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Cardiopulmonary exercise testing (CPET) provides a noninvasive and integrated assessment of the response of the respiratory, cardiovascular, and musculoskeletal systems to exercise. This information improves the diagnosis, risk stratification, and therapeutic management of several clinical conditions. Additionally, CPET is the gold standard test for cardiorespiratory fitness quantification and exercise prescription, both in patients with cardiopulmonary disease undergoing cardiac or pulmonary rehabilitation programs and in healthy individuals, such as high-level athletes. In this setting, the relevance of practical knowledge about this exam is useful and of interest to several medical specialties other than cardiology. However, despite its multiple established advantages, CPET remains underused. This article aims to increase awareness of the value of CPET in clinical practice and to inform clinicians about its main indications, applications, and basic interpretation.

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BACKGROUND: Heart failure (HF) remains a prevalent syndrome with significant morbidity and mortality. Optimal drug and device therapies are crucial to reduce the risk of death or HF admission. Yet, less symptomatic patients with good functional capacity are often perceived as having a low risk of adverse events and their attending physicians may suffer from prescription inertia or refrain from performing therapy optimization. Maximum or peak oxygen consumption (pVO2) assessed during cardiopulmonary exercise testing (CPET) is often used as a prognosis indicator and surrogate marker for functional capacity. Our goal was to assess clinical outcomes in a seemingly low risk HF population in Weber class A (pVO2>20 mL/kg/min) with reduced left ventricular ejection fraction (LVEF). METHODS: Single-center retrospective observational study enrolling consecutive HF patients with LVEF<40% (HFrEF) performing CPET between 2003 and 2018. Those with pVO2 >20 mL/kg/min were included. The primary endpoint was a composite of all-cause death or HF hospitalizations at two years after CPET. We also assessed the rates of N-terminal pro b-type natriuretic peptide (NT-proBNP) elevations at baseline. RESULTS: Seventy-two patients were included (mean age of 53±10 years; 86% male; 90% NYHA I-II; median LVEF 32%; median pVO2 24 mL/kg/min). At baseline, 93% had an NT-proBNP level >125 pg/mL (median NT-proBNP 388 [201-684] pg/mL). Overall, seven patients (10%) met the primary endpoint: three died (4%) and five (7%) had at least one HF admission. Among those who died, only one patient had an HF admission during follow up. CONCLUSION: In a clinically stable HFrEF population with good functional capacity, persistent neurohormonal activation was present in the majority, and one in ten patients died or had a HF admission at two years' follow-up. These findings support the urgent need to motivate clinicians to pursue optimal drug uptitration even in less symptomatic patients.

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Despite constant medical evolution, the reimbursement policy of Portuguese National Health Service (NHS) for the study and risk stratification of coronary heart disease has remained unchanged for several decades. Lack of adjustment to contemporary clinical practice has long been evident. However, the recent publication of the European Guidelines for diagnosis and treatment of chronic coronary syndromes further highlighted this gap and the urgent need for a change. Prompted by these Guidelines, the Working Group on Nuclear Cardiology, Cardiac Magnetic Resonance and Cardiac CT, the Working Group on Echocardiography and the Working Group on Stress Pathophysiology and Cardiac Rehabilitation of the Portuguese Society of Cardiology, began a process of joint reflection on the current limitations and how these recommendations could be applied in Portugal. To this end, the authors suggest that the new imaging methods (stress echocardiogram, cardiac computed tomography and cardiac magnetic resonance), should be added to exercise treadmill stress test and myocardial perfusion scintigraphy in the available exam portfolio within the Portuguese NHS. This change would allow full adoption of European guidelines and a better use of tests, according to clinical context, availability and local specificities. The adoption of clinical guidance standards, based on these assumptions, would translate into a qualitative improvement in the management of these patients and would promote an effective use of the available resources, with potential health and financial gains.

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A 55-year-old patient presented with stable angina pectoris with normal physical examination on rest electrocardiogram and cardiac echocardiogram. Treadmill test revealed exercise-induced left posterior fascicular block, which is an uncommon and easily unnoticed marker of coronary artery disease. A dobutamine stress echocardiogram was performed, with a clearly positive result. Coronary angiography revealed critical stenosis in the right coronary artery.

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INTRODUCTION: Brugada syndrome (BrS) is a channelopathy associated with ventricular arrhythmias and sudden cardiac death. In patients at high risk of sudden death, an implantable cardioverter-defibrillator is indicated. Subcutaneous implantable cardioverter-defibrillators (S-ICDs) are an alternative to transvenous systems, with reduced risk of infection and complications associated with system extraction or explantation. OBJECTIVE: To test electrocardiographic eligibility for S-ICD placement after exercise stress testing (EST) in patients with BrS. METHODS: The sample included 35 consecutive patients with BrS. Electrocardiographic eligibility was assessed using the Boston Scientific model 2889 EMBLEM™ S-ICD automated screening tool, in four phases: decubitus and orthostatism, and before and after EST. Those who had at least one acceptable vector in the four measurements were considered eligible. RESULTS: In this study, 71.4% of patients were male and mean age was 53.86±12 years. In screening prior to EST, 14.3% of patients (n=5) were not eligible for an S-ICD. There was a statistically significant association between ineligibility and presence of complete right bundle branch block and history of syncope. After EST, 16.7% of initially eligible patients no longer had eligible vectors (n=5). CONCLUSION: In this study, 16.7% of patients previously eligible for an S-ICD were no longer eligible after EST. This result demonstrates the importance of screening after EST in all patients with BrS and with indication for an S-ICD, and may influence decisions concerning which ICD to implant or whether to institute pharmacological measures that avoid inappropriate therapies.

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AIM: The aim of the study was to compare functional capacity in different types of congenital heart disease (CHD), as assessed by cardiopulmonary exercise testing (CPET). METHODS: A retrospective analysis was performed of adult patients with CHD who had undergone CPET in a single tertiary center. Diagnoses were divided into repaired tetralogy of Fallot, transposition of the great arteries (TGA) after Senning or Mustard procedures or congenitally corrected TGA, complex defects, shunts, left heart valve disease and right ventricular outflow tract obstruction. RESULTS: We analyzed 154 CPET cases. There were significant differences between groups, with the lowest peak oxygen consumption (VO2) values seen in patients with cardiac shunts (39% with Eisenmenger physiology) (17.2±7.1ml/kg/min, compared to 26.2±7.0ml/kg/min in tetralogy of Fallot patients; p<0.001), the lowest percentage of predicted peak VO2 in complex heart defects (50.1±13.0%) and the highest minute ventilation/carbon dioxide production slope in cardiac shunts (38.4±13.4). Chronotropism was impaired in patients with complex defects. Eisenmenger syndrome (n=17) was associated with the lowest peak VO2 (16.9±4.8 vs. 23.6±7.8ml/kg/min; p=0.001) and the highest minute ventilation/carbon dioxide production slope (44.8±14.7 vs. 31.0± 8.5; p=0.002). Age, cyanosis, CPET duration, peak systolic blood pressure, time to anaerobic threshold and heart rate at anaerobic threshold were predictors of the combined outcome of all-cause mortality and hospitalization for cardiac cause. CONCLUSION: Across the spectrum of CHD, cardiac shunts (particularly in those with Eisenmenger syndrome) and complex defects were associated with lower functional capacity and attenuated chronotropic response to exercise.

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INTRODUCTION AND AIMS: Selecting patients for heart transplantation is challenging. We aimed to identify the most important risk predictors in heart failure and an approach to optimize the selection of candidates for heart transplantation. METHODS: Ambulatory patients followed in our center with symptomatic heart failure and left ventricular ejection fraction ≤40% prospectively underwent a comprehensive baseline assessment including clinical, laboratory, electrocardiographic, echocardiographic, and cardiopulmonary exercise testing parameters. All patients were followed for 60 months. The combined endpoint was cardiac death, urgent heart transplantation or need for mechanical circulatory support, up to 36 months. RESULTS: In the 263 enrolled patients (75% male, age 54±12 years), 54 events occurred. The independent predictors of adverse outcome were ventilatory efficiency (VE/VCO2) slope (HR 1.14, 95% CI 1.11-1.18), creatinine level (HR 2.23, 95% CI 1.14-4.36), and left ventricular ejection fraction (HR 0.96, 95% CI 0.93-0.99). VE/VCO2 slope was the most accurate risk predictor at any follow-up time analyzed (up to 60 months). The threshold of 39.0 yielded high specificity (97%), discriminated a worse or better prognosis than that reported for post-heart transplantation, and outperformed peak oxygen consumption thresholds of 10.0 or 12.0 ml/kg/min. For low-risk patients (VE/VCO2 slope <39.0), sodium and creatinine levels and variations in end-tidal carbon dioxide partial pressure on exercise identified those with excellent prognosis. CONCLUSIONS: VE/VCO2 slope was the most accurate parameter for risk stratification in patients with heart failure and reduced ejection fraction. Those with VE/VCO2 slope ≥39.0 may benefit from heart transplantation.

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INTRODUCTION: Cardiac rehabilitation (CR) has been demonstrated to improve exercise capacity in acute coronary syndrome (ACS), but not all patients derive the same benefit. Careful patient selection is crucial to maximize resources. OBJECTIVE: To identify in a heterogeneous ACS population which patients would benefit the most with CR, in terms of functional capacity (FC), by using cardiopulmonary exercise testing (CPET). METHODS: A retrospective analysis of consecutive ACS patients who underwent CR and CPET was undertaken. CPET was performed at baseline and after 36 sessions of exercise. Peak oxygen uptake (pVO2), percentage of predicted pVO2, minute ventilation/CO2 production (VE/VCO2) slope, VE/VCO2 slope/pVO2 and peak circulatory power (PCP) (pVO2 times peak systolic blood pressure) were assessed in two moments. The differences in pVO2 (ΔpVO2), %pVO2, PCP and exercise test duration were calculated. Patients were classified according to baseline pVO2 (group 1, <20 ml/kg/min vs. group 2, ≥20 ml/kg/min) and left ventricular ejection fraction (group A, <50% vs. group B, ≥50%). RESULTS: We analyzed 129 patients, 86% male, mean age 56.3±9.8 years. Both group 1 (n=31) and group 2 (n=98) showed significant improvement in FC after CR, with a more significant increase in pVO2, in group 1 (ΔpVO2 4.4±7.3 vs. 1.6±5.4; p=0.018). Significant improvement was observed in CPET parameters in group A (n=34) and group B (n=95), particularly in pVO2 and test duration. CONCLUSION: Patients with lower baseline pVO2 (<20 ml/kg/min) presented more significant improvement in FC after CR. CPET which is not routinely used in assessement before CR in context of ACS, could be a valuable tool to identify patients who will benefit the most.

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OBJECTIVES: The aim of the present study was to determine the long-term prognostic value provided by the exercise electrocardiographic (ECG) response to nuclear myocardial perfusion imaging (MPI) in the evaluation of patients with chest pain, focusing on patients with a discrepancy between the two tests. METHODS: A total of 1460 consecutive patients (777 female; 62.6 ± 11.4 years) undergoing exercise myocardial single-photon emission computed tomography (SPECT) were included. The endpoint was the occurrence of acute coronary syndrome, heart failure or cardiac death during follow-up. RESULTS: Ischemic ECG changes were observed during stress testing in 271 patients (18.5%) and 362 patients (24.7%) had positive (abnormal) exercise MPI results. There was a discrepancy between ECG and SPECT findings in 471 patients (32.2%). During the follow-up period (14.0-39.6 months), 224 patients (15.3%) presented cardiac events. The hazard ratios (HR) of ECG and MPI results to predict events were 1.506 (95% CI: 1.113-2.039) and 10.481 (95% CI: 7.799-14.080), respectively. In patients with negative MPI, the ECG response did not predict events (HR 1.214 [95% CI: 0.646-2.282]), the same as in patients with positive MPI (HR 1.203 [95% CI: 0.848-1.705]). Only in hypertensive patients with positive SPECT did the ECG show significant prognostic value (HR 1.937 [95% CI: 1.030-3.642]). In multivariate analysis, positive MPI proved an independent long-term prognostic factor (HR 10.536 [95% CI: 7.759-14.308]), but not ECG (HR 1.356 [95% CI: 0.994-1.850]). CONCLUSION: MPI results (normal vs. abnormal) had strong predictive value and discrepant ECG results had no significant additive prognostic value.

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