J. Wells Askew

Takotsubo Cardiomyopathy: A Unique Cardiomyopathy With Variable Ventricular Morphology

Takotsubo cardiomyopathy is an important differential diagnosis of acute coronary syndrome. It is characterized by normal (or near-normal) coronary arteries, regional wall motion abnormalities that extend beyond a single coronary vascular bed, and often, a precipitating stressor. Variants of the classical left ventricular apical ballooning, including mid- or basal left ventricular wall motion abnormalities, are increasingly recognized. Takotsubo cardiomyopathy is not rare, and heightened awareness of this unique cardiomyopathy likely will lead to a higher reported incidence. Diagnosis of takotsubo cardiomyopathy has important implications for clinical management at presentation and afterward. The long-term prognosis is generally favorable; however, a small subset has potentially life-threatening complications during the initial presentation. The pathophysiologic mechanism is unknown, but catecholamine excess likely has a central role.

Temporal trends in compliance with appropriateness criteria for stress single-photon emission computed tomography sestamibi studies in an academic medical center

BACKGROUND The purpose of this study was to apply published appropriateness criteria for single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) in a single academic medical center to determine if the percentage of inappropriate studies was changing over time. In a previous study, we applied the American College of Cardiology Foundation/American Society of Nuclear Cardiology (ASNC) appropriateness criteria for stress SPECT MPI and reported that 14% of stress SPECT studies were performed for inappropriate reasons. METHODS Using similar methodology, we retrospectively examined 284 patients who underwent stress SPECT MPI in October 2006 and compared the findings to the previous cohort of 284 patients who underwent stress SPECT MPI in May 2005. RESULTS The indications for testing in the 2 cohorts were very similar. The overall level of agreement in characterizing categories of appropriateness between 2 experienced cardiovascular nurse abstractors was good (kappa = 0.68), which represented an improvement from our previous study (kappa = 0.56). There was a significant change between May 2005 and October 2006 in the overall classification of categories for appropriateness (P = .024 by chi(2) statistic). There were modest, but insignificant, increases in the number of patients who were unclassified (15% in the current study vs 11% previously), appropriate (66% vs 64%), and uncertain (12% vs 11%). Only 7% of the studies in the current study were inappropriate, which represented a significant (P = .004) decrease from the 14% reported in the 2005 cohort. CONCLUSIONS In the absence of any specific intervention, there was a significant change in the overall classification of SPECT appropriateness in an academic medical center over 17 months. The only significant difference in individual categories was a decrease in inappropriate studies. Additional measurements over time will be required to determine if this trend is sustainable or generalizable.

The Timing and Impact of Follow-Up Studies After Normal Stress SPECT Sestamibi Studies

Background—The purpose of this study was to determine the prevalence and timing of routine follow-up single-photon emission computed tomography (SPECT) studies after a normal stress SPECT scan compared with the patients warranty period (ie, time to 1% risk of death or myocardial infarction). Methods and Results—We identified patients at Mayo Clinic Rochester who had normal stress SPECT scans in 2002. Of 2354 patients without prior coronary artery disease, 309 (13%) had routine follow-up scans. The time to routine follow-up was a median of 2.1 years (25th percentile, 1.2 years; 75th percentile, 3.6 years). This interval was a median of 45% of the warranty period. Of the 309 patients, only 9 (3%) underwent subsequent coronary angiography, without revascularization. Of 656 patients with prior coronary artery disease, 171 (26%) had routine follow-up scans. The time to routine follow-up was a median of 1.6 years (25th percentile, 1.0 years; 75th percentile, 2.7 years). This interval was a median of 164% of the warranty period. Of the 171 patients, only 7 (4%) underwent coronary angiography, without revascularization. Conclusions—In patients without prior coronary artery disease, routine follow-up SPECT scans are performed infrequently but well before the end of the patients warranty period. Routine follow-up scans are performed more commonly in patients with prior coronary artery disease but generally after the end of the warranty period. Routine follow-up SPECT scans have minimal impact on referral to catheterization or revascularization.

Carcinoid Valve Disease

Opinion statementCarcinoid is a rare neuroendocrine tumor that typically originates in the gastrointestinal tract and can result in a constellation of symptoms, mediated by vasoactive substances, referred to as carcinoid syndrome. Carcinoid valve and heart disease is characterized by the plaque-like, endocardial fibrous tissue deposits, primarily affecting the right heart endocardium and valves, which result as a consequence of the disease process. Potential mechanisms for the carcinoid valve disease include the complex role of excess serotonin and its interaction with serotonin receptors and transporters. Carcinoid valve and heart disease is a frequent occurrence in patients with carcinoid syndrome and is accountable for substantial morbidity and mortality. Cardiac surgery remains the most effective treatment option for carcinoid valve disease and a multidisciplinary approach at an experienced center is recommended for patients with metastatic carcinoid and carcinoid heart disease.

Occurrence of atrial fibrillation during dobutamine stress echocardiography: Incidence, risk factors, and outcomes

BACKGROUND The reported incidence of atrial fibrillation (AF) occurring during dobutamine stress echocardiography (DSE) ranges from 0.5% to 4%. The aim of this study was to characterize the incidence, risk factors, and outcomes of AF precipitated during DSE. METHODS The clinical and echocardiographic data of consecutive patients over a 50-month period who were in sinus rhythm and underwent DSE were retrospectively reviewed. RESULTS A total of 11,806 consecutive patients underwent DSE and met all inclusion criteria. AF developed during DSE in 122 patients (1%), 71 of whom had histories of AF. The duration of AF was <1 hour in 74 patients (61%) and<24 hours in 117 patients (96%). Of the 47 patients who were still in AF when dismissed from the echocardiography laboratory, 21 had outpatient follow-up within 24 hours, eight were already inpatients, and 18 were triaged to the emergency department or hospital. Spontaneous cardioversion occurred in 114 patients (93%). There were no reported complications. The clinical characteristic most strongly associated with the development of AF during DSE was a history of AF (odds ratio, 18.4 if no history of congestive heart failure; P<.001). The presence or extent of stress-induced myocardial ischemia was not predictive of the development of AF. CONCLUSIONS AF is an infrequent complication of DSE. Most patients return to sinus rhythm spontaneously within 1 hour. Patients with persistent AF can be safely dismissed from the echocardiography laboratory to have outpatient follow-up within 24 hours unless they have suboptimal heart rate control, hypotension, significant symptoms, or markedly abnormal findings on DSE.

New Toys for Nuclear Cardiologists

Gordon Liljestrand is credited with establishing modern nuclear cardiology as a noninvasive imaging modality in 1939.1 Table summarizes major technological advancements in myocardial perfusion imaging over the past 70 years that have led to more accurate assessment of coronary artery disease (CAD). Most of these technical advances have involved radioisotopes and computer software. Camera hardware has undergone relatively little change since the introduction of the gamma camera, also commonly referred to as the scintillation camera, by Hal Anger in 1958.2 The gamma camera has performed admirably as the workhorse for myocardial perfusion imaging over the years but has several limitations. Sensitivity and resolution are modest. Imaging is inefficient as the heart occupies only a small portion of the field of view. Imaging places several demands on the patient, requiring relatively long imaging times (8 to 12 minutes) while lying motionless on a narrow, hard table with one or both arms fully abducted to minimize the distance between the patients chest and the rotating detectors. The relatively long imaging times require administration of fairly high doses of radioisotopes with attendant higher radiation exposure, an issue of increasing medical and societal concern.3 View this table: Table. Developments in Nuclear Cardiology Article see p 51 In the past few years, there have been tremendous advances in gamma camera technology due to the replacement of the conventional sodium iodide (NaI)-based systems with solid-state detectors using cesium iodide coupled to photodiodes or novel semiconductor-based detectors using cadmium zinc telluride (CZT). The most promising of these new technologies is the CZT detector, which directly converts gamma radiation to an electronic pulse and thereby eliminates the need for a scintillating crystal and photomultiplier tubes. The CZT detector is substantially smaller than a NaI-based detector. In addition, the CZT detector offers substantially better energy resolution and spatial resolution than …

Abnormal Electron Beam Computed Tomography Results: The Value of Repeating Myocardial Perfusion Single-Photon Emission Computed Tomography in the Ongoing Assessment of Coronary Artery Disease

OBJECTIVE To determine whether asymptomatic patients with atherosclerosis, indicated by the presence of coronary artery calcium on electron beam computed tomography, are at enough risk for progression of disease to justify a repeated stress single-photon emission computed tomography (SPECT) examination after an initial normal to low-risk perfusion study. PATIENTS AND METHODS We retrospectively identified patients who had abnormal results on electron beam computed tomography (coronary artery calcium score > 0) and normal to low-risk results on SPECT (defined as a summed stress score of 0-3) within a 3-month period from January 1, 1995, to October 31, 2002. Of the 504 identified patients, 285 remained after exclusion criteria were applied. Of the 285 patients, 69 (mean +/- SD age, 58.2 +/- 7.6 years; 91% male) underwent at least 1 repeated myocardial perfusion SPECT imaging study within 4 years of their initial assessment as normal or at low risk without recurrence of symptoms. The value of repeated SPECT imaging was assessed by detection of a substantial change in the repeated SPECT study and by documentation of a clinical event (death, nonfatal myocardial infarction, or revascularization). Follow-up was 100% complete at a mean of 4.3 +/- 1.6 years. RESULTS Only 4 patients (6%) had a substantial progression in their SPECT risk category; substantial changes on the SPECT scans occurred only in patients with a coronary artery calcium score greater than 100. Three patients underwent revascularization, yielding a 5-year rate for survival free of revascularization of 94% (95% confidence interval, 88%-100%). No deaths or nonfatal myocardial infarctions were reported. CONCLUSION The principal findings of this study indicate that asymptomatic patients with initial normal or low-risk results from stress SPECT performed because of abnormal coronary artery calcium scores who remain asymptomatic are at low risk of death, myocardial infarction, or coronary revascularization. Three patients underwent revascularization by percutaneous coronary intervention despite the absence of symptoms. A substantial change in SPECT results (defined as progression from normal or low-risk summed stress score to intermediate- or high-risk summed stress score) affected 6% of patients and was not associated with any adverse hard events (nonfatal myocardial infarction or death).

Noninvasive Stress Testing for Coronary Artery Disease

Stress testing remains the cornerstone for noninvasive assessment of patients with possible or known coronary artery disease (CAD). The most important application of stress testing is risk stratification. Most patients who present for evaluation of stable CAD are categorized as low risk by stress testing. These low-risk patients have favorable clinical outcomes and generally do not require coronary angiography. Standard exercise treadmill testing is the initial procedure of choice in patients with a normal or near-normal resting electrocardiogram who are capable of adequate exercise. Stress imaging is recommended for patients with prior revascularization, uninterpretable electrocardiograms, or inability to adequately exercise.

Evaluation of Molecular Breast Imaging in Women Undergoing Myocardial Perfusion Imaging with Tc-99m Sestamibi

BACKGROUND Our objective was to explore the potential benefits of molecular breast imaging (MBI) as a screening technique in women undergoing stress myocardial perfusion studies. METHODS MBI was offered to women receiving Tc-99m sestamibi injection for myocardial perfusion stress testing. During the required waiting period after stress isotope injection, MBI was performed using a dedicated breast imaging gamma camera system. MBI examinations were interpreted by breast radiologists, with review of a recent mammogram in cases with positive MBI. RESULTS Of 322 women enrolled, 313 completed MBI, comprising 5 with known breast cancer, 2 with known high-risk benign breast lesions, and 306 who were asymptomatic for breast disease with a recent negative mammogram. Analysis was limited to the 306 patients with no known breast disease. MBI was positive in 22 of 306, giving a recall rate of 7.2% (95% confidence interval [CI] 4.8-10.6]. MBI detected 4 new cancers, resulting in a supplemental diagnostic yield of 13.1/1000 women screened (95% CI 5.1-33.2). The number of cancers diagnosed per abnormal MBI examinations (PPV(1)) was 18% (4 of 22) (95% CI 7.3-38.5), and the number diagnosed per MBI-prompted biopsies (PPV(3)) was 44% (4 of 9) (95% CI 18.9-73.3). CONCLUSIONS The addition of MBI to clinically indicated stress myocardial perfusion imaging studies in women results in a high diagnostic yield of newly detected breast cancers while generating a low rate of additional unnecessary workup.

Quality Improvement Using the AUC: Is it This Easy?

The rapid increase in cardiac imaging services throughout the 1990s was the source of increasing concern on the part of third-party payers. In response, the American College of Cardiology Foundation, working with other partners, developed a series of appropriate use criteria (AUC) for cardiac