Ehtasham A. Qureshi

Practical applications in stress echocardiography: Risk stratification and prognosis in patientswith known or suspected ischemic heart disease

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.

Peripheral Arterial Responses to Treadmill Exercise Among Healthy Subjects and Atherosclerotic Patients

BackgroundPeripheral cutaneous vascular beds, such as the fingertips, contain a high concentration of arteriovenous anastomoses, richly innervated by &agr;-adrenergic nerve fibers, to control heat regulation. Nevertheless, for a variety of technical reasons, finger blood flow responses to exercise have not been well studied in health and disease. Hence, we compared finger pulse-wave amplitude (PWA) responses to exercise among 50 normal volunteers and 57 patients with atherosclerotic coronary artery disease (CAD) using a robust, modified form of volume plethysmography. Methods and ResultsPWA was quantified for each minute of exercise as a ratio relative to baseline. Exercise PWA responses were compared with clinical, hemodynamic, ECG, and myocardial single photon emission computed tomography parameters. Among normal subjects, 38 (76%) manifested vasodilation throughout exercise and 12 (24%) manifested initial vasodilation followed by vasoconstriction at high heart rate thresholds. None manifested vasoconstriction throughout exercise. By contrast, 20 CAD patients (35%) manifested progressive vasoconstriction from the onset of exercise, and 10 others (18%) manifested vasoconstriction at low heart rate thresholds (P <0.001 versus normals) after initial vasodilation with exercise. Patients exhibiting vasodilation versus vasoconstriction during exercise had similar clinical and exercise profiles, except for a greater use of ACE inhibitors and a greater level of achieved metabolic equivalents among the former (P <0.05 for both). ConclusionsHalf of our CAD patients manifested diminution in PWA that was consistent with peripheral arterial vasoconstriction during the early phases of treadmill exercise. Such paradoxical vasoconstrictive responses were not observed in normal subjects and, therefore, they may represent generalized vascular pathology secondary to atherosclerosis.

Terrorism and the Heart: Implications for Arrhythmogenesis and Coronary Artery Disease

The destruction of the World Trade Center and associated terrorist activities of September 11, 2001 have spurred interest in understanding the medical consequences of terrorist activity. Currently, there is a paucity of data regarding this subject. Potential effects, however, can be garnered by studying the medical effects of other acute stressors, such as earthquakes, missile attacks, and the like. None of these stressors have been studied extensively, but there is enough data available concerning earthquakes to indicate that in some instances, the effects of the earthquake may last at least a period of weeks, if not months, following the earthquake. Since the World Trade Center attack was associated with a rise in post-traumatic stress syndrome and affective disorders afterwards, there is accordingly interest in both the acute and more prolonged health effects that could be engendered following terrorist attacks. Known pathophysiological effects of acute stress, whether produced in a laboratory environment or by studying naturally occurring acute stressors, include: the induction or potentiation of cardiac arrhythmias; the induction of myocardial ischemia in susceptible patients with underlying coronary artery disease; acute increases in arterial blood pressure with its ability to cause shear stress; the precipitation of worsening endothelial function and/or endothelial injury; coagulation abnormalities; and hemoconcentration. These all represent important areas for study following the occurrence of future terrorist activity. Based on existing epidemiological and pathophysiological data concerning the cardiac effects of acute life stressors, it would behoove physicians to closely monitor high-risk cardiac patients following future terrorist events. In addition, physician-scientists should be well prepared to use new epidemiological markers which could provide rapid information following future events, such as the evaluation of patients using pre-versus post-event serum markers or tracing records available among patients fitted with implantable cardiovertor-defibrillators.

Risk Stratification and Prognosis in Octogenarians Undergoing Stress Echocardiographic Study

Background: The prognostic value of stress echocardiography (SE) for the diagnosis and risk stratification of coronary artery disease in octogenarians is not well defined. Methods: Follow‐up of 5 years (mean 2.9 ± 1.0 years) for confirmed nonfatal myocardial infarction (n = 17) and cardiac death (n = 37) was obtained in 335 patients, age ≥80 years (mean age 84 ± 3 years, 44% male), undergoing SE (33% treadmill, 67% dobutamine). Left ventricular (LV) regional wall motion was assessed by a consensus of two echocardiographers and scored as per standard five‐point scale, 16‐segment model of wall motion analysis. Ischemic LV wall segment was defined as deterioration in the thickening and excursion during stress (increase in wall‐motion score index (WMSI) ≥1). Results: By univariate analysis, inducible ischemia (chi‐square = 38.4, P < 0.001), left ventricular ejection fraction (chi‐square = 41.2, P < 0.001), a history of previous myocardial infarction (chi‐square = 22.3, P < 0.01), hypertension (chi‐square = 33, P < 0.01), and age (chi‐square = 27.7, P < 0.01) were significant predictors of future cardiac events. WMSI, an index of inducible ischemia, provided incremental prognostic information when forced into a multivariable model where clinical and rest echocardiography variables were entered first. WMSI effectively stratified octogenarians into low‐ and high‐risk groups (annualized event rates of 1.2 versus 5.8%/year, P < 0.001). Conclusions: Stress echocardiography yields incremental prognostic information in octogenarians and effectively stratifies them into low‐ and high‐risk groups. Precise therapeutic decision making in very elderly patients should incorporate combined clinical and stress echocardiography data.

Paradoxical diminution in finger blood flow with exercise predicts adverse outcomes among patients with coronary artery disease

Background: Whereas normal subjects increase finger blood flow during exercise (EX), patients (pts) wth coronary disease (CAD) have been shown to manifest a paradoxical decrease in fmger blood flow with EX. The clinical significance of this obsewatlon is unknown. Methods: 327 CAD pts (mean age 56 * 10,64% male) underwent EX myocardial perfusion SPECT while measuring finger blood flow using peripheral arterial tonometry. Pulse wave amplitude (PWA) ratio was assessed for each EX minute and PWA slope values were determined; slope values ~0 = vasoconstriction. SPECT scans were read blindly using a conventional 20.segment, B-point scale. A follow up of 1.86 + 1 .O years was obtaine for cardiac death, non-fatal myocardlal infarction and revascularization z-60 days after EX testing. Results: There were a total of 34 events (annualized event rate of 5,7%/year). A negative (versus positwe) slope for PWA during EX was associated with a greater frequency of cardiac events (hazards ratio 3.3 (1.2 9.5), pcO.OOl)](figure). Negative PWA slope was the most potent predictor of events by multivariate analysis, and remained so even after significant clinkxl variables including EX and SPECT results, were forced first into the analysis (adjusted risk ratlo = 2.62 [1.07,6.42]). Conclusions: Paradoxical decrease in finger blood flow during EX is associated with an increased frequency of cardiac events. Moreover, this measure adds incremental value to existing clinical and exercise SPECT data for cardiac risk assessment

Risk stratification and prognosis in octogenarians: A stress echocardiographic study

ABSTRACTS Noninvasive Imaging 409A women with undiagnosed chest pain syndrome (CPS), no prior established cardiac disease and at least 2 risk factors were randomized to one of three diagnostic protocols, primarily utilizing either EST, exercise echo (EXE) or Dobutamine stress echo (DSE). After establishing a diagnosis of cardiac or non-cardiac CP, patients were followed for at least 2 years to assess symptom and clinical course. Results: The testing protocols defined 15.2% of the patients as havmg cardiac and 84.8% non-cardiac CP. Initially indsterminate testing occurred in 25.9% of EST patients, 5.3% of EXE patients, and none of the DSE patients. In a mean follow-up of 27.3 months. 12 patients (7.6%) were determined to have had cardiac chest pain based on clinical events (including 2 MIS, no deaths), 113(71.5%) non cardiac chest pain, and 33(20.9%) remain clinically unresolved. The positive and negative predictive values for the testing modalities based on these clinical outcomes is as follows: EST 50.0%. 97.4%; EXE: 44.4%, 100%; DSE 75.0%,97.1% Conclusions: 1. Chest pain is uncommonly associated with ischemic disease in women and has a favourable prognosis. 2. Echo based testing modalities are less commonly indeterminate than EST and therefore likely to provide more timely and cost effective diagnoses. 3. All testing modalities have excellent negative predictive values. Echo based testing appears lo provide fewer false positives. populations for percentages of pattents wth abnormal scans (65% vs 57%. p=O.O8) or high-risk scans (22% vs lB%, p=O.21). Conclusions: (1) Clinical and ECG characteristics and SPECT results were similar between these 2 populations of asymptomatic diabetics, suggesting that referral bias did not account for the high prevalence of abnormal and high-risk SPECT in these patients. (2) Among a community-based population of asymptomatic diabehcs. almost one-quarter (22%) had high-risk scans.