outcomes included all cause mortality and performance status after 36-month follow-up.

Figure 1.  Inclusion flow chart of the patient material.

Data were collected prospectively in an institutional cardiological and surgical database. It included information about risk factors, admissions, procedures and discharge status of patients, but also findings of repeat angiograms or repeat interventions. Pre- and perioperative variables were defined according to the Society of Thoracic Surgeons (STS) definitions. Survival analysis was based on the Finnish nationwide population registry.

HRQoL was measured by the 15D instrument, a generic and standardized self-administered measure 9, which has also been tested for invasive treatment of CAD 8, 10. It describes the health status along 15 dimensions 9, 10, which cover the physical, psychological and social aspects of health defined by the World Health Organization (WHO). Each dimension comprises five response options. The 15D produces a single score on a 0-1 scale, 15D score, which represents overall HRQoL. A maximum score 1 indicated no problems on any dimension and the minimum score 0 signifies being dead. The follow-up analysis was performed between surviving patients. In case of drop-out the patient was monitored and taken into account until the last completed questionnaire. The same concerns deceased patients (15D score=0), which were excluded from statistical analysis from the time of death onwards. The minimum clinically and practically important change in the 15D score which the patients on average can feel as a change was defined as =0.03 or =−0.03, correspondingly 11, 12. Physical performance was defined according to the New York Heart Association (NYHA) classification and recorded both preoperatively and at the follow-up visit after 36 months.

Demographic characteristics and post procedural outcome variables are presented as percentages. Continuous variables are reported as mean±standard deviation (SD) or as median [range]. Cumulative survival was calculated using the Kaplan-Meier method supplemented with log-rank test to compare survival between the groups. Baseline and follow-up variables were compared using Pearson χ² Test and Mann-Whitney U-test. Differences of 15D scores between study groups were assessed by the paired samples test. Statistical analysis was performed using SPSS 14.0 statistical software for Windows. All reported p-values are two-sided and p<0.05 was considered statistically significant.

Results

The median follow-up was 36.0 months. 30-day mortality was 0.8% (2 patients) in the CABG group and 0% in the PCI group. Three year survival was 95.0 and 95.6%, correspondingly (p=0.677). The mean age as well as the patients′ age distribution was even between the groups. The proportion of female patients was significantly higher in the PCI group (p=0.004). The structural (i.e. coronary artery lesions) and the functional status (i.e. ejection fraction, EF) of the heart was poorer in CABG patients. The same concerns preoperatively higher NYHA Class of CABG patients (Table I). A median of 4 (range 1–7) anastomoses was performed surgically. The median number of coronary artery lesions treated by PCI was 1 (range 1–3). Coronary stenting with an available stent was performed in 87% of procedures.

Table I.  Baseline characteristics.

Characteristics	CABG (n=240) %	PCI (n=229) %	p-value
Age, years (SD)	66.1 (8.8)	64.5 (10.2)	0.064
Sex
Female	20.6	31.4	0.004
Age groups			0.164
<65 yr	39.2	47.6
65 – 74 yr	44.2	36.7
>75 yr	16.7	15.8
LVEF			<0.001
< 30%	2.9	1.3
30 – 50%	42.1	17.9
> 50%	54.5	59.8
Previous MI	33.3	24.5	0.042
Hypertension	54.6	57.6	0.516
Hyperlipidaemia	73.3	69.4	0.359
Diabetes	25.8	18.3	0.059
COPD	10.0	10.0	1.000
ASO	10.8	8.3	0.433
Previous PCI	5.0	7.9	0.258
Previous CABG	3.3	8.3	0.028
NYHA Class			<0.001
Class I	2.1	11.4
Class II	44.2	45.0
Class III	47.9	39.7
Class IV	5.8	3.9
Data missing	0.4	21.3
LMCA stenosis>50%	29.6	2.2	<0.001
No. of diseased vessels			<0.001
3-VD	65.0	14.8
2-VD	28.8	34.9
1-VD	6.3	50.2

LVEF, left ventricular ejection fraction; MI, myocardial infarction; COPD, chronic obstructive pulmonary disease; ASO, arteriosclerosis obliterans (peripheral or carotid artery disease); NYHA, New York Heart Association; LMCA, left main coronary artery; VD, vessel disease.

Complete 15D data were received on 93.4% of surviving CABG patients and on 94.9% of surviving PCI patients. The mean 15D score reflecting the preoperative quality of life, was 0.8275 (SD 0.0891) for CABG patients and 0.8321 (SD 0.0986) for PCI patients (NS). In the follow-up the mean 15D score improved significantly from the preoperative level until six months in both groups (0.8579, SD 0.1095, p<0.001 for CABG and 0.8456, SD 0.1054, p=0.009 for PCI group). Thus, the change was statistically significant in both groups and clinically relevant for the CABG patients. The mean 15D score deteriorated during the later observation period and returned to the same level as before the intervention in both groups by 36 months (Figure 2). Changes in the 15D score occurred as a function of time, but when the mean 15D score was compared between the study groups at different observation times no statistical difference was found. This finding was also independent of age.

Figure 2.  15D level score of the study groups at follow-up control points. Statistical difference is reported against preoperative level separately for CABG and PCI patients.

During the first six months after intervention improvement was seen in six dimensions (moving, breathing, usual activities, discomfort, distress and symptoms, vitality) among the CABG patients and in five dimensions (breathing, usual acitivites, discomfort, depression, vitality) among the PCI patients. Up to 36 months a significant improvement was still seen in breathing, in distress and symptoms and in vitality among the CABG patients and in breathing among the PCI patients. Five dimensions of the 15D (mobility, breathing, usual activities, discomfort and symptoms and vitality) describe the physical experiences of humans and may be important in estimating development of HRQoL after invasive treatment for CAD patients. In CABG patients all mentioned dimensions improved during the first six months after the intervention, whereas PCI patients improved on four of these dimensions. Clinically relevant improvement was more frequent in the CABG group as compared to the PCI group (Table II).

Table II.  Clinically noticeable change of HRQoL among the study groups.

	CABG		PCI
	No. of patients	%	No. of patients	%	p-value
Clinical improvement
0 – 6 months	113/231	48.9	82/224	36.6	0.008
0 – 36 months	86/216	39.8	58/210	27.6	0.010
Clinical impairment
0 – 6 months	50/231	21.6	56/224	25.0	0.438
0 – 36 months	78/216	36.1	69/210	32.9	0.541

We also compared the 15D profile of the study cohort with a sample of 4 603 age- and sex-matched people from the Health 2000 project of the Finnish National Public Health Institute. The 15D score of the population was still higher than that of the study cohort 36 months after treatment. The statistical difference was highly significant in six dimensions (seeing, breathing, sleeping, usual activities, discomfort and symptoms, vitality and sexual functioning) in favour of population and significant on three other dimensions (moving, seeing and hearing) (Figure 3).

Figure 3.  15D profiles and scores of the study cohort of CABG and PCI patients 36 months after treatment in comparison to the reference population. ^*p<0.05, **p<0.001.

A total of 85.9% of CABG patients and 67.5% of PCI patients experienced improvement of the performance state and their NYHA Class was at least one step lower after three years than before the treatment (p<0.001). Moreover, 68.3% of patients in CABG group and 58.3% in PCI group reported they were asymptomatic in their normal lives after 3 years (p=0.022). Postoperative NYHA differed significantly between the two treatment groups (Mann-Whitney U-test p=0.025). Patients in the PCI group also underwent both repeat PCI (14.8 vs. 1.3%, p<0.001) and repeat CABG (5.7 vs. 0.8%, p=0.003) significantly more frequently in comparison to CABG patients within the following 3 years after the initial intervention.

Discussion

Functional status and quality of life are important outcomes of mechanical interventions for patients with CAD. The focus of the care is to restore the quality life of individual CAD patients to as normal as possible. Randomized clinical trials have demonstrated the superiority of CABG to medical management for patients with CAD 17, 18. Coronary angioplasty, too, improves substantially patient-perceived physical functioning and vitality as compared with continued medical treatment 19. Both CABG and PCI improve significantly rates of early death, myocardial infarction, relief from angina and angina-related health status 16, 20, 21. Moreover, bypass surgery and angioplasty improve quality of life for patients with chronic stable angina 4, 7, 8, 13, 14. On the other hand, when compared with PCI, CABG is associated with lower middle-term mortality, less angina and fewer repeat revascularization procedures 15 and better health status and quality of life 4, 16.

In the present study we analyzed two non-randomized patient groups in an attempt to ascertain the change of HRQoL after invasive intervention for CAD. The groups were constituted on a clinical basis according to the coronary angiography findings, thus representing a real-world sample. This kind of setting allows at most comparison inside the treatment group but a cautious comparison between the two treatments. Although general risk factors and coexisting diseases occurred evenly, the groups differed significantly by coronary anatomy and by physiological performance of the heart. However, despite both poorer performance and more numerous and diffuse coronary artery lesions the baseline HRQoL of CABG patients did not differ from that of PCI patients. The finding may indicate quite poor correlation between severity of CAD and HRQoL.

In our study both CABG patients and PCI patients achieved a statistically better HRQoL 6 months postoperatively in comparison to baseline. In the CABG group the improvement was seen despite of poorer baseline state, i.e. seriousness of coronary angiography findings or functional state of the heart. Later on HRQoL continued to progress similarly towards the end of the study period and declined to the preoperative level at 36 months after the intervention in both groups. Of single dimensions breathing and vitality improved in both groups during the first months after treatment and breathing continued to be improved in long-term follow-up in both groups. Ease of breathing may best indicate relief from symptoms of CAD, while the 15D lacks a descriptive dimension for chest pain. Decrease in the NYHA class, which was detected in both groups, supports this assumption. Subsequent impairment of HRQoL may depend much on natural changes of the senses or autonomic functions of the body in advanced ages.

The 15D also provides an opportunity to estimate a clinically important or clinically relevant change in the HRQoL of an individual or of a group of individuals. CABG patients experienced a greater clinical improvement in HRQoL compared to PCI patients throughout the follow-up. On the other hand as many as one third of patients in both groups reported clinically poorer HRQoL after 36 months. This may be a surprising but also an expected finding as we remember that generic instruments consider physical, psychological and social aspects of life as a whole for estimating HRQoL. The normal ageing process also affects numerous dimensions by which the instrument used assesses quality of life. It is also worth considering patients who achieved a score change greater than -0.03 but less than 0.03. This group included e.g. individual patients with initially high state of HRQoL. Thus, a clinically relevant change of the 15D score may not be attainable despite relief from the symptoms the patients had been treated for. The same concerns preoperatively coexisting or subsequent diseases, which substantially may effect on HRQoL.

The present study has limitations, which should be considered in the interpretation of the results. This is a single-center study, neither random nor totally consecutive, but is based on clinical practice. The background for the study was angina, for which patients were referred to undergo invasive assessment. The treatment option was decided by the physician. The severity of the underlying CAD and the selection of the treatment mode is a problem. In clinical practice it is expected that the more severely or diffusely the coronary arteries are diseased the more likely the option for treatment is surgery. On the other hand, single VD is treated by catheterization technique rather than surgery. The possible selection bias is only partly redressed by a fairly even distribution of patients regarding demographic characteristics and coexisting conditions among the groups. However, the decision-making and the character of interventions was stable throughout the study period as most of the operations were conventional procedures with cardiopulmonary bypass and in most of the percutaneous interventions stenting was used. In addition, the baseline HRQoL of patients was elicited before coronary angiography and subsequent evaluation was prospective. A disease specific measure might have been worth considering in addition to the generic instrument used in assessing outcome.

Conclusions

On the basis of our study results we conclude that both CABG and PCI improve the HRQoL of CAD patients with stable angina. The change takes place as a function of time in both groups and is most significant during the first months after coronary revascularization. There is no significant difference between the groups when HRQoL is compared at different follow-up time points. CABG patients may experience a better clinical improvement in HRQoL and higher performance status during mid-term follow-up. To achieve the observed improvement CABG patients are subjected to more demanding and complicated procedure, whereas PCI patients may need significantly more auxiliary examinations and repeat interventions later on to reach the same outcome. HRQoL cannot be the only factor to determine outcome after invasive treatment of CAD but it has to be placed in the context of the overall situation.

Acknowledgements

The study was supported by the Medical Research Fund of Vaasa Hospital District, Finland. The paper has been presented as abstract in 18^th World Congress of the World Society of Cardio-Thoracic Surgeons, April 30-May 3, 2008, Kos, Greece.