The initial slope of the VCO2/VO2-curve (s1) in cardiopulmonary exercise testing is a strong and independent predictor of outcome in patients with previous myocardial infarction

Predictive role of peak VO2 for short- and long-term major adverse cardiac events in patients with high cardiovascular risk

BACKGROUND

The objective of this study was to assess the accuracy of VO2 measurements in predicting long-term major adverse cardiac events (MACEs) in patients with high cardiovascular risk.

METHODS

Based on a 10-year atherosclerotic cardiovascular disease risk score, 333 patients with high cardiovascular risk were included in this retrospective analysis. The study endpoint was MACEs, comprising all-cause mortality, cardiovascular mortality, non-fatal myocardial infarction or stroke, and coronary revascularization. The study cohort was divided into two groups according to the frequency of MACE occurrence. Measurements of VO2 were assessed for the prediction of MACEs.

RESULTS

The best predictive accuracy for 1‑year MACEs was determined to be a VO2 max value of ≥ 20.3 mL/kg/min, with 60% specificity and 60% sensitivity (area under the curve [AUC]: 0.61; 95% confidence interval [CI]: 0.51-0.71; p < 0.001), and for 5‑year MACEs it was ≥ 19.9 mL/kg/min, with 69% specificity and 64% sensitivity (AUC: 0.69; 95% CI: 0.62-0.76; p < 0.001). Multivariable Cox regression analysis, after adjusting for univariable factors, showed that VO2 max was independently associated with both short- and long-term MACEs in patients at high cardiovascular risk (hazard ratio [HR]: 0.900, 95% CI: 0.858-0.943, p < 0.001).

CONCLUSION

According to the results of this pilot study, VO2 max can predict both short- and long-term MACEs in patients at high cardiovascular risk.

Power Output and Efficiency During Supine, Recumbent, and Upright Cycle Ergometry

Recumbent and supine cycling are common exercise modes in rehabilitation and clinical settings but the influence of postures on work efficiency is unclear. Therefore, the aim of this study was to compare metabolic and ventilatory efficiency during upright, recumbent, and supine postures. Potential differences should be assessed for suitable diagnostics and for prescriptions of training that probably is performed in alternative postures. Eighteen healthy subjects (age: 47.2 ± 18.4 years; 10 female, 8 male) participated in the study and each completed three incremental cycle ergometer tests until exhaustion in upright, recumbent (40°), and supine positions. Gas exchange, heart rate (HR), and lactate concentrations were analyzed and efficiency was calculated subsequently. Testing sessions were performed in random order within a 2-week period. Upright cycling resulted in significantly higher peak values [power output, oxygen uptake (Vo₂), HR] as well as performance at lactate and ventilatory thresholds in comparison to recumbent or supine positions. Vco₂/Vo₂ slope and ventilatory efficiency (VE/Vco₂ slope) were not affected by posture. Aerobic work efficiency (Vo₂/P slope) and gross efficiency (GE) differed significantly between postures. Hereby, GE was lowest in supine cycling, particularly obvious in a mainly aerobic condition at 70 Watt [Median 11.6 (IQR 10.9-13.3) vs. recumbent: 15.9 (IQR 15.6-18.3) and upright: 17.4 (IQR 15.1-18.3)]. Peak power as well as GE and work efficiency values are influenced by cycling position, reinforcing the importance of adjusting test results for training prescriptions. Surprisingly, ventilatory efficiency was not affected in this study and therefore does not seem to falsify test results for pulmonary diagnostics.

Different outcomes of a cardiac rehabilitation programme in functional parameters among myocardial infarction survivors according to ejection fraction

Introduction

Exercise-based cardiac rehabilitation (EBCR) is part of the management of patients who have suffered an acute myocardial infarction (AMI). Patients with a reduced ejection fraction (EF) comprise a higher-risk subgroup and are referred less often for these programmes. This study aimed at assessing the impact of the baseline EF on the functional benefits, as assessed by peak oxygen uptake (pVO₂) and exercise duration, of an EBCR programme in AMI survivors.

Methods

Observational, retrospective cohort study including all patients admitted to a tertiary centre due to an AMI who completed a phase II EBCR programme after discharge, between November 2012 and April 2017. Functional parameters were assessed by a symptom-limited cardiopulmonary exercise test.

Results

A total of 379 patients were included [40.9% with reduced EF (<50%) at discharge]. After the programme, pVO₂ and exercise duration increased significantly (p < 0.001). Patients with a reduced EF had a lower pVO₂ and completed a shorter duration of exercise at the beginning and end of the programme. This group presented a higher increase in pVO₂ (p = 0.001) and exercise duration (p = 0.007). This was maintained after adjusting for age, gender, history of coronary artery disease, number of sessions, Killip classification, arterial hypertension, dyslipidaemia, diabetes mellitus, smoking status and baseline pVO₂.

Conclusion

A phase II EBCR programme was associated with significant improvements in pVO₂ and exercise duration among AMI survivors, irrespective of baseline EF classification. Those with a reduced baseline EF derived an even greater improvement, highlighting the importance of EBCR in this subgroup of patients.

BNP and NT-proBNP as prognostic markers in persons with chronic stable heart failure

Prognosis permits clinicians to separate persons with heart failure (HF) into subgroups based on likely health outcomes. Treatment is partly guided by these likely outcomes. This systematic review explores whether brain natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) are independent predictors of prognosis in persons with chronic stable HF. We electronically searched Medline, Embase, AMED, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and CINAHL for English-language articles published between 1989 and mid-2012. We utilized trained reviewers and standardized forms to screen articles for inclusion and extracted data from included articles. All included studies were summarized in narrative and tabular form. We used the Hayden criteria to assess the risk of bias. Sixteen BNP publications and 88 NT-proBNP publications were included in the systematic review. BNP was positively associated with all-cause and HF mortality. NT-proBNP was positively associated with all-cause and cardiovascular mortality. BNP and NT-proBNP levels are useful for estimating prognosis in persons with chronic stable HF. Further research is required to establish optimal cutpoints and to assess whether prognostic effects differ by age, sex, or time period.

Leukocyte telomere length and left ventricular function after acute ST-elevation myocardial infarction: data from the glycometabolic intervention as adjunct to primary coronary intervention in ST elevation myocardial infarction (GIPS-III) trial

Background

Telomere length has been associated with coronary artery disease and heart failure. We studied whether leukocyte telomere length is associated with left ventricular ejection fraction (LVEF) after ST-elevation myocardial infarction (STEMI).

Methods and results

Leukocyte telomere length (LTL) was determined using the monochrome multiplex quantitative PCR method in 353 patients participating in the glycometabolic intervention as adjunct to primary percutaneous coronary intervention in STEMI III trial. LVEF was assessed by magnetic resonance imaging. The mean age of patients was 58.9 ± 11.6 years, 75 % were male. In age- and gender-adjusted models, LTL at baseline was significantly associated with age (beta ± standard error; −0.33 ± 0.01; P < 0.01), gender (0.15 ± 0.03; P < 0.01), TIMI flow pre-PCI (0.05 ± 0.03; P < 0.01), TIMI flow post-PCI (0.03 ± 0.04; P < 0.01), myocardial blush grade (−0.05 ± 0.07; P < 0.01), serum glucose levels (−0.11 ± 0.01; P = 0.03), and total leukocyte count (−0.11 ± 0.01; P = 0.04). At 4 months after STEMI, LVEF was well preserved (54.1 ± 8.4 %) and was not associated with baseline LTL (P = 0.95). Baseline LTL was associated with n-terminal pro-brain natriuretic peptide (NT-proBNP) at 4 months (−0.14 ± 0.01; P = 0.02), albeit not independent for age and gender.

Conclusion

Our study does not support a role for LTL as a causal factor related to left ventricular ejection fraction after STEMI.

G-CSF stimulation and coronary reinfusion of mobilized circulating mononuclear proangiogenic cells in patients with chronic ischemic heart disease:five-year results of the TOPCARE-G-CSF trial

Prognosis of patients with heart failure remains poor despite improved conventional and interventional treatment regimens. The improvement of neovascularization and repair processes by administration of bone marrow-derived cells modestly improved the recovery after acute myocardial infarction. However, circulating patient-derived cells are reduced in number and function particularly in chronic heart failure. Therefore, we tested the hypothesis whether the mobilization of circulating mononuclear proangiogenic cells (CPCs) by G-CSF may overcome some of these limitations. In the present pilot study, 32 patients with at least 3-month-old myocardial infarction were randomized to G-CSF alone (G-CSF group) or intracoronary infusion of G-CSF-mobilized and cultured CPCs into the infarct-related artery (G-CSF/CPC group). Primary endpoint of the study was safety. Efficacy parameters included serial assessment of LV function, NT-proBNP levels, and cardiopulmonary exercise testing. G-CSF effectively mobilized circulating CD34(+)CD45(+) cells after 5 days in all patients (408 ± 64%) without serious adverse events. At 3 months, NYHA class and global LV function did not show significant improvements in both treatment groups (G-CSF: ΔLVEF 1.6 ± 2.4%; p = 0.10; G-CSF/CPC: ΔLVEF 1.4 ± 4.1%; p = 0.16). In contrast, target area contractility improved significantly in the G-CSF/CPC group. During 5-year follow-up, one patient died after rehospitalization for worsening heart failure. Eleven patients underwent further revascularization procedures. NT-proBNP levels, cardiopulmonary exercise capacity, and NYHA class remained stable in both treatment groups. The results from our pilot trial indicate that administration of G-CSF alone or G-CSF-mobilized and cultured CPCs can be performed safely in patients with chronic ischemic heart disease. However, only minor effects on LV function, NT-proBNP levels, and NYHA classification were observed during follow-up, suggesting that the enhancement of CPCs by G-CSF alone does not substantially improve intracoronary cell therapy effects in patients with chronic ischemic heart failure.

Prevalence of ventricular discordance and its relation to functional capacity in idiopathic dilated cardiomyopathy

INTRODUCTION

Although left ventricular (LV) dilatation is the most distinguishing morphologic feature of idiopathic dilated cardiomyopathy (IDC), right ventricular (RV) dilatation may variably contribute to total cardiac enlargement. The prevalence and functional importance of the relative degree of left and right ventricular dilatation has not been comprehensively studied using cardiac magnetic resonance imaging (MRI).

METHODS

Our prospective study included 58 consecutive IDC patients with a LV ejection fraction <40% and NYHA functional class > or =2. MRI was performed with a 1.5 Tesla scanner for RV and LV dimensional and functional analysis. Cardiopulmonary exercise testing was used for evaluation of exercise capacity. Patients were grouped into tertiles based on the distribution of LV end-diastolic volume.

RESULTS

Compared to control subjects a considerable heterogeneity in the relative degree of left and right ventricular dilatation was noted in IDC patients. Within the entire patient group, a strong correlation between the degree of ventricular volume discordance and the extent of LV enlargement was observed (r = 0.8; P < 0.001). Tertile analysis revealed that the LV/RV volume ratio significantly differed in the three subgroups of patients (1.0 +/- 0.3 vs. 1.5 +/- 0.4 vs. 2.1 +/- 0.9; P < 0.001). Only weak correlations between MRI data and patients' functional capacity were found. LV ejection fraction was identified as the only independent predictor of maximum oxygen consumption in our setting.

CONCLUSION

In IDC patients the degree of ventricular volume discordance is strongly related to the extent of left ventricular enlargement. However, comprehensive biventricular assessment of cardiac function by MRI adds little to our understanding of the cardiac mechanisms limiting exercise tolerance when compared to exclusive left ventricular measurements.