P1421 Patients with severe aortic regurgitation showed systolic dysfunction and increased stroke work despite preserved EF; clues for reconsidering optimal time point of surgery

Background

Current guidelines recommend surgery in patients with severe aortic regurgitation (AR) with clinical symptoms or subnormal ejection fraction (EF). Furthermore, surgery should be considered in patients with severe AR, preserved EF and increased left ventricular diameters (LVEDD >70mm, LVESD >50mm). The aim of the study was to investigate LV systolic function as well as mechanical energetics using non-invasive pressure-volume- and strain analysis in patients with severe AR and preserved EF as well as moderately dilated ventricles (LVEDD <70mm).

Methods and Results

Echocardiographic strain and single beat pressure-volume analyses were performed in patients with severe AR and moderately increased ventricular size (LVEDD < 70mm, EF >50% n = 39) as well as healthy, age-matched controls (n = 20) using echo-derived volume and arm-cuff blood pressure measurements. Load independent parameters of systolic contractile function like end-systolic elastance (Ees) and end-systolic volume at 100mmHg (ESV100) were calculated as well as stroke work ((SW) and total pressure volume area (PVA = SW + potential energy). Patients with AR demonstrated significant depression of systolic function beyond ejection fraction: global longitudinal strain was reduced compared to controls (-16 ±2.5% vs. -21.5 ±2%; p < 0.001). Accordingly load independent parameters of LV contractility like Ees (1.5mmHg/ml ±0.7 vs. 2.25mmHg/ml ±0.7; p < 0.001), ESV100 (65.7ml ±19.4 vs. 42.4ml ±19.8; p < 0.05) were reduced despite comparable ejection fractions (EF: 0.56% ±0.05 vs. 0.60% ±0.07 p = 0,10). End-diastolic volume of AR patients was markedly elevated (236ml ±90 vs. 136ml ±30; p < 0.001), while PVA (20470mmHg x ml ±10400 vs. 11907mmHg x ml ±2877; p < 0.01) and stroke work (13200mmHg x ml ±5700 vs. 7606 mmHG x ml ±2048; p< 0.01) were markedly elevated indicating waste of energy.

Conclusion

Patients with severe AR and moderately enhanced LV showed depressed values of contractility and waste of energy using more advanced parameters of LV systolic function although EF was preserved. The data may demonstrate that surgery is performed too late in many of those patients and may give clues for reconsidering guidelines to meet the optimal time point of surgery.

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Randomised clinical trial: gastrointestinal events in arthritis patients treated with celecoxib, ibuprofen or naproxen in the PRECISION trial

AIM

To evaluate GI safety of celecoxib compared with 2 nonselective (ns) NSAIDs, as a secondary objective of a large trial examining multiorgan safety.

METHODS

This randomised, double-blind controlled trial analysed 24 081 patients. Osteoarthritis or rheumatoid arthritis patients, needing ongoing NSAID treatment, were randomised to receive celecoxib 100-200 mg b.d., ibuprofen 600-800 mg t.d.s. or naproxen 375-500 mg b.d. plus esomeprazole, and low-dose aspirin or corticosteroids if already prescribed. Clinically significant GI events (CSGIE-bleeding, obstruction, perforation events from stomach downwards or symptomatic ulcers) and iron deficiency anaemia (IDA) were adjudicated blindly.

RESULTS

Mean treatment and follow-up durations were 20.3 and 34.1 months. While on treatment or 30 days after, CSGIE occurred in 0.34%, 0.74% and 0.66% taking celecoxib, ibuprofen and naproxen. Hazard ratios (HR) were 0.43 (95% CI 0.27-0.68, P = 0.0003) celecoxib vs ibuprofen and 0.51 (0.32-0.81, P = 0.004) vs naproxen. There was also less IDA on celecoxib: HR 0.43 (0.27-0.68, P = 0.0003) vs ibuprofen; 0.40 (0.25-0.62, P < 0.0001) vs naproxen. Even taken with low-dose aspirin, fewer CSGIE occurred on celecoxib than ibuprofen (HR 0.52 [0.29-0.94], P = 0.03), and less IDA vs naproxen (0.42 [0.23-0.77, P = 0.005]). Corticosteroid use increased total GI events and CSGIE. H. pylori serological status had no influence.

CONCLUSIONS

Arthritis patients taking NSAIDs plus esomeprazole have infrequent clinically significant gastrointestinal events. Co-prescribed with esomeprazole, celecoxib has better overall GI safety than ibuprofen or naproxen at these doses, despite treatment with low-dose aspirin or corticosteroids.

Cardiac digital angiography: applications in ventriculography and coronary arteriography

Clearly, computer-based digital subtraction offers several advantages over conventional approaches to contrast angiography. Using the newer method, in many situations contrast loads can be beneficially reduced, radiation exposure can be markedly diminished, and right ventricle evaluations can be simplified. In addition, storage of data on magnetic tape is less space consuming, and less costly, than storage on film. Over the 5- to 10-year life expectancy of a digitally equipped laboratory, these advantages probably justify the 30-50% increase in the initial monetary outlay for equipment in excess of that required for a conventionally equipped laboratory. However, the greatest promise of digital angiography is in the area of coronary arteriography. If three-dimensional reconstruction of coronary lesions and determination of regional flow can be effected, important advances in diagnosis and in prognostication theoretically might be expected, leading to more appropriate selection of therapy for individual patients than now can be achieved. However, currently available information does not yet indicate the extent to which such potential advantages will be realized. Thus, it will be several years before we will know whether the exciting potential of digital angiography in this area can be reached.

Ischaemic cardiac events and use of strontium ranelate in postmenopausal osteoporosis: a nested case-control study in the CPRD

We explored the cardiac safety of the osteoporosis treatment strontium ranelate in the UK Clinical Practice Research Datalink. While known cardiovascular risk factors like obesity and smoking were associated with increased cardiac risk, use of strontium ranelate was not associated with any increase in myocardial infarction or cardiovascular death.

INTRODUCTION

It has been suggested that strontium ranelate may increase risk for cardiac events in postmenopausal osteoporosis. We set out to explore the cardiac safety of strontium ranelate in the Clinical Practice Research Datalink (CPRD) and linked datasets.

METHODS

We performed a nested case-control study. Primary outcomes were first definite myocardial infarction, hospitalisation with myocardial infarction, and cardiovascular death. Cases and matched controls were nested in a cohort of women treated for osteoporosis. The association with exposure to strontium ranelate was analysed by multivariate conditional logistic regression.

RESULTS

Of the 112,445 women with treated postmenopausal osteoporosis, 6,487 received strontium ranelate. Annual incidence rates for first definite myocardial infarction (1,352 cases), myocardial infarction with hospitalisation (1,465 cases), and cardiovascular death (3,619 cases) were 3.24, 6.13, and 14.66 per 1,000 patient-years, respectively. Obesity, smoking, and cardiovascular treatments were associated with significant increases in risk for cardiac events. Current or past use of strontium ranelate was not associated with increased risk for first definite myocardial infarction (odds ratio [OR] 1.05, 95 % confidence interval [CI] 0.68-1.61 and OR 1.12, 95 % CI 0.79-1.58, respectively), hospitalisation with myocardial infarction (OR 0.84, 95 % CI 0.54-1.30 and OR 1.17, 95 % CI 0.83-1.66), or cardiovascular death (OR 0.96, 95 % CI 0.76-1.21 and OR 1.16, 95 % CI 0.94-1.43) versus patients who had never used strontium ranelate.

CONCLUSIONS

Analysis in the CPRD did not find evidence for a higher risk for cardiac events associated with the use of strontium ranelate in postmenopausal osteoporosis.

Clinical profiles and outcomes in patients with chronic heart failure and chronic obstructive pulmonary disease: an efficacy and safety analysis of SHIFT study

BACKGROUND

Heart failure (HF) and chronic obstructive pulmonary disease (COPD) frequently coexist, with undefined prognostic and therapeutic implications. We investigated clinical profile and outcomes of patients with chronic HF and COPD, notably the efficacy and safety of ivabradine, a heart rate-reducing agent.

METHODS

6505 ambulatory patients, in sinus rhythm, heart rate ≥ 70 bpm and stable systolic HF were randomised to placebo or ivabradine (2.5 to 7.5mg bid). Multivariate Cox model analyses were performed to compare the COPD (n=730) and non-COPD subgroups, and the ivabradine and placebo treatment effects.

RESULTS

COPD patients were older and had a poorer risk profile. Beta-blockers were prescribed to 69% of COPD patients and 92% of non-COPD patients. The primary endpoint (PEP) and its component, hospitalisation for worsening HF, were more frequent in COPD patients (HRs f, 1.22 [p=0.006]; and 1.34 [p<0.001]) respectively, but relative risk was reduced similarly by ivabradine in both COPD (14%, and 17%) and non-COPD (18% and 27%) patients (p interaction=0.82, and 0.53, respectively). Similar effect was noted also for cardiovascular death. Adverse events were more common in COPD patients, but similar in treatment subgroups. Bradycardia occurred more frequently in ivabradine subgroups, with similar incidence in patients with or without COPD.

CONCLUSIONS

The association of COPD and HF results in a worse prognosis, and COPD represents a barrier to optimisation of beta-blocker therapy. Ivabradine is similarly effective and safe in chronic HF patients with or without COPD, and can be safely combined with beta-blockers in COPD.

Anxiety and cardiovascular symptoms: the modulating role of insomnia

BACKGROUND

Anxiety and insomnia are associated with cardiovascular (CV) symptoms. We assessed whether the relation between anxiety and CV symptoms is modulated by insomnia.

METHODS

Independently living women (n = 1,440; mean age = 59.36 +/- 6.53 years) were recruited by cluster sampling technique. We obtained data on demographic characteristics, health beliefs, access to health care, CV symptoms, sleep, stress and anxiety levels.

RESULTS

Overall, 56% of the sample reported insomnia; 46% reported CV symptoms, and 54% were highly anxious. There was a greater likelihood for highly anxious women and those experiencing insomnia to report CV symptoms (r(s) = 0.31* and r(s) = 0.32*, respectively). In logistic regression analysis, the adjusted odds ratios for reporting CV symptoms were 1.39 for patients with insomnia and 2.79 for those with anxiety. With control for insomnia, we observed a 3-fold reduction in the magnitude of the association between anxiety and CV symptoms (r(p) = 0.09*). Stepwise adjustments for sociodemographic factors, CV risk markers, and factors anchoring health beliefs and access to health care showed lesser impact on the relationships. With simultaneous control for those covariates, the correlation was r(p) = 0.13*; * p < 0.01.

CONCLUSION

The association of CV symptoms with anxiety is partly accounted for by insomnia.

Preoperative predictors of late postoperative outcome among patients with nonischemic mitral regurgitation with 'high risk' descriptors and comparison with unoperated patients

Among patients with chronic nonischemic mitral regurgitation (MR), high short-term mortality risk can be identified by left (LV) and/or right ventricular (RV) ejection fraction (EF) criteria (LVEF </=45% and/or RVEF </=30%). Mitral valve replacement or repair (MVR) significantly improves outcome in this subgroup, but predictors of late postoperative survival are not known, and the benefit of MVR has not been defined in patients matched for severity of LV and RV dysfunction. Therefore, prospective assessment of 14 consecutive high risk MR patients was performed before MVR and during 9 years (average) postoperatively to define echocardiographic and radionuclide angiographic predictors of survival; survival also was evaluated in a contemporaneous series of 9 high risk unoperated MR patients, and in subgroups of operated and unoperated patients matched for EF. Of 14 MVR patients, 4 died (3 cardiac: 1 sudden, 2 congestive heart failure). Only preoperative RVEF </=20% significantly predicted postoperative deaths (rest p = 0.032; exercise p = 0.05). Of 9 unoperated patients, 8 died. Mortality risk of unoperated patients remained higher than that of MVR patients when groups were matched for preoperative LVEF (p = 0.0001). Among patients with RVEF >20%, MVR significantly improved survival versus medical treatment (rest: p < 0.0001, exercise: p = 0.0003). In high risk MR patients, MVR improves survival; preoperative RV performance can define subgroups with different long-term postoperative survival.

Abnormal gene expression of cardiac fibroblasts in experimental aortic regurgitation

Extensive primary fibrosis precedes heart failure and death in experimental chronic aortic regurgitation. To seek the molecular basis for this observation, this study analyzed the RNA pool for genes that are up-or downregulated in aortic regurgitation fibroblasts. Differential display reverse transcriptase polymerase chain reaction was used to compare RNA extracted from cardiac fibroblasts isolated from three healthy New Zealand white rabbits and from three with aortic regurgitation. Using two base anchoring oligo d(T) primers (T11VN) together with arbitrary upstream primers, numerous differences in normal versus aortic regurgitation gene expression were apparent on differential display reverse transcriptase polymerase chain reaction. The aortic regurgitation cell cultures showed numerous differentially up-and downregulated genes compared with cell cultures of normal cardiac fibroblasts. The results showed that pathologic fibrosis in chronic experimental aortic regurgitation is associated with abnormal cardiac fibroblast gene expression, which may be pathogenic for the fibrous lesion.

Severe mitral regurgitation due to mitral valve prolapse: risk factors for development, progression, and need for mitral valve surgery

Patients with mitral valve prolapse (MVP) may develop severe mitral regurgitation (MR) and require valve surgery. Preliminary data suggest that high body weight and blood pressure might add to the irreversible factors of older age and male gender in increasing risk of these complications. Fifty-four patients with severe MR due to MVP were compared with 117 control subjects with uncomplicated MVP to elucidate factors independently associated with severe MR: the need for valve surgery and the cumulative risk of requiring mitral valve surgery. Patients with severe MR were older (p<0.00005), more overweight (p = 0.002), had higher systolic (p = 0.0003) and diastolic (p = 0.007) blood pressures, and were more likely to have hypertension (p = 0.0001) and to be men (p<0.001). In both groups, men had higher blood pressure and relative body weight than women. In multivariate analysis, older age was most strongly associated with MR; higher body mass index, hypertension, and gender were independent predictors of severe MR in analyses that excluded age. Among the 54 patients with severe MR, the 32 (59%) who underwent mitral valve surgery during 11 years of follow-up were older, more overweight, and more likely to be hypertensive than those not requiring surgery. Among patients undergoing mitral valve surgery in 3 centers, mitral prolapse was the etiology in 25%, 67% of whom were men. Using these data and national statistics, we estimate that the gender-specific cumulative risk for requiring valvular surgery for severe MR in subjects with MVP is 0.8% in women and 2.6% in men before age 65, and 1.4% and 5.5% by age 75. Thus, subjects with MVP who are older, more overweight, and hypertensive are at greater risk for severe MR and valve surgery. Higher blood pressure and relative weight in men with MVP appear to contribute to the gender difference in risk for severe MR.

Prognostication in 3-vessel coronary artery disease based on left ventricular ejection fraction during exercise : influence of coronary artery bypass grafting

BACKGROUND

Previous data indicate that left ventricular ejection fraction (LVEF) provides prognostic information among patients with coronary artery disease (CAD), but the value of such testing specifically for defining benefits of coronary artery bypass grafting (CABG) may relate to severity of exercise-inducible ischemia measured noninvasively before surgery.

METHODS AND RESULTS

To determine the independent prognostic importance of preoperative ischemia severity for predicting outcomes of CABG among patients with extensive CAD, we monitored 167 stable patients with angiographically documented 3-vessel CAD (average follow-up of 9 years in event-free patients) who previously had undergone rest and exercise radionuclide cineangiography. Their course was correlated with data obtained during initial radionuclide testing, coronary arteriography, and clinical evaluation at study entry. Fifty-two patients received medical treatment only, and 115 underwent CABG (44 early [</=1 month after initial study]). Multivariate Cox model analysis indicated that change (Delta) in LVEF from rest to exercise during radionuclide study was the strongest independent predictor of major cardiac events (P=0.003) before surgery and also predicted magnitude of CABG benefit (P=0.04). Patients with DeltaLVEF -8% or less derived significant survival-prolonging and event-reducing benefit from CABG performed </=1 month after initial testing (P<0.02 for cardiac death and P=0.008 for cardiac events], early CABG versus medical-treatment-only patients); similar benefits were absent among patients with DeltaLVEF more than -8%, and among those in whom CABG was deferred.

CONCLUSIONS

Assessment of ischemia severity based on LVEF response to exercise enables effective prognostication among patients with 3-vessel CAD and defines the likelihood of life-prolonging and event-reducing benefits from CABG.

Myocardial connexin43 expression in left ventricular hypertrophy resulting from aortic regurgitation

Intercellular conduction in the working myocardium of the mammalian heart is mediated by gap junctions composed of connexin43 or 45. Recently, it has been shown that myocardial connexin expression is malleable and may be altered with disease. To better understand myocardial conduction in left ventricular hypertrophy resulting from volume overload, we used indirect immunofluorescence microscopy to examine cardiac connexin43 expression in 10 New Zealand white rabbits with surgically induced aortic regurgitation (AR) and in 10 age-matched sham-operated controls. Animals were sacrificed at approximately 1 month or > or =2.5 years after operation. All AR animals developed eccentric hypertrophy; none evidenced heart failure. The heart-to-body weight ratios for the 1 month AR and control groups were 2.9+/-0.8 vs 1.8+/-0.2 g/kg (p < or = 0.01) while ratios for the > or =2.5 year AR and control groups were 2.4+/-0.3 vs 1.9+/-0.3 (p < or = 0.05). No significant differences in posterior wall thickness were found among any of the groups. Although the overall pattern of connexin43-like immunoreactivity was similar for all four groups, staining in the I month AR animals tended to be less than that of age-matched controls; staining was increased in the > or =2.5 year AR animals and was greater than control (p < 0.05), in which staining did not change with animal age. This disease duration-related increase differs from the long-term decrease in connexin43 expression associated with other forms of heart disease and suggests that alterations in connexin expression may play a role in the rhythm abnormalities commonly seen in AR.

Differential response to vesnarinone by cardiac fibroblasts isolated from normal and aortic regurgitant hearts

Vesnarinone, a quinoline derivative with modest positive inotropic action, has been shown in several studies to benefit patients with clinical congestive heart failure. The cellular basis of its clinical benefit is not known, although the drug has several pharmacologic effects demonstrated both in isolated cardiac myocytes and in other noncardiac cell types. To investigate the possibility that the clinical benefit of vesnarinone is based, at least in part, on the inhibition of pathologic myocardial fibrosis, we examined its effects on cultured cardiac fibroblasts isolated from both normal and aortic regurgitant New Zealand White rabbit hearts. As in people, rabbits with moderate-to-severe aortic regurgitation often develop congestive heart failure that, at necropsy, is characterized by exuberant myocardial fibrosis. A dose-response curve was constructed with vesnarinone concentrations ranging from 10(-4 ) to 10(-9 ) mol/L. Cellular survival was decreased by exposure to nanomolar concentrations of drug but not at the higher doses tested. Fibroblasts isolated from normal hearts responded maximally at 10(-7 ) mol/L vesnarinone, whereas fibroblasts from aortic regurgitant hearts responded maximally at 10(-8 ) mol/L. These concentrations of drug are more than an order of magnitude lower than those believed to be associated with clinical benefit from earlier studies. Our results indicate that vesnarinone can suppress cardiac fibroblast proliferation and suggest that this action may be useful in therapies designed to prevent congestive heart failure in aortic regurgitation.

Fibrosis, myocyte degeneration and heart failure in chronic experimental aortic regurgitation

Myocardial fibrosis and myocyte degeneration have been reported in patients with chronic aortic regurgitation (AR), and may be related to the pathophysiology of congestive heart failure (CHF) in this disease. To define the relationship between myocardial histopathologic variations and CHF in chronic AR, we performed gross and microscopic evaluations of postmortem tissue from a rabbit model of chronic AR manifesting left ventricular (LV) responses to AR similar to those in humans. Moderate-to-severe chronic AR (echocardiographic regurgitant fraction = 52 +/- 13%) was induced by closed-chest aortic valve perforation in 11 New Zealand White rabbits; 5 control rabbits were sham operated. Six of the 11 AR rabbits died 1.5 +/- 0.8 years (range 0.6-2.8 years) after AR induction; all 6 had gross and histologic anatomic evidence of CHF at necropsy. The remaining 5 AR rabbits survived until sacrifice at 2.9 +/- 0.1 years of AR; none had pathologic evidence of CHF. Cardiac hypertrophy and the extent of LV fibrosis and myocyte necrosis all were greatest among the 6 AR CHF rabbits. No inflammatory response was apparent in any animal. Moderate-to-severe chronic experimental AR frequently results in CHF which is strongly associated with myocardial fibrosis and necrosis, without evidence of inflammation. These histopathologic variations may be pathophysiologically related to CHF development.

Myocardial collagen in cardiac hypertrophy resulting from chronic aortic regurgitation

Myocardial fibrosis and abnormal myocardial collagen content are common in many forms of pathological cardiac hypertrophy, including that mediated by pressure overload. Recently, in an experimental animal model of chronic aortic regurgitation (AR), we found a strong relation between myocardial fibrosis and congestive heart failure development. To determine if these fibrotic lesions are composed of collagen, as they are in pressure overload, and to determine if potential preventive therapies should be developed similarly in both diseases, we assessed left ventricular collagen content at three time points after AR induction. Moderate to severe AR was induced in 19 New Zealand White rabbits by inserting a catheter through the carotid artery to perforate the aortic valve leaflets. Animals were killed (1) when they showed echocardiographically discernible systolic dysfunction or (2) if normal cardiac function continued, either early (1 month) or late (>3 years) after operation. Fourteen age-matched, sham-operated controls and seven normal unoperated rabbits also were studied. Collagen concentrations were determined biochemically by hydroxyproline measurement. Fibrosis was measured histologically using Mason's trichrome stain and the fibrous collagen-specific stain, Picro-Sirius Red. Our results show an age-related increase in left ventricular collagen concentration with no specific increase among animals with evidence of fibrosis. We conclude that, unlike pressure overload, volume overload produces fibrotic lesions not composed predominantly of excess collagen and that the therapy needed to prevent fibrosis may be different in these conditions. Further study is needed to define the chemical characteristics of the fibrous lesions and the pathophysiological importance of this finding.

Time-voltage QRS area of the 12-lead electrocardiogram: detection of left ventricular hypertrophy

Identification of left ventricular hypertrophy (LVH) using 12-lead ECG criteria based primarily on QRS amplitudes has been limited by poor sensitivity at acceptable levels of specificity. Because the product of QRS voltage and duration, as an approximation of the time-voltage area of the QRS complex, can improve accuracy of the 12-lead ECG for LVH, we examined the diagnostic value of true time-voltage area measurements of QRS complexes from the standard 12-lead ECG. Standard 12-lead ECGs and echocardiograms were obtained in 175 control subjects without LVH and in 74 patients with regurgitant valvular heart disease and LVH defined by echocardiographic criteria (indexed LV mass >110 g/m2 in women and >125 g/m2 in men). Standard voltage criteria, voltage-duration products (voltage multiplied by QRS duration), and true time-voltage areas of the QRS were calculated for Sokolow-Lyon criteria (SV1 +RV(5/6)) and the 12-lead sum of voltage criteria. Test sensitivities were compared using gender-specific partitions with matched specificity of 98% in the 175 subjects without LVH. Measurement of the time-voltage area significantly improved sensitivity for both criteria. The 76% sensitivity of the 12-lead sum area and 65% sensitivity of Sokolow-Lyon area were significantly greater than the 54% sensitivity of the approximation of QRS area provided by each voltage-duration product (P<.001 and P=.021) and than the 46% and 43% sensitivities of the respective simple voltage criteria (each P<.001). Comparison of receiver operating characteristic curves confirmed the superior overall performance of time-voltage area criteria compared with both voltage-duration products and simple voltage criteria. These results suggest that use of time-voltage areas can dramatically improve identification of LVH by 12-lead ECG. Further study of this approach is needed to identify optimal criteria for LVH based on the time-voltage area measurements from the 12-lead ECG.

Prediction of indications for valve replacement among asymptomatic or minimally symptomatic patients with chronic aortic regurgitation and normal left ventricular performance

BACKGROUND

Optimal criteria for valve replacement are unclear in asymptomatic/minimally symptomatic patients with aortic regurgitation (AR) and normal left ventricular (LV) performance at rest. Moreover, previous studies have not assessed the prognostic capacity of load-adjusted LV performance ("contractility") variables, which may be fundamentally related to clinical state. Therefore, 18 years ago, we set out to test prospectively the hypothesis that objective noninvasive measures of LV size and performance and, specifically, of load-adjusted variables, assessed at rest and during exercise (ex), could predict the development of currently accepted indications for operation for AR.

METHODS AND RESULTS

Clinical variables and measures of LV size, performance, and end-systolic wall stress (ESS) were assessed annually in 104 patients by radionuclide cineangiography at rest and maximal ex and by echocardiography at rest; ESS was derived during ex. During an average 7.3-year follow-up among patients who had not been operated on, 39 of 104 patients either died suddenly (n = 4) or developed operable symptoms only (n = 22) or subnormal LV performance with or without symptoms (n = 13) (progression rate=6.2%/y). By multivariate Cox model analysis, change (delta) in LV ejection fraction (EF) from rest to ex, normalized for deltaESS from rest to ex (deltaLVEF-deltaESS index), was the strongest predictor of progression to any end point or to sudden cardiac death alone. Unadjusted deltaLVEF was almost as efficient. Symptom status modified prediction on the basis of the deltaLVEF-deltaESS index. The population tercile at highest risk by deltaLVEF-deltaESS progressed to end points at a rate of 13.3%/y, and the lowest-risk tercile progressed at 1.8%/y.

CONCLUSIONS

Currently accepted symptom and LV performance indications for valve replacement, as well as sudden cardiac death, can be predicted in asymptomatic/minimally symptomatic patients with AR by load-adjusted deltaLVEF-deltaESS index, which includes data obtained during exercise.

Safety of prostaglandin E1 for the treatment of peripheral arterial occlusive disease in patients with congestive heart failure. The Alprostadil Investigators

OBJECTIVES

To confirm the safety of prostaglandin E ( 1 ) (PGE ( 1 ) ) when administered in 100 mL normal saline to patients with severe peripheral occlusive disease (PAOD; Fontaine class III or IV) and concomitant compensated chronic congestive heart failure (CHF) and to explore possible hemodynamic benefits of PGE ( 1 ) in CHF.

BACKGROUND

PGE ( 1 ) has been found to be effective in the treatment of severe PAOD. The agent may beneficially affect left ventricular performance or hemodynamics in patients with CHF. However, it must be administered intravenously (in saline diluent, adding potential hazard in patients with volume CHF).

METHODS

In a randomized, double-blinded protocol, 50 patients received intravenous (i.v.) infusion of either 60 microg PGE ( 1 ) or placebo, each dissolved in 100 mL saline solution administered over 2 hours each day for 14 days. During the succeeding 14 days, i.v. PGE ( 1 ) was administered to all patients in open-label fashion. Safety was assessed by clinical evaluation of symptoms and signs of CHF or other adverse events, by catheter-based and echocardiographic search for objective cardiac functional influences, and by echocardiogram monitoring for cardiac rhythm. PAOD status also was defined.

RESULTS

No evidence of clinical or objective cardiac functional influence was detected. With the usual dosage approved in PAOD, no significant influence on cardiac performance was observed.

CONCLUSION

PGE ( 1 ) is safe for treatment of PAOD in patients with concomitant chronic, compensated CHF.

Protein turnover in compensated chronic aortic regurgitation

We recently demonstrated dynamic alterations in protein turnover 3 days and 1 month after surgical induction of aortic regurgitation (AR). To characterize protein synthesis and degradation during the long-term plateau phase, we performed [3H]-leucine infusion 2.5 years after induction of AR in 10 New Zealand White rabbits and 12 sham-operated controls. Protein fractional synthesis rates were obtained by analyses of plasma and protein hydrolysates, growth rates from protein concentration and heart weight measurements, and degradation rates by subtraction of growth from synthesis rates. AR (regurgitant fraction 25 +/- 11%) caused a 57% increase in left ventricular (LV) weight in comparison with controls (7.4 +/- 1.7 vs. 4.7 +/- 0.6 g, p < 0.001) and no evidence of heart failure. Although concentrations of total cardiac protein, myosin heavy chain and actin were similar, the enlarged AR hearts had increased amounts of total cardiac protein (1,009 +/- 312 vs. 682 +/- 120 mg/LV, p < 0.05), myosin heavy chain (148 +/- 91 vs. 81 +/- 29 mg/LV, p < 0.05), and actin (73 +/- 42 vs. 44 +/- 16 mg/LV, p < 0.06). Individual protein fractional synthesis and degradation rates were closely balanced. However, myosin fractional synthesis rates were 152% (p < 0.01) greater than those of total cardiac protein in AR animals, while only 52% (p < 0.05) greater in controls (AR vs. controls, p = 0.05). Variations in actin turnover between AR and control animals did not attain statistical significance. Myosin and actin fractional synthesis rates correlated closely in AR rabbits (R = 0.81, p < 0.02), but not among controls (R = 0.41, NS). Thus, selective alterations in myofibrillar protein turnover contribute to the maintenance of increased myofibrillar protein content in the 'compensatory' LV hypertrophy of chronic AR.

Relation of ultra-low frequency heart rate variability to the clinical course of chronic aortic regurgitation

We examined the relation of the standard deviation of the 5-minute mean RR intervals over 24 hours (SDANN), a measure of ultra-low frequency heart rate variability (HRV) (<0.0033 Hz), and other measures of HRV to clinical outcome events in 50 asymptomatic or minimally symptomatic patients with chronic severe aortic regurgitation (AR) who underwent ambulatory electrocardiography as part of a prospective study of the natural history of regurgitant valvular diseases. At entry, all patients were in sinus rhythm and had New York Heart Association functional class I or minimal II congestive heart failure, with left ventricular (LV) ejection fraction > or = 45% and LV end-diastolic dimension > or = 5.5 cm in women and > or = 5.9 cm in men. End points were defined as progression to aortic valve replacement (n = 19) or sudden cardiac death (n = 1) during the mean follow-up period of 8.1 +/- 3.8 years. With the median SDANN of 145 ms as a partition value, the average annual risk of end-point events in patients with low SDANN was significantly greater than the event rate in patients with high SDANN (11%/year vs 2%/year, p <0.0003). In multivariate analysis, reduced SDANN was associated with end-point events independent of LV function, LV end-systolic dimension, and symptom status (p = 0.001). We conclude that reduced ultra-low frequency HRV measured as SDANN is strongly related to progression to valve surgery in asymptomatic and minimally symptomatic patients with chronic AR.

Usefulness of subnormal midwall fractional shortening in predicting left ventricular exercise dysfunction in asymptomatic patients with systemic hypertension

We have recently shown that a subgroup of asymptomatic hypertensive patients exhibit subnormal left ventricular (LV) midwall fiber shortening at rest and that this finding predicts morbidity and mortality independently of age, blood pressure (BP), or the presence of LV hypertrophy. However, it is unknown whether abnormal midwall fractional shortening predicts either subnormal LV functional reserve or extracardiac damage in asymptomatic hypertensive patients. Accordingly, we compared radionuclide cineangiographic LV ejection fraction at rest and maximum exercise as well as clinical findings between 89 patients with normal and 16 patients with subnormal midwall fractional shortening by echocardiogram. Patients with low midwall fractional shortening were similar in gender, age, and systolic BP to those with normal shortening but had higher mean diastolic BP and body mass indexes (both p < 0.05). The 2 groups also had similar resting ejection fraction (56 +/- 9% vs 55 +/- 15%, with normal or subnormal shortening, respectively, p = NS). Patients with subnormal midwall fractional shortening had higher LV mass and tended to have higher urinary protein excretion and serum creatinine levels. Subnormal LV ejection fraction with exercise (< 54%) was observed in 13 of 89 patients (15%) with normal midwall fractional shortening but in 7 of 16 patients (44%) with subnormal shortening (p < 0.05). Multiple linear regression analysis revealed that midwall fractional shortening independently predicted exercise performance (p < 0.001). Thus, subnormal midwall fractional shortening predicts depressed LV fractional reserve in asymptomatic hypertensive patients and may contribute to identification of patients with extracardiac target-organ damage.

Antimyosin antibody imaging in experimental aortic regurgitation

BACKGROUND

Fiber dropout and myocyte necrosis precede heart failure in experimental aortic regurgitation (AR). The current study aimed to determine whether this process can be detected by noninvasive scintigraphic imaging.

METHODS AND RESULTS

111In-labeled antimyosin antibody Fab fragment (1 to 1.5 mCi) (Myoscint) was administered to each of 34 New Zealand White rabbits: 11 early (3 to 5 weeks) after surgical AR induction; 9 late (98 to 128 weeks) after AR induction; 5 normal and 3 sham-operated age-matched with early AR; and 3 normal and 3 sham-operated age-matched with late AR. Echocardiographic fractional shortening was indistinguishable among control, early AR, and late AR groups. In vivo gamma camera imaging 24 and 48 hours after isotope administration, post-mortem heart activity determination (percentage injected dose per gram), and autoradiography were performed. At 24 and 48 hours, heart-to-lung counts-per-pixel ratios from in vivo images were greater (p < 0.05) in the late AR rabbits than in each of the three other groups. No significant differences were found when early AR and older or younger control rabbits were compared. Heart activity (percentage injected dose per gram) in late AR rabbits trended toward higher values than in age-matched control rabbits (p = 0.057), but in early AR it was indistinguishable from that in the corresponding control (p = 0.413, difference not significant). The autoradiographic endocardial/epicardial activity ratio in late AR rabbits was greater than in control and early AR rabbits (1.27 +/- 0.13 vs 1.06 +/- 0.09 and vs 1.13 +/- 0.10, respectively, p < 0.02).

CONCLUSIONS

Whereas isotope uptake in late AR rabbits differed from that in control and early AR rabbits, systolic function was indistinguishable. Thus 111In-labeled antimyosin antibody imaging may permit noninvasive detection of AR-induced myocardial damage before functional deterioration.

Rhythm annotation and interobserver reproducibility of measures of heart rate variability

Interobserver reproducibility is high for time domain and power spectral measures of heart rate variability, with greater reproducibility for low-frequency measures, and especially for the standard deviation of the 5-minute RR intervals over 24 hours, than for high-frequency measures. Overall interobserver variability of < 8% for these measures is largely (50% to 75%) explained by interobserver differences in annotation of supraventricular ectopy and sinus arrhythmia.

Biodistribution and autoradiographic localization of I-125--labeled synthetic Peptide in aortic atherosclerosis in cholesterol-fed rabbits

I-125 labeled SP4 is a synthetic oligopeptide derived from apolipoprotein B of low-density lipoprotein that has been shown to localized in atherosclerotic plaques in experimental animals. However, its biodistribution and mechanism of localization need to be further elucidated. Twenty-four cholesterol-fed (CF) and 20 normal (NL) New Zealand White rabbits were injected with I-125-SP4 and killed 15 to 30 min (6 NL; 6 CF) or 2 h (14 NL; 18 CF) later. We obtained aortic autoradiograms and activity concentrations (% injected dose/gm) in aortic segments and other tissues. The uptake of I-125-SP4 was higher in CF than in NL rabbits in all aortic segments (p < 0.05). I-125-SP4 was cleared rapidly in both CF and NL rabbits with 60 to 70% of the injected dose cleared from the blood by 1 h. No statistically significant differences in radiotracer biodistribution were observed between NL and CF rabbits although activity tended to be higher in the liver, gallbladder, and intestine in NL rabbits and in the kidney and spleen in CF rabbits. Silver grains were distributed mainly on foam cells of the fatty streaks in aortic microautoradiograms from two additional rabbits that had been injected with I-125-SP4. There were 23,518 plus minus 15,878 (SD) grains/mm(2) in fatty plaques but only 14,669 plus minus 11,035 grains/mm(2) in media muscle (p < 0.0001 [9 sections, 17 areas evaluated] in an atherosclerotic animal) in injected animals and 13,439 plus minus 5,565 grains/mm(2) in media muscle (two sections, four areas) in the normal control animals (NS versus media of atherosclerotic animal). I-125-SP4 specifically localizes in aortic atherosclerotic plaques in CF rabbits. There is no significant difference in tissue distribution between normal and CF rabbits except in the aorta. Preliminarily, it appears that the site of tracer uptake is on foam cells and this suggests the possibility of relative specificity for fatty plaque.

Combined rest and exercise electrocardiographic repolarization findings in relation to structural and functional abnormalities in asymptomatic aortic regurgitation

The relationship of combined rest and exercise electrocardiographic (ECG) repolarization abnormalities to left ventricular geometry and function was examined in 48 patients with asymptomatic chronic pure aortic regurgitation and no recent use of digitalis. Echocardiographic and radionuclide cineangiographic findings were compared in groups defined by the presence or absence of the "strain" pattern of repolarization abnormality on the resting ECG and also by the presence or absence of standard positive repolarization changes during upright treadmill exercise ( > 0.1 mV additional horizontal or downsloping ST depression). These hierarchic groups demonstrated trends toward progressively abnormal left ventricular dimensions, mass, wall stress, and change in ejection fraction with exercise. Although the presence of the strain pattern on the resting ECG alone was most strongly correlated with underlying functional and geometric abnormalities, an abnormal exercise test response was independently associated with abnormal left ventricular systolic dimension. The large group of patients with no symptoms and normal resting repolarization had only 0% to 4% prevalences of markedly increased systolic dimension (> 55 mm), reduced ejection fraction at rest (< 45%), or reduced ejection fraction during exercise (< 40%), whereas the small group of patients with abnormal resting repolarization and a positive exercise test response had 50% to 83% prevalences of these findings. These data suggest a possible role for rest and exercise ECG in the serial evaluation of patients with aortic regurgitation.

Variability of the ventricular response in atrial fibrillation and prognosis in chronic nonischemic mitral regurgitation

Although reduced heart rate (HR) variability during sinus rhythm is associated with an adverse prognosis in a variety of clinical settings, the significance of measures of variability of the ventricular response in atrial fibrillation (AF) requires clarification. AF is common among patients with chronic severe mitral regurgitation (MR) and potentially limits the application of HR variability techniques in this population. Therefore, this study examined the physiologic correlates and prognostic significance of measures of HR variability in 21 patients with nonischemic causes of chronic severe MR who had chronic AF and underwent 24-hour ambulatory electrocardiography as part of a prospective study of the natural history of regurgitant valvular heart disease. Patients were followed for up to 9.1 years and end points of mortality and progression to mitral valve surgery were tabulated. Time- and frequency-domain measurements of high-, low-, and ultra-low-frequency HR variability were computed and compared with resting ventricular function by radionuclide cineangiography and outcome. All measures of HR variability were covariate (pair-wise r values between 0.48 and 0.99, all p values < 0.03), and none of the variables was significantly related to age, ventricular premature complex (VPC) density, or right or left ventricular ejection fraction. Reductions in time-domain measurements of ultra-low- and high-frequency HR variability were significant predictors of the combined risk of mortality or requirement for mitral valve surgery (p = 0.02 and p = 0.05, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of tomographic and planar radionuclide ventriculography in the assessment of regional left ventricular function in patients with left ventricular aneurysm before and after surgery

METHODS AND RESULTS

To compare tomographic and planar radionuclide ventriculography (RNVG) in assessing regional left ventricular (LV) function and predicting improvement in LV ejection fraction (LVEF) after operation in patients with LV aneurysm, 18 patients with aneurysm underwent both tomography and planar RNVG 1 month before and 3 weeks to 6 months after aneurysmectomy and coronary artery bypass grafting. All patients also underwent preoperative contrast angiography at catheterization. The percent shortening of the apical, anterior, lateral, inferior, and basal segments was calculated from tomographic long-axis and short-axis slices and corresponding planar images (anterior and 30- and 70-degree left anterior oblique views). No significant differences in anterior, apical, and lateral percent shortening were apparent before aneurysmectomy between tomographic and planar studies. However, preoperative basal percent shortening was 47% +/- 13% from tomographic and 28% +/- 14% from planar images (p < 0.001). Preoperative tomography generally agreed better with contrast angiographic results than did planar imaging. After aneurysmectomy, basal function improved to 57% +/- 12% (p < 0.01) by tomography. For all patients, LVEF increased from 29% +/- 8% before to 38% +/- 9% (p < 0.01) after aneurysmectomy. However, the greatest improvement (31% +/- 11% to 41% +/- 9%; p < 0.01) was in the 15 patients with greater than 30% basal shortening by tomography before aneurysmectomy; in contrast, no change of LVEF occurred in the three patients with lesser preoperative basal percent shortening. Moreover, greater than 30% basal percent shortening by tomography before aneurysmectomy identified the group most likely to have an increase in LVEF of 5% or more from before to after aneurysmectomy. Prediction of postoperative results was not possible from preoperative planar data. Thus in patients with LV aneurysm, tomographic RNVG appears to provide information that is different and more accurately predictive of results after aneurysmectomy than that available from planar imaging.

Right and left ventricular performance 10 years after Mustard repair of transposition of the great arteries

Twenty-two late survivors of Mustard repair of transposition of the great arteries underwent treadmill exercise testing to assess exercise endurance, and radionuclide cineangiography to measure rest and exercise right ventricular (RV) and left ventricular (LV) ejection fraction (EF). Mean age at Mustard repair was 1.8 +/- 2.4 years and at initial exercise study 14.1 +/- 4.5 years. All patients were asymptomatic at study entry. Treadmill endurance time (9 to 12 minutes) was within the normal range for age in 18 of 20 patients. LVEF and RVEF at rest were within normal limits (55 +/- 8% and 52 +/- 9%, respectively). All LVEFs and RVEFs during exercise were also within the normal range (64 +/- 8% and 57 +/- 9%, respectively). However, the magnitude of increase in EF (rest to exercise) was subnormal for the right ventricle in 7 patients and for the left ventricle in 2 patients. Exercise RVEF was higher in patients with simple transposition who underwent repair at < 1 year of age than in those who underwent operation at age > 1 year (62 +/- 10% vs 52 +/- 7%). Serial study in 6 patients revealed no change in average RVEF or LVEF after an average interval of 4.4 years. One patient with complex transposition subsequently developed refractory congestive heart failure requiring cardiac transplantation. It is concluded that exercise endurance and LVEF and RVEF at rest and exercise are generally well preserved up to 19 years after Mustard repair, particularly in cases of simple transposition of the great arteries repaired before 1 year of age.

Natural history of the asymptomatic/minimally symptomatic patient with severe mitral regurgitation secondary to mitral valve prolapse and normal right and left ventricular performance

The natural history of patients with severe nonischemic mitral regurgitation (MR) from mitral valve prolapse, who are asymptomatic or minimally symptomatic and have normal right ventricular (RV) and left ventricular (LV) performance, has not been evaluated previously. To define natural history in this population and to determine if any objective variables could predict disease progression, 31 patients were followed annually with severe MR due to prolapse, who at entry were asymptomatic or minimally symptomatic and had normal RV and LV performance at rest by radionuclide cineangiography. Average follow-up in patients not reaching surgical end point was 4.7 years. The Kaplan-Meier product limit estimates were used to determine the rate of progression to either "operable" symptoms or to previously defined "high risk" ventricular performance descriptors, if the latter occurred first. Univariate comparisons of Kaplan-Meier curves and multivariate Cox proportional hazards analyses were used to define prognostically important variables measured at entry. Fourteen patients developed symptoms warranting referral for operation; none developed high-risk ventricular performance descriptors. The annual end point risk was 10.3%. Of all covariates, only change in RV ejection fraction from rest to exercise was significantly associated with disease progression. Annual risk of progression to surgical end point was 4.9% in the subgroup in which this parameter increased with exercise and 14.7% in the subgroup without an increase (p = 0.04). Patients with severe MR due to mitral valve prolapse, who are asymptomatic or minimally symptomatic with normal ventricular performance, can be expected to progress to surgical indications at an annual rate of 10.3%.(ABSTRACT TRUNCATED AT 250 WORDS)

Heart failure due to chronic experimental aortic regurgitation

Previously reported experimental models of aortic regurgitation generally have manifested normal systolic performance and have not developed heart failure [Magid et al. Am. J. Physiol. 263 (Heart Circ. Physiol. 32): H226-H233, 1992]. To determine whether more severe chronic experimental aortic regurgitation would generate systolic malperformance, heart failure, and emulate the human disease process, 11 New Zealand White rabbits underwent surgical induction of aortic regurgitation and 5 control animals underwent sham operation. Doppler echocardiography was performed serially for up to 3 yr, and pathological studies were performed at necropsy. Left ventricular internal dimension at end diastole increased 80% (P < 0.00002) and left ventricular weight increased 250% (P < 0.0002) in aortic regurgitant rabbits (regurgitant fraction 52 +/- 13%) compared with baseline values. Six of 11 aortic regurgitant animals died with pathological evidence of congestive heart failure at 1.5 +/- 0.8 yr postoperatively; 2 of these developed severe systolic malperformance, manifest as fractional shortenings of 15 and 19% at 1.6 and 1.7 yr, respectively. Five of 11 aortic regurgitant animals survived until killed at 2.9 +/- 0.1 yr. Thus moderate-to-severe chronic aortic regurgitation in rabbits frequently results in heart failure and systolic dysfunction and may usefully model chronic aortic regurgitation and heart failure in humans.

Assessment of coronary artery disease by radionuclide cineangiography. History, current applications, and new directions

In recent years, the utility of radionuclide cineangiography in prognostication has made it a mainstay of management decision making. With evolution of therapeutic modalities and concomitant alteration in management strategies, however, the technique and its application are undergoing parallel evolution to optimize response to current needs. Thus, in addition to standard planar rest and exercise assessment of left ventricular function, newer approaches are involving combined perfusion and function assessment, application of pharmacological stress to permit technically advantageous variations in imaging protocols, and application of SPECT technology in collecting blood pool data for tomographic display and analysis.

Risk stratification in the elderly patient after coronary artery bypass grafting: the prognostic value of radionuclide cineangiography

BACKGROUND

Recent data have shown that assessment of left ventricular function by radionuclide cineangiography (RNCA) predicts survival and cardiac events among non-age-selected patients who have previously undergone coronary artery bypass grafting (CABG). However, the prognostic value of this noninvasive approach is not known for elderly patients who now undergo CABG with progressively increasing frequency and who survive longer because of operation. Such easily applied prognostic indexes may be useful to determine whether survival benefits are likely to be maintained or additional therapy should be considered.

METHODS AND RESULTS

To obtain information on factors related to long-term survival and cardiac events among elderly patients after CABG and, specifically, to determine the prognostic implications of left ventricular performance at rest and during exercise for predicting all causes of death, major nonsurgical cardiac events (death or myocardial infarction), and event-free or surgery-free survival, we evaluated the late postoperative course of 41 patients, aged 65 years and older, who had undergone RNCA 1 month or more (mean 2.3 +/- 2.4 years; range 0.1 to 9 years) after CABG. Average follow-up among patients with event-free survival was 8.8 years after index radionuclide assessment. During follow-up 13 patients died with no known intercurrent event, five patients had nonfatal myocardial infarctions, and five underwent late (> or = 3 months after RNCA) repeat CABG or percutaneous transluminal coronary angioplasty. Log-rank comparisons of Kaplan-Meier product limit estimate curves identified only left ventricular ejection fraction at rest as significantly predictive of survival (p < 0.04). Patients with left ventricular ejection fraction at rest of less than 45% had a 7.8% average annual mortality risk, which was more than three times that of patients with normal resting function. Statistical trends also were found between mortality rates and completeness of revascularization (p < 0.06), major nonsurgical cardiac events and extent of anatomic disease (p < 0.08), and event-free or surgery-free survival and our index of completeness of revascularization (p = 0.08) and age at index RNCA (p < 0.07).

CONCLUSIONS

Assessment of left ventricular ejection fraction at rest is prognostically useful after CABG among elderly patients. The efficacy and timing of this approach should be confirmed in further investigations with larger and more varied patient subgroups.

Electrocardiographic diagnosis of left ventricular hypertrophy by the time-voltage integral of the QRS complex

OBJECTIVES

This study was conducted to test the hypothesis that the time-voltage integral of the QRS complex can improve the electrocardiographic (ECG) identification of left ventricular hypertrophy.

BACKGROUND

Standard ECG criteria have exhibited poor sensitivity for left ventricular hypertrophy at acceptable levels of specificity. However, left ventricular mass may be more closely related to the time-voltage integral of the summed left ventricular dipole than to QRS duration or voltages used in standard ECG criteria.

METHODS

Standard 12-lead ECGs, orthogonal lead signal-averaged ECGs and echocardiograms were obtained in 62 male control subjects without left ventricular hypertrophy and 51 men with left ventricular hypertrophy defined by echocardiographic criteria (indexed left ventricular mass > 125 g/m2). Voltage of the QRS complex was integrated over the total QRS duration in leads X, Y and Z to calculate the time-voltage integral of each orthogonal lead, of the maximal spatial vector complex and of the horizontal, frontal and sagittal plane vector complexes.

RESULTS

At matched specificity of 99%, the 73% (37 of 51) sensitivity of the time-voltage integral of the vector QRS complex in the horizontal plane was significantly greater than the 10% sensitivity of the Romhilt-Estes point score, the 16% sensitivity of QRS duration alone, the 22% sensitivity of Cornell voltage, the 33% sensitivity of the 12-lead sum of QRS voltage and the 37% sensitivity of Sokolow-Lyon voltage (each p < 0.001). Sensitivity of the horizontal plane time-voltage integral was also greater than the 10% to 51% sensitivity of the time-voltage integral calculated in the individual X, Y or Z leads (p < 0.01 to < 0.001), the 18% and 35% sensitivity of the time-voltage integrals of the frontal and sagittal plane vectors (p < 0.001) and the 49% sensitivity of the time-voltage integral of the maximal spatial vector complex calculated from all three orthogonal leads (p < 0.001). Comparison of receiver operating characteristic curves confirmed that the superior performance of the horizontal plane time-voltage integral relative to standard and other signal-averaged criteria was independent of partition value selection.

CONCLUSIONS

These findings suggest that use of the time-voltage integral of the QRS complex, a method that can be readily implemented on commercially available computerized ECG systems, can improve the accuracy of ECG methods for the identification of left ventricular hypertrophy.

External imaging of atherosclerosis in rabbits using an 123I-labeled synthetic peptide fragment

The oligopeptide fragment of apolipoprotein B, SP-4, has demonstrated pronounced uptake in the healing edges of balloon-injured rabbit aortic endothelium. To assess 123I-labeled SP-4 for identification of atherosclerotic plaques by gamma camera imaging, 14 Watanabe heritable hyperlipidemic (WHHL) and 5 normal rabbits were imaged 5 minutes and 12 and 24 hours after intravenous injection of 123I-SP-4. In addition, two WHHL and two normal rabbits were injected with 125I-SP-4 for autoradiography. Twelve of the 14 WHHL, but none of the normal, rabbits had visually apparent focal radioiodine accumulation in the region of the aorta. Focus-to-lung and focus-to-heart count ratios were 2.4 +/- 1.3 and 1.0 +/- 0.4, respectively. Five of the visually positive WHHL rabbits were reimaged 4 and 8 weeks later with 123I-NaI and 123I-SP-2 (an apo E peptide), respectively, as negative controls. Perceptible, but faint, aortic localization of 123I-NaI and of 123I-SP-2 was seen in only one animal each. The distributions of atherosclerotic lesions on photographs of the opened WHHL aortas and of film blackening on 125I-SP-4 autoradiograms were identical. In contrast, the two normal rabbit aortas did not exhibit plaques on photographs or film blackening on autoradiograms. Thus, in an animal model closely simulating human atherosclerotic disease, SP-4 localizes specifically in aortic atherosclerotic lesions.

Prognostic value of left ventricular ejection fraction response to exercise during long-term follow-up after coronary artery bypass graft surgery

BACKGROUND

Recent data, albeit based on operations often performed more than 15 years ago, suggest that survival benefits of coronary artery bypass graft surgery (CABG) generally are lost within 10 years after operation. A reliable noninvasive method for periodic assessment of ischemia severity after operation might permit optimal timing of additional therapy to minimize loss of benefits.

METHODS AND RESULTS

To determine the impact of left ventricular ejection fraction (LVEF) during exercise on prognosis in patients who have undergone CABG, results of rest and exercise radionuclide cineangiography were correlated with mortality, major nonsurgical cardiac events, and cardiac event-free or surgery-free survival in 192 patients who underwent index radionuclide study > or = 1 month (average, 26 months) after CABG. Average follow-up after study was 8.7 years among event-free patients. Initial events during follow-up included 31 deaths, 19 nonfatal myocardial infarctions, and 33 late repeat CABG or angioplasties (PTCA). Stepwise Cox regression analysis identified change (delta) in LVEF with exercise as the strongest independent predictor of cardiac death, major nonsurgical cardiac events, and cardiac event-free or surgery-free survival (P < .0001, all outcomes). Change in heart rate with exercise, completeness of revascularization, and New York Heart Association functional class for angina provided additional independent information. With each 10% decrement in delta LVEF, the hazard of cardiac death increased more than twofold, and the hazard of major nonsurgical cardiac events considered alone or in combination with repeat CABG or PTCA increased > 1.5 times.

CONCLUSIONS

Thus, assessment of delta LVEF is prognostically useful after CABG. Assessment of this variable may help determine the need for repeat CABG. The utility of this approach now should be confirmed by longitudinal prognostic study.

Prognostic value and physiological correlates of heart rate variability in chronic severe mitral regurgitation

BACKGROUND

A variety of measures of heart rate variability have been devised to measure high-frequency (0.15-0.40 Hz), low-frequency (0.04-0.15 Hz), or ultralow-frequency (< 0.0033 Hz) fluctuations in sinus cycle length. Although measures of low-frequency and ultralow-frequency heart rate variability have been shown to correlate with prognosis in several populations with ischemic heart disease, their relevance to patients with primary valvular heart disease remains to be determined.

METHODS AND RESULTS

Thirty-eight patients with nonischemic causes of chronic severe mitral regurgitation who were in sinus rhythm underwent 24-hour ambulatory electrocardiography as part of a prospective study of the natural history of regurgitant valvular heart disease. Patients were followed for as long as 9.2 years, and end points of mortality, progression to mitral valve surgery, and development of chronic atrial fibrillation were tabulated. Time- and frequency-domain measurements of high-frequency, low-frequency, and ultralow-frequency heart rate variability were computed and compared with resting ventricular function by radionuclide cineangiography and outcome. The standard deviation of the 5-minute mean RR intervals (SDANN), a measure of ultralow-frequency heart rate variability, was correlated with left ventricular ejection fraction (r = 0.49, p = 0.002) and right ventricular ejection fraction (r = 0.43, p = 0.007), whereas low-frequency and high-frequency heart rate variabilities were not. Heart rate, ultralow-frequency heart rate variability, and, to a lesser extent, high-frequency heart rate variability exhibited significant diurnal variation, but low-frequency heart rate variability did not. Heart rate and ultralow-frequency, low-frequency, and combined low- and high-frequency heart rate variability predicted mortality and total events. The most powerful predictor of subsequent events was SDANN: Patients with reduced SDANN were significantly more likely to develop end-point events (p < 0.001) with increased progression to mitral valve surgery (p < 0.001) as well as increased early mortality (p = 0.02). In a multivariate proportional hazards model, SDANN retained independent predictive power (p = 0.001). Likewise, SDANN was the only variable that was significantly associated with the subsequent development of atrial fibrillation (relative risk, 3.1; p = 0.03).

CONCLUSIONS

Ultralow-frequency heart rate variability, as measured by SDANN, correlates with right and left ventricular performance and predicts development of atrial fibrillation, mortality, and progression to valve surgery in patients with chronic severe mitral regurgitation.