Philippe Meyer

Acute Responses to High-Intensity Intermittent Exercise in CHD Patients

PURPOSEnalthough the acute physiological responses to continuous exercise have been well documented in CHD patients, no previous study has examined the responses to high-intensity intermittent exercise in these patients. The purpose of this study was to compare the physiological responses to a high-intensity interval exercise (HIIE) protocol versus a moderate-intensity continuous exercise (MICE) protocol of similar energy expenditure in CHD patients.nnnMETHODSntwenty patients with stable CHD (19 males and 1 female, 62 ± 11 yr) were assigned in random order to a single session of HIIE corresponding to 15-s intervals at 100% of peak power output (PPO) and 15-s passive recovery intervals and, 2 wk later, to an isocaloric MICE corresponding to 70% of PPO.nnnRESULTSnboth protocols were equivalent in terms of energy expenditure. The HIIE protocol resulted in lower mean ventilation (P < 0.001) for a small difference in metabolic demand. All participants preferred the HIIE mainly because the perceived exertion measured by the Borg scale was lower (P < 0.05). No elevation of serum concentration of troponin T was found in all participants at baseline and at 20 min and 24 h after the exercise sessions, thus excluding the presence of any exercise-induced myocardial injury in our patients.nnnCONCLUSIONSnwhen considering physiological responses, safety, and perceived exertion, the HIIE protocol seemed to be well tolerated and more efficient in this group of stable CHD patients.

Prediction of complications in pregnant women with cardiac diseases referred to a tertiary center

BACKGROUNDnPrediction of adverse maternal and neonatal events in women with heart disease is not well established. We aimed to assess cardiac, obstetrical and neonatal complications in pregnant women with heart disease referred to our tertiary care center and validate a previously proposed risk index.nnnMETHODSnWe included 227 women with cardiac disease followed for 312 pregnancies at our tertiary center from 1992 to 2007. Cardiac risk was assessed using the previously proposed Cardiac Disease in Pregnancy (CARPREG) score and its association with maternal and neonatal outcomes was determined.nnnRESULTSnMaternal cardiac lesions were predominantly congenital (81.4%). CARPREG risk was low (score=0) in 66.3% and intermediate (score=1) in 33.7% pregnancies. Maternal cardiac events complicated 7.4% pregnancies, with pulmonary edema occurring most frequently (3.8%). An intermediate score was associated with a higher rate of cardiac events (19.0% vs. 1.4%, odds ratio [OR] 15.6, 95% confidence interval (95%CI) 4.5-54.4, p<0.0001). Adverse events occurred in 27.5% neonates. Preterm deliveries occurred in 16.7% pregnancies, more commonly in patients with intermediate scores (OR 2.4, 95%CI 1.2-4.6, p=0.01). The sensitivity and negative predictive values of a low score were respectively 87% and 99% for total cardiac events and both 100% for primary cardiac events including pulmonary edema and sustained arrhythmia.nnnCONCLUSIONnThe CARPREG risk index has a high sensitivity and negative predictive value with regards to cardiac complications in pregnant women with heart disease. It may, therefore, be routinely used to improve the assessment of cardiac risk before and during pregnancy.

Digoxin and Reduction of Heart Failure Hospitalization in Chronic Systolic and Diastolic Heart Failure

In the Digitalis Investigation Group trial, digoxin-associated decrease in the combined end point of heart failure (HF) hospitalization or HF mortality was significant in systolic but not in diastolic HF. To assess whether this apparent disparity could be explained by differences in baseline characteristics and sample size, we used propensity score matching to assemble a cohort of 916 pairs of patients with systolic and diastolic HF who were balanced in all measured baseline covariates. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) of the effect of digoxin on outcomes separately in systolic and diastolic HF, at 2 years (protocol prespecified), and at the end of 3.2 years of median follow-up. HF hospitalization or HF mortality occurred in 28% and 32% of patients with systolic HF (HR digoxin vs placebo 0.85, 95% CI 0.67 to 1.08, p = 0.188) and 20% and 25% in those with diastolic HF (HR 0.79, 95% CI 0.60 to 1.03, p = 0.085) receiving digoxin and placebo, respectively. At 2 years, HRs for this combined end point were similar for systolic HF (0.72, 95% CI 0.55 to 0.95, p = 0.022) and diastolic HF (0.69, 95% CI 0.50 to 0.95, p = 0.025). Digoxin also decreased 2-year HF hospitalization in systolic HF (HR 0.73, 95% CI 0.54 to 0.97, p = 0.033) and diastolic HF (HR 0.64, 95% CI 0.45 to 0.90, p = 0.010). In conclusion, as in patients with systolic HF, digoxin was equally effective in those with diastolic HF, who constitute half of all patients with HF, yet have few evidence-based therapeutic options.

Acute responses to intermittent and continuous exercise in heart failure patients.

BACKGROUNDnThe purpose of this study was to compare cardiopulmonary responses, exercise adherence, tolerance, and safety of optimized high-intensity interval exercise (HIIE) compared with moderate-intensity continuous exercise (MICE) in patients with heart failure and reduced ejection fraction (HFREF).nnnMETHODSnTwenty patients with HFREF (aged 61 ± 9.9 years) were randomly assigned to HIIE corresponding to 2 × 8 minutes of 30-second intervals at 100% of peak power output and 30-second passive recovery intervals and to a 22-minute MICE corresponding to 60% of peak power output. Gas exchange, electrocardiogram, and blood pressure were measured continuously. Cardiac troponin T (cTnT), C-reactive protein (CRP), and brain natriuretic peptide (BNP) were measured before, 20 minutes after, and 24 hours after HIIE and MICE.nnnRESULTSnCardiopulmonary responses did not differ between MICE and HIIE. Higher exercise adherence and efficiency were observed on HIIE with a similar perceived exertion and time spent above 90% of peak oxygen consumption compared with MICE. Neither HIIE nor MICE caused any significant arrhythmias or increased CRP, BNP, or cTnT.nnnCONCLUSIONSnCompared with MICE, HIIE demonstrated a higher exercise adherence and was well tolerated in patients with HFREF, while still providing a high-level physiological stimulus and leaving indices of inflammation (CRP), myocardial dysfunction (BNP), and myocardial necrosis (cTnT) unaffected.

A Propensity-Matched Study of Elevated Jugular Venous Pressure and Outcomes in Chronic Heart Failure

The independence of association between elevated jugular venous pressure (JVP) and outcomes in heart failure (HF) has not been well studied. The objective of propensity-matched study was to determine if an elevated JVP had intrinsic associations with outcomes in chronic systolic and diastolic HF. Of the 7,788 participants in the Digitalis Investigation Group trial, 1,020 (13%) had elevated JVP at baseline. Propensity scores for elevated JVP were estimated for all patients based on 32 baseline characteristics and were used to match 827 pairs of patients with normal and elevated JVP. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated to compare outcomes associated with elevated versus normal JVP during 34 months of median follow-up. Before matching, all-cause mortality occurred in 31% and 47% (unadjusted HR 1.70, 95% CI 1.54 to 1.88, p <0.0001), and all-cause hospitalization occurred in 60% and 71% (unadjusted HR 1.35, 95% CI 1.25 to 1.47, p <0.0001) of patients with normal and elevated JVP, respectively. After matching, all-cause mortality occurred in 48% and 45% (matched HR 0.95, 95% CI 0.80 to 1.12, p = 0.521), and all-cause hospitalization occurred in 70% and 70% (matched HR 0.97, 95% CI 0.87 to 1.09, p = 0.613) of patients with normal and elevated JVP, respectively. Elevated JVP had no intrinsic associations with cardiovascular mortality (matched HR 0.93, 95% CI 0.77 to 1.12, p = 0.440) or hospitalization for HF (matched HR 0.94, 95% CI 0.78 to 1.14, p = 0.532). In conclusion, an elevated JVP is a marker of higher burden of sickness and poor outcomes. However, elevated JVP had no intrinsic association with mortality or hospitalization in chronic HF.

A Single Bout of High-Intensity Interval Exercise Does Not Increase Endothelial or Platelet Microparticles in Stable, Physically Fit Men With Coronary Heart Disease

BACKGROUNDnHigh-intensity interval exercise (HIIE) is gaining in popularity in fitness centres, even among coronary heart disease (CHD) patients. However, whether HIIE can have deleterious acute effects on the vasculature in CHD has not been studied. We hypothesized that when compared with moderate-intensity continuous exercise (MICE), a single bout of HIIE could lead to vascular damage and increasing numbers of circulating endothelial and platelet microparticles (EMPs, PMPs) in stable, physically fit CHD patients.nnnMETHODSnNineteen male CHD patients (aged 62 ± 11 years) underwent, in random order, a single session of HIIE corresponding to 15-second intervals at 100% of peak power output and 15-second passive recovery intervals, and an isocaloric MICE session. EMPs (CD31+ and/or CD62E+ and CD42b-); PMPs (CD42b+); nitrates and nitrites; prostacycline; and troponin T, cardiac form (cTnT), were measured 10 minutes before exercise and 20 minutes, 24 hours, and 72 hours after both exercise sessions.nnnRESULTSnEMPs, PMPs, nitrates and nitrites, prostacycline, and cTnT remained unchanged after both HIIE and MICE exercise sessions. Initial EMP concentration correlated inversely with EMP concentration 20 minutes post exercise, irrespective of exercise modality (r = 0.78, P < 0.0001).nnnCONCLUSIONSnA single HIIE session with very short exercise and passive recovery periods appears safe and does not induce changes to markers of endothelial function. Future studies are required to determine the safety of a long-term HIIE training program.

Exposure to extreme cold lowers the ischemic threshold in coronary artery disease patients

BACKGROUNDnCold temperature is known to commonly precipitate angina pectoris in patients with symptomatic coronary artery disease (CAD). It was previously shown that the ischemic threshold was lower during exercise testing at -8 degrees C than at +20 degrees C in patients with a history of cold-induced angina, whereas it was unchanged in patients without cold-induced angina. Few data exist on the impact of more severe cold exposure on myocardial ischemia.nnnOBJECTIVEnTo determine the effect of extreme cold exposure (-20 degrees C) on the ischemic threshold among CAD patients.nnnMETHODSnThirteen men with CAD and documented exercise-induced ischemia performed two treadmill exercise tests, one at +20 degrees C and one at -20 degrees C, in random order. Electrocardiograms were recorded every 30 s and analyzed separately in random order by two experienced readers blinded to temperature.nnnRESULTSnThe mean (+/- SD) time to ischemic electrical threshold was 53+/-60 s lower at -20 degrees C than at +20 degrees C (P=0.008), corresponding to a relative change of -8.0+/-10.5%. All other exercise parameters, including total exercise time and rate-pressure product, were unchanged during exposure to extreme cold.nnnCONCLUSIONnExposure to extreme cold (-20 degrees C) lowers the ischemic threshold during exercise testing in patients with CAD, even if asymptomatic or without a history of cold-induced angina. Patients with CAD and evidence of exertional angina or myocardial ischemia wishing to perform exercise at extremely low temperatures should discuss this matter with their physicians.

Comparison of Carbohydrate and Lipid Oxidation During Continuous and Intermittent Exercise in Patients With Chronic Heart Failure

Skeletal muscle substrate oxidation was compared during moderate-intensity continuous exercise (MICE) and high-intensity intermittent exercise (HIIE) in patients with heart failure and reduced ejection fraction (HFREF). Eighteen patients (aged 60 ± 9 years; LVEF, 26 ± 7%) randomly performed MICE (22 minutes at 60% of peak power) and HIIE (30 seconds at 100% of peak power interspersed by 30 seconds rest for 16 minutes). Carbohydrate and lipid oxidation calculated using the Frayn equation were 4.8- and 1.42-fold higher during MICE and 5- and 1.22-fold higher during HIIE (P < 0.0001). HIIE and MICE can similarly and favourably increase carbohydrate and lipid oxidation in patients with HFREF.

HIGH-INTENSITY INTERVAL EXERCISE IN CHRONIC HEART FAILURE: COMPARISON OF CARBOHYDRATE AND LIPID OXIDATION

BACKGROUND: high-intensity interval exercise has been extensively used with athletes and healthy subjects. There are a few evidences that it could improves physiology and functional capacity in heart failure patients, but still some answers about muscle metabolism need to be addressed. METHODS: substrate oxidation was compared during 4 different high intensity intermittent exercise (HIIE) protocols in patients with heart failure and reduced ejection fraction (HFREF). Eighteen males (56 17 years, LVEF: 28 7%) randomly performed 4 HIIE with measurement of gas exchange. Exercise intensity protocols were set at 100% of peak power output (PPO). Interval duration was 30 seconds (A and B) or 90 seconds (C and D), and recovery was passive (A and C) or active (50% of PPO in B and D). Energy expenditure was calculated using Weir equation and substrate oxidation (glucose: CHO, and lipid) was calculated by the Frayn equation (for quantitative measure) and from a table of non-protein respiratory quotient (qualitative measure) using gas exchange analysis. RESULTS: mean O2peak was 17.8 4.6 ml/min/kg (or 1.54 4.6 L/min) and peak power output was 109 31 Watts. At rest, fat oxidation averaged 0.13 0.04 g/min, representing 68 22 % of total substrate utilisation. CHO oxidation averaged 0.16 0.1 g/min representing 31 22% of total. During exercise, absolute CHO oxidation significantly decreased and absolute lipid oxidation significantly increased in each HIIE protocol (P<0.0001). Protocol B induced higher energy expenditure after 8-10 minutes of exercise compare to passive recovery modes (A and C) (P<0.0001). Short duration intervals with passive recovery (mode A) resulted in significantly lower CHO oxidation in absolute terms compare to modes with active recovery (B and D) (P<0.0001). In relative terms (%), CHO oxidation in mode A was significantly lower than mode C only, after 8-10 minutes of exercise. Lipid oxidation in absolute terms was significantly lower in mode C compare to the other 3 modes of HIIE at time 8-10 min whereas in relative terms it was significantly lower than mode A only (P<0.0001). All together, these 4 HIIE protocols showed increased lipid oxidation over time, and short interval duration with passive recovery showed higher lipid oxidation compared to the others. CONCLUSION: the choice of an active mode during HIIE may favors glucose oxidation during exercise in patients with HFREF, if the improvement of glucose metabolism is targeted.