Health-related quality of life increases after first-time acute myocardial infarction: A population-based study

We prospectively evaluated HRQOL in 60 patients admitted to the hospital (academic, regional referral centre with a 24-hour interventional cardiology service) due to the first AMI and participating in the AFFECT EV Quality of Life Substudy (14). The study protocol, designed in compliance with the Declaration of Helsinki, was approved by the Ethics Committee of Medical University of Warsaw (approval number: KB/112/2016) and published previously (15).

All participants provided written informed consent. Study inclusion and exclusion criteria are listed in Table 1. Patients were eligible for enrolment if they (i) were admitted to the hospital due to the first ST-segment elevation of acute myocardial infarction (STEMI) or non-STEMI (NSTEMI) qualified for early invasive revascularisation, and (ii) underwent percutaneous coronary intervention (PCI) with stent implantation. STEMI was diagnosed based on persistent ST-segment elevation of at least 0.1 mV in at least two contiguous electrocardiography leads or a new left bundle-branch block (16). NSTEMI was diagnosed as ST-segment changes on ECG including ST depression, transient ST elevation and T-wave changes, along with a positive cardiac troponin test indicating myocardial necrosis in patients with the typical anginal chest pain (17).

Between January 2017 and June 2018, 60 patients were enrolled, and 56 patients were included in the final analysis (mean age 64.3±9.7 years, 75% male). The study flow chart is showed in Figure 1. Four patients did not attend the follow-up visit after 6 months and were excluded from the study.

Figure 1

Patients’ baseline and clinical data were extracted from medical records. Before discharge, patients underwent echocardiography. All patients received standard treatment after AMI according to the guidelines, depending on the individual clinical characteristics and comorbidities. All patients who qualified for a cardiac rehabilitation were involved in the rehabilitation program. HRQOL was assessed during the index hospitalization and after 6 months using the following standardised questionnaires: (i) MacNew Heart Disease, (ii) World Health Organization Quality of Life (WHOQOL) BREF and (iii) Short Form (SF) 36 Health Survey. All questionnaires have been validated in the Polish population (11, 12, 13). The same two investigators (K.P. and A.Ć.) obtained questionnaire data during the index hospitalisation and follow-up.

The MacNew Heart Disease survey was designed to evaluate symptoms and well-being levels in patients with symptomatic coronary artery disease and with HF (18) after AMI. It consists of 27 questions grouped into 3 domains: physical, mental, and social. In addition, the global HRQOL is calculated as the sum of points from the 3 domains. The license was obtained from MacNewTM (Innsbruck, Austria).

The WHOQOL BREF evaluates general QOL and covers 4 domains: physical health, psychological health, social relationships, and environmental stability (19). It consists of 26 items referring to energy and fatigue, mobility, self-esteem, social support, and financial resources. The questionnaire was obtained as a courtesy of the Prof. Krystyna Jaracz (Department of Neurological and Psychiatric Nursing, Poznan University of Medical Sciences, Poznan, Poland).

The SF-36 Health Survey consists of 36 questions grouped into 8 domains, including general health, physical functioning, limitations due to physical health problems, limitations due to emotional problems, bodily pain, vitality, social functioning, and mental health (20). The questionnaire was interpreted according to the Polish version developed by Prof. Jan Tylka (21). The license was obtained as a courtesy of Dr. Krzysztof Gąsecki (Chair of Social Pedagogy and Educational Research Methodology, Faculty of Social Sciences, University of Warmia and Mazury, Olsztyn, Poland).

The primary outcome was the change in the HRQOL between the index hospitalization and 6-month follow-up using the MacNew questionnaire, which was specifically designed to evaluate QOL in patients after AMI. The secondary outcomes were the changes in HRQOL from the index hospitalization to 6 months using the WHOQOL BREF and SF-36 questionnaires. Based on the literature, we defined an improvement in the HRQOL as an improvement between the index hospitalisation and follow-up of at least 1 unit in the MacNew questionnaire and at least 10 units in the WHOQOL BREF and SF-36 questionnaires (22, 23, 24).

To determine the clinical variables which potentially affect HRQOL after AMI, we collected data regarding the following explanatory factors: demographics (age, gender), BMI, diagnosis at admission, cardiovascular risk factors (smoking, hypertension, dyslipidaemia, diabetes), laboratory parameters at admission (creatinine, haemoglobin level, low-density lipoprotein-cholesterol concentration, platelet count, troponin I concentration), left ventricle ejection fraction (LVEF) at admission, pharmacotherapy at discharge and attendance to cardiac rehabilitation.

The sample size was calculated by a two-sided t-test at a significance level of 0.05 using the following assumptions:(i) mean difference between the timepoints=1, (ii) standard deviation (SD) at the index hospitalisation and follow-up±1.5, and (iii) nominal test power=0.9. Based on this sample size estimation, a total of 49 patients should be enrolled in the study to observe a significant difference in the HRQOL between the index hospitalization and 6-month follow-up. Taking into account that up to 20% of patients could be potentially lost during follow-up, 60 patients were included in the study.

We conducted statistical analysis using IBM SPSS Statistics, version 27.0. Categorical variables were presented as numbers and percents. The Shapiro–Wilk test was used to test for normal distribution of continuous variables. Continuous variables were presented as a mean and standard deviation, or as a median with inter-quartile range. Differences in quality of life between the two time points were assessed using the Wilcoxon signed rank test. Characteristics of patients with and without altered HRQOL after AMI in each of the three questionnaires were compared using the Mann–Whitney U test (continuous variables) and Chi-square test (categorical variables). The logistic regression model was performed manually (step-by-step), where HRQOL was used as a dependent variable and variables, which significantly differed between patients with and without altered HRQOL at 6 months and which were predictors of improved HRQOL in univariate analysis were used as independent variables. The area under receiver operating characteristic (AUC under ROC) curve was used to determine the cut-off of continuous variables associated with altered HRQOL. Mortality and other adverse events were reported descriptively. For univariate analysis, a p-value below 0.1 was considered significant. For all other analyses, a p-value below 0.05 was considered significant.

Patient characteristics are presented in Table 2. Of 56 patients included in the analysis, 61% had arterial hypertension, 23% suffered from diabetes mellitus, 64% had dyslipidaemia and 52% were smokers. At admission, 79% of patients were presented with STEMI. All patients had a successful PCI with at least 1 stent implantation. The median LVEF post-PCI was 52% (27-68%). All patients received dual antiplatelet therapy and statin and more than 90% of patients received a β-blocker and an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Until the 6-month follow-up, there were no deaths and no recurrent thrombotic events during the study, neither in STEMI nor in NSTEMI patients.

Figure 2 shows the changes in HRQOL between the index hospitalization and follow-up visit at 6 months. Whereas global, social, and physical functioning did not change (p≥0.063), whereas emotional functioning improved after AMI (p=0.002), as measured by the MacNew questionnaire. Physical health, psychological health, and environmental functioning did not change (p≥0.321), whereas social relationships improved after AMI (p=0.042), as measured by WHOQOL BREF. The global HRQOL improved after AMI (p=0.044), as assessed by SF-36.

Figure 2

Patients with improved HRQOL in SF-36 had a higher baseline BMI (p=0.046), often with dyslipidaemia (p=0.046) and lower LVEF at discharge (p=0.013), compared to patients without improved HRQOL in SF-36. There were no significant differences between the characteristics of patients with and without improved HRQOL after AMI when administering the MacNew (emotional functioning) and WHOQOL BREF (social relationships) surveys.

Table 3 shows the results of univariate analysis for prediction of improved HRQOL in SF-36 using explanatory factors. BMI, left ventricle EF<50% and dyslipidaemia predicted improved HRQOL at p<0.1 (odds ratio [OR] 5.094, 95% confidence interval [CI] 0.987-1.269, p=0.080 for BMI; OR 5.863, 95% CI 1.441-23.851, p=0.013 for LVEF<50%; OR 2.917, 95% CI 0.914-9.309, p=0.071 for dyslipidaemia, respectively)

Table 4 shows the results of multivariate logistic regression including clinical variables which differed between patients with and without improved QOL in SF-36 and which were predictors of improved QOL in univariate analysis. EF was the only variable independently associated with improved QOL in multivariate analysis (OR 4.463, 95% CI 1.045 - 19.059, p=0.043). The cut-off for EF associated with improved HRQOL determined based on the ROC curve was 50% (AUC 0.70, CI 0.56-0.84, p=0.013).

The main limitation of our study is its single-centre design, which might limit the generalizability of the results. Since our hospital is an academic, regional referral centre, our results might not be applicable to smaller centres without 24-hour interventional cardiology services. Secondly, the small sample size might increase the risk of potential enrolment bias. Thirdly, the observational study design does not allow any conclusions to be drawn regarding causality when identifying the possible improvement or decline of HRQOL predictors over time. Moreover, the present study was a substudy of the AFFECT EV study (14), wherefore the inclusion and/or exclusion criteria may have influenced the results. Thus, the applicability of the results to a general post-AMI population remains limited. Although we sought to collect thorough clinical data, the information on accompanying psychiatric disorders was limited. In addition, the data regarding the changes in LVEF over time was not collected, which could have influenced the QOL. Also, the patients’ social networks, which were not taken into consideration, may have had an impact. Finally, our logistic regression model is based on only 56 patients and included 3 variables, which makes it hypothesis-generating. Altogether, the results should be interpreted with caution and re-evaluated in future studies.

The results showing improvement of QOL in Poland after AMI enable the cautious conclusion to be drawn that Poland’s interventional treatment and early implementation of cardiac rehabilitation results in similar effects among Polish patients after AMI, as observed in other European countries and the US (22, 23, 24). Our results exhibit a need for well-designed studies concerning the association between different clinical variables and QOL after MMI, as extant published studies provide inconsistent results.

The optimistic observations regarding the increase in QOL are most probably attributable to the availability of 24-hour interventional cardiology service. However, one should not forget the importance of providing first aid in a timely manner, which greatly influences the prognosis of the patient undergoing AMI, and consequently QOL post-AMI (40). Therefore, even in presence of well-developed infrastructure and well-established algorithms in patients after AMI, large-scale education programmes are indispensable for further improving QOL after AMI (41).