Prognostic power of anaerobic threshold parameters in patients with transposition of the great arteries and systemic right ventricle

The cardiorespiratory optimal point as a discriminator of lesion severity in adults with congenital heart disease

BACKGROUND

Peak oxygen consumption (VO2peak), which depends on maximal exertion and is reduced in adults with congenital heart disease (ACHD), is associated with lesion severity. The lowest ventilatory equivalent for oxygen (the minimum value of VE/VO2) reflects the cardiorespiratory optimal point (COP) as best possible respiration-circulatory interaction and may discriminate between lesion types without the need for maximal exertion. However, data on COP in ACHD is scarce.

METHODS

We retrospectively analyzed stable ACHD with moderate (N.=13) and severe lesions (N.=17) reporting to our outpatient clinic undergoing cardiopulmonary exercise testing. The primary outcome of the study was the difference of COP between moderate and severe lesions. Secondary outcomes were between group differences of the submaximal variable exercise oxygen uptake efficiency slope (OUES) and peak O2 pulse (O2pulsemax) as a surrogate for peripheral oxygen extraction and stroke volume increase during exercise.

RESULTS

The group of severe lesions displayed higher COP (29.5±7.0 vs. 25.2±6.2, P=0.028) as well as lower O2pulsemax (13.3±8.4 vs. 14.9±3.4 mL/beat/kg 102, P=0.038). VO2peak (17.4±6.5 vs. 20.8±8.5 mL/kg/min, P=0.286) and OUES (1.5±0.7 vs. 1.8±0.9, P=0.613) showed a trend towards lower values in severe lesions. COP was a better between group discriminator than O2pulsemax (area under the curve 73.8% vs. 72.4%).

CONCLUSIONS

As a submaximal variable, COP discriminated between moderate and severe lesions and may prove beneficial in a highly vulnerable population that is often unable to undergo exertional testing.

Cardiorespiratory Optimal Point Is a Submaximal Exercise Test Variable and a Predictor of Mortality Risk: THE BALL STATE ADULT FITNESS LONGITUDINAL LIFESTYLE STUDY (BALL ST)

PURPOSE

The cardiorespiratory optimal point (COP) is the minimum ventilatory equivalent for oxygen. The COP can be determined during a submaximal incremental exercise test. Reflecting the optimal interaction between the respiratory and cardiovascular systems, COP may have prognostic utility. The aim of this investigation was to determine the relationship between COP and all-cause mortality in a cohort of apparently healthy adults.

METHODS

The sample included 3160 apparently healthy adults (46% females) with a mean age of 44.0 ± 12.5 yr who performed a cardiopulmonary exercise test. Cox proportional hazards models were performed to assess the relationship between COP and mortality risk. Prognostic peak oxygen uptake (V˙ o2peak ) and COP models were compared using the concordance index.

RESULTS

There were 558 deaths (31% females) over a follow-up period of 23.0 ± 11.9 yr. For males, all Cox proportional hazards models, including the model adjusted for traditional risk factors and V˙ o2peak , had a positive association with risk for mortality ( P < .05). For females, only the unadjusted COP model was associated with risk for mortality ( P < .05). The concordance index values indicated that unadjusted COP models had lower discrimination compared with unadjusted V˙ o2peak models ( P < .05) and V˙ o2peak did not complement COP models ( P ≥ .13).

CONCLUSIONS

Cardiorespiratory optimal point is related to all-cause mortality in males but not females. These findings suggest that a determination of COP can have prognostic utility in apparently healthy males aged 18-85 yr, which may be relevant when a maximal exercise test is not feasible or desirable.

The role of cardiopulmonary exercise testing in predicting mortality and morbidity in people with congenital heart disease: a systematic review and meta-analysis

AIMS

The role of cardiopulmonary exercise testing (CPET) in predicting major adverse cardiovascular events (MACE) in people with congenital heart disease (ConHD) is unknown. A systematic review with meta-analysis was conducted to report the associations between CPET parameters and MACE in people with ConHD.

METHODS AND RESULTS

Electronic databases were systematically searched on 30 April 2020 for eligible publications. Two authors independently screened publications for inclusion, extracted study data, and performed risk of bias assessment. Primary meta-analysis pooled univariate hazard ratios across studies. A total of 34 studies (18 335 participants; 26.2 ± 10.1 years; 54% ± 16% male) were pooled into a meta-analysis. More than 20 different CPET prognostic factors were reported across 6 ConHD types. Of the 34 studies included in the meta-analysis, 10 (29%), 23 (68%), and 1 (3%) were judged as a low, medium, and high risk of bias, respectively. Primary univariate meta-analysis showed consistent evidence that improved peak and submaximal CPET measures are associated with a reduce risk of MACE. This association was supported by a secondary meta-analysis of multivariate estimates and individual studies that could not be numerically pooled.

CONCLUSION

Various maximal and submaximal CPET measures are prognostic of MACE across a variety of ConHD diagnoses. Further well-conducted prospective multicentre cohort studies are needed to confirm these findings.

Cardiorespiratory optimal point during exercise testing is related to cardiovascular and all-cause mortality

Cardiorespiratory optimal point (COP) during exercise may be a potentially clinically useful cardiopulmonary exercise testing (CPET) variable, but its prognostic relevance for adverse cardiovascular disease (CVD) outcomes is unknown. We aimed to assess the association of COP during exercise with fatal mortality outcomes and the extent to which COP could improve the prediction of CVD mortality. Cardiorespiratory optimal point, the minimum value of the ventilatory equivalent for oxygen (VE/VO2) in a given minute of a CPET, was defined in 2,205 men who underwent CPET. Hazard ratios (HRs) (95% confidence intervals [CIs]) for outcomes and measures of risk discrimination for CVD mortality were calculated. During a median follow-up of 28.8 years, 402 fatal CHDs, 607 fatal CVDs, and 1,348 all-cause mortality events occurred. COP was continually associated with each outcome in a dose-response manner. On adjustment for established and emerging risk factors, the HRs (95% CIs) for fatal CHD, fatal CVD, and all-cause mortality were 3.05 (1.94-4.81), 2.82 (1.91-4.18) and 2.46 (1.85-3.27), respectively, per standard deviation increase in COP. After further adjustment for high sensitivity C-reactive protein, the HRs were 2.82 (1.78-4.46), 2.57 (1.73-3.81), and 2.27 (1.70-3.02), respectively. Addition of COP to a CVD mortality risk prediction model containing established risk factors was associated with a C-index change of 0.0139 (0.0040 to 0.0238; p = 0.006) at 25 years. COP during exercise is directly associated with fatal cardiovascular and all-cause mortality events in dose-response fashions. COP during exercise may improve the prediction of the long-term risk for CVD mortality.