Faculty Bibliography

OBJECTIVES: The purpose of this study was to define appropriate parameters for risk stratification and prognosis in patients undergoing stress echocardiography. BACKGROUND: Stress echocardiography is an established technique for the diagnosis of coronary artery disease. However, current data on risk stratification of patients undergoing stress echocardiography are limited. METHODS: We evaluated 1,500 patients (59 +/- 13 years old; 51% male) undergoing stress echocardiography (34% with treadmill exercise and 66% with dobutamine). Resting left ventricular ejection fraction (EF) and regional wall motion were assessed by the consensus of two echocardiographers. Follow-up (mean 2.7 +/- 1.0 years) for confirmed non-fatal myocardial infarction (n = 31) and cardiac death (n = 44) were performed. RESULTS: By univariate analysis, both the peak wall motion score index (WMSI) (p < 0.0001) and EF (p < 0.0001) were significant predictors of cardiac events. Peak WMSI effectively risk stratified patients into low (0.9%/year), intermediate (3.1%/year), and high (5.2%/year) risk groups (p < 0.0001). A threshold of 45% EF provided further risk stratification of all WMSI groups. By multivariate logistic regression analysis, peak WMSI (relative risk [RR] 2.1, 95% confidence interval [CI] 1.0 to 4.4; p = 0.04) and EF (RR 1.0, 95% CI 0.9 to 1.0; p = 0.01) were both predictors of cardiac events. CONCLUSIONS: Stress echocardiography yields prognostic information for risk stratification of patients with known or suspected ischemic heart disease. A normal stress echocardiographic study (peak WMSI = 1.0) confers a benign prognosis (0.9%/year cardiac event rate). Peak WMSI >1.7 and EF < or =45% are independent markers of patients at high risk of an adverse clinical outcome.

BACKGROUND: Dobutamine-atropine stress echocardiography (DASE) is an established test for the diagnosis and risk stratification of patients with coronary artery disease. Atropine use to attain target heart rate prolongs test time. HYPOTHESIS: The aim of this study was to assess the utility of isometric handgrip exercise (33% maximal voluntary contraction x 4 min) with DASE. METHODS: We prospectively evaluated 131 patients undergoing DASE randomized to handgrip exercise or no handgrip. Effect of handgrip exercise on endpoints: time to target heart rate (85% maximum predicted), recovery time, total test time, mean dobutamine and atropine dosage, and the number of ischemic responses were assessed. Effect of current beta-blocker medication use was also evaluated. RESULTS: Heart rate rose more quickly in the handgrip group. At 6-10 min (peak handgrip), mean heart rate rose 51 +/- 14 beats/min in the handgrip group compared with 38 +/- 18 beats/min in the no handgrip group (p < 0.0001). With handgrip, overall dobutamine study time was reduced by a mean of 4.3 min (16.4 +/- 6.9 vs. 20.7 +/- 8.4, p = 0.004) in all patients, and by a mean of 5.9 min in patients not on beta-blocker medication (p = 0.001). The handgrip group also had a lower mean dose of dobutamine (25.8 +/- 13.5 vs. 32.4 +/- 16.4 mg, p = 0.025). The mean atropine dose was also lower (0.2 +/- 0.4 vs. 0.4 +/- 0.5 mg, p = 0.04). Handgrip exercise, however, did not decrease endpoints in patients on beta-blocker medication. CONCLUSIONS: Use of isometric handgrip exercise with DASE decreases time to target heart rate, recovery time, overall study time, and mean dosage of dobutamine and atropine. In patients not on beta-blocker medication, handgrip exercise should be routinely incorporated into all DASE protocols.

OBJECTIVES: The goal of this study was to determine the impact of race on identification of hypertrophic cardiomyopathy (HCM). BACKGROUND: Sudden death in young competitive athletes is due to a variety of cardiovascular diseases (CVDs) and, most commonly, HCM. These catastrophes have become an important issue for African Americans, although HCM has been previously regarded as rare in this segment of the U.S. population. METHODS: We studied the relationship of race to the prevalence of CVDs causing sudden death in our national athlete registry, and compared these findings with a representative multicenter hospital-based cohort of patients with HCM. RESULTS: Of 584 athlete deaths, 286 were documented to be due to CVD at ages 17 +/- 3 years; 156 (55%) were white, and 120 (42%) were African American. Most were male (90%), and 67% participated in basketball and football. Among the 286 cardiovascular deaths, most were due to HCM (n = 102; 36%) or anomalous coronary artery of wrong sinus origin (n = 37; 13%). Of the athletes who died of HCM, 42 (41%) were white, but 56 (55%) were African American. In contrast, of 1,986 clinically identified HCM patients, only 158 (8%) were African American (p < 0.001). CONCLUSIONS: In this autopsy series, HCM represented a common cause of sudden death in young and previously undiagnosed African American male athletes, in sharp contrast with the infrequent clinical identification of HCM in a hospital-based population (i.e., by seven-fold). This discrepancy suggests that many HCM cases go unrecognized in the African American community, underscoring the need for enhanced clinical recognition of HCM to create the opportunity for preventive measures to be employed in high-risk patients with this complex disease.

Our understanding of the pathophysiology of obstruction in hypertrophic cardiomyopathy has evolved since initial descriptions in the late 1950s. This review addresses the cause of obstruction, from early ideas that a muscular outflow tract sphincter was the cause, through the discovery of systolic anterior motion (SAM) of the mitral valve, to current understanding that flow drag, the pushing force of flow, is the dominant hydrodynamic mechanism for SAM. The continuing redesign and modification of surgical procedures to relieve outflow obstruction have corresponded to ideas about the cause of this condition. In this review we discuss the evolution of surgical procedures to relieve obstruction and review modern surgical approaches. Medical and nonsurgical methods for reducing obstruction are reviewed, as well as efforts to prevent sudden arrhythmic cardiac death. Echocardiography has become central to understanding this complex phenomenon, and for clinical diagnosis, operative planning and intraoperative management.