Farres, Sam

Purpose: Despite the 2022 American Heart Association/American College of Cardiology guidelines recommending cardiac rehabilitation (CR) after aortic dissection repair, both patient participation in CR and the associated clinical outcomes remain poorly understood. Methods: Adults (≥18 years of age) discharged alive following thoracic aortic dissection surgery across the Mayo Clinic Enterprise (January 2012 to November 2022), with follow-up until May 2024, were included (IRB #24-001141). Data were presented using summary statistics and logistic regression modeling. Results: A total of 186 patients were referred; 37% were female, and the median age was 64 (51, 73) years. Dissections were classified as type A (43%), type B (18%), or a combination, and 55% had residual dissection. Over half (53%) did not start CR, with older age (aOR = 0.97: 95% CI, 0.94 - 0.99; P = .003), family history of aortic dissections and/or aneurysms (aOR = 0.17: 95% CI, 0.04 - 0.54; P = .005), and tobacco use (aOR = 0.35: 95% CI, 0.13 - 0.91; P = .037) being associated with lower odds of enrollment. Of the 87 who enrolled, 34 did so at a Mayo Clinic facility. There were no complications, with no difference in adverse outcomes. Among those with evaluations at graduation from CR (n = 21), quality of life (Dartmouth index 16 [14, 19] vs 25 [22, 30]; P = .002) and 6-minute walk distance (488 [375, 531] vs 302 [235, 398] m; P = .001) improved. Conclusions: Following thoracic aortic dissection repair, CR significantly improved quality of life and functional capacity without adverse events. Further work is needed to improve enrollment and establish data-driven safety margins for exercise.

Introduction: Peripheral arterial disease (PAD) is caused by a lack of blood flow to the musculature relative to its metabolism which results in pain. PAD impacts up to 20% of patients around the world. PAD involves macrovascular and microvascular dysfunction. Near-infrared spectroscopy (NIRS) measures muscle oxygenation levels and assesses microvascular function. The standard of care for diagnosing PAD is the ankle-brachial index (ABI), which assesses macrovascular disease, and the 6-minute walk test (6MWT), which measures gait speed and claudication. NIRS has the potential to monitor progression of PAD. Hypothesis: NIRS measurement of muscle oxygenation, during a standard test of vascular occlusion and post-occlusive hyperemia, the vascular occlusion test (VOT), is predictive of PAD severity as determined by ABI and 6MWT. Methods: We studied 24 patients diagnosed with PAD. The mean age of the patients was 71.3 years, including 54% (n=13) males and 46% (n=11) females. The VOT consisted of rest, occlusion, and reperfusion phases each lasting 5 min (15 min total). Muscle oxygen saturation levels were recorded at 2 hertz. For every patient, 6 features were extracted from the VOT data using computational methods. The VOT features from 15 patients were used to train function-fitting neural network models to predict ABI and 6MWT Continuous Distance. The models were then used to predict ABI and 6MWT Continuous Distance from the VOT features of 9 test patients not used in the training, Results: For patients in the test set, the ABI and 6MWT Continuous Distance predicted by the models differed from the actual measurements by 14%±13% and 15%±17%, respectively (Figure 1). For patients in the training set, the ABI and 6MWT Continuous Distance predicted by the models differed from the actual measurements by 0±0% and 12%±11%, respectively (Figure 1). Conclusion: The VOT has the potential to predict the ABI and 6MWT Continuous Distance of patients diagnosed with PAD, suggesting that the VOT can be automated and used to monitor the severity of PAD. With more data from both healthy patients and PAD patients, and improvement of the model, we anticipate that the VOT will complement ABI and 6MWT in the diagnosis and monitoring of PAD.

Introduction: Peripheral artery disease (PAD), an atherosclerotic disease of the peripheral arteries, also results in microvascular dysfunction. PAD patients are recommended to undergo supervised walking and medical management; however, compliance with supervised walking programs is limited due to inconvenience and pain, necessitating alternative non-pharmacological interventions. We have shown that daily muscle stretching improved microvascular function in aged rats. This prompted us to study the effect of daily muscle stretching on microvascular function of the calf muscles in PAD patients. Methods: A randomized, single-blinded study was conducted on 24 PAD patients. Patients were assigned to either stretching or placebo stretching using a dorsiflexion splint (Image 1) for 30 min/day, 5 days/wk for 4 wks. Calf muscle oxygen saturation (smO 2 ) was recorded using near-infrared spectroscopy during the six-minute walking test (6MWT) before (Visit 1) and after (Visit 2) stretching or placebo stretching. The percentage decrease in smO 2 (from baseline) at minute 1 (Δ1) and minute 2 (Δ2) of the 6MWT was determined. Two-way ANOVA was used to compare Δ1 and Δ2 between the stretching and placebo stretching groups. Results: The mean age of the patients was 74.1±11.4 yrs with 52% (13/23) males. There was no significant difference in the changes in smO 2 during the 6MWT at either minute 1 (Δ1: 44.1±7.3% vs 27.1±7.0%, p=0.12) or minute 2 (Δ2: 78.7±8.2% vs 58.1±7.9%, p=0.08) between the stretching group and placebo stretching group at Visit 1. In contrast, at Visit 2, there was a significantly greater change in smO 2 at minute 2 (D2: 83.1±8.2% vs 51.3±7.9%, p=0.008) in the stretching group compared to the placebo stretching group with a trend towards a statistically greater change in smO 2 at minute 1 (Δ1: 39.0±7.3% vs 20.4±7.0%, p=0.06) (Image 2). Conclusion: Daily stretching of the calf muscles for 4 weeks is associated with increased oxygen extraction by the calf muscles during walking.

Background: Despite expert opinion recommending patient-tailored cardiac rehabilitation (CR) after acute aortic dissection, both patient participation in CR and the associated risk factor modification after CR following aortic dissection repair are poorly understood. Objectives: To describe the characteristics of patients referred to CR, as well as the enrollment rate and outcomes of those referred to CR following thoracic aortic dissection. Methods: We reviewed electronic health records of adults (≥18) discharged alive following thoracic aortic dissection surgery across the Mayo Clinic Enterprise (01/01/2020-11/15/2022) with follow-up to 05/15/2024 (IRB #24-001141). Data are presented using summary statistics. Results: During the study period, 85 patients were included (median [IQR] age: 65 [50-75] years; 40% female; Table 1 ). Across 84% (N=71) who were referred to CR at discharge, 55% (N=39) enrolled. In those patients referred versus not referred to CR, the prevalence of type A dissection (75% vs. 43%), end-organ involvement (27% vs. 0%), and underlying CAD (54% vs. 21%) were greater while current tobacco use (9% vs. 29%) was lower. Of those enrolled at Mayo Clinic (N=16), CR was started 35 (28-65) days following surgery. These patients completed 21 (13-30) CR sessions at an exercise intensity of 59% (50-65%) maximum predicted heart rate. CR was discontinued in 44% (N=7) due to non-cardiac reasons ( Table 2 ). Of the 9 patients who completed CR, general health status (Dartmouth index: 19 [17-21] vs. 26 [22-34]), depressive symptoms (PHQ-9: 1 [0-1] vs. 4 [1-4]), and exercise capacity (6MWT: 214 [196-244] vs. 384 [305-597] meters) improved ( Table 2 ). There were no reported complications or deaths, with stable aortic sizes reported at 18 months. Conclusions: CR improves functional capacity and well-being without complications in patients after thoracic aortic dissection surgery. Further investigation is needed to better assess CR efficacy and usage in this population.