Empirical fear profiles among American youth.

Fears among children can range from relatively innocuous fears of simple objects to significant phobias that affect youths' everyday functioning in the home, school, or community environments. This study investigated empirically derived fear profiles among American youth ages 7-19 (N=556). Based upon youths' scores on the 5 factors of the Fear Survey Schedule for Children-II (FSSC-II; Burnham & Gullone (Behav Res Ther, 35, 1997)), multistage Euclidean grouping was applied and produced 5 replicable fear cluster profiles with unique contours. Logistic regression odds ratios revealed specific associations of profile group membership with demographic characteristics such as child age, sex, and ethnicity.

Platelet reactivity in coronary ostial blood: a reflection of the thrombotic state accompanying plaque rupture and of the adequacy of anti-thrombotic therapy.

BACKGROUND: Optimal anti-thrombotic therapy for acute coronary syndromes (ACS) should suppress pro-thrombotic activity at the site of plaque rupture. We sought to determine whether platelet reactivity is increased in blood in the immediate vicinity of a ruptured plaque and is apparent even when blood is obtained by sampling from a catheter placed proximal to the lesion. METHODS: Blood was obtained from a catheter placed in the aorta and from the same catheter after engaging the culprit coronary artery. Platelet reactivity was determined with the use of flow cytometry by surface expression of P-selectin. RESULTS: In preliminary studies we demonstrated that a marker of thrombin activity, fibrinopeptide A, was similarly increased in blood taken from the coronary sinus and coronary arterial ostium of patients with ACS. Subsequently blood was obtained from the aorta and coronary arterial ostium through a coronary guide catheter for assessment of platelet reactivity in 23 subjects with ACS and 22 subjects with stable angina. The percentage of platelets expressing P-selectin in response to 0.2 microM adenosine diphosphate (ADP) was greater in coronary arterial samples from patients with ACS (aorta=6.1+/-1%, coronary artery=8.8+/-1.6%, p=0.02) compared with that in patients with stable symptoms (aorta=6.9+/-1.2, coronary artery=6.5+/-1.4, p=NS). CONCLUSIONS: Coronary arterial blood obtained from the ostium through a coronary guide catheter can be used to determine whether thrombin activity and platelet reactivity are increased in the immediate vicinity of a ruptured atherosclerotic plaque. The simplicity of the approach developed should facilitate its use in future studies designed to determine the impact of optimal suppression of platelet reactivity and the pro-thrombotic state before coronary interventions on short- and long-term clinical outcomes.

Platelet reactivity characterized prospectively: a determinant of outcome 90 days after percutaneous coronary intervention.

BACKGROUND: Platelet activation is pivotal in the pathogenesis of complications after percutaneous coronary interventions (PCI). We previously reported substantial interindividual variability in activation of glycoprotein (GP) IIb/IIIa in response to a low concentration of ADP. We assessed GP IIb/IIIa activation prospectively to determine whether this could differentiate patients at low risk from those at high risk for complications early and late after PCI. Methods and Results-- A total of 112 patients undergoing PCI were studied. Platelet reactivity was determined with the use of flow cytometry. Patients were classified into high and low platelet reactivity groups on the basis of extent of activation of GP IIb/IIIa in response to 0.2 micromol/L ADP. The median value was used for differentiation. The incidence during 90-day follow-up interval of a composite end point (myocardial infarction, urgent revascularization, or repeat revascularization) was determined in each group. Follow up was completed in all 112 patients. The 2 groups were similar with respect to diverse clinical characteristics. Nevertheless, the incidence of the composite end point occurred in 26.8% of the high and 7.1% in the low platelet reactivity group (P=0.01). The difference in the composite end point was most striking during the 30- to 90-day interval after PCI (16.7% versus 1.9%; P=0.02). Repeat revascularization was more frequent in those with increased platelet reactivity (17.9% versus with 3.6%, P=0.029). CONCLUSIONS: Prospective assessment of platelet GP IIb/IIIa activation permits stratification of patients into low- and high-risk groups with respect to adverse events after PCI.

Quantification by flow cytometry of the efficacy of and interindividual variation of platelet inhibition induced by treatment with tirofiban and abciximab.

BACKGROUND: After exposure of platelets to abciximab and tirofiban in vitro, we have observed variable inhibition of fibrinogen binding and a lack of inhibition of alpha-granule degranulation. DESIGN: To determine whether such changes occur with treatment, platelet reactivity was assayed in blood from 50 patients receiving abciximab or tirofiban. METHODS: Platelet reactivity was determined before and during steady-state infusions of abciximab (0.125 microg/kg/min) or tirofiban, with either the PRISM-PLUS dosage (0.1 microg/kg/min) or the RESTORE dosage (0.15 microg/kg/min). Fibrinogen binding and P-selectin expression were determined by flow cytometry after stimulation of platelets with ADP (0.2 or 1 microM) or thrombin-receptor agonist peptide (TRAP, 25 microM). RESULTS: Both dosages of tirofiban and abciximab reduced fibrinogen binding in response to 0.2 microM ADP comparably. However, fibrinogen binding in response to 1.0 microM ADP or 25 microM TRAP was inhibited to a greater extent by the RESTORE dosage of tirofiban and abciximab than by the PRISM-PLUS dosage of tirofiban (P< 0.05). Furthermore, only the RESTORE dosage of tirofiban and abciximab reduced P-selectin expression in response to ADP. Inhibition with each regimen varied markedly between patients. CONCLUSIONS: The RESTORE dosages of tirofiban and abciximab each inhibit fibrinogen binding and alpha-granule degranulation similarly. However, substantial interindividual variation in inhibition of fibrinogen binding is evident.

Journal reprints as dissemination of psychological research: courtesy, obligation, or obsolescence?

The proliferation of journals and the escalation of journal prices have made it difficult for psychologists, especially those in rural areas without access to comprehensive libraries, to obtain journal articles. A traditional source of otherwise unavailable papers is to request a reprint directly from the author. Although previous researchers found this method to be 60%-80% successful, there have been major changes in journal operations and alternative media since this research was conducted. In the present study, reprints were requested from 473 corresponding authors from 10 American Psychological Association journals. The compliance rate was 84% and reprints took, on average, 32 days to arrive. There was no difference in the rate or in the speed of response due to the requestor's status as an academic or applied psychologist. Although functional, the traditional reprint request method was slow, uncertain, and costly. It is suggested that a demand still exists for reprints, but that electronic reprints should replace the traditional paper format. Key words: reprints, scientific communication

Survival of patients with diabetes and multivessel coronary artery disease after surgical or percutaneous coronary revascularization: results of a large regional prospective study. Northern New England Cardiovascular Disease Study Group.

OBJECTIVES: We sought to assess survival among patients with diabetes and multivessel coronary artery disease (MVD) after percutaneous coronary intervention (PCI) and after coronary artery bypass grafting surgery (CABG). BACKGROUND: The Bypass Angioplasty Revascularization Investigation (BARI) demonstrated that diabetics with MVD survive longer after initial CABG than after initial PCI. Other randomized trials or observational databases have not conclusively reproduced this result. METHODS: A large, regional database was linked to the National Death Index to assess five-year mortality. Of 7,159 consecutive patients with diabetes who underwent coronary revascularization in northern New England during 1992 to 1996, 2,766 (38.6%) were similar to those randomized in the BARI trial. Percutaneous coronary intervention was the initial revascularization strategy in 736 patients and CABG in 2,030. Cox proportional hazards regression was used to calculate risk-adjusted hazard ratios (HR) and 95% confidence intervals (CI 95%). RESULTS: Patients who underwent PCI were younger, had higher ejection fractions and less extensive coronary disease. After adjusting for differences in baseline clinical characteristics, patients with diabetes treated with PCI had significantly greater mortality relative to those undergoing CABG (HR = 1.49; CI 95%: 1.02 to 2.17; p = 0.037). Mortality risk tended to increase more among 1,251 patients with 3VD (HR = 2.02; CI 95%: 1.04 to 3.91; p = 0.038) than among 1,515 patients with 2VD (HR = 1.33; CI 95%: 0.84 to 2.1; p = 0.21). CONCLUSIONS: In this analysis of a large regional contemporary database of patients with diabetes selected to be similar to those enrolled in the BARI trial, five-year mortality was significantly increased after initial PCI. This supports the BARI conclusion on initial revascularization of patients with diabetes and MVD.

Safety and efficacy of percutaneous coronary interventions performed immediately after diagnostic catheterization in northern new england and comparison with similar procedures performed later.

"Ad hoc" percutaneous coronary interventions (PCIs)-those performed immediately after diagnostic catheterization-have been reported in earlier studies to be safe with a suggestion of higher risk in certain subgroups. Despite increasing use of this strategy, no data are available in recent years with new device technology. We studied use of an ad hoc strategy in a large regional population to determine its use and outcomes compared with staged procedures. A database from the 6 centers performing PCIs in northern New England and 1 center in Massachusetts was analyzed. During 1997, excluding only patients requiring emergency procedures or those with a prior PCI, 4,136 PCIs were performed, 1,748 (42.3%) of these being ad hoc procedures. Patients having ad hoc procedures were less likely to have peripheral vascular disease, renal failure, prior myocardial infarction, or coronary artery bypass surgery, congestive heart failure, or poor left ventricular function, and more likely to have received preprocedural intravenous heparin or nitroglycerin or to have required an urgent procedure. Narrowings treated during ad hoc procedures were less frequently types B and C or in saphenous vein grafts. Adjusted rates of clinical success were not different between ad hoc and non-ad hoc procedures (93.7% vs 93.6%); there was no difference in the incidence of death (0.6% vs 0.5%), emergency (0. 9% vs 0.8%) or any (1.4% vs 0.8%) coronary artery bypass surgery, or myocardial infarction (2.6% vs 2.0%). As currently practiced in our region, ad hoc intervention is used selectively with outcomes similar for ad hoc and non-ad hoc procedures.

Incremental validity of WISC-III profile elevation, scatter, and shape information for predicting reading and math achievement.

The use of cognitive subtest profiles to hypothesize about children's learning strengths and weaknesses implicitly assumes that subtest profiles are predictive of academic performance. To test this assumption, Wechsler Intelligence Scale for Children-Third Edition (WISC-III) subtest profiles were decomposed into elevation, scatter, and shape components and sequentially regressed onto reading and math achievement scores for 1,118 nonexceptional and 538 exceptional students. Profile elevation was statistically and practically significant for both exceptional (R = .36-.61) and nonexceptional (R = .72-.75) students. Profile scatter did not aid in the prediction of achievement. Profile shape accounted for an additional 5%-8% of the variance in achievement measures. It was concluded that using WISC-III subtest scatter and shape to predict academic performance was not supported by the accumulated scientific evidence.

The relationship between operator volume and outcomes after percutaneous coronary interventions in high volume hospitals in 1994-1996: the northern New England experience. Northern New England Cardiovascular Disease Study Group.

OBJECTIVES: The purpose of this study was to examine the relationship between annual operator volume and outcomes of percutaneous coronary interventions (PCIs) using contemporaneous data. BACKGROUND: The 1997 American College of Cardiology (ACC)/American Heart Association task force based their recommendation that interventionists perform > or = 75 procedures per year to maintain competency in PCI on data collected largely in the early 1990s. The practice of interventional cardiology has since changed with the availability of new devices and drugs. METHODS: Data were collected from 1994 through 1996 on 15,080 PCIs performed during 14,498 hospitalizations by 47 interventional cardiologists practicing at the five high volume (>600 procedures per hospital per year) hospitals in northern New England and one Massachusetts-based institution that support these procedures. Operators were categorized into terciles based on their annualized volume of procedures. Multivariate regression analysis was used to control for case-mix. In-hospital outcomes included death, emergency coronary artery bypass graft surgery (eCABG), non-emergency CABG (non-eCABG), myocardial infarction (MI), death and clinical success (> or = 1 attempted lesion dilated to < 50% residual stenosis and no death, CABG or MI). RESULTS: Average annual procedure rates varied across terciles from low = 68, middle = 115 and high = 209. After adjusting for case-mix, clinical success rates were comparable across terciles (low, middle and high terciles: 90.9%, 88.8% and 90.7%, Ptrend = 0.237), as were all the adverse outcomes including death (low-risk patients = 0.45%, 0.41%, 0.71%, Ptrend = 0.086; high-risk patients = 5.68%, 5.99%, 7.23%, Ptrend = 0.324), eCABG (1.74%, 2.05%, 1.75%, Ptrend = 0.733) and MI (2.57%, 1.90%, 1.86%, Ptrend = 0.065). CONCLUSIONS: Using current data, there is no significant relationship between operator volumes averaging > or = 68 per year and outcomes at high volume hospitals. Future efforts should be directed at determining the generalizability of these results.

Changing outcomes in percutaneous coronary interventions: a study of 34,752 procedures in northern New England, 1990 to 1997. Northern New England Cardiovascular Disease Study Group.

OBJECTIVES: We sought to evaluate the changing outcomes of percutaneous coronary interventions (PCIs) in recent years. BACKGROUND: The field of interventional cardiology has seen considerable growth in recent years, both in the number of patients undergoing procedures and in the development of new technology. In view of recent changes, we evaluated the experience of a large, regional registry of PCIs and outcomes over time. METHODS: Data were collected from 1990 to 1997 on 34,752 consecutive PCIs performed at all hospitals in Maine (two), New Hampshire (two) and Vermont (one) supporting these procedures, and one hospital in Massachusetts. Univariate and multivariate regression analyses were used to control for case mix. Clinical success was defined as at least one lesion dilated to <50% residual stenosis and no adverse outcomes. In-hospital adverse outcomes included coronary artery bypass graft surgery (CABG), myocardial infarction and mortality. RESULTS: Over time, the population undergoing PCIs tended to be older with increasing comorbidity. After adjustment for case mix, clinical success continued to improve from a low of 88.2% in earlier years to a peak of 91.9% in recent years (p trend <0.001). The rate of emergency CABG after PCI fell in recent years from a peak of 2.3% to 1.3% (p trend <0.001). Mortality rates decreased slightly from 1.2% to 1.1% (p trend 0.007). CONCLUSIONS: There has been a significant improvement in clinical outcomes for patients undergoing PCIs in northern New England, including a significant decline in the need for emergency CABG.

Multivariate prediction of in-hospital mortality after percutaneous coronary interventions in 1994-1996. Northern New England Cardiovascular Disease Study Group.

OBJECTIVES: Using recent data, we sought to identify risk factors associated with in-hospital mortality among patients undergoing percutaneous coronary interventions. BACKGROUND: The ability to accurately predict the risk of an adverse outcome is important in clinical decision making and for risk adjustment when assessing quality of care. Most clinical prediction rules for percutaneous coronary intervention (PCI) were developed using data collected before the broader use of new interventional devices. METHODS: Data were collected on 15,331 consecutive hospital admissions by six clinical centers. Logistic regression analysis was used to predict the risk of in-hospital mortality. RESULTS: Variables associated with an increased risk of in-hospital mortality included older age, congestive heart failure, peripheral or cerebrovascular disease, increased creatinine levels, lowered ejection fraction, treatment of cardiogenic shock, treatment of an acute myocardial infarction, urgent priority, emergent priority, preprocedure insertion of an intraaortic balloon pump and PCI of a type C lesion. The receiver operating characteristic area for the predicted probability of death was 0.88, indicating a good ability to discriminate. The rule was well calibrated, predicting accurately at all levels of risk. Bootstrapping demonstrated that the estimate was stable and performed well among different patient subsets. CONCLUSIONS: In the current era of interventional cardiology, accurate calculation of the risk of in-hospital mortality after a percutaneous coronary intervention is feasible and may be useful for patient counseling and for quality improvement purposes.

Cause of in-hospital death in 12,232 consecutive patients undergoing percutaneous transluminal coronary angioplasty. The Northern New England Cardiovascular Disease Study Group.

BACKGROUND: Some deaths after percutaneous coronary angioplasty (PTCA) occur in high-risk situations (eg, shock), whereas others are unexpected and related to procedural complications. To better describe the epidemiologic causes of death after PTCA, we undertook a systematic review of all in-hospital PTCA deaths in Northern New England from 1990 to 1993. METHODS: The medical records of 121 patients who died during their acute hospitalization for PTCA were reviewed with a standardized data extraction tool to determine a mode of death (eg, low output failure, arrhythmia, respiratory failure) and a circumstance of death (eg, death attributable to a procedural complication, preexisting acute cardiac disease). Any death not classified as a procedural complication was reviewed by a committee and the circumstance of death assigned by a majority rule. RESULTS: Low-output failure was the most common mode of death occurring in 80 (66.1%) of 121 patients. Other modes of death included ventricular arrhythmias (10.7%), stroke (4.1%), preexisting renal failure (4.1%), bleeding (2.5%), ventricular rupture (2.5%), respiratory failure (2.5%), pulmonary embolism (1.7%), and infection (1.7%). The circumstance of death was a procedural complication in 65 patients (53.7%) and a preexisting acute cardiac condition in 41 patients (33.9%). Women were more likely to die of a procedural complication than were men. CONCLUSION: Procedural complications account for half of all post-PTCA deaths and are a particular problem for women. Other deaths are more directly related to patient acuity or noncardiac, comorbid conditions. Understanding why women face an increased risk of procedural complications may lead to improved outcomes for all patients.

MacPotthoff: automated calculation of the Potthoff regression bias procedure.

Test bias, in contrast to test fairness, is best conceptualized in validity terms amenable to statistical analysis. Evidence of predictive validity may be most salient in many situations. Evaluation of predictive bias is generally operationalized via linear regression. Potthoff (1978) provided an efficient and parsimonious regression bias procedure that allows both simultaneous and separate tests of regression slopes and intercepts across groups. A Macintosh computer program, MacPotthoff, is presented for automated calculation of Potthoff regression bias statistics.

Determinants of rebound thrombin activity after cessation of heparin in patients undergoing coronary interventions.

This study was designed to characterize hemostatic activation (using fibrinopeptide A (FPA), a marker of thrombin activity, and beta-thromboglobulin (BTG), a marker of platelet activation) sequentially in the coronary and peripheral circulation in patients during percutaneous coronary intervention (PCI) and several hours after PCI and discontinuation of heparin therapy. Heparin administered during PCI is known to nonuniformly suppress thrombin activity in the coronary. Persistent elevations of FPA in coronary sinus (CS) blood during PCI have been associated with subsequent ischemic events. As a related consideration, rebound thrombin activity has been demonstrated in peripheral blood samples several hours after cessation of heparin therapy in patients with acute coronary syndromes. Accordingly, we hypothesized that increased thrombin activity occurs in the coronary circulation after PCI and is induced by cessation of intravenous heparin to facilitate vascular sheath removal. Such a rebound prothrombotic effect, may contribute to suboptimal outcomes after PCI. In 21 patients undergoing PCI, heparin-bonded catheters were employed to obtain sequential CS and femoral vein (FV) blood samples for measurement in the coronary and peripheral circulation of plasma FPA, a marker of thrombin activity in vivo, and BTG released by platelets during degranulation. Following heparin administration samples were obtained immediately prior to (base) and during (start and end) PCI. Late samples were obtained several hours after PCI (284 +/- 46 min, mean +/- SD) following the cessation of heparin and prior to planned vascular sheath removal. Mean FPA concentration in CS blood was low at baseline (3.82 +/- 2.09 ng/ml) and did not increase during PCI. Mean FPA concentration in CS blood increased significantly several hours after cessation of heparin (3.42 +/- 2.36 vs. 7.82 +/- 9.98, end vs. late, P < 0.001). In contrast, mean FPA concentration in FV blood was highest at baseline following vascular sheath insertion, decreased during PCI (69%, P < 0.05, base vs. end), and trended upward after PCI and cessation of heparin. Mean FPA values were higher at all times in FV compared with CS blood samples and were not concordant after PCI. Elevation of coronary circulation FPA after PCI was maximal in patients with myocardial infarction within 7 days (13.7 +/- 12.4 vs. 5.6 +/- 7.9 ng/ml, P = 0.08), but was not influenced by heparin treatment prior to PCI, a history of unstable angina, or coronary stent placement during PCI (9 of 21 patients). BTG values showed less variation than did FPA values, and cessation of heparin after PCI was not associated with an increase in BTG in CS or FV blood samples. An increase in thrombin activity occurs in the coronary circulation after PCI following discontinuation of heparin. The extent of increased thrombin activity was greatest in patients with recent myocardial infarction and was not exacerbated by coronary stent placement during PCI. This phenomenon may contribute to the important minority of ischemic complications early after PCI.

Operator volume and outcomes in 12,998 percutaneous coronary interventions. Northern New England Cardiovascular Disease Study Group.

OBJECTIVES: We sought to determine whether there is a relation between operator volume and outcomes for percutaneous coronary interventions (PCIs). BACKGROUND: A 1993 American College of Cardiology/American Heart Association task force stated that cardiologists should perform > or = 75 procedures/year to maintain competency in PCIs; however, there were limited data available to support this statement. METHODS: Data were collected from 1990 through 1993 on 12,988 PCIs (12,118 consecutive hospital admissions) performed by 31 cardiologists at two hospitals in New Hampshire and two in Maine and one hospital in Massachusetts supporting these procedures. Operators were categorized into terciles based on annualized volume of procedures. Univariate and multivariate regression analyses were used to control for case-mix. Successful outcomes included angiographic success (all lesions attempted dilated to < 50% residual stenosis) and clinical success (at least one lesion dilated to < 50% residual stenosis and no adverse outcomes). In-hospital adverse outcomes included coronary artery bypass graft surgery (CABG), myocardial infarction (MI) and death. RESULTS: After adjustment for case-mix, higher angiographic (low, middle and high terciles: 84.7%, 86.1% and 90.3%, p-trend 0.006) and clinical success rates (85.8%, 88.0% and 90.7%, p-trend 0.025), with fewer referrals to CABG (4.54%, 3.75% and 2.49%, p-trend <0.001), were seen as operator volume increased. There was a trend toward higher MI rates for high volume operators (2.00%, 1.98% and 2.57%, p-trend 0.06); all terciles had similar in-hospital mortality rates (1.09%, 0.96% and 1.05%, p-trend 0.8). CONCLUSIONS: There is a significant relation between operator volume and outcomes in PCIs. Efforts should be directed toward understanding why high volume operators are more successful and encounter fewer adverse outcomes.

Decrease in forces responsible for diastolic suction during acute coronary occlusion.

BACKGROUND: The production of left ventricular (LV) restoring forces generated during contraction, which are responsible for diastolic suction, is dependent on end-systolic volume (ESV) and systolic transmural and 3D deformation. We tested the hypothesis that acute coronary occlusion would result in loss of forces that cause suction. METHODS AND RESULTS: Ten open-chest dogs were subjected to a 10-minute acute coronary occlusion (proximal left anterior descending coronary artery). A servomotor connected to the left atrium (LA) was used to rapidly clamp LA pressure during systole below the level of the succeeding LV diastolic pressure, resulting in nonfilling diastoles during which the LV fully relaxed at its ESV. LA clamps at multiple ESVs (conductance catheter) allowed delineation of positive and negative portions of the fully relaxed LV pressure-volume relation (FRPVR). A negative fully relaxed pressure (FRP) indicates the presence of restoring forces. After 10 minutes of acute coronary occlusion, there was an upward shift of the FRPVR. Thus, for example, at matched ESVs before and during coronary occlusion, FRP was -1.1+/-1.1 (+/-SD) mm Hg before versus 0.2+/-1.2 mm Hg after 10 minutes of coronary occlusion (P<.05). CONCLUSIONS: Acute coronary occlusion results in a rapid decrease in forces responsible for suction. This phenomenon is independent of the level of ESV and may contribute to ischemic diastolic dysfunction.

Altered expression of troponin T isoforms in mild left ventricular hypertrophy in the rabbit.

Alterations in troponin T (TnT) isoforms have been reported in severe human and experimental heart failure (HF), and may play a role in the depressed myofibrillar ATPase activity observed in this condition. It is unclear whether these alterations reflect very severe hemodynamic derangement or are a component of mild hypertrophic stress. Therefore, we studied the expression of TnT isoforms (SDS-PAGE, Western blots), myosin isoforms, myofibrillar ATPase activity, and left ventricular (LV) mechanoenergetics (rbc perfused, isovolumically contracting isolated heart) in a rabbit model of mild hypertrophy (LVH) due to gradual hypertension caused by 12 weeks of cellophane wrap of the kidneys (n=12). LV/body weight ratio increased by 28% in LVH compared to shams (P<0.001); no animals had evidence of HF. In LVH, the percentage of TnT2 was modestly but significantly increased compared to shams [6.2+/-1.9 (+/-S.D. ) v 3.7+/-1.0%, P<0.05], mainly as a consequence of a parallel decrease in TnT4 (P=0.07). Sham hearts ranged from 75-100% V3 isomyosin, whereas all LVH hearts had 100% of the V3 form. There were no significant differences in myofibrillar ATPase activity or mechanical variables, including contraction and relaxation rates. The slope of the VO2-pressure-volume-area relation (a measure of the energy conversion efficiency of the contractile machinery) was also unchanged. We conclude that in the rabbit, shifts in TnT isoforms toward a more "fetal" pattern occur during mild LVH and, therefore, are likely to be a general feature of the response to hemodynamic stress, rather than a phenomenon confined to end-stage disease. These modest shifts are not associated with major alterations in LV myofibrillar ATPase activity or mechanoenergetics.