United Kingdom (Commonwealth Union)_ New research presented at Heart Failure 2023, a scientific congress of the European Society of Cardiology (ESC), revealed that individuals with strong leg muscles have a reduced likelihood of developing heart failure following a heart attack. Heart failure is a common complication of myocardial infarction, with approximately 6-9% of heart attack patients progressing to this condition. Previous studies have also indicated that strong quadriceps muscles are associated with a reduced risk of mortality in individuals with coronary artery disease.
This particular study aimed to investigate whether leg strength is linked to a decreased risk of heart failure following an acute myocardial infarction. The study involved 932 patients who were hospitalized between 2007 and 2020 due to an acute myocardial infarction. None of the participants had pre-existing heart failure or developed heart failure complications when they stayed in the hospital. The median age of the patients was 66 years, and the majority (81%) were male.
To measure leg strength, maximal quadriceps strength was assessed. Patients were asked to sit on a chair and contract their quadriceps muscles as forcefully as possible for five seconds. A handy dynamometer fixed to the ankle recorded the maximum strength value in kilograms. This measurement was conducted for both legs, and the researchers calculated the average of the two values. To account for differences in body weight, strength was expressed relative to body weight, with quadriceps strength in kilograms divided by body weight in kilograms and multiplied by 100 to obtain a percentage value.
Based on their strength values, patients were classified as either having “high” or “low” leg strength, depending on whether their value was above or below the median for their gender. The median value for women was 33% of their body weight, while for men it was 52% of their body weight. Of the participants, 451 showed low quadriceps strength, and 481 showed high strength. During an average follow-up period of 4.5 years, 67 patients (7.2%) progressed to heart failure. The incidence of heart failure was found to be 10.2 per 1,000 person-years in patients with high quadriceps strength, whereas it was 22.9 per 1,000 person-years in patients with low strength. The researchers then examined the relationship between quadriceps strength (low vs high) and the risk of developing heart failure.
The analysis included known factors associated with heart failure development after myocardial infarction, including age, sex, body mass index, previous myocardial infarction or angina pectoris, diabetes, atrial fibrillation, chronic obstructive pulmonary disease, peripheral arterial disease, and renal function. Comparing patients with low quadriceps strength to those with high strength, the study found that high strength levels were linked to a 41% lower risk of developing heart failure (hazard ratio [HR]: 0.59; 95% confidence interval [CI] 0.35–1.00; p=0.048). Further, the investigators also evaluated the relationship between quadriceps strength as a continuous variable and the risk of heart failure. They discovered that each 5% increase in body weight-adjusted quadriceps strength was linked to an 11% reduction in heart failure risk (HR 0.89; 95% CI 0.81–0.98; p=0.014).
