Current Trends in the Practice of Medicine Vol. 27, No. 1, 2011 The Thyroid Nodule Clinic INSIDE THIS ISSUE The Challenge Most thyroid nodules—about 95%—are entirely Points to Remember benign. However, identifying the occasional 2 Perspectives on thyroid cancer requires careful evaluation of every • Thyroid nodules are common, with the Continuing nodule found, using a combination of clinical palpable nodules found in 4% to 7% of Evolution of Therapy assessment, neck palpation, ultrasound imaging the adult US population and solitary or for Atrial Fibrillation (Figure 1), and, in many cases, analysis of a biopsy multiple nodules found at much higher specimen (Figure 2, see page 2). rates during ultrasonographic screening. Sometimes, thyroid nodules are noticed by 4 Advances in Seizure the patient or a family member or are discovered • Early diagnosis improves the likelihood Prevention and Prediction during a routine physical examination. They rarely that a cancer can be discovered while still cause symptoms, unless they are large enough contained within the thyroid gland and to interfere with swallowing. Thyroid cancer can amenable to surgery. 6 Childhood Fractures: invade and damage the recurrent laryngeal nerve, When to Worry causing hoarseness. Such invasion and damage are • Mayo Clinic endocrinologists opened the infrequent, however. Most nodules are incidental Thyroid Nodule Clinic in 2009, providing A discoveries, and now many more such nodules are coordinated care, a thorough assessment, discovered because of the increased use of imaging and a definitive diagnosis completed at a performed for other reasons, including carotid single visit. ultrasonography, neck or chest computed tomog- raphy, magnetic resonance imaging, and even positron emission tomography. Early and prompt diagnosis improves the likelihood that a cancer can be discovered while still contained within the thyroid gland and amenable to surgery. Once soft tissue invasion has occurred or lymph nodes are extensively involved, the chance of surgical cure drops substantially and there is a much higher incidence of meta- static spread of these late-stage cancers. Prompt diagnosis is also important for the patient because the finding of a nodule often raises fears about cancer and a delay in diagnosis fuels the concern and anxiety. The most recent set of guidelines from the American Thyroid Association specifies that the evaluation of a thyroid nodule should include clinical assessment to determine the number, size, and location of all nodules within the gland; mea- surement of serum thyrotropin (TSH) to exclude Figure 1. Ultrasound-guided fine-needle aspiration hyperthyroidism; ultrasonography to assess the of a thyroid nodule. nodule for features of malignancy; and fine-needle aspiration (FNA) of nodules that meet the appro- priate size and ultrasound criteria. However, not every nodule needs to be biopsied, so the clinical scenario and ultrasound features are important in selecting the appropriate nodule for biopsy. Mayo Clinic endocrinologists opened the Thyroid Nodule Clinic in 2009 to streamline this evaluation and provide a coordinated approach that meets the needs of patients with thyroid nod- ules. The Thyroid Nodule Clinic provides a 1-stop thyroid nodule evaluation that includes a focused clinical assessment, ultrasound evaluation, and FNA—all typically performed within a 60-minute appointment at a single visit. The ultrasound allows Mayo staff to select both palpable and impalpable nodules for biopsy and target the most suspicious nodule, which is not always the largest nodule. Using ultrasound guidance for those biopsies, Mayo Clinic endocrinologists typically perform more than 600 biopsies per year and expect a clear diagnosis in more that 95% of cases at the first attempt. Because of the coordinated assessment provided through the Thyroid Nodule Clinic, FNA Figure 2. Thyroid cytology of a specimen of papil- results are typically available within 2 hours, so the lary thyroid carcinoma showing papillary archi- patient usually receives a definitive result of the tecture and nuclear enlargement with crowding of entire assessment within 4 hours. Patients with a classic papillary thyroid cancer (Papanicolaou stain, benign nodule can be reassured, and those with original magnification ×100). a malignant or suspicious nodule can be offered an appropriate surgical referral, often within 24 provide for these patients, while lowering costs, hours. Mayo Clinic endocrinologists believe that improving efficiency, and providing a better service the Thyroid Nodule Clinic improves the care they to referring physicians. Perspectives on the Continuing Evolution of Therapy for Atrial Fibrillation Scope of the Problem ing heart disease, may have more persistent or Atrial fibrillation (AF) remains the leading even chronic AF. Nevertheless, the previously arrhythmia in North America, both in num- held belief that most paroxysmal AF ultimately bers of patients affected and the frequency progresses to a chronic form has been ques- of accompanying sequelae. The prevalence tioned. Recent studies have suggested that pro- continues to increase, despite progress in the gression occurs in only 20% to 40% of patients treatment of contributing factors. Although over the course of 3 to 5 years, although longer- 1% of individuals in their 60s may have AF, the term data are lacking. prevalence increases to 10% to 12% in individ- uals older than 80 years. Currently 2.5 million Drug Therapy for AF Americans have AF, but with the aging popula- Because of stroke risk, most patients require tion and improved cardiovascular survival, this some form of antithrombotic therapy in the number may increase to 5 million or 6 million form of aspirin, warfarin, or dabigatran. Those by the year 2050. patients with no risk factors may completely In most patients, AF is initially paroxysmal; forgo antithrombotic therapy, while recently other patients, particularly those with underly- published guidelines suggest that therapy with 2 MAYO CLINIC | ClinicalUpdate aspirin alone is adequate in patients at low risk with a CHADS score less than 1. Patients Points to Remember with several risk factors (age >75 years, hyper- tension, diabetes, prior stroke or transient • Atrial fibrillation (AF) is an increasing ischemic attack, left ventricular dysfunction) burden on the global health care system are at higher risk, necessitating anticoagulation because of the numbers of patients therapy with warfarin. affected, the impact of stroke, and the While relatively rare in the absence of other cost of both inpatient and outpatient heart disease, the possibility of an AF contribu- therapy. tion to ventricular dysfunction should be con- sidered in patients who have a rapid ventricular • Because of stroke risk, most patients response rate and reduced ejection fraction. with AF require some form of anti- Establishing appropriate rate control, however, thrombotic therapy in the form of requires some assessment of rate during rest aspirin, warfarin, or the newer direct and exertion. While most guidelines recommend antithrombin agents such as dabigatran. that resting rates during AF be less than 90 to 100 bpm, a recent large clinical trial has shown • A number of observational studies have that a resting rate less than 110 bpm is adequate shown that ablation is of benefit in for rate control. During exercise, the heart rate eliminating AF, reducing its frequency, should be maintained at less than 120 bpm. and improving patients’ quality of life. Restoration of normal sinus rhythm may be the most effective means of rate control. A number of studies have shown the useful- tality may accompany AF, comparative studies ness of membrane-active, antiarrhythmic drug examining the utility of rate vs rhythm control therapy for maintaining sinus rhythm. Approxi- therapy have had disappointing results. mately 30% to 40% of patients treated with antiarrhythmic therapy achieve control over the Nonpharmacologic Therapy for AF course of 1 year of follow-up. These data have A number of observational studies have shown been validated by larger comparative clinical that AF ablation is of benefit in eliminating AF, trials. Similar results have been reported in reducing its frequency, and improving patients’ studies designed to compare rate and rhythm quality of life (Figure). In most studies, 75% control therapy. Although an increase in mor- to 85% of patients with paroxysmal AF have been rendered free of this arrhythmia over the course of 1 year of observation. Even in patients with persis- tent or chronic AF after ablation, the incidence of the arrhythmia is significantly decreased in 10% to 20%. When Mayo researchers reviewed outcomes of ablation performed at Mayo Clinic, they found (over 2 years of follow- up) that the response to ablation was excel- lent in more than 75% of patients with par- oxysmal AF. Patients with persistent and chronic AF likewise have shown enhanced Figure. Computer-generated map of left atrial activation. Red dots indicate benefit, although ablation sites. a more aggressive MAYO CLINIC | ClinicalUpdate 3 ablative approach has been required. In those notable benefit in patients with underlying with paroxysmal AF, ablation for the isola- dilated cardiomyopathies. In many patients, tion of pulmonary veins may be sufficient, not only was AF eliminated, but a substantial while wider-area circumferential ablation with improvement in ejection fraction was observed, additional linear ablation or energy delivery particularly