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(Circulation. 2000;102:1245.)
© 2000 American Heart Association, Inc.
Clinical Investigation and Reports |
Relationship of Infarct Artery Patency and Left Ventricular Ejection Fraction to Health-Related Quality of Life After Myocardial Infarction
The GUSTO-I Angiographic Study Experience
From the George Washington University Cardiovascular Research Institute (K.S.C., C.F.L., D.B., Y.C.D., P.W., A.M.R.), Washington, DC; MEDTAP International (K.S.C.), Bethesda, Md; and The George Washington University Biostatistics Center (S.W.G.), Washington, DC.
Correspondence to Karin S. Coyne, PhD, RN, MPH, MEDTAP International, 7101 Wisconsin Ave, Suite 600, Bethesda, MD 20814. E-mail coyne{at}medtap.com
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Abstract |
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Background—Post–myocardial infarction global ejection fraction and infarct-related artery patency might be expected to be associated with health-related quality-of-life (HRQOL) outcomes, but this association has not been previously shown. The GUSTO-I Angiographic Study cohort 2-year follow-up afforded an examination of such potential relationships.
Methods and Results—A total of 1848 patients (87.7% response rate) who were enrolled in the GUSTO-I Angiographic Study were contacted for a telephone interview regarding their current HRQOL (physical function, psychological well-being, perceived health status, and social function) 2 years after MI. In multivariable models, left ventricular ejection fraction (EF) was significantly related to physical (P=0.021) and social (P=0.014) function, psychological well-being (P=0.042), and perceived health status (P=0.024). Infarct-related artery patency was not directly related to any HRQOL outcome. A decreasing EF was predictive of poorer outcomes in each HRQOL dimension. Men consistently had better outcomes in all HRQOL dimension with the exception of perceived health status. Increasing age was predictive of poorer outcomes in all dimensions of HRQOL except for psychological well-being where the inverse occurred; younger patients experienced greater depression, anxiety and worry than their older counterparts. The presence of comorbidities increased the likelihood of worse outcomes in all dimensions.
Conclusions—This is the first study to demonstrate a significant relationship between EF and long-term HRQOL outcomes. This advantage in left ventricular function preservation should be added to the mortality advantage when considering the impact of treatment strategies for myocardial infarction.
Key Words: myocardial infarction • quality of life • left ventricular function • patency • sex
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Introduction |
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Each year,
1.1 million persons have a
myocardial infarction (MI), with the majority surviving the acute
event.1 Increases in survival after MI can in large part
be attributed to aggressive therapies that limit myocardial damage by
achieving infarct-related artery (IRA) patency and preserving left
ventricular (LV) function.2 3 4 In addition to
the mortality advantage of patent infarct arteries and preserved LV
function, advantages might also be expected to be seen in
health-related quality-of-life (HRQOL) outcomes, which are based on the
premise that a person’s clinical status affects his or her quality of
life.5 6 Unfortunately, despite the plethora of HRQOL
research on MI survivors, a relationship between
physiological outcome after MI (namely, LV
function) and HRQOL has yet to be demonstrated.7 8 9 10 11
Furthermore, the effect of patency on HRQOL outcomes has not yet been
reported. The GUSTO-I Angiographic Study, which has a large single-source angiographic database of acute MI patients, permits the relationship between physiological outcome and HRQOL to be fully examined. The purpose of the present study was to test the hypotheses that (1) patients with patent arteries at 90 minutes would report higher HRQOL 2 years after MI than would those with closed arteries and (2) patients with quantitatively better LV function would report better HRQOL 2 years after MI than would those with depressed LV function.
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Methods |
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Patients
Patients from 75 centers in 10 countries were recruited into the GUSTO-I Angiographic Study12 from June 1991 through February 1993. The eligibility criteria have been previously described.13 Patients were contacted for telephone interviews during the follow-up period from February 1994 through July 1995. Patients randomized into the GUSTO-I Angiographic Study were contacted by clinical site personnel 2 years after their GUSTO-recorded MI. For sites at which patients could not be contacted for follow-up interviews, trained interviewers at central facilities in Leuven, Belgium, and Washington, DC, interviewed patients. When patients could not be interviewed due to extraneous factors (eg, no translation available, incarceration), vital status was obtained. To standardize the interview process, all interviewers were trained and given detailed scripts to read during the interview. The follow-up study was either approved or exempted by the institutional review board or ethical committee of all participating hospitals. Patients provided verbal consent at the start of the telephone interview. All patients were given the opportunity to refuse participation, to not answer specific questions, or to terminate the interview at any time.
Angiographic Core Laboratory
The assessments of LV function and coronary artery
patency were described previously.12 Patients were
randomized to 1 of 4 treatment regimens13 and to 1 of 4
angiographic time periods (90 or 180 minutes, 24 hours, or 5 to 7
days). Patency was assessed according to Thrombolysis in
Myocardial Infarction (TIMI) flow grade14 ; only the
90-minute patient cohort was used for the patency analysis.
Left ventriculograms were obtained in a 30° right anterior oblique
projection within a relatively narrow time window after MI (median
4.9 days after MI [25th/75th percentiles 0.185, 6.48 days]). All
ejection fractions (EFs) were calculated in a standardized manner with
the area-length method15 with ventriculographic
silhouettes being acquired digitally at end systole and end
diastole and the borders defined by a core laboratory
angiographer.
HRQOL Assessment
HRQOL was defined as a multidimensional concept that reflects a
person’s perception of their physical, psychological, and social
function and health status.16 17 A battery approach, which
combines previously validated generic and disease-specific
questionnaires to create a multidimensional profile, was used to
capture HRQOL.18 Each questionnaire was translated into
Dutch, French, German, and Spanish through forward-backward methodology
with an expert review of the final translation.19
The "physical function" dimension of HRQOL was assessed with the Duke Activity Status Index,20 which was developed specifically to evaluate physical activities in cardiac populations. "Psychological well-being" was measured with the emotional component of the Minnesota Living With Heart Failure Questionnaire21 (modified in wording only to "living after a heart attack"). "Social function" was assessed with 2 questions: 1 from the SF-3622 and 1 from the Minnesota Living With Heart Failure Questionnaire. "Perceived health status" was assessed with the general health component of the Medical Outcomes Study SF-36,22 which has been used in a multitude of clinical settings as a "direct" evaluation of a person’s personal health.
Symptoms
Cardiac symptoms (dyspnea and angina) were treated as an
antecedent or a contributing factor to HRQOL, with the incidence of
each reported descriptively. Symptoms were assessed according to the
Rand Dyspnea Severity Scale23 and the Rose Angina
Questionnaire.24 The Rand Dyspnea Severity Scale
was scored by creating a Guttman Scalogram with 5 levels (from 0 for no
dyspnea to 4 for severe dyspnea).23 Angina was scored
dichotomously.
All selected questionnaires have previously demonstrated reliability and validity.8 9 11 20 21 22 23 24 25 26 27 28 The occurrence of repeat hospitalizations during the 2-year period and current medication use were also assessed. Test-retest reliability was assessed by contacting a subset of patients for a second interview within 10 to 20 days after the first interview.
Statistical Analysis
Descriptive statistics for continuous end points are
presented as median and interquartile range values and as
percentages for discrete variables. To facilitate subgroup
analyses by country, all participating European countries were
analyzed as 1 country, resulting in the following groups:
Australia, Canada, Europe, and United States. Test-retest reliability
was assessed with intraclass correlations for continuous variables
and Cohen’s 
for discrete or ordinal data.29 The
internal consistency of each dimension was assessed using
Cronbach’s 
.30 Group differences were evaluated with
contingency tables for categorical variables and ANOVA for
continuous variables. The Student-Newman-Keuls procedure was
applied a posterior to identify differences in continuous
group mean values.31
Responses from this fairly healthy patient sample were not normally distributed; thus, multivariate logistic regression was used to further test the study hypotheses. Outcome variables were made dichotomous with patients who scored in the worst 25th percentile of each dimension considered to represent an "event"; patients outside of the worst 25th percentile were considered to represent a nonevent.32 TIMI and EF models were conducted separately with the same covariates in each model. The Hosmer and Lemeshow goodness-of-fit test was used to evaluate model fit, with a nonsignificant P value indicative of adequate fit.33 Covariates placed in all models were age, sex, body mass index, treatment group, location of infarction, previous MI, previous CABG, diabetes, hypertension, hyperlipidemia, and a composite score of in-hospital events. The in-hospital event score was created as an index of the patient’s severity of illness during acute hospitalization and was calculated by summing the occurrence of the following events: major bleeding, stroke, congestive heart failure/pulmonary edema, reinfarction, recurrent ischemia, atrial fibrillation, defibrillation, permanent pacemaker insertion, and CABG. Patients with incomplete data were excluded from multivariable modeling. All probability values reported were 2-tailed; a level of P<0.05 defined statistical significance.
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Results |
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Of the original 2431 patients, 323 died before the 2-year follow-up. Of the remaining 2108 patients, a total of 1848 patients responded to the telephone interview (response rate 87.7%), 56 (2.6%) were lost to follow-up, 86 (4.1%) refused to be interviewed, and 118 (5.6%) were unable to be interviewed. Of the 1848 interviews, 17 were obtained via proxy and subsequently excluded from analysis. The median time to contact patients was 2.2 years (mean 2.3 years). Table 1
displays the baseline
characteristics of the interviewed patients versus those who were not
interviewed. Deceased patients had been significantly older with more
comorbidities and lower EFs than the other patients. Each instrument of
the HRQOL battery demonstrated high internal consistency
and test-retest reliability. Tables 2 and 3 display the scores for each dimension
of HRQOL and the frequency of dyspnea and angina by patency grade and
EF. There were no differences in HRQOL outcomes by initial patency
grade except patients with closed arteries (TIMI 0 or 1) reported
significantly more angina (P=0.03) at 2 years than did those
with patent arteries. When the final IRA patency grade was assessed in
patients who had emergent PTCA (15.4%), there were no significant
differences in HRQOL outcomes or symptoms. For descriptive purposes
only, EF was dichotomized at 40% to emphasize differences in HRQOL
according to good versus poor LV function. EFs of 
40 were associated
with poorer function in each dimension, more dyspnea and angina, and a
greater rehospitalization rate at 2 years after MI. Significant
differences also existed between men and women, with women reporting
significantly poorer HRQOL in each dimension and experiencing more
dyspnea than men. There were no sex differences in rehospitalization
rates. No differences were noted in HRQOL scores across country or
treatment groups.
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To further examine the effects of patency and EF on HRQOL,
multivariable models were performed. TIMI flow was not a
significant predictor in any of the HRQOL dimensions examined in the
present study. In contrast, EF (as a continuous variable) was a
significant predictor of all HRQOL outcomes (Table 4). Female sex was predictive of a poorer
HRQOL outcome in 3 of 4 dimensions. Increasing age was a significant
predictor in each HRQOL dimension with the exception of psychological
well-being, where the inverse occurred. The calculated probabilities of
poor physical function and poor psychological well-being given the
effects of EF, sex, age, and comorbidities are displayed in Figures 1 and 2,
respectively. Women consistently had higher probabilities of
poorer outcomes than men, and the presence of comorbidities
additionally compounded the probability of a poorer outcome for both
sexes. Important to note (Figure 2), age was inversely related
to psychological well-being, indicating that younger patients
experienced greater psychological distress (eg, depression and worry)
after MI. A 50-year-old patient with no comorbidities has essentially
the same probability of a poor psychological well-being as a
70-year-old patient with comorbidities. The effects of EF and
comorbidities on the probability of "poor" social function and
perceived health status were similar to those displayed in Figure
1.
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Repeat hospitalizations were predicted with the in-hospital event score and the presence of anterior infarction and diabetes. The occurrence of angina at the 2-year time point was predicted by younger age, female sex, anterior infarction, and the presence of diabetes; TIMI flow and EF were not related to angina. The occurrence of severe dyspnea (score >2) was predicted by EF, female sex, body mass index, and previous MI.
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Discussion |
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The long-term mortality benefits of reperfusion, by both IRA patency and preserved LV function, have been documented.3 34 However, the goal of reperfusion is not only to decrease long-term mortality rates but also to improve morbidity rates and HRQOL. This is the first study to demonstrate a relationship between EF and HRQOL after MI. Preserved EF after MI was predictive of HRQOL, specifically physical function, psychological well-being, perceived health status, and social function. These results provide additional information on the long-term benefits of reperfusion.
Previous investigations failed to show such relationships (between EF and HRQOL) after MI or in cardiac populations7 8 9 10 11 but differed from the present study in many ways. The GUSTO-I angiographic follow-up study was the only HRQOL study in which EF was obtained in a standardized manner (left ventriculography) and during a specific timeframe and analyzed at a central angiographic core laboratory. Previous trials used a variety of EF measures (eg, echocardiograms, radionuclide imaging) obtained at various time points before trial entry.35 36 37 In addition, no central core laboratory analysis of LV function occurred in prior studies. The consistency in the measurement and analysis of EF in the present study minimized measurement error.
This patient population was also considerably healthier than previous study populations that examined this relationship and consisted primarily of patients with congestive heart failure. The mean EF in this sample was 58.2, whereas the other study populations required EFs of <35 or 40 for patient eligibility, thereby creating patient samples with uniformly poor LV performance and limited variability in EF.35 36 37
Furthermore, in the present study, multivariable logistic regressions were used to examine the relative and joint effects of sociodemographic and clinical factors on HRQOL after MI. Patients at the highest risk for poor HRQOL (ie, those in the worst 25th percentile) were those who had a combination of factors. Patients with low EF and with comorbidities who were female were at the highest risk of poor HRQOL, whereas patients with high EF and with no comorbidities who were male were at the lowest risk.
In this multivariable analysis, IRA patency at 90 minutes was not related to HRQOL, which is surprising given its strong relationship to death.2 34 This is likely due to the fact that early IRA patency provides clinical benefits primarily through better preservation of LV function, which appears to be the final pathway to improved outcome. In addition, patency rates evolve, and what may have been documented as patent at 90 minutes may or may not have been patent at 4 months or 1 year. Although IRA patency is strongly related to death, it does not appear to independently affect long-term HRQOL outcomes except through its effects on LV preservation.
The negative impact of long-term comorbidities on HRQOL has been previously noted.10 22 This analysis was limited in that only comorbidities that were related to cardiac disease (eg, hypertension, diabetes, previous MI) were recorded. Other prevalent comorbidities (eg, arthritis, cancer) were not collected at the time of the initial infarction, so their predictive impact cannot be assessed.
Women consistently reported lower HRQOL than men (with the exception of perceived health status). This finding was consistent with previous post-MI research.38–41 Using multiple regression, Ekeberg et al38 found that age, severity of illness, and previous medical history did not account for lower HRQOL in women. Shumacher et al10 found that women had significantly lower scores in social and physical functioning, life satisfaction, and mental health and more symptoms than men, despite controlling for age, EF, comorbidities, perceived stress, country, and other treatment variables. Interestingly, in a general population health survey, women also reported lower HRQOL than men,22 which indicates that sex differences in HRQOL are not particular to post-MI patients.
One must speculate whether the sex differences in HRQOL are biological or methodological. A recurrent explanation of why women report lower HRQOL is that they have more psychosomatic complaints and better symptom recall and are more vocal about their negative feelings.42 43 If this explanation is correct, then a self-report bias may explain the differences. However, the noted HRQOL differences may also be attributed to a methodological bias, because there appears to be an underrepresentation of women in post-MI HRQOL studies. Alternatively, the differences may be real, indicating that women do fare worse after MI. This issue cannot be answered within this analysis but merits further investigation.
A potential limitation of the present study is the temporal relationship between the event (the GUSTO MI) and the HRQOL interview 2 years later. Much can and does happen to individuals during a 2-year period, including reinfarctions, medication changes, and major life events. Interim events may have a greater potential effect on a patient’s current HRQOL status than patency or EF. This temporal relationship must be considered when reviewing the findings of the present study. In addition, no baseline HRQOL data were collected, thereby limiting this analysis to cross-sectional HRQOL data.
Another potential limitation is that the population in this analysis was highly selective in that all patients qualified for thrombolytic therapy and were treated in settings with 24-hour angiographic capabilities. Thus, the results of this trial may not be generalizable to the general post-MI population; patients who do not qualify for thrombolytic therapies may not experience similar outcomes.
Importantly and despite these limitations, the present study sheds light on potential predictors of poor HRQOL after MI. Patients with such attributes may be identified at hospital discharge and targeted for additional follow-up or interventions to decrease negative outcomes.
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Acknowledgments |
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This work was funded by a grant from Genentech, Inc (South San Francisco, Calif). The authors gratefully acknowledge the participation of the GUSTO-I angiographic sites, the patients who participated, and the staff of the George Washington Cardiovascular Research Institute. The authors would also like to thank Nancy Kline Leidy, PhD, for her comments on and critique of an earlier version of the manuscript.
Received February 4, 2000; revision received April 6, 2000; accepted April 13, 2000.
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