Allison, Thomas G.

Purpose: Subjects with normal weight obesity (NWO), defined as normal BMI but high body fat (BF)%, are at increased cardiovascular risk. Factors contributing to NWO are not well studied. We hypothesized that NWO is associated with reduced physical activity and unhealthy eating patterns. Methods: We analyzed 5942 people ≥18 years with normal BMI (18.5-24.9 kg/m 2 ) from the NHANES III survey (1988-1994), a representative sample of the US population. Subjects were classified as NWO based on BF% (>35% in women and >25% in men). Leisure-time physical activity was measured with a standard survey. Subjects were stratified as INACTIVE (no physical activity reported), ACTIVE (3-6 METs for ≥ 5 times/week or >6 METs, ≥3 times/week), or insufficiently active (those who were not INACTIVE but did not meet criteria for ACTIVE). Total activity was expressed in METs/hr/month, assuming an exercise duration of 30 minutes for each day reported. A Healthy Eating Index was based on 24-hour dietary recall data. Analyses were weighted for the complex study design. Results: Mean age was 43 years, 54.4% were men; 1170 people (19.7%) with normal BMI had NWO. Table shows demographics, physical activity and nutritional habits by group. After controlling for age, gender, poverty levels, smoking status and Healthy Eating Index, METs/hr/month was an independent predictor of NWO (OR per 100 MET/hours/month is 0.72(95%CI 0.60;0.88). People who were inactive and insufficiently active had higher odds of NWO as compared with active people (OR-1.47; 95%CI 1.10;1.96 and OR-1.60, 95% CI 1.25; 2.05, respectively). Also, strength training was independently associated with a decreased odds of NWO (0.63; 95%CI 0.44;0.89). Dietary pattern was not predictive of NWO. Conclusions: Physical activity, particularly resistance exercise, but not diet, was associated with NWO independently of potential confounders. Promoting physical activity may be an important interventional strategy in these patients.

Abstract Coronary artery disease (CAD) is a leading health challenge worldwide. Exercise stress testing is a foundational non-invasive diagnostic tool. Nonetheless, its variable accuracy prompts the exploration of more reliable methods. Recent advancements in machine learning (ML), including deep learning and natural language processing, have shown potential in refining the interpretation of stress testing data. Adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we conducted a systematic review of ML applications in stress electrocardiogram (ECG) and stress echocardiography for CAD prognosis. Medical Literature Analysis and Retrieval System Online, Web of Science, and the Cochrane Library were used as databases. We analysed the ML models, outcomes, and performance metrics. Overall, seven relevant studies were identified. Machine-learning applications in stress ECGs resulted in sensitivity and specificity improvements. Some models achieved rates of above 96% in both metrics and reduced false positives by up to 21%. In stress echocardiography, ML models demonstrated an increase in diagnostic precision. Some models achieved specificity and sensitivity rates of up to 92.7 and 84.4%, respectively. Natural language processing applications enabled the categorization of stress echocardiography reports, with accuracy rates nearing 98%. Limitations include a small, retrospective study pool and the exclusion of nuclear stress testing, due to its well-documented status. This review indicates the potential of artificial intelligence applications in refining CAD stress testing assessment. Further development for real-world use is warranted.

AbstractBackgroundLong 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.MethodsWe 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.ResultsOverall, 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).ConclusionTESTs should be used with caution when trying to interpret supine‐stand changes for diagnosis of LQTS.

This review emphasizes the importance of cardiopulmonary exercise testing (CPET) in patients diagnosed with hypertrophic cardiomyopathy (HCM). In contrast to standard exercise testing and stress echoes, which are limited due to the ECG changes and wall motion abnormalities that characterize this condition, CPET allows for the assessment of the complex pathophysiology and severity of the disease, its mechanisms of functional limitation, and its risk stratification. It is useful tool to evaluate the risk for sudden cardiac death and select patients for cardiac resynchronization therapy (CRT), cardiac transplantation, or mechanical circulatory support, especially when symptomatology and functional status are uncertain. It may help in differentiating HCM from other forms of cardiac hypertrophy, such as athletes’ heart. Finally, it is used to guide and monitor therapy as well as for exercise prescription. It may be considered every 2 years in clinically stable patients or every year in patients with worsening symptoms. Although performed only in specialized centers, CPET combined with echocardiography (i.e., CPET imaging) and invasive CPET are more informative and provide a better assessment of cardiac functional status, left ventricular outflow tract obstruction, and diastolic dysfunction during exercise in patients with HCM.

Background: Data on the occurrence of syncope and presyncope with hemodynamic instability during graded exercise test (GXT) are limited. Methods: We reviewed the Mayo Integrated Stress Center database for non-imaging GXTs performed between January 2006 and December 2010 and registered syncopic/presyncopic episodes. Electronic medical records were reviewed for clinical information, outcomes, and mortality. SAS was used to provide background statistics. Results: During the study period, a total of 40,715 GXTs were performed on 33,885 unique patients, including 16,306 (40.0%) GXTs on patients with known cardiovascular disease (CVD). High risk for cardiac syncope is defined as prior cardiac arrest/ventricular tachycardia, ischemic cardiomyopathy, implanted defibrillator, history of atrial fibrillation, sotalol, amiodarone, LQTS, HOCM, aortic stenosis was identified in 3263 patients (6.0%), while risk factors for non-cardiac syncope (POTS, history of dizziness/spells/syncope, rest SBP < 100 mmHg, age ≥ 80 years, female age < 30 years, beta blocker use) were found in 15,925 patients (39.1%). Despite the presence of so many patients at risk, only 8 episodes of syncope occurred (0.020% per test; 0.023% per individual patient). Another 5 episodes of near-syncope with documented hypotension were aborted by the quick action of the testing staff (0.012% per test; 0.015% per individual patient). Only 1 patient (a 71yo M with severeCAD) required electrical cardioversion for ventricular fibrillation. None of the other patients, including all 6 women, presented with tachyarrhythmias. There were no deaths and no significant musculoskeletal trauma. Conclusion: Despite many patients with risk factors for cardiac and non-cardiac syncope in the cohort, syncope, and near-syncope with hemodynamic instability were very rare findings on guideline-directed GXTs.

Introduction: Breathing efficiency (V E /VCO 2 slope or nadir) predicts mortality in heart failure (HF). The usual pattern of V E /VCO 2 vs. exercise intensity is a characteristic “shallow bowl” configuration allowing estimate of a V E vs. VCO 2 slope both in normal controls (C) and HF patients. Slope or nadir in HF is generally > 33 vs. 25-30 in C. This pattern of V E /VCO 2 may not be true for other CV diseases. Objective: Compare V E /VCO 2 versus exercise time curves in patients with history of chronic thromboembolic pulmonary hypertension type 4 (PHT4) to HF and C referred for dyspnea on exertion. Methods: We identified 40 consecutive cases of PHT4 versus 40 HF and 40 C over the same age range retrospectively selected from our cardiopulmonary exercise test (CPX) database. V E /VCO 2 was plotted against exercise time (minutes of exercise ≈ METs), and groups were compared statistically for V E /VCO 2 and peak VO 2 by ANOVA followed with Tukey test, with significance set at P < .05. Results: Figure shows higher V E /VCO 2 in PHT4 vs. HF and C with a different pattern vs. exercise intensity. In severe cases (example shown) V E /VCO 2 may increase continuously without plateau reaching peak values > 80. There was statistically significant difference between peak VO 2 between C group vs HF and PHT4, but not among HF and PHT4, although V E /VCO 2 was significant different among the three groups. Age and sex was not different among them. Conclusion: V E /VCO 2 was elevated in PHT4 compared to HF and C. We interpret continuously increasing V E /VCO 2 as a marker of progressively worsening ventilation: perfusion mismatch. Interpretation of V E /VCO 2 in PHT4 cannot be based simply on nadir or slope as in HF, but a plot of the data should be visually examined to gain full understanding of the ventilatory abnormality.

AbstractWe present a novel description of Bezold–Jarisch Reflex (BJR) during cardiopulmonary exercise testing (CPET) in three young female patients with Group 1 pulmonary arterial hypertension (PAH). These three cases presented within 26 months, representing only 0.8% of 11,387 tests on patients with PAH undergoing CPET during this time frame.

Introduction and Hypothesis: In patients with hypertrophic cardiomyopathy (HCM), ventricular tachycardia (VT) is associated with adverse prognosis. Cardiopulmonary exercise testing (CPET) is part of the standard clinical evaluation in HCM. However, limited data are available on the incidence of VT and other adverse events during CPET in HCM. Methods: We reviewed the Mayo Clinic’s Integrated Stress Center Database for CPETs performed on HCM patients between January 2011 and July 2016. Patients were referred for clinical CPET by a physician, and medications were continued for the test. Electronic medical records were reviewed for clinical information and CPET data. Results: A total of 1,208 CPETs were performed on 976 HCM patients during the study period. Most tests were symptom-limited (94.6%), most common symptom was dyspnea (55%). Despite the relatively high number of patients with a history of VT (10.4%) and/or cardiac arrest (1.6%), there was a low rate of adverse events. Non-sustained VT occurred in 6 patients, most frequently during active recovery (3/6), and 2 of these 6 patients had prior history of VT. A 34 year-old female patient experienced sustained VT degenerating into ventricular fibrillation terminated by ICD shock. One patient had syncope during the test but no arrhythmia. Importantly, none of the patients died within 48 hours of the exercise test. Conclusions: In a large cohort of HCM patients, the incidence of VT or other adverse events was a rare finding during symptom-limited CPET.