Treadmill Exercise Stress Test Research Articles

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

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. 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. 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 ≥20ms 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). TESTs should be used with caution when trying to interpret supine-stand changes for diagnosis of LQTS.

Sex differences in individuals with high normal blood pressure who developed hypertension in three-year follow-up

Abstract Background Recent data demonstrated that females are at risk for cardiovascular disease at a lower blood pressure (BP) level than males. Purpose Identify normotensive individuals with high normal BP who are going to develop hypertension in three-year follow-up and demonstrate differences according to their gender. Methods 100 individuals with high normal BP were followed-up for 3 consecutive years. During enrolment they underwent ambulatory BP monitor (ABPM), electrocardiogram (ECG), echocardiogram, carotid-femoral pulse wave velocity (PWV), sympathetic drive assessed by muscle sympathetic nerve activity (MSNA), a negative for ischemia treadmill exercise stress test (TST) (Bruce protocol) and blood sampling. Follow-up was scheduled every 6 months for 3 consecutive years, where BP measurements were assessed in office and with ABPM. All participants offered lifestyle advise to lower their BP. Endpoint was development of hypertension (HTN). Results 19 males and 21 females developed HTN. Office and ABPM measurements did not differ significantly but women who developed HTN demonstrate higher pulse pressure 50vs45 mmHg (p=0.03). In ABPM systolic blood pressure (SBP) differ (123 vs 119 mmHg, p=0.01) in future hypertensive females. Additionally night-time SBP differ in both genders who were going to develop HTN (women: 116vs111 mmHg, p=0.007 and men: 116vs111 mmHg, p=0.043). Both genders demonstrate significantly different PWV values among future hypertensives and those who remained normotensives (women: 8.2vs7.2 m/s, p<0.001, men: 8.3vs7.2 m/s, p<0.001). Males and females who developed hypertension had higher sympathetic activity as reflected from MSNA levels (men: 33vs27 bursts/minute, p<0.001, women: 36vs28 bursts/minute, p<0.001). Both genders who developed HTN had higher SBP at peak exercise (men: 208vs184 mmHg, p<0.0001, women: 197vs173 mmHg, p<0.0001) as also steeper SBP/MET slope (men: 6.7vs5.0, p=0.038, women: 7.1vs3.8, p<0.0001), while their maximal heart rate achieved differ (men: 158bpm vs 167bpm, p=0.014, women: 153bpm vs 162bpm, p<0.0001). Only in women's baseline ECG who developed HTN had wider p-wave duration (103vs94ms, p=0.032) and QRS length (88vs80ms, p=0.018). While echocardiographicly they displayed increased left ventricular mass index (LVMI) (81vs72 g/m²,p=0.006), atrial diameter (37vs34 mm,p<0.0001) and decrease E/A ratio of transmitral flow velocity (0.8vs1.0, p=0.005). Kidney function assessed by 2021 CKD-EPI eGFR reveals a deterioration in those women who are going to develop HTN (87 vs 97 mL/min/1.73 m², p=0.009). Conclusions Both men and women benefit from treadmill exercise stress test as a prognostic tool that can reveal the likelihood of development of hypertension in both sexes and arouse the need to research for target organ damage in women who are in prehypertensive state and may benefit from an early intervention until clarify sex-specific thresholds for diagnosis of hypertension.

Cardiorespiratory Fitness and Risk of Cardiovascular Events and Mortality in Middle Age Patients without Known Cardiovascular Disease.

Low cardiorespiratory fitness is an established risk predictor for chronic non-communicable diseases. We aimed to investigate the prognostic significance of fitness level on the risk of major adverse cardiac events (MACE, the composite of myocardial infarction, stroke, or all-cause death), in a contemporary cohort of middle-aged subjects without cardiovascular disease. Retrospective analysis of patients aged 40-60 years without a history of cardiovascular disease. Degree of fitness was determined according to a graded, maximal treadmill exercise stress testing (EST) time achieved, classified into age- and sex-specific quintiles (Q), and categorized as low (Q1), moderate (Q2-Q4) or high (Q5) fitness groups. A multivariable Cox proportional hazard regression model was used to assess the association of fitness level with the risk of MACE. A total of 6836 patients were included, of which 44.5% were women, and the mean age was 52 years. Overall, 289 MACE events occurred during a median follow-up of 7 years. Level of fitness was inversely associated with the presence of cardiovascular risk factors. The multivariable adjusted hazard ratio (95% confidence interval) for MACE was 1.65 (1.12-2.44) and 2.17 (1.40-3.38) in those at moderate and low fitness levels, compared to the high-fitness group (reference), respectively. For each decrease of one metabolic equivalent (MET) unit achieved at peak exercise, the relative risk for MACE increased by 18%. The association between low fitness and MACE was not modified by other risk factors (P-for-interaction non-significant). Low fitness level, as captured by a maximal treadmill EST, is an independent risk predictor for MACE among middle-age individuals without known cardiovascular disease. The association of low fitness with high burden of cardiometabolic risk factors highlight the importance of lifestyle intervention in this patient population.

Plasma Proteomic Kinetics in Response to Acute Exercise

Regular exercise has many favorable effects on human health, which may be mediated in part by the release of circulating bioactive factors during each bout of exercise. Limited data exist regarding the kinetic responses of plasma proteins during and after acute exercise. Proteomic profiling of 4163 proteins was performed using a large-scale, affinity-based platform in 75 middle-aged adults who were referred for treadmill exercise stress testing. Plasma proteins were quantified at baseline, peak exercise, and 1-h postexercise, and those with significant changes at both exercise timepoints were further examined for their associations with cardiometabolic traits and change with aerobic exercise training in the Health, Risk Factors, Exercise Training and Genetics Family Study, a 20-week exercise intervention study. A total of 765 proteins changed (false discovery rate < 0.05) at peak exercise compared to baseline, and 128 proteins changed (false discovery rate < 0.05) at 1-h postexercise. The 56 proteins that changed at both timepoints included midkine, brain-derived neurotrophic factor, metalloproteinase inhibitor 4, and coiled-coil domain-containing protein 126 and were enriched for secreted proteins. The majority hadconcordant direction of change at both timepoints. Across all proteins assayed, gene set enrichment analysis showed increased abundance of coagulation-related proteins at 1-h postexercise. Forty-five proteins were associated with at least one measure of adiposity, lipids, glucose homeostasis, or cardiorespiratory fitness in Health, Risk Factors, Exercise Training and Genetics Family Study, and 20 proteins changed with aerobic exercise training. We identified hundreds of novel proteins that change during acute exercise, most of which resolved by 1 h into recovery. Proteins with sustained changes during exercise and recovery may be of particular interest as circulating biomarkers and pathways for further investigation in cardiometabolic diseases. These data will contribute to a biochemical roadmap of acute exercise that will be publicly available for the entire scientific community.

SEX DIFFERENCES IN INDIVIDUALS WITH OFFICE HIGH NORMAL BLOOD PRESSURE WHO DEVELOPED HYPERTENSION IN 3-YEAR FOLLOW-UP

Objective: Recent data demonstrated that females develop target organ damage earlier than men. Normotensive individuals with office high normal blood pressure (BP) who remain at normotensive range for at least 3 years demonstrate hemodynamic differences according to their gender. Design and method: 100 individuals with high normal BP were followed-up for 3 consecutive years. During enrolment they underwent ambulatory BP monitor (ABPM), electrocardiogram (ECG), echocardiogram, carotid-femoral pulse wave velocity (PWV), sympathetic drive was assessed by muscle sympathetic nerve activity (MSNA) to assess sympathetic drive, a negative for ischemia treadmill exercise stress test (TST) (Bruce protocol) and blood sampling. Follow-up was scheduled every 6 months for 3 consecutive years, where BP measurements were assessed in office and with ambulatory BP monitoring (ABPM). All participants offered lifestyle advise to lower their BP. Endpoint was development of hypertension (HTN). Then they divided into males and females (postmenopausal). Results: 19 males and 21 females developed HTN. Men were younger than women (51vs58y, p = 0.03). Office and ABPM measurements did not differ significantly. Men exhibit higher waist to hip ratio (0.92vs0.86, p = 0.012), higher uric acid levels (5.6vs4.7mg/dL) and better kidney function according 2021 CKD-EPI GFR (97vs87,p = 0.03). Contrary HDL levels were lower (54vs66mg/dL, p = 0.048). From those who remained normotensive (24 males and 36 females), men exhibit increased left ventricular mass index (90vs82, p = 0.045) compared to women. Interestingly to those who became hypertensive left ventricular mass index was similar (79vs81gr/m2, p = 0.53). Women had greater sympathetic drive as recorded from MSNA levels (33vs36bursts/min,p = 0.012) and MSNA per 100bpm (47vs54burst,p = 0.041). Arterial stiffness as recorded from c-fPWV (8.3vs8.2m/s) did not differ significantly among genders. In TST (Bruce protocol) men exercised two extra minutes on average (9vs7min, p &lt; 0.0001), achieving greater exercise duration and METs (11.2vs8.8, p = &lt; 0.0001) accordingly. SBP at peak exercise was higher in men (208vs197mmHg, p = 0.03). Conclusions: Women who became hypertensive equalized their heart volume with men, demonstrate greater sympathetic activity and worsening of their kidney function. Additionally, their exercise capacity was significantly reduced in comparison with men. Overall, it seems there are structural alterations in heart and kidneys that demonstrates the need to prevent earlier the organ damage during high blood pressure stage in women.

SYMPATHETIC OVERDIVE IS RELATED TO HYPERTENSION DEVELOPMENT IN 3-YEAR FOLLOW-UP STUDY OF INDIVIDUALS WITH HIGH NORMAL BLOOD PRESSURE

Objective: Assess the relation of blood pressure response to treadmill exercise test in subjects with high normal blood pressure (BP) while sympathetic overactivity assessed by muscle sympathetic nerve activity (MSNA) are linked with development of hypertension (HTN) in both genders. Design and method: 100 individuals with high normal BP were followed-up for 3 consecutive years. During enrolment they underwent ambulatory BP monitor (ABPM), electrocardiogram (ECG), echocardiogram, sympathetic drive was assessed by MSNA, a negative for ischemia treadmill exercise stress test (Bruce protocol) and blood sampling. Follow-up was scheduled every 6 months for 3 consecutive years, where BP measurements were assessed in office and with ABPM. All participants offered lifestyle advise to lower their BP. Endpoint was development of HTN. Then they divided into males(M) and females(F) who remained normotensive or developed HTN. Results: 19 males(officeBP:134/85mmHg) and 21 females(officeBP:134/83mmHg) developed HTN. Both genders who developed HTN had higher night systolic BP (M:116vs111mmHg,p = 0.043, F:p = 0.007). Additionally, hypertensive women had higher office pulse pressure (50vs45mmHg,p = 0.03) and 24hour SBP(123vs119mmHg,p = 0.01). MSNA was higher for both hypertensive genders (M:33vs27burst/min,p &lt; 0.0001 &amp; F:36vs28burst/min,p &lt; 0.0001). In both genders hypertensives developed hypertensive response to exercise (M:0.78vs0.04,p &lt; 0.0001 and F:0.85vs0.27,p &lt; 0.0001), exhibit greater increases of SBP at all stages of Bruce protocol (3min M:156vs148mmHg,p = 0.04, F:162vs145mmHg,p &lt; 0.0001, 6min M:181vs165,p = 0.017, F:185vs158,p &lt; 0.0001, peak M:208vs184,p &lt; 0.0001, F:197vs173,p &lt; 0.0001, peak SBP/MET-slope M:6.7vs5.0,p = 0.038, F:7.1vs3.8,p &lt; 0.0001). Their maximum exercise heart rate was lower (M:158vs167bpm,p = &lt;0.014 and F:153vs162bpm,p &lt; 0.0001). Only hypertensive women exhibit echocardiographicly increased left ventricular mass index (81vs72 gr/m2,p = 0.006), left atrium diameter (3.7vs3.4mm p &lt; 0.0001), intraventricular septum (0.94vs0.89cm,p = 0.007), isovolumic relaxation time (106vs80ms,p = 0.042) and decreased transmitral flow E/A (0.8vs1.0,p = 0.005). At their baseline ECG had longer P-wave duration (103vs94ms,p = 0.032) and QRS (88vs80ms,p = 0.018). Finally, the 2021 CKD-EPI GFR demonstrated a deterioration in women's renal function (87vs97, p = 0.009). Conclusions: In both men and women with high normal BP, MSNA identifies a state of increased sympathetic activation and exercise testing provides a prognostic value as a hypertension screening tool identifying a state of increased sympathetic drive which leads to development of hypertension. Moreover, women suffer a deterioration of kidney function as also an increase of heart's volume indicating an earlier target organ damage than men.

Cardiorespiratory fitness is an important marker of cognitive performance in older Latin Americans

AbstractBackgroundOur previous research with older non‐Hispanic whites demonstrated that with increasing cardiorespiratory fitness (CRF) there was a concomitant linear increase in processing speed (PS) performance. PS has also been found in a number of reports as a potential precursor to memory decline associated with Alzheimer’s disease and cognitive aging. The purpose of this study was to examine whether the same cognitive benefits imbued by CRF generalize within a healthy Latino aging community living in Costa Rica (CR).Method415 community dwelling older adults (315 CR and 100 non‐Hispanic whites living in the United States) with a mean age of 71 (SD = 5.29) years old were recruited from the Epidemiology and Development of Alzheimer’s Disease (EDAD), a large international study of Latino cognitive aging. Participants completed neuropsychological testing and a graded treadmill exercise stress test. We compared the relationship between Oxygen Uptake Efficiency Slope (OUES) and a composite measure of PS (Digit Symbol, Block Design, and Stroop Color Naming). Confirmatory factor analysis was conducted.ResultCRF (OUES) significantly predicted PS within the CR (B = 0.50; p &lt; .001) group and non‐Hispanic white (B = 0.25; p &lt; .05) group after controlling for age and sex. The relationship between CRF and the PS factor showed a non‐significant misfit when the relationship was constrained to be equal on both groups (χ² (1) = 0.39, p = 0.53), hence the relationship is equivalent between groups.ConclusionIn a healthy sample of older individuals living in CR we found the same score profile and interrelationships that were identified among non‐Hispanic whites living in the United States. CRF and PS are clinically meaningful therapeutic targets for dementia prevention among older Latin Americans.

PO-01-076 DIAGNOSIS OF CORONARY VASOSPASM PROMPTED BY EPISODIC ST ELEVATION ON A CONSUMER MOBILE ECG DEVICE

Mobile ECG-enabled devices are increasingly used by consumers with limited data on sensitivity to detect ischemic ECG changes. Coronary vasospasm is an important cause of sudden cardiac arrest. The aim of this report is to present a case of a man who was determined to have coronary vasospasm resulting in ST elevation and VF. The patient came to medical attention after recording apparent ST elevation on a consumer mobile ECG device. N/A The patient is a 64-year-old man with paroxysmal atrial fibrillation previously treated with catheter ablation with an implantable loop recorder in place. Two weeks prior to his presentation to our institution, he collapsed at church. He was found to be pulseless and underwent bystander CPR. In-field ECG revealed ventricular fibrillation requiring defibrillation (Figure 1A). Subsequent ECG revealed inferior ST elevation. Coronary angiography demonstrated significant stenosis in the left circumflex artery and mild disease in the right coronary artery. Percutaneous coronary intervention of the left circumflex artery was performed with drug eluting stent. The patient was prescribed aspirin, clopidogrel, and metoprolol. Implantable cardioverter defibrillator placement was deferred as his cardiac arrest was felt to be due to an acute coronary syndrome treated with revascularization. Over the subsequent two weeks, the patient reported episodic sensations of chest uneasiness. He recorded a 6 lead ECG on his AliveCor Kardia device at baseline (Figure 1B) and during symptoms (Figure 1C). Exercise treadmill stress testing revealed no evidence of ischemia. Due to ongoing symptoms, he presented to our institution. Baseline ECG was normal. On telemetry, dynamic ST changes were noted with morphology matching the tracing recorded on his Kardia device, followed by degeneration into nonsustained VF (Figure 1D-F). Coronary angiography revealed a patent left circumflex artery stent and stable non-obstructive right coronary artery disease. Echocardiography was normal. Cardiac biomarkers were normal. A diagnosis of coronary vasospasm was made. The patient was managed with amlodipine and isosorbide mononitrate. After an informed discussion, the patient was discharged with a wearable cardioverter defibrillator. He has not had any arrhythmias or ischemic symptoms during follow-up. While typically used to diagnose arrhythmias, mobile ECG monitors may record ischemic electrocardiographic changes. These may assist in the diagnosis of coronary vasospasm.

CMR tissue characterization and course of acute SARS-CoV-2 type B.1.1.529-associated myocarditis in a professional soccer player

We report the case of a young professional soccer player who underwent cardiac MRI (CMR) for work-up of discrete intermittent chest pain and subtle ST segment elevations in the ECG after having been tested positive for SARS-CoV-2 type B.1.1.529 despite full vaccination including recent mRNA booster. Troponin levels were significantly increased and myocarditis was suspected. Comprehensive CMR including CINE and late gadolinium enhancement as well as multi-parametric T1/T2 mapping techniques revealed local hypokinesia and swelling of the posterolateral wall with non-ischemic late gadolinium enhancement and increased T2 relaxation time compatible with acute viral myocarditis. The patient was admitted to a cardiology ward for rhythm and troponin monitoring and was discharged after two days of uneventful rhythm monitoring and with decreased troponin levels. Adhering to current recommendations the patient was advised to abstain from moderate- to high-intensity sports and exercise for 3-6 months. After 6 months of exercise avoidance, follow-up ECG showed regression of prior ST segment elevations, and Holter ECG as well as a treadmill exercise stress test did not reveal any abnormalities. Follow-up CMR was performed before return-to-sports which revealed persisting myocardial fibrosis but complete regression of myocardial edemam and excluded ongoing inflammation. This example underscores the value of multi-parametric CMR tissue characterization for the work-up of suspected SARS-CoV-2 associated myocarditis, as well as for follow-up before return-to-sports.

Absent Right Coronary Artery in an Active Young Female

Absent Right Coronary Artery in an Active Young Female

415 DOES MYOCARDIAL BRIDGING TRIGGER MYOCARDIAL ISCHEMIA?

Abstract Background Myocardial bridging (MB) is a congenital epicardial coronary abnormality, in which a segment of the artery runs through the myocardium, determining dynamic stenosis during systole. Whether MB can be responsible by itself for myocardial ischemia remains unclear. Thus, we aimed to evaluate whether the dynamic stenosis related to MB can cause signs and symptoms of myocardial ischemia. Methods We enrolled 41 consecutive patients who underwent coronary angiography because of chest pain suspected for ischemic heart disease and were found to have MB in the absence of any significant flow-limiting coronary stenosis and any other cardiac disease. A group of 14 patients who also underwent coronary angiography because of chest pain suspected for ischemic heart disease, but found to be free of any coronary or cardiac abnormality (including MB) and also showed negative results at exercise stress test (EST) served as controls. All enrolled patients underwent a maximal treadmill EST according to standard Bruce protocol. A complete echocardiographic examination was performed at rest and at peak exercise. Results Baseline EST parameters were comparable between groups, whereas peak diastolic blood pressure (pDBP) was slightly higher in the MB group (p=0.044). No clinically significant differences were found in baseline echocardiographic parameters, although the E wave deceleration time (DcT) was longer (p=0.038) and global longitudinal strain (GLS) was higher (p=0.05) in the MB group. During exercise, left ventricular ejection fraction (LVEF) improved significantly in both groups (p&amp;lt;0.001), without any difference between the 2 groups. GLS did not show any significant changes with exercise in both groups. Moreover, among MB patients, no differences were found in stress echocardiographic results between those with positive vs. those with negative EST. Conclusions We failed to demonstrate any significant ischemic impairment of LV systolic and diastolic function at maximal EST in patients with MB. Moreover, we also failed to demonstrate any LV dysfunction in MB patients that developed ECG signs of myocardial ischemia during EST, as compared to those without evidence of myocardial ischemia. Thus, our data question about the ability of MB itself to trigger significant myocardial ischemia in clinical practice.

Exercise increases arterial stiffness independent of blood pressure in older Veterans.

Exercise-induced changes in arterial function could contribute to a hypertensive response to exercise (HRE) in older individuals. We performed the present analysis to define the acute arterial stiffness response to exercise in ambulatory older adults. Thirty-nine Veterans (>60 years old), without known cardiovascular disease, participated in this study, including 19 Veterans who were hypertensive (70.8 ± 6.8 years, 53% women) and 20 Veterans who were normotensive (72.0 ± 9.3 years, 40% women). Arterial stiffness parameters were measured locally with carotid artery ultrasound and regionally with carotid-femoral pulse wave velocity (cfPWV) before and during the 10 min after participants performed a Balke maximal exercise treadmill stress test. The arterial stiffness response to exercise was similar for control and hypertensive participants. At 6 min postexercise, cfPWV was significantly increased (Δ1.5 ± 1.9 m/s, P = 0.004) despite mean blood pressure (BP) having returned to its baseline value (Δ1 ± 8 mmHg, P = 0.79). Arterial mechanics modeling also showed BP-independent increases in arterial stiffness with exercise ( P < 0.05). Postexercise cfPWV was correlated with postexercise SBP ( r = 0.50, P = 0.004) while baseline cfPWV ( r = 0.13, P = 1.00), and postexercise total peripheral resistance ( r = -0.18, P = 1.00) were not. In older Veterans, exercise increases arterial stiffness independently of BP and the arterial stiffness increase with exercise is associated with increased postexercise SBP. BP-independent increases in arterial stiffness with exercise could contribute to a HRE in older adults.

Abstract 13568: Characterization of the Maladaptive QTc Response During the Treadmill Exercise Test in Untreated Patients With Long QT Syndrome

Background: Long QT syndrome (LQTS) is a genetic heart disease affecting about 1 in 2000 persons. Around 40% of patients with LQTS can have a nondiagnostic, normal QTc at rest. The treadmill exercise stress test (TEST) can help unmask patients with concealed LQTS with a characteristic maladaptive, paradoxical increase in QTc ( 460 ms) during the recovery phase. In fact, the recovery phase QTc value has been added to the latest diagnostic score for LQTS. Objective: To characterize the TEST-derived QTc profile of untreated patients with LQTS and determine its diagnostic and prognostic utility. Methods: Retrospective analysis was performed on TEST data derived from 249 patients with LQTS (129 LQT1, 64 LQT2 and 56 LQT3) untreated at the time of their TEST compared with 236 controls. The Bazett’s corrected QTc was calculated at rest (sitting, supine, and standing), during exercise at 1 min, 3 mins, and peak exercise, and during recovery phase at 1, 3 and 5 mins. Results: The mean resting QTc was significantly higher in LQTS patients (457 ± 30 ms) compared to controls (420 ± 24 ms; p&lt;0.0001) as well as at every stage during the TEST (p&lt;0.001). For LQT1 patients, highest QTc was observed at peak exercise (mean 496 ± 38 ms) and during the third minute of recovery phase (mean 500 ± 40 ms). In contrast, LQT2 patients showed the lowest QTc (mean 452 ± 48 ms) during peak exercise but the greatest QTc latency (QTc at 5 min - QTc at 1 min recovery; mean QTc latency 33 ± 77 ms; p=0.005) compared to controls. For LQT3, the mean QTc was greatest at rest compared to controls (p&lt;0.001), and there was no difference during exercise and recovery phases. Among 162 LQT1 and LQT2 patients that presented with concealed LQTS, 119 (73%) showed a maladaptive QT response. ROC analysis showed that in patients with LQT1, a maladaptive QTc &gt; 523 ms at 3 min of recovery was highly predictive of breakthrough cardiac events (AUC 0.84; sensitivity 100%, specificity 72%); no such association was identified for LQT2 or 3. Conclusions: This comprehensive characterization of the QTc response before, during, and after a TEST in the largest untreated cohort of patients with LQTS provides important genotype-specific characteristics and can be used as a predictor for potential LQT1-triggered cardiac events after diagnosis and treatment.

Abstract 11237: Dose Response and Long QT Genotype During Exercise Stress Testing in Children

Introduction: Beta-blockers (BB) are first-line therapy for long QT syndrome (LQTS). Many physicians rely on repeated exercise stress tests (ESTs) to establish the optimal dose in each patient. Hypothesis: Increased BB dose is associated with a decrease in maximum heart rate, influenced by precision-medicine factors including genotype. Methods: Retrospective chart review of treadmill ESTs with the outcome variable “% predicted heart rate (HR)” = (maximum HR achieved/(220-age))*100. Genotype positive patients had pathogenic or likely pathogenic variants, re-adjudicated in 2022. Doses of BB other than nadolol were converted to nadolol equivalents using an established methodology. Results: We evaluated 345 ESTs in 132 LQTS patients (58% genotype positive) from 2003-21. The mean age at first EST was 12.5 years (standard deviation 4.0 years). Most patients were prescribed nadolol (59%) or atenolol (28%). When controlled for person-level fixed effects, we observed an inverse relationship between BB dose and % predicted HR. The dose-response slope was steeper in genotype positive patients than genotype negative patients (-4.8 vs. -3.3, Figure , p&lt;0.01). We observed mild decreases in blood pressure as BB dose increased, (mean 5 mmHg decrease in systolic blood pressure per 1 mg/kg increase in BB). However, neither maximum VO2 nor maximum respiratory exchange ratio were affected by increased BB dose (the slope of each was indistinguishable from 0 in person-level fixed effects models). Conclusion: In children with LQTS, genotype positive patients were more sensitive to BB than genotype negative patients. We developed a multivariate model to predict the dose of BB required to achieve therapeutic beta-blockade, conditional on individual patient demographics and genotype. The model may decrease the need for serial ESTs. BB dose did not affect maximum VO2 or respiratory exchange ratio, which is reassuring for children and adolescents with LQTS who exercise.

TREADMILL STRESS TEST VENTILATORY PATTERN USING A WEARABLE DEVICE AS AN ADDITIONAL MARKER FOR CV DISEASE

TREADMILL STRESS TEST VENTILATORY PATTERN USING A WEARABLE DEVICE AS AN ADDITIONAL MARKER FOR CV DISEASE

Vext - A Virtual Exercise Training Program For Pediatric Solid Organ Transplant Recipients: A Feasibility Study.

Pediatric solid organ transplant (SOT) recipients report lower strength and physical activity levels than their healthy peers. Virtual exercise programs may reduce barriers to exercise and allow for additional access to specialized care. PURPOSE: To determine the feasibility of an 8-week virtual exercise program (VEXT) in pediatric solid organ transplant recipients. METHODS: A strength-based program was designed by a clinical exercise physiologist (AD). A treadmill exercise stress test was completed prior to starting the program. Self-report surveys were used to assess quality of life (Pediatric Quality of Life Inventory, PedsQL), fatigue (Pediatric Quality of Life Multidimensional Fatigue Scale, PedsQL-Fatigue), and physical activity (Physical Activity Questionnaire for Children and Adolescents, PAQ-C/A) prior to and after completion of the program. The strength sub-test of the Bruininks-Oseretsky Test of Motor Proficiency (BOT-2) was administered virtually. Classes were conducted via Zoom (Zoom Video Communications Inc, San Jose, CA), 3 times per week for 30 minutes. Weekly engagement with the study team was provided by a web-based text messaging platform (WelTel Inc., Vancouver, BC). Medians (inter-quartile range, IQR) are reported. RESULTS: Baseline findings are reported for 12 participants (4 liver, 5 kidney, 3 heart SOT recipients; 58% females). The median age was 12 (11-14) years. PedsQL score was [69.57 (55.98-79.89); Normal: 85.66 ± 11.99]. PedsQL-Fatigue score was [66.67 (45.84-76.89); Normal: 82.19 ± 12.27]. PAQ-C/A score was [Females: 1.72 (1.27-2.11); Normal: 2.70 ± 0.63, Males: 2.87 (2.60-2.87); Normal: 3.01 ± 0.72]. The median strength subtest Z-score was -1.00 (-1.35 to -0.60). Exercise times for 10 of the participants who followed the BCCH protocol was 7.04 minutes [(5.68 - 8.86); Controls: 15.25 (13.82 - 16.75)]. The remaining 2 participants followed a modified protocol due to physical limitations. CONCLUSIONS: At baseline, pediatric SOT recipients report a lower quality of life, higher fatigue, and lower physical activity levels than healthy children. Eleven of twelve participants have a low strength score. A virtual exercise program may help to increase strength, increase physical activity levels and, in turn, may improve quality of life in these children.

Exercise Capacity and Perceived Exertion on Treadmill Stress Test Performed While Wearing vs Without a Surgical Mask: A Randomized Clinical Trial in Healthy Adults

BackgroundThe graded exercise treadmill stress test (GXT) is among the most frequently performed tests in cardiology. The COVID-19 pandemic led many healthcare facilities to require patients to wear a mask during the test. This study evaluated the effect of wearing a surgical face mask on exercise capacity and perceived exertion. MethodsIn this prospective, randomized crossover trial, 35 healthy adults performed a GXT using the Bruce protocol while wearing a surgical mask, and without a mask. The primary outcome was exercise capacity in metabolic equivalents (MET), and the secondary outcome was exercise perception on the modified Borg scale (from 0 to 10). Effort duration, heart rate, oxygen saturation, and blood pressure were also analyzed. ResultsExercise capacity was reduced by 0.4 MET (95% confidence interval [CI] –0.7 to –0.2) during the GXT with a mask (11.8 ± 2.7 vs 12.3 ± 2.5 MET, P = 0.001), and the final perceived effort increased by 0.5 points (95% CI 0.2 to 0.8; 8.4 ± 1.3 vs 7.9 ± 1.6, P = 0.004). Effort duration was cut down by 24 seconds (CI –0:39 to –0:09; 10:03 ± 2:30 vs 10:27 ± 2:16 [minutes:seconds], P = 0.003). Oxygen saturation was slightly lower at the end of the test when participants wore a mask. No significant differences occurred in heart rate or blood pressure during the test. ConclusionWearing a surgical mask causes a statistically significant decrease in exercise capacity and increase in perceived exertion. This small effect is not clinically significant for the interpretation of test results.

Effects of Tobacco Consumption on Aerobic Fitness in Indian Adult Men

Background and Aim: Smokeless tobacco products like khaini, guthakha, betel quid, zarda are very commonly consumed by men and women of all age group followed by smoking of bidi, cigarette and hookah. Tobacco consumption is associated with poor cardiorespiratory, gastrointestinal and overall health. Compromised physical fitness is seen in tobacco consumers and severity depends on type of product and duration of use. Aerobic or cardiorespiratory fitness is compromised in tobacco consumers. This study was planned to check the effect of tobacco consumption on aerobic fitness of Indian adult men of 18 to 60 years of age group. Methods: Participants for this study were recruited from Pramukhswami Medical College and its affiliated institutes after obtaining permission from the Institutional Ethics Committee (IEC). A total 74 adult men of 18-60 years’ age groups were enrolled for the present study after their voluntary consent. A total 24 participants who consume tobacco were placed in study group and a total 50 participants who were not consuming tobacco products were placed control group. All participants were apparently healthy at the time of Treadmill exercise stress test following Bruce protocol. Predicted VO2 max (PVO2 max) was calculated on the basis of total exercise time in minutes and seconds on Treadmill machine as per Bruce’s formula of calculating indirect maximal oxygen consumption. Results: PVO2 max values obtained by Treadmill exercise test following Bruce protocol in study group was 29.16 ± 8.88 ml/kg/min while control group was 36.47 ± 9.7. A statistically significant reduction in aerobic fitness was seen in study group as compared to control group. Conclusion: Aerobic fitness was significantly less in tobacco consumer Indian adult men of 18-60 years’ age group as compared to who do not consume tobacco.

Parameters indicating development of hypertension in three-year follow-up study of subjects with high normal blood pressure

Abstract Funding Acknowledgements Type of funding sources: None. Background/Introduction The clinical importance of a hypertensive response to exercise (HRE) in subjects with high normal blood pressure (BP) is not fully elucidated, while sympathetic overactivity followed by arterial stiffening are linked with development of hypertension (HTN). Purpose The aim of this study was to assess the relation of HRE with sympathetic drive as assessed by muscle sympathetic nerve activity (MSNA) and arterial stiffness in subjects with high normal BP who developed hypertension in a 3 year follow up. Methods 100 subjects with high normal office BP [systolic BP=130-139 mmHg and diastolic BP=85-89 mmHg] underwent a treadmill exercise stress test. Arterial stiffness was evaluated based on carotid to femoral pulse wave velocity (PWV). Sympathetic drive was assessed by MSNA levels. Follow up was every 6 months for 3 years, where BP was measured at both office (OffBP) and ambulatory blood pressure monitoring (ABPM). All participants offered lifestyle advises. Endpoint was development of HTN diagnosed either from OffBP or from ABPM. Then they were divided into Group I: those developed HTN and Group II: those remained normotensive. Results Mean age 54±8 years, 42 males, baseline offBP: 132/82 mmHg, ABPM: 122/76 mmHg). Out of them, 50 subjects developed HRE (BP ³210mmHg in men and ³190 mmHg in women) and 40 HTN. Group I developed higher HRE (75% vs. 13%, p=0.026), higher levels of PWV (8.35 vs 7.5 m/sec, p=0.043) and MSNA levels (37 vs. 31 bursts, p=0.04), while did not differ at their metabolic profile. Echocardiographically left ventricular mass index did not differ statistically as E/A ratio of mitral valve inflow (0.92 vs 1.05, p=0.034). Those who developed HTN was related to night systolic BP from ABPM (116 vs 112 mmHg, p&amp;lt;0.04), as also to intermediate stage intervals of 3 min (160 vs 147 mmHg, p=0.068) and 6 min (181 vs 164, p=0.035) of Bruce protocol. A novel metric, the SBP/MET-slope [(peak SBP—resting SBP)/(peak MET-1)] found to add crucial information. Regarding those who developed HTN, SBP/MET-slope was higher in all stages till peak exercise (stage 1: 6.25 vs 4.25, stage 2: 7.6 vs 5.3, peak: 7.22 vs 5.1, p=0.035). It was noticed that they performed a higher exercise capacity (10 vs 11.5 METs) and additionally differ significantly in their maximal heart rate (HR) at peak exercise (154 vs 164, p=0.001). Conclusion In subjects with high normal BP, a HRE, the intermediate BP intervals along with the SBP/MET-slope, identifies a state of systemic vascular resistance, arterial stiffening and sympathetic overdrive, as reflected by increased PWV and MSNA levels respectively. Additionally, exercise capacity demonstrates cardiovascular functional tolerance. These findings suggest that exercise testing provides determining clinical information regarding the overall cardiovascular status, proving its superior prognostic value as a hypertension screening tool, that alarms the physician to warn the patient to take action.

Blood pressure response during treadmill exercise testing and the risk for future development of atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Aims Hypertension is a well-established risk factor for the onset and progression of atrial fibrillation (AF). Blood pressure (BP) response during routine exercise stress testing (EST) may identify subjects at increased risk for developing AF. Methods A retrospective analysis of treadmill EST performed by the Bruce protocol in patients aged ≥40 years without a history of AF (n=17,617; 42% women). BP was measured at rest, peak exercise, and 2-minute recovery, and was analyzed for association with the risk for developing AF. Results AF was documented in 4.5% of patients during mean follow-up of 7 years. The incidence rate of AF per 1000 person-years increased with the rise in CHA2DS2VASc score (3.26 in score=0 to 19.78 in scores≥6). Adjusting for CHA2DS2VASc score and exercise capacity, a multivariate analysis of systolic BP at rest (≥130 vs. ≤110 mmHg), peak-exercise (&amp;gt;170 vs. ≤150 mmHg), and recovery (&amp;gt;150 vs. ≤130 mmHg), were associated with increased risk for AF: hazard ratio (HR) 1.68 (95% CI, 1.40-2.01), 1.38 (1.15-1.64), 1.54 (1.27-1.86), respectively. Similarly, diastolic BP analysis at rest (≥90 vs. &amp;lt;80 mmHg), peak-exercise (≥100 vs. &amp;lt;90 mmHg), and recovery (&amp;gt;90 vs. ≤80 mmHg), were associated with increased risk for AF: 1.78 (1.34-2.35), 2.22 (1.37-3.59), 1.73 (0.90-3.25). The association with AF was also observed when BPs were analyzed as continuous variables, including after additional adjustment of exercise and recovery measurements to resting BP. Conclusions Systolic and diastolic BP at rest, peak-exercise and recovery phases of EST may provide independent predictive information regarding future risk for developing AF.