Allison, Thomas G.

Abstract Introduction Sleep disordered breathing (SDB) is associated with adverse cardiovascular outcomes and decreased cardiorespiratory fitness (CRF). The risk of long-term major adverse cardiovascular events (MACE) when SDB and decreased CRF co-occur has not been determined. Methods We included consecutive patients that underwent a symptom-limited cardiopulmonary exercise test followed by first-time diagnostic polysomnography within 6 months. Patients were stratified based on the presence of moderate-severe SDB (apnea/hypopnea index ≥15/hour) and decreased CRF defined as <70% predicted peak oxygen consumption (VO2). MACE was a composite outcome of myocardial infarction (MI), coronary artery bypass graft (CABG), percutaneous coronary intervention (PCI), stroke/transient ischemic attack (TIA) and death. Cox-proportional hazard models adjusting for factors known to influence CRF and MACE were constructed. Results Of 498 included patients (60±13 years, 28.1% female), 175 (35%) had MACE (MI=17, PCI=14, CABG=13, stroke=20, TIA=12, deaths=99) at a median follow-up of 8.7 years (interquartile range=6.5-10.3 years). After adjusting for age, sex, beta-blockers, systemic hypertension, diabetes mellitus, coronary artery disease, cardiac arrhythmia, chronic obstructive pulmonary disease, smoking and positive airway pressure (PAP) usage, decreased CRF alone (HR=1.91, 95%CI=1.15-3.18, p=0.012), but not SDB alone (HR=1.26, 95%CI=0.75-2.13, p=0.389) was associated with increased risk of MACE. Those with SDB and decreased CRF had increased risk of MACE compared to patients with decreased CRF alone (HR=1.85, 95%CI=1.21-2.84, p<0.005) after accounting for these confounders; the risk was attenuated after additionally adjusting for adequate adherence to PAP (HR=1.85, 95%CI=0.99-3.05, p=0.05). Conclusion The incidence of MACE, including mortality, was high in this sample. Moderate-severe SDB with concurrent decreased CRF was associated with higher risk of MACE than decreased CRF alone. These results highlight the importance of including CRF in the risk assessment of patients with SDB, and conversely, that of screening for SDB in patients with low peak VO2. Support None.

Exercise-induced hypertension is a predictor of cardiovascular events in patients with coarctation of aorta (COA). However, it is unclear whether mild COA diagnosis is an independent risk factor of exercise-induced hypertension. We hypothesized that for every unit increase in exercise, patients with COA (without hemodynamically significant coarctation) will have a higher rise in systolic blood pressure (SBP) compared with matched controls. One hundred forty-nine patients with COA (aortic coarctation peak velocity <2 m/s) who underwent exercise testing were matched 1:1 to controls using propensity score method based on age, sex, body mass index, hypertension diagnosis, and SBP at rest. We compared exercise-induced change in SBP between patients with COA and controls and also assessed the correlation between Doppler-derived aortic vascular function indices (effective arterial elastance index and total arterial compliance index) and exercise-induced changes in SBP. Compared with controls, patients with COA had a greater change in SBP per unit metabolic equivalent (β=2.86; 95% CI, 1.96–4.77 versus 1.07, 95% CI, −0.15 to 1.75; P =0.018) and per unit oxygen pulse (β=4.57; 95% CI, 2.97–7.12 versus 1.45, 95% CI, −0.79 to 2.09, P <0.001). There was a correlation between SBP peak −SBP rest and elastance index ( r =0.38, P =0.032) and between SBP peak −SBP rest and total arterial compliance index ( r =−0.51, P =0.001), suggesting an association between vascular dysfunction and exercise-induced BP changes. Patients with COA, without significant obstruction, had higher exercise-induced changes in SBP after adjustment for other risk factors for hypertension. Considering the already known prognostic importance of exercise-induced hypertension, the current study highlights the potential role of exercise testing for risk stratification of patients with mild COA.

Abstract BACKGROUND A decrease in diastolic blood pressure (DBP) with exercise is considered normal, but the significance of an increase in DBP has not been validated. Our aim was to determine the relationship of DBP increasing on a stress test regarding comorbidities and mortality. METHODS Our database was reviewed from 1993 to 2010 using the first stress test of a patient. Non-Minnesota residence, baseline cardiovascular (CV) disease, rest DBP &lt;60 or &gt;100 mm Hg, and age &lt;30 or ≥80 were exclusion criteria. DBP response was classified: normal if peak DBP–rest DBP &lt; 0, borderline 0–9, and abnormal ≥10 mm Hg. Mortality was determined from Mayo Clinic records and Minnesota Death Index. Logistic regression was used to determine the relationship of DBP response to the presence of comorbidities. Cox regression was used to determine total and CV mortality risk by DBP response. All analyses were adjusted for age, sex, and resting DBP. RESULTS Twenty thousand seven hundred sixty patients were included (51 ± 11 years, female n = 7,314). Rest/peak averaged DBP 82 ± 8/69 ± 15 mm Hg in normal vs. 79 ± 9/82 ± 9 mm Hg in borderline vs. 76 ± 9/92 ± 11 mm Hg in abnormal DBP response. There were 1,582 deaths (8%) with 557 (3%) CV deaths over 12 ± 5 years of follow-up. In patients with borderline and abnormal DBP response, odds ratios for obesity, hypertension, diabetes, and current smoking were significant, while hazard ratios for total and CV death were not significant compared with patients with normal DBP response. CONCLUSIONS DBP response to exercise is significantly associated with important comorbidities at the time of the stress test but does not add to the prognostic yield of stress test.

Background Heart rate ( HR ) recovery has been investigated in specific patient cohorts, but there is less information about the role of HR recovery in general populations. We investigated whether HR recovery has long‐term prognostic significance in primary prevention. Methods and Results Exercise tests performed between 1993 and 2010 on patients aged 30 to 79 years without cardiovascular disease were included. Mortality was determined from Mayo Clinic records and Minnesota Death Index. Total, cardiovascular , and non‐cardiovascular mortality was reported according to HR recovery <13 bpm using Cox regression. 19 551 patients were included, 6756 women (35%), age 51±10 years. There were 1271 deaths over follow‐up of 12±5 years. HR recovery declined after age 60, and was also lower according to diabetes mellitus, hypertension, obesity, current smoking, and poor cardiorespiratory fitness but not sex or β‐blockers. Adjusting for these factors, abnormal HR recovery was a significant predictor of total (hazard ratio [95% confidence interval]=1.56 [1.384–1.77]), cardiovascular (1.95 [1.57–2.42]), and non‐cardiovascular death (1.41 [1.22–1.64]). Hazard ratios for cardiovascular death according to abnormal HR recovery were significant in all age groups (30–59, 60–69, 70–79), in both sexes, in patients with and without hypertension, obesity, and diabetes mellitus, but not in patients taking β‐blockers, current smokers, and patients with normal cardiorespiratory fitness. Conclusions HR recovery is a powerful prognostic factor predicting total, cardiovascular, and non‐cardiovascular death in a primary prevention cohort. It performs consistently well according to sex, age, obesity, hypertension, and diabetes mellitus but shows diminished utility in patients taking β‐blockers, current smokers, and patients with normal cardiorespiratory fitness.

Although improvement in cardiac output and hemodynamic parameters is routinely demonstrated in patients implanted with continuous-flow left ventricular assist devices (CF-LVADs), improvement in exercise capacity is inconsistently seen. Our purpose was to determine whether native cardiac factors, LVAD factors, or comorbid factors were associated with lack of improvement. Review of all patients undergoing preimplant cardiopulmonary exercise testing (CPET) and CPET on LVAD therapy at one institution was performed between 2007 and 2014 (n = 49). Comprehensive assessment of echocardiographic parameters, right heart catheterization data, medications, and comorbid illness was undertaken. There was no mean improvement in peak oxygen consumption (VO2; 11.8–12.4 ml/kg/min; p = 0.26), although exercise time (5.1 [46% predicted] to 5.8 min [56% predicted]; p = 0.02) and nadir of the ratio of minute ventilation to carbon dioxide production slope (VE/VCO2; 39–36; p = 0.001) improved. Factors most strongly associated with improvement in VO2 were Heartmate II pulsatility index (PI; R = 0.48; p = 0.001), power (R = −0.40; p = 0.009), pump flow (R = −0.40; p = 0.008), and pump speed (R = −0.32; p = 0.04). Peak heart rate (HR) was also associated with improvement in VO2 (R = 0.41; p = 0.004). Left ventricular ejection fraction (LVEF; R = 0.004; p = 0.77), right ventricular (RV) function (R = 0.22; p = 0.28), and aortic valve opening (R = 0.20; p = 0.57) were not associated with improvement in VO2. Our data suggest that less reliance on LVAD support was modestly associated with improvement in exercise capacity. Further studies should seek to determine the optimal level of device support prospectively in relation to exercise capacity.

Background: A women-based formula for calculation of age-predicted maximum heart rate [age-predicted maximum heart rate=206−(0.88×age)] was established in asymptomatic volunteer women undergoing treadmill exercise tolerance testing (ETT). We sought to perform a comparison of the performance of this women-based formula for prediction of peak heart rate to the traditional formula [220−age] and our own database-generated prediction formula in a large database of women undergoing ETT. Methods: We performed a retrospective analysis of all consecutive women who underwent symptom-limited Bruce protocol ETT at the Mayo Clinic from 1994 to 2010. Women with known cardiovascular disease or those using beta blockers, calcium channel blockers, or digitalis were excluded. Separate analyses were performed according to symptomatic status. Results: The study included 11,029 women (89.4% Caucasian) with a mean age 52±12 years; 3,632 (33%) were referred specifically for evaluation of symptoms. Age-predicted maximum heart rate calculated by the traditional formula was achieved by 49.7% of women versus 69.9% by the women-based formula with most of the underestimation observed in older women. Average absolute deviation between achieved and predicted peak heart rate (HR) was 10.85±9.18 bpm for traditional versus 11.98±9.00 for women-based formulas (dependent t =−16.64, p <0.0001). The linear regression line calculated from our population [HR=201−(0.67×age)] was closer to the women-based formula, both in terms of intercept and slope than the traditional formula. Peak HR was shown to be slightly affected (−2.5 bpm) by symptom status at referral, whereas smoking and diabetes more significantly reduced achieved peak HR. Conclusions: The women-based formula underestimated peak HR, especially in older women, but was observed to be closer in both intercept and slope to the regression line determined from our study in this large population of female patients. These sex-unique observations should be taken into account when determining adequacy and targets for ETT in women.