Cardiopulmonary exercise testing and efficacy of percutaneous coronary intervention: a substudy of the ORBITA trial

AIMS

Oxygen-pulse morphology and gas exchange analysis measured during cardiopulmonary exercise testing (CPET) has been associated with myocardial ischaemia. The aim of this analysis was to examine the relationship between CPET parameters, myocardial ischaemia and anginal symptoms in patients with chronic coronary syndrome and to determine the ability of these parameters to predict the placebo-controlled response to percutaneous coronary intervention (PCI).

METHODS AND RESULTS

Patients with severe single-vessel coronary artery disease (CAD) were randomized 1:1 to PCI or placebo in the ORBITA trial. Subjects underwent pre-randomization treadmill CPET, dobutamine stress echocardiography (DSE) and symptom assessment. These assessments were repeated at the end of a 6-week blinded follow-up period.A total of 195 patients with CPET data were randomized (102 PCI, 93 placebo). Patients in whom an oxygen-pulse plateau was observed during CPET had higher (more ischaemic) DSE score [+0.82 segments; 95% confidence interval (CI): 0.40 to 1.25, P = 0.0068] and lower fractional flow reserve (-0.07; 95% CI: -0.12 to -0.02, P = 0.011) compared with those without. At lower (more abnormal) oxygen-pulse slopes, there was a larger improvement of the placebo-controlled effect of PCI on DSE score [oxygen-pulse plateau presence (Pinteraction = 0.026) and oxygen-pulse gradient (Pinteraction = 0.023)] and Seattle angina physical-limitation score [oxygen-pulse plateau presence (Pinteraction = 0.037)]. Impaired peak VO2, VE/VCO2 slope, peak oxygen-pulse, and oxygen uptake efficacy slope was significantly associated with higher symptom burden but did not relate to severity of ischaemia or predict response to PCI.

CONCLUSION

Although selected CPET parameters relate to severity of angina symptoms and quality of life, only an oxygen-pulse plateau detects the severity of myocardial ischaemia and predicts the placebo-controlled efficacy of PCI in patients with single-vessel CAD.

Abnormal end-tidal PO(2) and PCO(2) at the anaerobic threshold correlate well with impaired exercise gas exchange in patients with left ventricular dysfunction

BACKGROUND

The aim of the present study was to compare the end-tidal O(2) pressure (PETO(2)) to end-tidal CO(2) pressure (PETCO(2)) in cardiac patients during rest and during 2 states of exercise: at anaerobic threshold (AT) and at peak. The purpose was to see which metabolic state, PETO(2) or PETCO(2), best correlated with exercise limitation.

METHODS AND RESULTS

Thirty-eight patients with left ventricular (LV) ejection fraction <40% underwent cardiopulmonary exercise testing (CPX). PETO(2) and PETCO(2) were measured during CPX, along with peak O(2) uptake (VO(2)), AT, slope of the increase in ventilation (VE) relative to the increase in CO(2) output (VCO(2)) (VE vs. VCO(2) slope), and the ratio of the increase in VO(2) to the increase in work rate (ΔVO(2)/ΔWR). Both PETO(2) and PETCO(2) measured at AT were best correlated with peakVO(2), AT, ΔVO(2)/ΔWR and VE vs. VCO(2) slope. PETO(2) at AT correlated with reduced peak VO(2) (r=-0.60), reduced AT (r=-0.52), reduced ΔVO(2)/ΔWR (r=-0.55) and increased VE vs. VCO(2) slope (r=0.74). PETCO(2) at AT correlated with reduced peak VO(2) (r=0.67), reduced AT (r=0.61), reduced ΔVO(2)/ΔWR (r=0.58) and increased VE vs. VCO(2) slope (r=-0.80).

CONCLUSIONS

PETCO(2) and PETO(2) at AT correlated with peak VO(2), AT and ΔVO(2)/ΔWR, but best correlated with increased VE vs. VCO(2) slope. PETO(2) and PETCO(2) at AT can be used as a prime index of impaired cardiopulmonary function during exercise in patients with LV failure.

Coronary flow reserve is a comprehensive indicator of cardiovascular risk factors in subjects with chest pain and normal coronary angiogram

BACKGROUND

The aim of the present study was to analyze the parameters related to baseline coronary flow velocity (CFV) and coronary flow reserve (CFR) using Doppler transthoracic echocardiography (TTE), and to assess their associations with components of the Framingham risk score (FRS), which estimates 10-year risk of coronary heart disease, in subjects with chest pain and a normal coronary angiogram.

METHODS AND RESULTS

A total of 354 individuals (mean age: 55+/-11 years, M:F ratio =186:168) with angina or angina-like chest pain and a normal coronary arteriogram were enrolled. CFR, using TTE and adenosine or dipyridamole, was measured within 2 weeks after coronary angiogram. The clinical, electrocardiographic, echocardiographic and laboratory parameters related to baseline CVF and CFR were analyzed, and CFR was compared with FRS. There was an inverse correlation between baseline CFV and CFR (r=-0.374, P<0.001). On multivariate analysis the fulfilling of left ventricular hypertrophy criteria on electrocardiography was an independent predictor of baseline CFV for the upper 75% quartile (23.2> or =cm/s; odds ratio (OR) = 2.840, 95% confidence interval (CI) =1.155-6.983, P=0.023). On multivariate analysis hemoglobin A(1c) level was independently related to a CFR <2.0 (OR = 2.195, 95%CI = 0.920-1.005, P=0.013). CFR had an inverse correlation with FRS (r=-0.222, P<0.001). On multiple regression analysis among the components of the FRS system (FRSS), independent factors related to a CFR <2.0 included age (OR =1.033, 95%CI =1.000-1.067, P=0.041), high-density lipoprotein-cholesterol level (OR = 0.961, 95%CI = 0.933-0.991, P=0.012) and smoking status (OR = 2.461, 95%CI =1.078-5.618, P=0.033), respectively.

CONCLUSIONS

CFR can be a comprehensive indicator of cardiovascular risk factors, including parameters of the FRSS, in subjects with chest pain and a normal coronary angiogram.