Heart failure (HF) is a leading killer in the Western world and is a serious financial burden on health care budgets. Moreover, the life quality of many HF patients decreases through multiple morbidities. In order to improve the prognosis of HF patients, evidence-based treatments are developing.
This thesis investigated areas of secondary prevention in HF without evidence. Subjects included those accessing cardiac rehabilitation (CR) referral, exercise-based CR and aspirin and statin prescription. Outcomes consisted of all-cause mortality, hospital admission and exercise capacities. HF was evaluated mainly as the reduced ejection fraction (HF-REF) subtype, while applied statistical models were parametric and non-parametric. Missing values were assessed through multiple imputations.
First, the CR referral effect on mortality after an acute myocardial infarction event was evaluated. The Evaluation of Methods and Management of Acute Coronary Events (EMMACE)-I and II observational studies demonstrated CR referral as an independent predictor of survival in 2003, but not in 1995. Similar results were shown in HF subgroups. Although decreasing between the studies, CR referral was associated with treatment inequalities, thus suggesting a risk-treatment paradox.
Second, the effect of enrolment in exercise-based CR in HF patients was assessed through a meta-analysis incorporating randomised controlled trials (RCTs). Over a minimum of six months, follow-up exercise capacities and hospital admissions significantly improved in the exercise intervention group as compared with the control group. In contrast, mortality was not significantly improved through exercise, although a trend suggested exercise to be superior to a sedentary lifestyle.
Confounders were patient selection in RCT recruitment and the unequal quality of care.
Third, the average treatment effects of aspirin and statins in HF patients (EMMACE studies) improved survival rates during 90 months follow-up.
In HF populations, CR attendance influenced key outcomes significantly, whereas aspirin and statins were beneficial to survival in observational studies.
