An exercise stress test for contrast-enhanced duplex ultrasound assessment of lower limb muscle perfusion in patients with peripheral arterial disease.

OBJECTIVE: The aim of the present study was to develop a standardized contrast-enhanced duplex ultrasound (CE-DUS) protocol to assess lower-extremity muscle perfusion before and after exercise and determine relationships of perfusion with clinical and functional measures. METHODS: CE-DUS (EPIQ 5G, Philips) was used before and immediately after a 10-minute, standardized bout of treadmill walking to compare microvascular perfusion of the gastrocnemius muscle in older (55-82 years) patients with peripheral arterial disease (PAD) (n = 15, mean ankle-brachial index, 0.78 ± 0.04) and controls (n = 13). Microvascular blood volume (MBV) and microvascular flow velocity (MFV) were measured at rest and immediately following treadmill exercise, and the Modified Physical Performance Test (MPPT) was used to assess mobility function. RESULTS: In the resting state (pre-exercise), MBV in patients with PAD was not significantly different than normal controls (5.17 ± 0.71 vs 6.20 ± 0.83 arbitrary units (AU) respectively; P = .36); however, after exercise, MBV was ∼40% lower in patients with PAD compared with normal controls (5.85 ± 1.13 vs 9.53 ± 1.31 AU, respectively; P = .04). Conversely, MFV was ∼60% higher in patients with PAD compared with normal controls after exercise (0.180 ± 0.016 vs 0.113 ± 0.018 AU, respectively; P = .01). There was a significant between-group difference in the exercise-induced changes in both MBV and MFV (P ≤ .05). Both basal and exercise MBV directly correlated with MPPT score in the patients with PAD (r = 0.56-0.62; P < .05). CONCLUSIONS: This standardized protocol for exercise stress testing of the lower extremities quantifies calf muscle perfusion and elicits perfusion deficits in patients with PAD. This technique objectively quantifies microvascular perfusion deficits that are related to reduced mobility function and could be used to assess therapeutic efficacy in patients with PAD.

Post-exercise left atrial conduit strain predicted hemodynamic change in heart failure with preserved ejection fraction.

OBJECTIVES: Left ventricle function directly impacts left atrial (LA) conduit function, and LA conduit strain is associated with exercise intolerance in patients with heart failure with preserved ejection fraction (HFpEF). Pulmonary capillary wedge pressure (PCWP) before and during exercise is the current gold standard for diagnosing HFpEF. Post-exercise ΔPCWP can lead to worse long-term outcomes. This study examined the correlation between LA strain and post-exercise ΔPCWP in patients with HFpEF. METHODS: We enrolled 100 subjects, including 74 with HFpEF and 26 with non-cardiac dyspnea, from November 2017 to December 2020. Subjects underwent echocardiography, invasive cardiac catheterization, and expired gas analysis at rest and during exercise. Arterial blood pressure, right atrial pressure, pulmonary artery pressure, and PCWP were recorded during cardiac catheterization. Cardiac output, stroke volume, pulmonary vascular resistance, pulmonary artery compliance, systemic vascular resistance, and LV stroke work were calculated using standard formulas. RESULTS: Exercise LA conduit strain significantly correlated with both post-exercise ΔPCWP (r = - 0.707, p < 0.001) and exercise PCWP (r = - 0.659; p < 0.001). Exercise LA conduit strain differentiated patients who did and did not meet the 2016 European Society of Cardiology HFpEF criteria with an area under the curve of 0.69 (95% confidence interval, 0.548-0.831) using a cutoff value of 14.25, with a sensitivity of 0.64 and a specificity of 0.68. CONCLUSIONS: Exercise LA conduit strain significantly correlates with post-exercise ΔPCWP and has a comparable power to identify patients with HFpEF. Additional studies are warranted to confirm the ability of LA conduit strain to predict long-term outcomes among patients with HFpEF. CLINICAL RELEVANCE STATEMENT: Exercise left atrial conduit strain was highly associated with the difference of post-exercise pulmonary capillary wedge pressure and may indicate increased mortality risk in patients with heart failure with preserved ejection fraction, and also has comparable diagnostic ability. KEY POINTS: • Left atrial conduit strain is associated with exercise intolerance in patients with heart failure with preserved ejection fraction. • Left atrial conduit strain during exercise can identify patients with heart failure with preserved ejection fraction. • Exercise left atrial conduit strain significantly correlates with the difference of pulmonary capillary wedge pressure during and before exercise which might predict the long-term outcomes of heart failure with preserved ejection fraction patients.

Risk assessment in patients with symptomatic and asymptomatic pre-excitation.

AIMS: Controversy remains as to whether the exercise stress test (EST) is sufficient for risk evaluation in patients with pre-excitation. This study aims to clarify the usefulness of EST in risk stratification in both asymptomatic and symptomatic patients presenting with pre-excitation. METHODS AND RESULTS: This prospective study includes consecutive asymptomatic and symptomatic patients with pre-excitation referred for risk assessment. All participants performed an incremental EST (bicycle) prior to an electrophysiology study (EPS). Primary data from the EST included loss of pre-excitation during exercise, and primary data from the EPS included the measurement of accessory pathway effective refractory period (APERP), shortest pre-excited RR interval (SPERRI), and inducible arrhythmia with the use of a beta-adrenergic receptor agonist if deemed necessary. One hundred and sixty-four patients (59 asymptomatic, 105 symptomatic) completed an EST and EPS. Forty-five patients (27%) demonstrated low-risk findings on EST, of which 19 were asymptomatic and 26 were symptomatic. Six patients with low-risk EST findings had SPERRI/APERP ≤ 250 ms at EPS, and two of them were asymptomatic. The sensitivity, specificity, positive predictive value, negative predictive value (NPV), and accuracy of low-risk EST for excluding patients with SPERRI/APERP ≤ 250 ms were 40, 91, 87, 51, and 60%, respectively. The number of patients with inducible arrhythmia at EPS was similar in the asymptomatic (36, 69%) and symptomatic (73, 61%) groups. CONCLUSION: Sudden loss of pre-excitation during EST has a low NPV in excluding high-risk APs. The EPS with the use of isoproterenol should be considered to accurately assess the risk of patients with pre-excitation regardless of symptoms (ClinicalTrials.gov Identifier: NCT03301935).

Proceed with caution: Standard protocol exercise stress tests fail to replicate the diagnostic utility of supine-stand tests for long QT syndrome.

BACKGROUND: Long QT syndrome (LQTS) is a sudden death predisposing condition characterized by ECG-derived prolongation of the QT interval. Previous studies have demonstrated that the supine-stand test may aid in the diagnosis of LQTS as patients fail to shorten their QT interval in response to standing up. The aim of this study was to evaluate the diagnostic accuracy of ECG data derived from standard protocol, clinically performed treadmill exercise stress tests (TESTs) in their ability to mimic the formal supine-stand test. METHODS: We performed a retrospective review of 478 TESTs from patients evaluated for LQTS. Patients referred for evaluation of LQTS but who were dismissed as normal served as controls. Heart rate & QT values were obtained from standard protocol TESTs. RESULTS: Overall, 243 patients with LQTS (125 LQT1, 63 LQT2, 55 LQT3; 146 [60%] female, mean age at TEST 30 ± 17 years) and 235 controls (142 [60%] female, mean age 24 ± 15 years) were included. The paired ΔQTc (QTcStand -QTcSupine ) was similar between LQTS (-5 ± 26) and controls (-2 ± 25; p = .2). During position change, the QT interval shortened by ≥20 ms in 33% of LQTS patients, remained unchanged in 62%, and increased in 5% of LQTS patients which was similar to controls (shortened in 40%, unchanged in 54%, and increased in 6% of controls; p = .2). Receiver-operator curve analysis to test the diagnostic ability of supine-stand ΔQT performed poorly in differentiating LQTS from controls with an of AUC 0.52 (p = .4). CONCLUSION: TESTs should be used with caution when trying to interpret supine-stand changes for diagnosis of LQTS.

Exercise-induced type 1 Brugada pattern in a child.

The exercise stress testing may unmask the type 1 Brugada pattern on the surface electrocardiogram in a portion of patients with Brugada syndrome. The occurrence of the type 1 Brugada pattern during an exercise test in pediatric patients is not common. Consequently, the diagnostic yield of the exercise test in this population is still to be explored. We present a case of exercise-induced type 1 Brugada pattern in a 12-year-old child with episodes of palpitations and discuss the available evidence on the role of the exercise stress test in the diagnosis and risk stratification of patients with Brugada syndrome.

Prognosis and clinical management of asymptomatic family members with RYR2-mediated catecholaminergic polymorphic ventricular tachycardia: a review.

Despite its low prevalence, the potential diagnosis of catecholaminergic polymorphic ventricular tachycardia (CPVT) should be at the forefront of a paediatric cardiologists mind in children with syncope during exercise or emotions. Over the years, the number of children with a genetic diagnosis of CPVT due to a (likely) pathogenic RYR2 variant early in life and prior to the onset of symptoms has increased due to cascade screening programmes. Limited guidance for this group of patients is currently available. Therefore, we aimed to summarise currently available literature for asymptomatic patients with a (likely) pathogenic RYR2 variant, particularly the history of CPVT and its genetic architecture, the currently available diagnostic tests and their limitations, and the development of a CPVT phenotype - both electrocardiographically and symptomatic - of affected family members. Their risk of arrhythmic events is presumably low and a phenotype seems to develop in the first two decades of life. Future research should focus on this group in particular, to better understand the development of a phenotype over time, and therefore, to be able to better guide clinical management - including the frequency of diagnostic tests, the timing of the initiation of drug therapy, and lifestyle recommendations.

A Case of Ventricular Fibrillation in Masked Long-QT Syndrome Coexisting with Coronary Vasospasm.

Although long-QT syndrome (LQTS) with a normal range QT interval at rest leads to fatal ventricular arrhythmias, it is difficult to diagnose. In this article, we present a rare case of a patient who suffered a cardiac arrest and was recently diagnosed with LQTS and coronary vasospasm. A 62-year-old man with no syncopal episodes had a cardiopulmonary arrest while running. During coronary angiography, vasospasm was induced and we prescribed coronary vasodilators, including calcium channel blockers. An exercise stress test was performed to evaluate the effect of medications and accidentally unveiled exercise-induced QT prolongation. He was diagnosed with LQTS based on diagnostic criteria. Pharmacotherapy and an implantable cardioverter defibrillator were used for his medical management. It is extremely rare for LQTS and coronary vasospasm to coexist. In cases of exercise-induced arrhythmic events, the exercise stress test might be helpful to diagnose underlying disease.

Spatiotemporal repolarization dispersion before and after exercise in patients with long QT syndrome type 1 versus controls: probing into the arrhythmia substrate.

Congenital long QT syndrome (LQTS) carries an increased risk for syncope and sudden death. QT prolongation promotes ventricular extrasystoles, which, in the presence of an arrhythmia substrate, might trigger ventricular tachycardia degenerating into fibrillation. Increased electrical heterogeneity (dispersion) is the suggested arrhythmia substrate in LQTS. In the most common subtype LQT1, physical exercise predisposes for arrhythmia and spatiotemporal dispersion was therefore studied in this context. Thirty-seven patients (57% on ß-blockers) and 37 healthy controls (mean age, 31 vs. 35; range, 6-68 vs. 6-72 yr) performed an exercise test. Frank vectorcardiography was used to assess spatiotemporal dispersion as Tampl, Tarea, the ventricular gradient (VG), and the Tpeak-end interval from 10-s signal averages before and 7 ± 2 min after exercise; during exercise too much signal disturbance excluded analysis. Baseline and maximum heart rates as well as estimated exercise intensity were similar, but heart rate recovery was slower in patients. At baseline, QT and heart rate-corrected QT (QTcB) were significantly longer in patients (as expected), whereas dispersion parameters were numerically larger in controls. After exercise, QTpeakcB and Tpeak-endcB increased significantly more in patients (18 ± 23 vs. 7 ± 10 ms and 12 ± 17 vs. 2 ± 6 ms; P < 0.001 and P < 0.01). There was, however, no difference in the change in Tampl, Tarea, and VG between groups. In conclusion, although temporal dispersion of repolarization increased significantly more after exercise in patients with LQT1, there were no signs of exercise-induced increase in global dispersion of action potential duration and morphology. The arrhythmia substrate/mechanism in LQT1 warrants further study.NEW & NOTEWORTHY Physical activity increases the risk for life-threatening arrhythmias in LQTS type 1 (LQT1). The arrhythmia substrate is presumably altered electrical heterogeneity (a.k.a. dispersion). Spatiotemporal dispersion parameters were therefore compared before and after exercise in patients versus healthy controls using Frank vectorcardiography, a novelty. Physical exercise prolonged the time between the earliest and latest complete repolarization in patients versus controls, but did not increase parameters reflecting global dispersion of action potential duration and morphology, another novelty.

Repeatability of ventricular arrhythmia characteristics on the exercise-stress test in RYR2-mediated catecholaminergic polymorphic ventricular tachycardia.

AIMS: In catecholaminergic polymorphic ventricular tachycardia (CPVT), the exercise-stress test (EST) is the cornerstone for the diagnosis, risk stratification, and assessment of therapeutic efficacy, but its repeatability is unknown. We aimed to test the repeatability of ventricular arrhythmia characteristics on the EST in patients with CPVT. METHODS AND RESULTS: EST-pairs (ESTs performed within 18 months between 2005 and 2021, on the same protocol, and without or on the exact same treatment) of patients with RYR2-mediated CPVT from two specialized centres were included. The primary endpoint was the repeatability of the maximum ventricular arrhythmia score [VAS: 0 for the absence of premature ventricular contractions (PVCs); 1 for isolated PVCs; 2 for bigeminal PVCs; 3 for couplets; and 4 for non-sustained ventricular tachycardia]. Secondary outcomes were the repeatability of the heart rate at the first PVC and the ΔVAS (the absolute difference in VAS between the EST-pairs). A total of 104 patients with 349 EST-pairs were included. The median duration between ESTs was 343 (interquartile range, 189-378) days. Sixty (17.2%) EST-pairs were off therapy. The repeatability of the VAS was moderate {Krippendorf α, 0.56 [95% confidence interval (CI), 0.48-0.64]}, and the repeatability of the heart rate at the first PVC was substantial [intra-class correlation coefficient, 0.78 (95% CI, 0.71-0.84)]. The use of medication was associated with a higher odds for a ΔVAS > 1 (odds ratio = 3.52; 95% CI, 2.46-4.57; P = 0.020). CONCLUSION: The repeatability of ventricular arrhythmia characteristics was moderate to substantial. This underlines the need for multiple ESTs in CPVT patients and CPVT suspicious patients and it provides the framework for assessing the therapeutic efficacy of novel CPVT therapies.

Risk Stratification in Pediatric Wolff-Parkinson-White: Practice Variation Among Pediatric Cardiologists and Electrophysiologists.

BACKGROUND: Published guidelines provide recommendations for risk stratification in pediatric Wolff-Parkinson-White (WPW). There are no data on provider concordance with these guidelines. We hypothesized that significant practice variation exists between pediatric cardiologists (PC) and electrophysiologists (EP). METHOD: The records of all patients, age 8 to 21 years, with a new ECG diagnosis of WPW between 1/1/2013 and 12/31/2018, from a single center, were retrospectively reviewed. Subjects were categorized on the basis of symptoms and resting ECG findings as one of the following: asymptomatic intermittent WPW, asymptomatic persistent WPW, or symptomatic WPW. The performance and results of diagnostic testing, including Holter monitor, event monitor, exercise stress test (EST), and electrophysiology study (EPS), were recorded. The primary outcome was concordance with published guidelines. A secondary outcome was documentation of a discussion of sudden cardiac death (SCD) risk. RESULTS: 615 patient encounters were analyzed in 231 patients with newly diagnosed WPW pattern on ECG (56% male; mean age at diagnosis 13.9 ± 2.5 years). EP were observed to have a significantly higher rate of guideline concordance than PC (95% vs. 71%, p < 0.001). There was significant practice variation between PC and EP in the documentation of a discussion of SCD risk: 96% in EP vs. 39% in PC (p < 0.001). CONCLUSION: Significant practice variation exists in the non-invasive and invasive risk stratification of pediatric WPW, with lower concordance to published guidelines amongst PC, when compared to EP. This report highlights the need to promote awareness of current WPW guidelines in the pediatric cardiology community at large.

Effect of treadmill exercise stress testing on troponin levels in children and adolescents.

BACKGROUND: Chest pain is a common complaint among paediatric patients and cardiac troponin (cTn) level is often part of the initial emergency department evaluation. It is well known that after intense endurance exercise cTn levels can be elevated in patients with otherwise healthy hearts, however the effect shorter duration exercise has on cTn levels in this population is not known. OBJECTIVE: Determine the behaviour of cTn levels in healthy children and adolescent patients after short burst, high-intensity aerobic exercise. METHODS: Patients without haemodynamically significant heart disease referred for a treadmill exercise stress test (EST) were recruited over a 6-month period. cTn levels were measured prior to exercise and 4 hours after exercise. RESULTS: Thirteen patients enrolled. Indications for EST were exertional syncope (six), chest pain (four), and long QT syndrome (three). The median exercise time was 12.9 (9.9-13.7) minutes with an average endurance at the fiftieth percentile for age and maximum heart rate rose to an average of 92 (74-98)% of the predicted peak for age. cTn levels prior to exercise were undetectable in all patients. There was no cTn rise in any patient after exercise. There were no ischaemic changes or arrhythmias on exercise electrocardiograms. CONCLUSION: Serum cTn levels do not rise significantly in healthy children after short duration, high-intensity aerobic exercise. Physicians evaluating paediatric patients with an elevated cTn level after less than prolonged strenuous activity likely cannot attribute this lab value solely to exercise and may need to undertake further cardiac investigation.

Assessment of paediatric exertional or peri-exertional syncope: does the story matter?

Exertional syncope has been suggested to correlate with a cardiac aetiology, particularly when occurring in mid-stride. The aim of the study is to evaluate the incidence of cardiac disease among children presenting with exertional syncope, determine the influence of timing within activity, and determine the utility of genetic testing and implantable event monitors in the evaluation of cardiac syncope. The patients ≤18 years old with exertional syncope who underwent exercise stress testing between 2008 and 2019 were retrospectively included. Patients were assessed to be in one of three groups: mid-exertion (mid-stride syncope), peri-exertion (syncope during activity but not moving), and post-exertion (within minutes of the activity). A total of 334 patients were included; 46 % were mid-exertion, 18 % were peri-exertion, and 36 % were post-exertion. Thirteen patients (3.8 %) were diagnosed with cardiac syncope; n = 9 (69 %) mid-exertion. Only mid-exertional syncope was significantly associated with a cardiac diagnosis (OR: 2.6). Cardiac diagnoses included inherited arrhythmia syndromes (n = 9), abnormal coronary origins (n = 2), and supraventricular tachycardia (n = 2). Only catecholaminergic polymorphic ventricular tachycardia (n = 5) was associated with mid-exertional syncope (OR: 1.4). The definitive diagnostic test was exercise testing (n = 8), echocardiogram (n = 2), genetic testing (n = 1), ambulatory monitor (n = 1), and EKG (n = 1). Mid-stride syncope was more likely to result in a cardiac diagnosis, and exercise testing is the most common definitive test as catecholaminergic polymorphic ventricular tachycardia was the primary aetiology of exertional syncope in our cohort. Implantable event monitors and genetic testing could be helpful in ruling out cardiac disease.

Moderators of peak respiratory exchange ratio during exercise testing in children and adolescents with Fontan physiology.

OBJECTIVES: Many patients with Fontan physiology are unable to achieve the minimum criteria for peak effort during cardiopulmonary exercise testing. The purpose of this study is to determine the influence of physical activity and other clinical predictors related to achieving peak exercise criteria, signified by respiratory exchange ratio ≥ 1.1 in youth with Fontan physiology. METHODS: Secondary analysis of a cross-sectional study of 8-18-year-olds with single ventricle post-Fontan palliation who underwent cardiopulmonary exercise testing (James cycle protocol) and completed a past-year physical activity survey. Bivariate associations were assessed by Wilcoxon rank-sum test and simple regression. Conditional inference forest algorithm was used to classify participants achieving respiratory exchange ratio > 1.1 and to predict peak respiratory exchange ratio. RESULTS: Of the n = 43 participants, 65% were male, mean age was 14.0 ± 2.4 years, and 67.4% (n = 29) achieved respiratory exchange ratio ≥ 1.1. Despite some cardiopulmonary exercise stress test variables achieving statistical significance in bivariate associations with participants achieving respiratory exchange ratio > 1.1, the classification accuracy had area under the precision recall curve of 0.55. All variables together explained 21.4% of the variance in respiratory exchange ratio, with peak oxygen pulse being the most informative. CONCLUSION: Demographic, physical activity, and cardiopulmonary exercise test measures could not classify meeting peak exercise criteria (respiratory exchange ratio ≥ 1.1) at a satisfactory accuracy. Correlations between respiratory exchange ratio and oxygen pulse suggest the augmentation of stroke volume with exercise may affect the Fontan patient's ability to sustain high-intensity exercise.

A Stepwise Guide to the Diagnosis and Treatment of Heart Failure With Preserved Ejection Fraction.

Heart failure with preserved ejection fraction (HFpEF) is a growing epidemic owing to an increasingly obese and aging patient population. Making the diagnosis of HFpEF is often challenging because patients frequently have multiple comorbidities and alternative reasons for dyspnea and exercise intolerance, symptoms that are hallmark to the disease. Additionally, a universal diagnostic algorithm and definition of HFpEF is lacking. The treatment of HFpEF has been equally challenging, as there remain exceedingly few therapies show to improve survival in HFpEF and thus management to date has focused on intensive optimization of HFpEF risk factors. In this review, we highlight a stepwise approach to the diagnosis and treatment of HFpEF including (1) how to establish a clinical diagnosis of HFpEF, (2) when to refer for invasive diagnostic testing, (3) current treatment approaches to HFpEF including pharmacologic, nonpharmacologic, and risk factor modification interventions, and (4) when to refer to a dedicated HFpEF center or advanced heart failure specialist. With this systematic stepwise approach to HFpEF diagnosis and management, we aim to improve accurate diagnosis of the disease as well as raise awareness of available therapeutic options for this challenging patient population.

Exercise-induced change in circulating NT-proBNP could not distinguish between patients with and without coronary artery disease: the CADENCE study.

Objective. In patients with chest pain, exercise stress test has a moderate accuracy for coronary artery disease (CAD). Adding a reliable cardiac biomarker to the exercise test could potentially improve the precision of the test. We investigated circulating NT-proBNP levels before and during exercise stress test in patients with and without angiographically verified CAD. We hypothesized that NT-proBNP would give an additive diagnostic value to the exercise stress test. Methods. In patients presenting with symptoms of stable CAD, venous blood samples were taken at rest and within 5 min of termination of a maximal stress test on a bicycle ergometer. All study participants underwent coronary angiography. Significant CAD was defined as ≥75% stenosis in one or more segments of the coronary arteries. Results. Of the 297 participants, significant CAD was found in 111 (37%) patients. Resting levels of NT-proBNP were significantly higher in patients with CAD compared with patients without CAD (74.18 vs. 56.03 ng/L), p = .005. During exercise, NT-proBNP levels increased in the total population (p < .001). The rise was, however, not significantly different between the two groups (8.24 vs. 8.51 ng/L), p = .700. Combining resting NT-proBNP with positive exercise stress test was superior to exercise test alone in predicting CAD, AUC = 0.68 vs. 0.64. Conclusion. Exercise-induced change in circulating NT-proBNP could not distinguish between patients with or without CAD. However, resting levels of NT-proBNP were significantly higher in patients with CAD than those without CAD.

Non-contrast myocardial perfusion in rest and exercise stress using systolic flow-sensitive alternating inversion recovery.

OBJECTIVE: To evaluate systolic flow-sensitive alternating inversion recovery (FAIR) during rest and exercise stress using 2RR (two cardiac cycles) or 1RR intervals between inversion pulse and imaging. MATERIALS AND METHODS: 1RR and 2RR FAIR was implemented on a 3T scanner. Ten healthy subjects were scanned during rest and stress. Stress was performed using an in-bore ergometer. Heart rate, mean myocardial blood flow (MBF) and temporal signal-to-noise ratio (TSNR) were compared using paired t tests. RESULTS: Mean heart rate during stress was higher than rest for 1RR FAIR (85.8 ± 13.7 bpm vs 63.3 ± 11.1 bpm; p < 0.01) and 2RR FAIR (83.8 ± 14.2 bpm vs 63.1 ± 10.6 bpm; p < 0.01). Mean stress MBF was higher than rest for 1RR FAIR (2.97 ± 0.76 ml/g/min vs 1.43 ± 0.6 ml/g/min; p < 0.01) and 2RR FAIR (2.8 ± 0.96 ml/g/min vs 1.22 ± 0.59 ml/g/min; p < 0.01). Resting mean MBF was higher for 1RR FAIR than 2RR FAIR (p < 0.05), but not during stress. TSNR was lower for stress compared to rest for 1RR FAIR (4.52 ± 2.54 vs 10.12 ± 3.69; p < 0.01) and 2RR FAIR (7.36 ± 3.78 vs 12.41 ± 5.12; p < 0.01). 2RR FAIR TSNR was higher than 1RR FAIR for rest (p < 0.05) and stress (p < 0.001). DISCUSSION: We have demonstrated feasibility of systolic FAIR in rest and exercise stress. 2RR delay systolic FAIR enables non-contrast perfusion assessment during stress with relatively high TSNR.

Correlation between impaired hemodynamic response and cardiopulmonary fitness in middle-aged type 2 diabetes mellitus patients: a case-control study.

PURPOSE: Impaired cardiorespiratory fitness (CRF) is a predictor of mortality in patients with type 2 diabetes mellitus (T2DM). It is still not known how the exercise hemodynamic response correlates with CRF. The purpose was to assess the correlation between hemodynamic changes and CRF in middle-aged patients with T2DM. METHODS: After 1:1 matching by age and sex, 139 T2DM patients and 139 non-T2DM controls who completed the exercise treadmill test were included. Maximal aerobic capacity (VO2max), exercise-induced changes in heart rate (ΔHR), systolic blood pressure (ΔSBP), diastolic blood pressure (ΔDBP), and rate-pressure product (ΔRPP) were measured. HRR1 was calculated as the maximum heart rate minus the heart rate after 1 min of rest. RESULTS: Compared to the control population, T2DM patients had decreased ΔHR (87 (77, 97) v 93 (84, 104) bpm, p < 0.05), ΔRPP (3833.64 ± 1670.34 v 4381.16 ± 1587.78 bpm∙mmHg, p < 0.05), HRR1 (21 (14, 27) v 21 (17, 27) bpm, p < 0.05), and VO2max (32.76 ± 5.63 v 34.68 ± 5.70 ml/kg/min, p < 0.05). Multiple linear regression analysis showed that ΔHR and HRR1, yielded a positive correlation with VO2max in T2DM patients (ß = 0.325, P < 0.001; ß = 0.173, P = 0.01). CONCLUSION: The presence of impaired hemodynamic response and VO2max in middle-aged T2DM patients and the association of impaired ΔHR, HRR1, and VO2max may indicate a physiological pathway of impaired CRF, and our results support the need for cardiorespiratory screening and individualized treatment of middle-aged T2DM patients.

Utility of Exercise Stress Testing in Pediatric Patients with T-Wave Inversions.

T-wave inversions (TWI) in inferolateral electrocardiogram (ECG) leads (II, III, aVF, V5-V6) are often suggestive of cardiac pathology in adult patients. They are a common reason of additional testing in pediatric patients. The goal of the study is to determine correlation of exercise stress test T-wave response with diagnosis of cardiac pathology. This is a retrospective review of pediatric patients < 21 years with the finding of baseline TWI in inferior (II, III, avF) and/or lateral (V5-V6) leads on 12-lead ECG. All patients underwent treadmill exercise stress test (EST) and an echocardiogram within 1 year of each other. Demographics, baseline ECG findings, echocardiogram results, and EST data were recorded. T-wave reversion was considered complete if T waves demonstrated normalization during exercise, partial if there was minimal improvement, and no response if there was no change or worsening of inversions. In our cohort of 72 patients with a mean age 14.6 (± 2.9) years and 61% males, 59 (82%) had a structurally normal heart. Thirteen patients had evidence of structural or functional heart disease. Of the 59 patients, 83% had either complete or partial T-wave response. Among the 13 patients with heart disease, two patients had genetic testing consistent with risk for hypertrophic cardiomyopathy and had complete and partial response on EST. Exercise stress testing for TWI in pediatric patients has low sensitivity and specificity for the diagnosis of cardiac disease and routine use in this patient population may not be indicated.

Potential overdiagnosis of long QT syndrome using exercise stress and QT stand testing in children and adolescents with a low probability of disease.

BACKGROUND: Long QT syndrome (LQTS) is a dangerous arrhythmia disorder that often presents in childhood and adolescence. The exercise stress test (EST) and QT-stand test may unmask QT interval prolongation at key heart rate transition points in LQTS, but their utility in children is debated. OBJECTIVE: To determine if the QT-stand test or EST can differentiate children with a low probability of LQTS from those with confirmed LQTS. METHODS: This retrospective study compares the corrected QT intervals (QTc) of children (<19 years) during the QT-stand test and EST. Patients were divided into three groups for comparison: confirmed LQTS (n = 14), low probability of LQTS (n = 14), and a control population (n = 9). RESULTS: Using the Bazett formula, confirmed LQTS patients had longer QTc intervals than controls when supine, standing, and at 3-4 min of recovery (p ≤ .01). Patients with a low probability of LQTS had longer QTc duration upon standing (p = .018) and at 1 min of recovery (p = .016) versus controls. There were no significant QTc differences at any transition point between low probability and confirmed LQTS. Using the Fridericia formula, differences in QTc between low probability and confirmed LQTS were also absent at the transition points examined, except at 1 min into exercise, where low probability patients had shorter QTc intervals (437 vs. 460 ms, p = .029). CONCLUSION: The diagnostic utility of the QT stand test and EST remains unclear in pediatric LQTS. The formula used for heart rate correction may influence accuracy, and dynamic T-U wave morphology changes may confound interpretation in low probability situations.

Does Premature Ventricular Contractions Affect Exercise Capacity in Teenagers with Normal Hearts?

Premature ventricular contractions (PVCs) are common in teenagers even in the absence of structural heart disease or channelopathy. The suppression of PVCs with exercise is a favorable prognostic indicator. There is a paucity of data regarding the relationship between exercise capacity and PVC burden in this population. Our objective was to evaluate the association between various exercise stress parameters and PVC burden ascertained with a 24 h Holter in children without structural heart disease and/or channelopathy. In this retrospective study, 447 patient's charts with a diagnosis of PVC were reviewed at a single tertiary center. The study cohort consisted of ninety one patients with no structural heart disease or channelopathy who underwent an echocardiogram, maximal stress test, and 24 h Holter monitor. The cohort was divided into two groups based on PVC burden by 24-h Holter monitoring: < 10% and ≥ 10%. Peak oxygen uptake (VO2 in ml/kg/min), an indicator of maximal aerobic capacity, was collected. Other exercise parameters included a) percentage of predicted VO2 (%VO2) based on age, weight, height, and gender b) percent oxygen pulse, c) Anaerobic threshold (AT), and d) Metabolic equivalents. Demographic and exercise stress test-derived parameters were compared between the two groups using student t test and a p value < 0.05 was considered significant. In our cohort of 91 patients, the mean (SD) age at exercise was 14.5 (3.2) years with 56 (62%) males. Left ventricle shortening fraction (LVFS) was ≥ 28% in all enrolled patients. PVCs were monomorphic in 72(80%) patients. The mean (SD) PVC burden was 14.43% (12.3) ranging from 0.1 to 49.8%. PVC burden was ≥ 10% in 48 (53%) patients. Eighty eight (97%) patients in the study cohort had suppression of PVCs with exercise. There were no significant differences between the two groups (< 10% vs. ≥ 10% PVC burden) with respect to demographic or exercise test-derived parameters. Univariate regression between PVC burden and %VO2 did not show significant correlation (r = - 0.04, p = 0.75). Children even with ≥ 10% PVC burden did not demonstrate any objective decrease in their exercise capacity. A plausible reason for no difference in exercise capacity in our cohort may be due to lower PVC load or shorter duration of PVCs compared to adults.