Improvements in exercise capacity of older adults during cardiac rehabilitation.

AIMS: Cardiac rehabilitation plays a vital role in secondary prevention of cardiovascular patients. Female sex and higher age, however, are associated with non-referral to cardiac rehabilitation. Improving exercise capacity during cardiac rehabilitation is essential to reduce morbidity and mortality risks. The objective of this study was to closely examine the beneficial changes in exercise capacity of older patients of both sexes during cardiac rehabilitation and to identify the most important predictors of the change in exercise capacity. METHOD: A sample of 13,612 patients (mean age = 69.10 ± 11.8 years, 63.7% men, 19% > 80 years) was analysed. Data were prospectively assessed from 2012-2018 in six Swiss in-patient cardiovascular rehabilitation clinics. Improvement in exercise capacity measured with the six-minute walking test represents the outcome variable. Univariate and multivariate analyses, as well as the random forest method were used to estimate variable importance. RESULTS: Mean improvement in the six-minute walking test was 113.5 ± 90.5 m (men = 118.7 ± 110.0; women = 104.4 ± 93.0, Cohen's d = 0.16). The presence of heart failure, diabetes mellitus and psychiatric diagnoses was related to reduced but nonetheless clinically relevant six-minute walking test improvement. Random forest analysis suggests that baseline exercise capacity, age, time in rehabilitation and heart failure were the most important predictors for improvement in exercise capacity. Clinically relevant improvements in exercise capacity (>45 m) were also present into old age (85 years) and for both sexes. CONCLUSION: As indicated by these results, efforts need to be increased to refer eligible patients to structured rehabilitation programmes, irrespective of patients' age and sex.

Prognostic value of heart rate variability after acute myocardial infarction in the era of immediate reperfusion.

INTRODUCTION: The incidence and significance of impaired heart rate variability (HRV) after acute myocardial infarction (AMI) have not yet been evaluated in cohorts of patients in whom early reperfusion was systematically attempted. Therefore, HRV was evaluated in 412 unselected patients with AMI (311 men, mean age: 60+/-12 years, anterior AMI in 172 patients) treated with direct coronary angioplasty (PTCA) within 12 hours of symptom onset (mean 3.5+/-2.0 h). Standard deviation of normal RR intervals (SDNN), square root of the mean of the sum of the squares of differences between adjacent RR intervals (RMSSD) and left ventricular ejection fraction (LVEF, mean: 55+/-15%) were measured 11+/-9 days after AMI before discharge. Angiotensin-converting enzyme (ACE) inhibitors and beta-blockers were prescribed at discharge in 81.1% and 70.1% of patients, respectively. RESULTS: Mean SDNN was 94+/-30 ms (range 14-155). SDNN was <50 ms in 7% of patients. Mean RMSSD was 34+/-32 ms (range 2-234). RMSSD was <15 ms in 21% of patients. Low SDNN (<50 ms) was unrelated to gender, age, infarct location or extension of CHD but was related to low LVEF (p<0.001, logistic regression analysis). During mean follow-up of 4.3+/-3 years, there were 31 deaths; 24 were cardiac. SDNN was higher in long-term survivors (102+/-39 ms) as compared to nonsurvivors (81+/-33 ms, p=0.02) but RMSSD was unrelated to the long-term vital status. Four-year survival of patients with a SDNN <50 ms vs >50 ms was 80% vs 92%, respectively (p<0.001, Kaplan Meier analysis). Low SDNN (odds ratio OR=2.0, p<0.05) but not RMSSD was an independent denominator for long-term mortality as were low LVEF (OR=1.0 decrease in LVEF, p<0.01, proportional hazards model) and age (OR=1.1, p<0.001). Only 3/31 fatalities and 1/24 cardiac deaths were predicted by a SDNN <50 ms and only 5/31 fatalities by a RMSSD <15 ms. CONCLUSION: The incidence of severely depressed HRV in patients after AMI is low (<10%) in the era of early reperfusion of the infarct vessel using direct PTCA. Mortality in patients with a very low HRV when assessed by SDNN is substantial but the positive predictive value of this parameter is low.