Clinical Research Directory

Cardiovascular Performance and Exercise Response in Patients With Persistent or Permanent Atrial Fibrillation and Heart Failure Pre and Post Cardioversion or Pace and Ablate

Heart Failure (HF) and Atrial Fibrillation (AF) are two conditions that commonly occur together. Clinical guidelines consider a resting heart rate of 100-110 beats per minute (bpm) acceptable for patients with HF and AF while 72 bpm is considered the average in healthy populations. A higher resting heart rate indicates that the heart is working harder to meet bodily demands, and though it may be considered safe for patients with HF and AF to have a heart rate of 110 bpm, the investigators believe it is having a significant negative impact on patient quality of life and their ability to exercise. The current study will test exercise ability using a treadmill test before and after either a cardioversion, where the patient's heartbeat is reset using electric shocks, or a pace and ablate method, where the patient receives a pacemaker to regulate their heart rhythm and an ablation (intentional damaging) of the node that coordinates the beats within the heart. This will allow investigators to compare how the heart responds to exercise when the patient is on rate-control and anticoagulation medication therapy (before cardioversion or pace and ablate) and after the procedures. During exercise, the investigators will do a blood test that lets investigators know how efficiently the heart is working and record any symptoms experienced. The investigators will also collect information about the patient's quality of life. Using this information, the investigators hope to better understand whether the current standard of a resting heart rate of 100-110 bpm is ideal for patient quality of life.

MWA vs RFA for the Treatment of Moderate-sized Benign Thyroid Nodules

Thyroid nodule is a common condition that affects up to 60% of the population. There is an estimated 10% lifetime probability of developing a thyroid nodule. Although most thyroid nodules are benign, up to 10-15% can enlarge to cause compressive symptoms including neck pressure and discomfort, dysphagia, dyspnea, and dysphonia. The conventional treatment for these benign but problematic nodules has been thyroidectomy. Although generally a low risk operation, thyroidectomy is associated with some risk for recurrent laryngeal nerve injury, bleeding, infection, and need for thyroid hormone supplementation. Since the early 2000s, ultrasound-guided percutaneous thermal ablation has emerged as a potential alternative treatment to surgery for benign thyroid nodules. Of the myriad ablation methods, the most commonly used techniques are radiofrequency ablation (RFA) and microwave ablation (MWA). \[1-3\] A growing body of evidence shows that RFA is an effective treatment for benign solid thyroid nodules, toxic adenomas, and thyroid cysts resulting in overall volume reduction ranges of 40-80% at 1 year, with durable resolution of compressive and hyperthyroid symptoms. However, RFA is not without its limitations. Radiofrequency waves can be limited by the heat sink effect and tissue char leading to longer procedure times and potentially less optimal outcomes in larger, hypervascular, and/or more cystic nodules. Microwave ablation (MWA) is another ablative technique that uses electromagnetic energy waves to cause tissue hyperthermia and coagulative necrosis. It generally causes higher ablation temperatures than RFA and is less subject to the heat sink effect, and therefore can facilitate more efficient ablation procedures. Current evidence comparing RFA versus MWA for thyroid ablation was limited and was either retrospective, non-randomized \[4-9\], under-powered, or with an unequal baseline. The results from these studies were also conflicting, suggesting suboptimal quality of evidence and bias due to non-standardized technique of ablation across studies. To date, there is no randomized controlled trial comparing the efficacy and safety of RFA versus MWA for the treatment of benign thyroid nodules. Given the higher ablation temperatures, freedom from heat sink effect, and no influence from impedance changes during ablation, MWA may achieve different treatment efficacy.