Prognostic implications of paradoxical low gradient severe aortic stenosis: a comprehensive analysis from a large multicentric registry

Background

Up to 40% of patients with severe aortic stenosis (SAS; indexed aortic valve area (AVAi) <0.6 cm2/m2) present with low transvalvular mean gradient (MG) despite a normal left ventricular ejection fraction (EF). There is intense debate about the prognostic significance of such entity, with some referring to it as an advanced form of the disease, others as an intermediate form between a moderate and a severe form.

Objectives

To compare outcome of patients with paradoxical low gradient SAS (PLG-SAS; i.e., mean gradient <40 mmHg and AVAi <0.6 cm2/m2) vs. moderate aortic stenosis (MAS; i.e. mean gradient <40 mmHg and AVAi >0.6 cm2/m2) and high gradient SAS (HG-SAS; i.e. mean gradient >40 mmHg and AVAi <0.6 cm2/m2).

Methods

2582 consecutive patients with aortic stenosis (PLG-SAS, n=933; MAS, n=876 and HG-SAS, n=773) and a preserved EF (>50%) from an international multicentric registry were studied. Five years mortality between groups was compared using Kaplan Meier analysis. Inverse probability weighting was used to adjust for clinical and imaging baseline characteristics. Additionally, to explore the impact of MG (<40 mmHg vs. >40 mmHg) in patients with AVAi <0.6 cm2/m2 (PLG-SAS vs. HG-SAS) and to explore the impact of AVAi (<0.6 cm2/m2 vs. >0.6 cm2/m2) in patients with MG <40 mmHg (PLG-SAS vs MAS) we performed 2 different propensity score analyses. Patients were censored at the time of surgery.

Results

Overall, during 23 [IQR,10–47] months of follow-up 1003 patients died and 770 patients underwent aortic valve replacement. IPW-adjusted natural history was significantly better in patients with MAS, intermediate for patients with PLG-SAS and worst in patients with HG-SAS (59 vs. 47 vs. 41%, p<0.001, see Figure 1A). Furthermore, at equal MG (448 pairs), survival was significantly better in patients with MAS compared with PLG-SAS (54% vs. 39% p<0.001, see Figure 1B) and at equal AVAi (377 pairs), survival was significantly better in patients with PLG-SAS compared with HG-SAS (43% vs. 32% p<0.001, see Figure 1C).

Conclusions

In this large multicentric cohort, survival of PLG-SAS patients was better than that of HG-SAS patients and worse than that of MAS patients. Furthermore, with a comparable mean gradient, the smaller the calculated AVAi, the worse the prognosis whereas with a comparable AVAi, the higher the mean gradient, the worse the prognosis. Taking together, these data demonstrate that PLG-SAS is an intermediate form in the disease continuum, HG-SAS being the most malignant form of AS.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Fonds National de la Recherche Scientifique (F.R.S.–FNRS)

Impact of recent 2021 ESC guideline changes on postoperative survival of patients with severe aortic regurgitation: insights from the AVIATOR registry

Background

Until 2021, the strongest guidelines on surgical correction of severe aortic regurgitation (AR) focused on the left ventricular systolic function (LVEF) and the presence of symptoms. However, those situations lead to an outcome penalty, even after surgical correction. Left ventricle end-systolic diameter (LVESD) gained in strength in 2021 European guidelines. Moreover, more inclusive cut-off values are now recommended (class IIb) in patients at low surgical risk, reflecting the will to recommend surgery before developing heart failure and its consequences on post-operative outcome.

Purpose

We sought to evaluate the impact of guidelines triggers and their recent changes on postoperative survival of patients with severe AR from a large multicentric international registry.

Method and results

Postoperative overall survival of 1899 patients operated for severe and chronic AR (mean age 49±15 years, 85% male) in the international multicenter surgery registry for aortic valve surgery, AVIATOR, was evaluated over a median of 37 months. Twelve patients (0.6%) died postoperatively, and 68 within 10 years. By multivariable Cox analysis, presence of heart failure symptoms (HR 2.60; 95% CI [1.20–5.66]; p=0; 016), and either LVESD >50 mm or >25 mm/m2 (HR 1.64; 95% CI [1.05–2.55]; p=0.029) predicted survival independently over and above age (HR 2.25 per SD, 95% CI [1.67–3.03], p<0.001), female gender and bicuspid phenotype. Therefore, patients operated on when meeting either old or new 2021 class I triggers had worse adjusted survival (respectively 86±2% and 87±2%) than patients operated on without meeting triggers (97±2%, p<0.01). However asymptomatic patients operated on while meeting new 2021 ESC class IIb triggers (ie LVESD >20 mm/m2 or LVEF between 50–55%, 10-year survival 97±3%). Moreover, the sub-group of patients having a dilated LVESD >50 mm or >25 mm/m2 but a preserved LVEF >50% had excellent survival (10-year survival 95±3%).

Conclusions

In severe AR, patients operated on when meeting any class I trigger have postoperative survival penalty. Asymptomatic patients operated on earlier have better survival. This supports early surgery in AR as encouraged by the recent ESC/EACTS guidelines.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Fondation Nationale de la Recherche Scientifique of the Belgian Government

Myocardial strain imaging: review of general principles, validation, and sources of discrepancies

Myocardial tissue tracking imaging techniques have been developed for a more accurate evaluation of myocardial deformation (i.e. strain), with the potential to overcome the limitations of ejection fraction (EF) and to contribute, incremental to EF, to the diagnosis and prognosis in cardiac diseases. While most of the deformation imaging techniques are based on the similar principles of detecting and tracking specific patterns within an image, there are intra- and inter-imaging modality inconsistencies limiting the wide clinical applicability of strain. In this review, we aimed to describe the particularities of the echocardiographic and cardiac magnetic resonance deformation techniques, in order to understand the discrepancies in strain measurement, focusing on the potential sources of variation: related to the software used to analyse the data, to the different physics of image acquisition and the different principles of 2D vs. 3D approaches. As strain measurements are not interchangeable, it is highly desirable to work with validated strain assessment tools, in order to derive information from evidence-based data. There is, however, a lack of solid validation of the current tissue tracking techniques, as only a few of the commercial deformation imaging softwares have been properly investigated. We have, therefore, addressed in this review the neglected issue of suboptimal validation of tissue tracking techniques, in order to advocate for this matter.

P787 Interstudy reproducibility in the real world of speckle tracking echocardiography in direct comparison with cardiac magnetic resonance

Funding Acknowledgements

Fond national de la recherche scientifique (FNRS)

Background

New research methods to assess cardiac function such as 2D speckle tracking echocardiography (STE) are emerging in clinical practice after showing incremental prognostic information beyond ejection fraction in a variety of settings. However, comprehensive data regarding the day to day reproducibility is still lacking.

Aim

To assess the inter and especially the day to day intravariability of RV and LV GLS STE in direct comparison with cMR in asymptomatic volunteers and in patients with heart failure.

Methods for the volunteers:30 asymptomatic volunteers ( 34 ± 9years, 33% were women) underwent 2 cMR and 2 echocardiography studies with a maximal interval between each study of 6 days and 20 minutes between each technique. RV strain was performed on a RV focus view and LV strain on 4, 3 and 2 chamber views using the segment software. cMR- RVEF and cMR-LVEF was performed in short axis view.

Preliminary Results: Volunteers

Average values for the the STE measurements was -24.2%±2.3 and -27.4%±2.1 for LV and RV GLS respectively. Average values for the 2 cMR measurements was 61.9% ±4.5 and 56.3%± 6.2% for cMR-LVEF and RVEF respectively. The interstudy varability coefficient of variability was lower in GLS-STE parameters (RV-GLS = 7.7% and LV-GLS = 6.3%) than for the cMR parameters (cMR-LVEF= 8.2% and cMR-RVEF= 12.9%). The superior interstudy reproducibility resulted in lower calculated sample sizes require by GLS compared with cMR to show clinically relevant changes in LV and RV function. (Figure 1)

Conclusion

LV and RV -GLS- STE has excellent interstudy reproducibility in normal hearts and is as good as cMR- LVEF and RVEF.

Echocardiography cMR LV-GLS-STE RV-GLS-STE LVEF RVEF Mean difference ±SD 0.6 ± 1.88 0.5± 1.73 1.14 ± 5.22 0.98 ± 7.23 Coefficient of variation 7.7% 6.3% 8.2% 12.9% Sample Size for 2% absolute change in GLS or 5% absolute change in cMR- EF 18 16 22 44 Sample size required to detect a clinically significant change in global longidutdinal strain speckle tracking (GLS-STE) echocardiographie and cMR - ejection fraction (EF). RV and LV indicate Right ventricular and left ventricular respectively.

P1393 Intervendor difference in global and regional 2D speckle tracking strain. comparison against cMR tagging

Funding Acknowledgements

Fondation de Recherche Scientifique Belge FRSM PDR 19488731

BACKGROUND

2D-speckle-tracking (ST) echocardiography is currently widely used for estimation of global (G) and regional myocardial deformation. In previous works, we showed good correlation between global longitudinal (LS) and circumferential strain (CS) from one 2DST vendor with cMR-Tagging, however with significant bias between both methods. Also, we found poorer agreement between 2DST and cMR-Tagging on regional basis. However it is unknown how 2DST from other vendors would comparte to cMR tagging.

PURPOSE

To asssess vendor differences in global and regional strain assessment and compare 1) the agreement of 2 different 2DST softwares for global and regional LS and CS among each other and against cMR-Tagging as reference; and 2) the accuracy of both softwares to detect infarcted segments.

METHODS

100 subjects with different cardiac disease (among which 31 with chronic infarct) underwent 2DST and tagging and LGE cMR on the same day. Global and regional CS (16 AHA segments) and LS (18 AHA segments) was computed using 2 different ST vendor softwares and compared to cMR-Tagging with HARP. Accuracy of regional 2D-ST by both vendors to detect infarcted segments (ie >75% transmurality of late gadolinium) was compared using ROC analysis.

RESULTS

Global LS (ICC = 0.87) and CS 2DST (ICC = 0.83, p < 0.001) agreed well between both vendors, but GCS values of vendor2 were significantly greater than that of vendor 1. Also we fond good correlation between ST of both vendors and cMR-Tagging for GLS (ICC = 0.80 and ICC = 0.69 for vendor 1 and 2 respectively) and GCS (ICC = 0.64 and ICC = 0.50 for vendor 1 and 2 respectively). Bias for GLS (-4.6 ± 2.9% and -6.1 ± 3.8% for vendor 1 and 2 respectively) vs cMR-Tagging was similar, however GCS of vendor 2 had higher bias vs cMR-Tagging (-16.0 ± 8.5%) than vendor 1 (-5.1 ± 5.8%).

Agreement for regional strains is shown in the figure below. Overall, regional LS and CS agreed adequately among both vendors. Agreement of regional LS and CS vs cMR-tagging was slightly better for vendor 1, with less bias than for vendor 2, and disagreement was similarly located (ie agreement with cMR-Tagging for LS in inferolateral inferior and inferoseptal basal segments). The predictive accuracy of regional CS and LS for detecting segments with infarct was higher for vendor 2 (AUC 0.76 and 0.68) than for vendor 1 (AUC 0.70 and 0.63) .

CONCLUSION

GLS agreed well among both vendors and with cMR-Tagging, confirming the universal validity of this measurement. However vendor 2 provided significantly greater GCS values and had higher bias against cMR-Tagging than vendor 1. On regional basis CS and LS agreed moderately well among both vendors, however vendor 2 agreed less with cMR-Tagging than vendor 1, but astoundingly had higher diagnostic accuracy for detecting infarct. Overall this findings call for further efforts in standardization of 2DST CS and regional strain.

Abstract P1393 Figure.

P324Impact of impaired right ventricular strain on the prognosis of HFpEF

Background

Right ventricle (RV) strain has emerged as an accurate and sensitive tool for RV function assessment and is a powerful predictor of survival in heart failure with reduced ejection fraction. The impact of impaired RV strain on prognosis of HFpEF patients however, remains unclear.

Purpose

We sought to analyze RV global longitudinal strain (RV-GLS) by 2D speckle tracking echocardiography (STE) in controls and HFpEF patients and determine its prognostic value.

Methods

Between January 2015 and June 2017, we prospectively enrolled 163 consecutive patients with HFpEF (78±9 years, 62% women) and 27 age and sex matched controls (76±5 years, 67% women). All patients underwent complete 2D echography. Myocardial deformation was assessed on a dedicated four chambers view, with a speckle tracking software. Due to poor tracking quality, RV-GLS could not be analyzed in 14 patients (7.4%). Impaired RV-GLS was defined as a GLS above −17.5% corresponding to the mean + 2 SD of age and sex matched controls. HFpEF patients were followed up for a combined outcome of all-cause mortality and first HF hospitalization.

Results

Mean RV-GLS was significantly altered in HFpEF patients compared to controls (−21.7±4.9% vs −25.9±4.2%; p<0.001). 28 HFpEF patients (19%) had an impaired RV-GLS.

During a mean follow-up of 19±9months, 73 HFpEF patients (49%) reached the combined outcome (15 all cause deaths and 58 first HF hospitalization). In univariate Cox regression analysis, loop diuretic medication (HR 1.92 [1.10–3.32], p=0.021), low hemoglobin (HR 0.85 [0.75–0.97], p=0.013), low eGFR (HR 0.97 [0.96–0.99], p<0.001), E wave velocity (HR 1.01 [1.00–1.02], p<0.001), septal E/e' (HR 1.03 [1.00–1.05], p=0.011) and impaired RV-GLS (HR 2.01 [1.19–3.40], p=0.009) were significantly associated with worse prognosis.

In multivariate Cox analysis, hemoglobin levels (HR 0.83 [0.72–0.96], p=0.01), eGFR (HR 0.98 [0.97–0.99]; p=0.009) and impaired RV-GLS (HR 2.48 [1.38–4.44], p=0.002), were independent predictors of the combined outcome. Kaplan-Meier event free survival curves show that HFpEF patients with RV-GLS above −17.5% had worse prognosis than those with better myocardial deformation (p=0.009, Figure).

Conclusions

RV-GLS is significantly different between controls and HFpEF patients. In HFpEF, impaired RV-GLS is associated with worse prognosis.

Chronic ischemic viable myocardium in man: Aspects of dedifferentiation

Histologic analysis of biopsies derived from patients with chronic dysfunctional but viable (hibernating) myocardium showed characteristic cell alterations. These changes consisted of a partial to complete loss of sarcomeres, accumulation of glycogen, and disorganization and loss of sarcoplasmic reticulum. Most of the adaptive changes that these affected cells undergo are suggestive of dedifferentiation. In the present study the expression and organizational pattern of contractile and cytoskeletal proteins such as titin, cardiotin, and α-smooth muscle actin were assessed in hibernating and normal myocardium because the expression and organization of these constituents have been related to certain stages of cardiomyocyte differentiation. In normal cells titin shows a cross-striated staining pattern, whereas cardiotin displays a fibrillar array, parallel to the sarcomeres. α-Smooth muscle actin is not expressed in adult cardiomyocytes. The expression of titin in a punctated pattern and the marked decrease to virtual absence of cardiotin in hibernating cardiomyocytes speak in favor of an embryonic phenotype of these cells. The re-expression of α-smooth muscle actin in hibernating cells strongly supports this hypothesis. The observations on three different structural proteins of heart muscle suggest that hibernating myocardium acquired aspects of muscle cell dedifferentiation.

Urotensin II induction of adult cardiomyocytes hypertrophy involves the Akt/GSK-3beta signaling pathway

Urotensin II (UII) a potent vasoactive peptide is upregulated in the failing heart and promotes cardiomyocytes hypertrophy, in particular through mitogen-activated protein kinases. However, the regulation by UII of GSK-3beta, a recognized pivotal signaling element of cardiac hypertrophy has not yet been documented. We therefore investigated in adult cardiomyocytes, if UII phosphorylates GSK-3beta and Akt, one of its upstream regulators and stabilizes beta-catenin, a GSK-3beta dependent nuclear transcriptional co-activator. Primary cultures of adult rat cardiomyocytes were stimulated for 48h with UII. Cell size and protein/DNA contents were determined. Phosphorylated and total forms of Akt, GSK-3beta and the total amount of beta-catenin were quantified by western blot. The responses of cardiomyocytes to UII were also evaluated after pretreatment with the chemical phosphatidyl-inositol-3-kinase inhibitor, LY294002, and urantide, a competitive UII receptor antagonist. UII increased cell size and the protein/DNA ratio, consistent with a hypertrophic response. UII also increased phosphorylation of Akt and its downstream target GSK-3beta. beta-Catenin protein levels were increased. All of these effects of UII were prevented by LY294002, and urantide. The UII-induced adult cardiomyocytes hypertrophy involves the Akt/GSK-3beta signaling pathways and is accompanied by the stabilization of the beta-catenin. All these effects are abolished by competitive inhibition of the UII receptor, consistent with new therapeutic perspectives for heart failure treatment.

NC100100, a new echo contrast agent for the assessment of myocardial perfusion--safety and comparison with technetium-99m sestamibi single-photon emission computed tomography in a randomized multicenter study

BACKGROUND AND HYPOTHESIS

Myocardial contrast echocardiography using second-generation agents has been proposed to study myocardial perfusion. A placebo-controlled, multicenter trial was conducted to evaluate the safety, optimal dose, and imaging mode for NC100100, a novel intravenous second-generation echo contrast agent, and to compare this technique with technetium-99m sestamibi (MIBI) single-photon emission computed tomography (SPECT).

METHODS

In a placebo-controlled, multicenter trial, 203 patients with myocardial infarction > 5 days and < 1 year previously underwent rest SPECT and MCE. Fundamental and harmonic imaging modes combined with continuous and electrocardiogram-- (ECG) triggered intermittent imaging were used. Six dose groups (0.030, 0.100, and 0.300 microliter particles/kg body weight for fundamental imaging; and 0.006, 0.030, and 0.150 microliter particles/kg body weight for harmonic imaging) were tested. A saline group was also included. Safety was followed for 72 h after contrast injection. Myocardial perfusion by MCE was compared with myocardial rest perfusion imaging using MIBI as a tracer.

RESULTS

NC100100 was well tolerated. No serious adverse events or deaths occurred. No clinically relevant changes in vital signs, laboratory parameters, and ECG recordings were noted. There was no significant difference between adverse events in the NC100100 (25.7%) and in the placebo group (17.9%, p = 0.3). Intermittent harmonic imaging using the intermediate dose was superior to all other modalities, allowing the assessment of perfusion in 76% of all segments. Eighty segments (96%) with normal perfusion by SPECT imaging also showed myocardial perfusion with MCE. However, a substantial percentage of segments (61-80%) with perfusion defects by SPECT imaging also showed opacification by MCE. This resulted in an overall agreement of 66-81% and a high specificity (80-96%), but in low sensitivity (20-39%) of MCE for the detection of perfusion defects.

CONCLUSION

NC100100 is safe in patients with myocardial infarction. Intermittent harmonic imaging with a dose of 0.03 microliter particles/kg body weight can be proposed as the best imaging protocol. Myocardial contrast echocardiography with NC 100100 provides perfusion information in approximately 76% of segments and results in myocardial opacification in the vast majority of segments with normal perfusion as assessed by SPECT. Although the discrepancies between MCE and SPECT with regard to the definition of perfusion defects requires further investigation, MCE with NC 100100 is a promising technique for the noninvasive assessment of myocardial perfusion.

Repair of aortic valve prolapse: experience with 44 patients*1

OBJECTIVES

In regurgitant tricuspid aortic valves, cusp prolapse may be isolated or associated with dilatation of the proximal aorta. Newly appearing cusp prolapse can also appear after an aortic valve sparing operation (AVSO) and be responsible for residual aortic regurgitation. In this report, we describe our experience in repairing prolapsing aortic cusps in 44 patients with aortic regurgitation.

METHODS

Between 1996 and 2003, 260 patients had aortic valve repair or valve sparing procedures in our department. All patients had peri-operative TEE. Prolapse of one or more of the aortic cusps was identified by TEE and confirmed by careful surgical inspection before and after valve sparing surgery. Forty-four patients with cusp prolapse were identified. Fifteen had an isolated prolapse, with a normal root (group I), 18 had cusp prolapse associated with dilatation of the proximal aorta (group IIa), and 11 had a newly appearing prolapse after AVSO (group IIb). Correction of the prolapsing cusp was achieved by either free edge plication, triangular resection or resuspension with PTFE. This procedure was associated with an aortic annuloplasty in group I, and with AVSO in groups II and III.

RESULTS

Post-operative TEE showed AR trivial or grade I regurgitation. At a mean of 23 months follow-up, one patient with recurrent regurgitation required an aortic valve replacement with a homograft. All remaining patients were in NYHA class I or II. Echocardiography confirmed the durability of the valve repair.

CONCLUSIONS

Among the common causes of aortic regurgitation, isolated cusp prolapse is frequent and is amenable to surgical repair with excellent mid-term results. In particular, in patents who are potential candidates for AVSO, identification and correction of an associated prolapse, either pre-existing or secondary to the AVSO procedure, may further extend the indications for this technique, increase its success rates and improve its long-term outcome.

[Target and therapeutic microbubbles]

Because ultrasound microbubbles lower the threshold for cavitation by ultrasound energy, they may be used as cavitation nuclei for drug and gene delivery. By tailoring the physical properties of microbubbles and coating materials, drugs and genetic drugs can be incorporated into ultrasound contrast agents. As the microbubbles enter the region of insonation, the microbubbles cavitate, locally releasing the therapeutic agents.

Predictive value of markers of myocardial reperfusion in acute myocardial infarction for follow-up left ventricular function

This study evaluated recently suggested invasive and noninvasive parameters of myocardial reperfusion after acute myocardial infarction (AMI), assessing their predictive value for left ventricular function 4 weeks after AMI and reperfusion defined by myocardial contrast echocardiography (MCE). In 38 patients, angiographic myocardial blush grade, corrected Thrombolysis In Myocardial Infarction frame count, ST-segment elevation index, and coronary flow reserve (n = 25) were determined immediately after primary percutaneous transluminal coronary angioplasty (PTCA) for first AMI, and intravenous MCE was determined before, and at 1 and 24 hours after PTCA to evaluate myocardial reperfusion. Results were related to global wall motion index (GWMI) at 4 weeks. MCE 1 hour after PTCA showed good correlation with GWMI at 4 weeks (r = 0.684, p <0.001) and was in an analysis of variance the best parameter to predict GWMI 4 weeks after AMI. The ST-segment elevation index was close in its predictive value. Considering only invasive parameters of reperfusion myocardial blush grade was the best predictor of GWMI at 4 weeks (R(2) = 0.3107, p <0.001). A MCE perfusion defect size at 24 hours of > or =50% of the MCE perfusion defect size before PTCA was used to define myocardial nonreperfusion. In a multivariate analysis, low myocardial blush grade class was the best predictor of nonreperfusion defined by MCE. Thus, intravenous MCE allows better prediction of left ventricular function 4 weeks after AMI than other evaluated parameters of myocardial reperfusion. Myocardial blush grade is the best predictor of nonreperfusion defined by MCE and is the invasive parameter with the greatest predictive value for left ventricular function after AMI. Coronary flow parameters are less predictive.

Insulin antagonizes AMP-activated protein kinase activation by ischemia or anoxia in rat hearts, without affecting total adenine nucleotides

AMP-activated protein kinase (AMPK) is known to be activated by phosphorylation on Thr172 in response to an increased AMP/ATP ratio. We report here that such an activation indeed occurred in anaerobic rat hearts and that it was antagonized (40-50%) when the hearts were pre-treated with 100 nM insulin. The effect of insulin (1) was blocked by wortmannin, an inhibitor of phosphatidylinositol-3-kinase; (2) only occurred when insulin was added before anoxia, suggesting a hierarchical control; (3) resulted in a decreased phosphorylation state of Thr172 in AMPK and (4) was unrelated to changes in the AMP/ATP ratio. This is the first demonstration that AMPK activity could be changed without a detectable change in the AMP/ATP ratio of the cardiac cell.

Positron emission tomography using(18)F-fluoro-deoxyglucose and euglycaemic hyperinsulinaemic glucose clamp: optimal criteria for the prediction of recovery of post-ischaemic left ventricular dysfunction. Results from the European Community Concerted Action Multicenter study on use of(18)F-fluoro-deoxyglucose Positron Emission Tomography for the Detection of Myocardial Viability

AIMS

To assess the accuracy of positron emission tomography to predict recovery of global cardiac function after revascularization in patients with coronary artery disease.

METHODS AND RESULTS

One hundred and seventy-eight patients (157 male, 58+/-10 years) with coronary artery disease and left ventricular dysfunction (mean ejection fraction 39+/-14%) were enrolled in six European centres. They underwent a common protocol for the assessment of viability using(18)F-fluoro-2-deoxyglucose (FDG) positron emission tomography during a standardized euglycaemic hyperinsulinaemic glucose clamp before revascularization by either surgery (n=140) or angioplasty (n=38). Seven patients were excluded because of incomplete revascularization of a dysfunctional region. Based on the recovery of global ejection fraction 2-6 months after revascularization, patients were classified into two groups: 82 patients who had a >5% improvement in ejection fraction postoperatively, and 89 patients without postoperative ejection fraction improvement. Optimal cut-off points for postoperative improvement of global cardiac function were computed, using receiver operating curve analysis. The highest sensitivity (79%) and specificity (55%) for predicting postoperative ejection fraction improvement by positron emission tomography was found when three or more dysfunctional segments had a relative FDG uptake >45% of normal remote myocardium (overall accuracy 67%).

CONCLUSIONS

In a large cohort of coronary patients with impaired ejection fraction, FDG positron emission tomography demonstrated high sensitivity and moderate specificity to predict improvement of cardiac function after coronary revascularization.

Exaggerated chronotropic and energetic response to dobutamine after orthotopic cardiac transplantation

BACKGROUND

After heart transplantation, the transplanted denervated heart displays both an exaggerated chronotropic and an exaggerated inotropic response to circulating catecholamines. This study assessed whether denervated transplanted hearts also display an exaggerated energetic response when challenged with dobutamine.

METHODS AND RESULTS

A total of 18 heart transplant recipients and 14 normal volunteers underwent measurements of myocardial oxygen consumption (MVO2), external work (EW), and pressure-volume area (PVA), at rest and during infusion of dobutamine. At rest, calculated myocardial (PVA/MVO2) and mechanical (EW/MVO2) efficiencies were similar among transplant recipients and normal volunteers. During low-dose dobutamine infusion (8 microg/kg/min), transplant recipients exhibited a larger increase in heart rate (to 126 +/- 14 vs 87 +/- 26 beats/min, p < 0.001) and MVO2 (to 269 +/- 43 vs 233 +/- 19 J/min/100g, p < 0.05) and a smaller increase in EW (64 +/- 18 vs 72 +/- 13 J/min/100g, p < 0.05) and PVA (70 +/- 16 vs 81 +/- 13 J/min/100g, p < 0.05) than did normal volunteers. As a result, both myocardial (26 +/- 4 vs 35 +/- 4%, p < 0.05) and mechanical (23 +/- 4 vs 30 +/- 4%, p < 0.001) efficiencies were lower during dobutamine infusion in transplant recipients than in normal volunteers. During the infusion of a higher dose of dobutamine (19 microg/kg/min), the chronotropic and inotropic responses of heart transplant recipients were even more exaggerated. The fall in myocardial efficiency induced by dobutamine correlated with the increase in heart rate (r = -0.58) and could be reproduced in normal volunteers by coadministration of atropine.

CONCLUSIONS

Transplant recipients exhibit a larger fall in contractile efficiency and a larger oxygen-wasting effect during dobutamine infusion than do normal volunteers. Because normal volunteers pre-medicated with atropine presented with a similar increase in heart rate and a similar fall in efficiency, the exaggerated energetic response of transplanted hearts to dobutamine likely resulted from the same mechanisms as their chronotropic supersensitivity, i.e., the loss of inhibitory parasympathetic innervation.

Serial evaluation of perfusion defects in patients with a first acute myocardial infarction referred for primary PTCA using intravenous myocardial contrast echocardiography

AIMS

To investigate whether myocardial contrast echocardiography using Sonazoid could be used for the serial evaluation of the presence and extent of myocardial perfusion defects in patients with a first acute myocardial infarction treated with primary PTCA, and specifically, (1) to evaluate safety and efficacy of myocardial contrast echocardiography to detect TIMI flow grade 0--2, (2) to evaluate the success of reperfusion and (3) to predict left ventricular recovery after 4 weeks follow-up.

METHODS AND RESULTS

Fifty-nine patients underwent serial myocardial contrast echocardiography, immediately before primary PTCA (MCE1), 1 h (MCE2) and 12--24 h after PTCA (MCE3). A perfusion defect was observed in 21 of 24 patients (88%) with anterior acute myocardial infarction. All but one had TIMI flow grade 0--2 prior to PTCA. Nine of 31 patients (29%) with inferior acute myocardial infarction showed a perfusion defect and all had TIMI flow grade 0-2 prior to PTCA. Restoration of TIMI flow grade 3 was achieved in 73% of the patients by primary PTCA. A reduction in size of the initial perfusion defect of at least one segment (16 segment model) or no defect vs persistent defect in patients with anterior acute myocardial infarction was associated with improved global left ventricular function at 4 weeks; mean global wall motion score index 1.29+/-0.21 vs 1.66+/-0.31 (P=0.009). Multiple regression analysis in patients with an anterior acute myocardial infarction revealed that the extent of the perfusion defect at MCE3 was a significant (P=0.0005) independent predictor for left ventricular recovery at 4 weeks follow-up. The only other independent predictor was TIMI flow grade 3 post PTCA (P=0.007).

CONCLUSION

Intravenous myocardial contrast echocardiography immediately prior to primary PTCA seems safe and is capable of detecting the presence of a perfusion defect and its subsequent dynamic changes, particularly in patients with a first anterior acute myocardial infarction. A significant reduction in size of the initial perfusion defect using serial myocardial contrast echocardiography predicts functional recovery after 4 weeks and these findings underscore the potential diagnostic value of intravenous myocardial contrast echocardiography.

Destruction of contrast microbubbles by ultrasound: effects on myocardial function, coronary perfusion pressure, and microvascular integrity

BACKGROUND

Recent experimental data indicate that ultrasound-induced destruction of ultrasound contrast microbubbles can cause immediate rupture of the microvessels in which these microbubbles are located.

METHODS AND RESULTS

To examine the functional and morphological significance of these findings in the heart, isolated rabbit hearts were perfused retrogradely with buffer containing ultrasound contrast agents and were insolated at increasing levels of acoustic energy with a broadband transducer emitting at 1.8 MHz and receiving at 3.6 MHz and operated in the triggered mode (1 Hz). At the end of each experiment, the hearts were fixed in glutaraldehyde and examined with light microscopy. Neither exposure to ultrasound alone or to contrast alone affected left ventricular developed pressure. By contrast, simultaneous exposure to contrast and ultrasound resulted in a reversible, transient mechanical index (MI)-dependent decrease in left ventricular developed pressure (to 83+/-5% of baseline at an MI of 1.6) and a transient MI-dependent increase in coronary perfusion pressure (to 120+/-6% of baseline at an MI of 1.6). Myocardial lactate release also showed significant increases with increasing MIs. Macroscopically, areas of intramural hemorrhage were identified over the beam elevation in hearts exposed to both contrast and high-MI ultrasound. Light microscopy revealed the presence of capillary ruptures, erythrocyte extravasation, and endothelial cell damage. The mean percentage of capillaries ruptured at an MI of 1.6 was 3.6+/-1.4%.

CONCLUSIONS

Simultaneous exposure of isolated rabbit hearts to ultrasound and contrast agents results in an MI-dependent, transient depression of left ventricular contractile function, a rise in coronary perfusion pressure, an increase in lactate production, and limited capillary ruptures.

Myocardial microangiopathy associated with antiphospholipid antibodies

Myocardial thrombotic microangiopathy is a well described post-mortem finding in patients with the catastrophic antiphospholipid (APL) syndrome. However, it has been only very rarely imaged in living patients. Here, we report two patients with APL antibodies presenting with scintigraphic, electrocardiographic and/or echocardiographic evidence of (sub)acute myocardial ischaemia, despite a normal coronary angiography. Formal proof of a thrombotic microangiopathy was obtained by a kidney biopsy in one patient. We emphasize the value of 99mTc-MIBI (2-methoxy isobutyl isonitrile) exercise stress myocardial scintigraphy for the detection of cardiac microangiopathy associated with the APL syndrome.

Echocardiographic detection and long-term outcome of coronary artery-left ventricle fistula after septal myectomy in hypertrophic obstructive cardiomyopathy

We describe a 51-year-old woman with an acquired coronary fistula to the left ventricle. Reports in the literature about acquired coronary fistulas to the left ventricle are scarce. In this patient, the fistula developed after septal myectomy for hypertrophic obstructive cardiomyopathy. Transesophageal echo-cardiography may be the preferred method to diagnose and evaluate these fistulas. Moreover, in contrast to fistulas to the right ventricle, conservative management carried a good prognosis in this patient.

No-flow ischemia inhibits insulin signaling in heart by decreasing intracellular pH

Glucose-insulin-potassium solutions exert beneficial effects on the ischemic heart by reducing infarct size and mortality and improving postischemic left ventricular function. Insulin could be the critical protective component of this mixture, although the insulin response of the ischemic and postischemic myocardium has not been systematically investigated. The aim of this work was to study the insulin response during ischemia by analyzing insulin signaling. This was evaluated by measuring changes in activity and/or phosphorylation state of insulin signaling elements in isolated perfused rat hearts submitted to no-flow ischemia. Intracellular pH (pH(i)) was measured by NMR. No-flow ischemia antagonized insulin signaling including insulin receptor, insulin receptor substrate-1, phosphatidylinositol 3-kinase, protein kinase B, p70 ribosomal S6 kinase, and glycogen synthase kinase-3. These changes were concomitant with intracellular acidosis. Perfusing hearts with ouabain and amiloride in normoxic conditions decreased pH(i) and insulin signaling, whereas perfusing at pH 8.2 counteracted the drop in pH(i) and the inhibition of insulin signaling by ischemia. Incubation of cardiomyocytes in normoxic conditions, but at pH values below 6.75, mimicked the effect of ischemia and also inhibited insulin-stimulated glucose uptake. Finally, the in vitro insulin receptor tyrosine kinase activity was progressively inhibited at pH values below physiological pH(i), being abolished at pH 6.0. Therefore, ischemic acidosis decreases kinase activity and tyrosine phosphorylation of the insulin receptor thereby preventing activation of the downstream components of the signaling pathway. We conclude that severe ischemia inhibits insulin signaling by decreasing pH(i).

The pathophysiology of myocardial hibernation: current controversies and future directions

It is now widely accepted that patients with chronic coronary artery disease can experience prolonged regional ischemic dysfunction that does not necessarily arise from irreversible tissue damage and, to some extent, can be reversed by restoration of blood flow. Recent clinical and experimental data suggest that this form of chronic but reversible left ventricular dysfunction represents a complex, progressive, and dynamic phenomenon. The initial stages of dysfunction are probably caused by chronic stunning. They are characterized by normal resting perfusion but reduced flow reserve, mild myocyte alterations, maintained membrane integrity (allowing the transport of both thallium and glucose), preserved capacity to respond to an inotropic stimulus, and no or little tissue fibrosis. After revascularization, functional recovery will probably be rapid and complete. On the other hand, the more advanced stages of dysfunction likely correspond to chronic hibernation. They usually are associated with reduced rest perfusion; increased tissue fibrosis; more severe myocyte alterations (degeneration[?], apoptosis); and a decreased ability to respond to inotropic stimuli. Nonetheless, membrane function and glucose metabolism may long remain preserved. After revascularization, functional recovery, if any, will probably be quite delayed and mostly incomplete.

Comparison of transthoracic echocardiography with second harmonic imaging with transesophageal echocardiography in the detection of right to left shunts

We compared the use of transthoracic echocardiography with second harmonic imaging after a peripheral intravenous injection of an agitated saline solution with transesophageal echocardiography (TEE) in the detection of right to left shunts at the cardiac and pulmonary level. Second harmonic mode transthoracic echocardiography and TEE are equally sensitive in detecting right to left shunts in patients undergoing a daily routine TEE.

Enhanced left ventricular endocardial border delineation with an intravenous injection of SonoVue, a new echocardiographic contrast agent: A European multicenter study

The safety and efficacy of SonoVue (also referred to as BR1), a new contrast agent for delineating endocardial border of the left ventricle after intravenous administration, was assessed. Two hundred and eighteen patients with suspected coronary artery disease undergoing fundamental echocardiography for the assessment of left ventricle were enrolled in a prospective multicenter, single blind, cross-over study with random sequence allocation of four different doses of SonoVue. Endocardial border definition in the apical and parasternal views was scored as 0 = not visible, 1 = barely visible, and 2 = well visualized before and after contrast enhancement. Analysis was performed by two pairs of off-site observers. Safety of SonoVue was also assessed. Results of our study indicated that the mean improvements in the endocardial border visualization score were as follows: 3.1 +/- 7.8 (95% CI, 2.5 and 3.7) for 0.5 ml, 3.4 +/- 8.0 (95% CI, 2.8 and 4.0) for 1 ml, 3.4 +/- 7.9 (95% CI, 2.8 and 4.0) for 2 ml, and 3.7 +/- 8.0 (95% CI, 3.1 and 4.3) for 4 ml (P < 0.05 for all doses from baseline). Changes from baseline in endocardial visualization scores were also seen in the apical views (P < 0.05) and they were dose-dependent (P < 0.001). Similar enhancements of endocardial visualization scores were observed in the apical views in patients with suboptimal baseline echocardiographic images. Diagnostic confidence for assigning a score and image quality also were significantly better following contrast enhancement. No significant changes in the laboratory parameters and vital signs were noted following contrast enhancement, and the side effects were minimal. It was concluded that SonoVue is safe and effective in delineating endocardial border, including in patients with suboptimal baseline images.

Time course of functional recovery after coronary artery bypass graft surgery in patients with chronic left ventricular ischemic dysfunction

Chronic left ventricular (LV) ischemic dysfunction, a condition often referred to as myocardial hibernation, is associated in humans with ultrastructural alterations of the myocytes, including the loss of myofilaments and the accumulation of glycogen. Given the severity of these structural changes, contractile function is unlikely to resume immediately upon revascularization. Therefore, the aim of the present study was to assess the time course of functional improvement after successful revascularization as well as its potential structural correlates. We studied 32 patients with coronary disease and chronic LV ischemic dysfunction who underwent bypass surgery. Dynamic positron emission tomography with N-13 ammonia and F-18 deoxyglucose to assess myocardial perfusion and glucose metabolism was performed in 29 patients. In all patients, a transmural biopsy was harvested from the center of the dysfunctional area, to quantify the increase in extracellular matrix and the presence of structurally altered cardiomyocytes. LV function was serially measured by digitized 2-dimensional echocardiography before and at 10 days, 2 months, and 6 months after revascularization. The time course of recovery of regional function was estimated from the monoexponential decrease in dysfunctional wall motion score. At follow-up, 19 patients had improved LV function, whereas 13 patients showed persistent dysfunction. Before revascularization, reversibly dysfunctional segments had higher myocardial blood flow (82 +/- 29 vs 53 +/- 21 ml. (min. 100 g)(-1), p = 0.044), higher glucose uptake (40 +/- 16 vs 21 +/- 9 micromol. (min. 100 g)(-1), p = 0.001), and less increase in extracellular matrix (25 +/- 15% vs 46 +/- 17%, p = 0.0008) than segments with persistent dysfunction. The extent to which function recovered was positively correlated with myocardial blood flow and negatively correlated with the increase in the extracellular matrix. In patients with reversible dysfunction, the return of segmental function was progressive and followed a monoexponential time course with a median time constant of 23 days (range 6 to 78). The rate of recovery correlated best with the proportion of altered cardiomyocytes in the biopsy. The present study thus indicates that the recovery of regional and global LV function after successful revascularization is progressive and follows a monoexponential time course that is influenced by the extent of the structural changes affecting cardiomyocytes.

Comparison of myocardial contrast echocardiography with NC100100 and (99m)Tc sestamibi SPECT for detection of resting myocardial perfusion abnormalities in patients with previous myocardial infarction

OBJECTIVE

To determine whether myocardial contrast echocardiography (MCE) following intravenous injection of perfluorocarbon microbubbles permits identification of resting myocardial perfusion abnormalities in patients who have had a previous myocardial infarction.

PATIENTS AND INTERVENTIONS

22 patients (mean (SD) age 66 (11) years) underwent MCE after intravenous injection of NC100100, a novel perfluorocarbon containing contrast agent, and resting (99m)Tc sestamibi single photon emission computed tomography (SPECT). With both methods, myocardial perfusion was graded semiquantitatively as 1 = normal, 0.5 = mild defect, and 0 = severe defect.

RESULTS

Among the 203 normally contracting segments, 151 (74%) were normally perfused by SPECT and 145 (71%) by MCE. With SPECT, abnormal tracer uptake was mainly found among normally contracting segments from the inferior wall. By contrast, with MCE poor myocardial opacification was noted essentially among the normally contracting segments from the anterior and lateral walls. Of the 142 dysfunctional segments, 87 (61%) showed perfusion defects by SPECT, and 94 (66%) by MCE. With both methods, perfusion abnormalities were seen more frequently among akinetic than hypokinetic segments. MCE correctly identified 81/139 segments that exhibited a perfusion defect by SPECT (58%), and 135/206 segments that were normally perfused by SPECT (66%). Exclusion of segments with attenuation artefacts (defined as abnormal myocardial opacification or sestamibi uptake but normal contraction) by either MCE or SPECT improved both the sensitivity (76%) and the specificity (83%) of the detection of SPECT perfusion defects by MCE.

CONCLUSIONS

The data suggest that MCE allows identification of myocardial perfusion abnormalities in patients who have had a previous myocardial infarction, provided that regional wall motion is simultaneously taken into account.

Myocardial perfusion and oxygen consumption in reperfused noninfarcted dysfunctional myocardium after unstable angina: direct evidence for myocardial stunning in humans

OBJECTIVES

To positively establish the diagnosis of myocardial stunning in patients with unstable angina and persistent wall motion abnormalities after reperfusion by coronary angioplasty.

BACKGROUND

Although myocardial stunning is thought to occur in several clinical conditions, definite proof of its existence in humans is still lacking, owing to the difficulty of measuring myocardial blood flow (MBF) in absolute terms.

METHODS

We studied 14 patients with unstable angina due to proximal left anterior descending coronary artery disease who presented persistent anterior wall motion abnormalities despite revascularization of the culprit lesion by percutaneous coronary angioplasty (PTCA) and who did not have clinical evidence of necrosis. Dynamic positron emission tomography (PET) with [13N]-ammonia and [11C]-acetate was performed 48 h after PTCA to determine absolute MBF and oxygen consumption (MVO2). Regional wall thickening and regional cardiac work were determined using two-dimensional echocardiography. Improvement of segmental wall motion abnormalities was followed for a median of 4 months (1.5 to 14 months).

RESULTS

As judged from the changes in segmental wall motion score, regional dysfunction was spontaneously reversible in 12/14 patients and improved from 2.2 +/- 0.3 to 1.2 +/- 0.3 at late follow-up (p < 0.001). With PET, [13N]-ammonia MBF was similar among dysfunctional and remote normally contracting segments (85 +/- 29 vs. 99 +/- 20 ml x min (-1) x 100g(-1), p = not significant [n.s.]), thus demonstrating a perfusion-contraction mismatch. Despite the reduced contractile function, dysfunctional myocardium presented near normal levels of MVO2 (6.5 +/- 4.2 vs. 8.0 +/- 1.9 ml x min (-1)x 100g(-1), p = n.s.). Consequently, the regional myocardial efficiency (regional work divided by MVO2) of the dysfunctional myocardium was found to be markedly decreased as compared with normally contracting myocardium (6 +/- 6% vs. 26 +/- 6%, p < 0.001).

CONCLUSIONS

This study demonstrates that human dysfunctional myocardium capable of spontaneously recovering contractile function after unstable angina endures a state of perfusion-contraction mismatch. These data for the first time provide unequivocal direct evidence for the existence of acute myocardial stunning in humans.

[Myocardial viability in man: state of the art and directions to pursue]

The advent of modern coronary revascularization procedures has profoundly modified the prognosis of patients with acute myocardial infarction or that of patients with chronic left ventricular ischemic dysfunction. Presumably, the beneficial effects of revascularization result from improving blood supply to dysfunctional but viable regions with subsequent improvement in regional and global left ventricular function. Various approaches have been proposed to predict the reversibility of left ventricular dysfunction after coronary revascularization. For the most part, these techniques allow detection of viable myocardium with a high sensitivity (80%). However, specificity has been more varied (+/- 55% for, +/- 75% for PET and +/- 85% dobutamine echocardiography). All these techniques also bear important prognostic implications that are independent and complementary to those usually available in these patients.

Cardiomyocyte remodelling during myocardial hibernation and atrial fibrillation: prelude to apoptosis

OBJECTIVE

Similar structural changes in the myocardium can be observed in chronic hibernating myocardium and in myocardium taken from hearts suffering chronic atrial fibrillation. We investigated whether or not these changes are indicative of apoptosis.

METHODS

Myocardial biopsies from 28 strictly selected patients with chronic hibernating myocardium and heart samples from 13 goats with pacing-induced chronic atrial fibrillation were used. Special attention was paid to processing the tissues immediately (fixation/freezing) in order to prevent artificial degenerative changes, thereby excluding false positive identification of apoptosis. Infarcted areas or infarcted border zones were excluded from our study. Apoptosis was detected with light and electron microscopy and terminal deoxynucleotidyl transferase nick end-labelling. Immunohistochemistry was used for detecting Bcl-2, P53 and PCNA-proteins associated with apoptosis/DNA damage.

RESULTS

The results obtained for chronic hibernating left ventricular myocardium were similar to those for chronic fibrillating atrial myocardium. No apoptotic nuclei, as characterised by extensive chromatin clumping, could be observed in normal or dedifferentiated cardiomyocytes under the electron microscope. The end-labelling assay did not reveal any cardiomyocytes with damaged DNA. Nor could we find any evidence of substantial expression of Bcl-2, P53 or PCNA, a result indicative of the absence of apoptotic threat or DNA damage.

CONCLUSION

Cardiomyocyte dedifferentiation, but not extensive degeneration through apoptosis, can be observed in chronic hibernating myocardium and chronic fibrillating atrium. Dedifferentiation may be the best way to survive prolonged exposure to the unfavourable conditions imposed by increased wall stress, a relative lowered oxygen environment, or both.

Prognostic value of myocardial ischemia and viability in patients with chronic left ventricular ischemic dysfunction

BACKGROUND

Previous studies showed that thallium scintigraphy and dobutamine echocardiography were accurate, noninvasive ways of predicting contractile recovery after revascularization in patients with left ventricular (LV) dysfunction. However, the prognostic impact of such methods remains uncertain.

METHODS AND RESULTS

We prospectively studied 137 consecutive patients with coronary disease and LV dysfunction who underwent exercise-redistribution-reinjection thallium scintigraphy and dobutamine echocardiography to identify myocardial ischemia and viability. A total of 94 patients subsequently underwent revascularization, and 43 underwent medical treatment. The primary endpoint was cardiac mortality, and mean follow-up was 33+/-10 months. Twenty-four patients died of cardiac causes. By Cox's regression analysis, long-term survival was related to the extent of coronary disease, the presence of diabetes, type of treatment, the presence of ischemic myocardium as determined by thallium scintigraphy, and the presence of viable myocardium as determined by both tests. Three-year survival was greater in patients with ischemic myocardium (as determined by thallium scintigraphy) or viable myocardium (as determined by both tests) who underwent revascularization than in the other groups (P=0.018 with thallium; P<0.001 with dobutamine). Subgroup analyses indicated that among patients with 1- or 2-vessel disease, only those with ischemic or viable myocardium improved survival after revascularization, whereas in patients with 3-vessel or left main diseases, revascularization always improved survival, albeit more in the presence of ischemic or viable myocardium.

CONCLUSIONS

Among the parameters commonly available in patients with LV ischemic dysfunction, the presence of ischemic myocardium (as determined by thallium scintigraphy) and that of viable myocardium (as determined by dobutamine echocardiography) are independent predictors of subsequent mortality. These observations may be useful in the preoperative selection of patients for revascularization.

The Ross operation: mid-term results

BACKGROUND

The Ross operation, although more demanding, is now widely accepted as an alternative solution for aortic valve replacement in young adults and children. A review of our experience to assess the mid-term results with the Ross operation is presented.

METHODS

From June 1991 through October 1997, 80 patients (mean age, 31 years) underwent aortic valve or root replacement with pulmonary autografts. Indications for operation were predominant aortic stenosis in 38 patients, aortic incompetence in 42 patients including endocarditis in 3 patients. Congenital lesions were present in 57 patients, either at pediatric (27 patients) or adult age (30 patients). Transthoracic echocardiography was performed preoperatively in all patients and serially after operation with the aims of measuring aortic and pulmonary annuli, evaluating transvalvular gradients and incompetence, and studying the left ventricular function. Intraoperative transesophageal echocardiography was used routinely. Complete root replacement was performed in 52 patients, intraluminal cylinder in 25 patients, and subcoronary implantation in 3 patients.

RESULTS

One patient died in the early postoperative period (1.2%). There was no late death. The actuarial survival at 5 years was 98%+/-1%. All survivors remained in New York Heart Association functional class I and were free of complications and medications. No gradient or significant aortic incompetence could be demonstrated in 73 patients. One patient developed late aortic incompetence grade 3 and reoperation is considered. On the pulmonary outflow tract, 6 patients had gradients between 20 and 40 mm Hg as calculated on echocardiography.

CONCLUSIONS

The pulmonary autograft gives excellent mid-term results with low mortality and no morbidity. It completely relieves the abnormal loading conditions of the left ventricle, resulting in a complete recovery of left ventricular function in most patients.

Relation of exercise capacity to left ventricular systolic function and diastolic filling in idiopathic or ischemic dilated cardiomyopathy

Although exercise intolerance is a cardinal symptom of patients with dilated cardiomyopathy (DC) and heart failure, the factors that limit exercise capacity in these patients remain a matter of debate. To assess the contribution of left ventricular (LV) diastolic filling to the variable exercise capacity of patients with DC, we studied 47 patients (60 +/- 12 years) with DC in stable mild-to-moderate heart failure with a mean LV ejection fraction of 28%. Exercise capacity was measured as total body peak oxygen consumption (VO2) during symptom-limited bicycle (10 W/min) and treadmill (modified Bruce protocol) exercise. LV systolic function and diastolic filling were assessed at rest before each exercise by M-mode, Doppler echocardiography, and radionuclide ventriculography. As expected, treadmill exercise always yielded higher peak VO2 than bicycle exercise (21 +/- 6 vs 18 +/- 5 ml/kg/min, range 12 to 35 and 7 to 30 ml/kg/min, respectively, p <0.001). Both of these VO2 measurements were highly reproducible (R = 0.98). With univariate analysis, close correlations were found between peak VO2 (with either exercise modalities) and Doppler indexes of LV diastolic filling, as well as with the radionuclide LV ejection fraction. Stepwise multiple regression analysis identified 3 nonexercise variables as independent correlates of peak VO2, of which the most powerful was the E/A ratio (multiple r2 = 0.38, p <0.0001), followed by peak A velocity (r2 = 0.54, p <0.0001) and mitral regurgitation grade (r2 = 0.58, p = 0.024). In conclusion, our data indicate that in patients with DC, peak VO2 is better correlated to diastolic filling rather than systolic LV function.

Expression of inducible nitric oxide synthase in human coronary atherosclerotic plaque

OBJECTIVE

Macrophages in atherosclerotic plaque may express the inducible isoform of NO synthase (iNOS), which produces large amounts of NO. On one hand, the production of NO can be protective by its vasodilatory, antiaggregant and antiproliferative effects. On the other hand, the formation of peroxynitrite from NO may favour vasospasm and thrombogenesis. In this study, we investigated whether iNOS is present in human coronary atherosclerotic plaque, and we correlated these data with the clinical instability of the patients.

METHODS

Fragments were retrieved by coronary atherectomy from 24 patients with unstable angina and 12 patients with stable angina. The presence of macrophages, and the production of TNF alpha, iNOS and nitrotyrosine were detected by immunocytochemistry.

RESULTS

Macrophage clusters were found in 67% of stable patients and 87% of patients with unstable angina (NS). TNF alpha was expressed in about 50% of cases in both groups. iNOS was not expressed in fragments from stable patients but was found in macrophages from 58% of unstable patients (P < 0.001). The expression of iNOS was associated with the presence of nitrotyrosine residues, a marker of peroxynitrite formation. Expression of iNOS was correlated both with complaints of angina at rest (P < 0.05) and with the presence of thrombus at morphological examination (P < 0.001).

CONCLUSION

The expression of iNOS may be induced in human coronary atherosclerotic plaque and is associated with different factors of instability.

Comparison of dipyridamole stress echocardiography and perfusion scintigraphy for cardiac risk stratification in vascular surgery patients

Dipyridamole single-photon emission computed tomography (SPECT) has a high negative predictive value for perioperative cardiac events, but events are infrequent in patients with a positive test. In contrast, dipyridamole echocardiography is more selective for detection of multivessel disease and thus may have a greater specificity for cardiac events. We therefore compared the ability of dipyridamole SPECT and echocardiography to predict perioperative and long-term cardiac events in 133 patients referred for vascular surgery. The group was also evaluated based on clinical features and ejection fraction. Four patients had surgery cancelled because of high risk and were excluded from further analysis. Among the 129 remaining patients, 21 had coronary revascularization (n=12) or an early cardiac end point (n=9). The sensitivity of SPECT for the prediction of early events (90%) was not significantly different from that of echocardiography (66%, p=NS). The specificity of SPECT (68%) was less than that of echocardiography (88%, p <0.001%), as was the accuracy (72% vs 84%, p=0.02). These findings were replicated after exclusion of patients with treatment end points. During long-term follow-up, 12 patients experienced > or = 1 event: 6 died from cardiac causes, 4 underwent revascularization, and 3 had myocardial infarction. Thus, the specificity of SPECT and echocardiography for late events were 58% and 80%, respectively (p <0.001). The 3-year survival of patients without ischemia during echocardiography or at SPECT was not different (93% vs 94%, p=NS).

Early calcific stenosis of the aortic sorin pericarbon valve implanted in the elderly

BACKGROUND

We reviewed our experience with the Sorin Pericarbon (Sorin, Saluggia, Italy) valve implanted in the aortic position.

METHODS

From January 1990 to January 1996, 143 consecutive patients had a Pericarbon valve implanted in the aortic position. The mean age was 75+/-5 years. Seventy-eight patients (55%) were in New York Heart Association (NYHA) class III or IV. Sixty patients (42%) had one or more concomitant procedures (51 coronary artery bypass grafting [CABG], 7 carotid endarterectomies, 9 others).

RESULTS

The hospital mortality rate was 12% (17 of 143 patients). The follow-up was 100% complete and the median time was 42 months (range, 2 to 79 months). There were 36 late deaths, 20 being cardiac-related: 5 non-valve-related, 11 valve-related, and 4 sudden unexpected deaths. The 5-year actuarial survival was 57%+/-5%. There were 6 early valve failures related to a calcific stenosis at a median time of 36 months (range, 5 to 66 months). Three patients had to undergo another operation and one of these patients died. One patient died the day before the planned reoperation and 2 patients are followed with a symptomatic aortic stenosis but refuse reoperation. Freedom from structural deterioration was 93%+/-3% at 4 years. Echocardiographic examination was obtained in 73 patients at a median time of 42 months (range, 4 to 79 months). Four additional asymptomatic patients were found to have calcifications of their prosthesis. The 5-year freedom from thromboembolic events and from endocarditis were, respectively, 87%+/-5% and 92%+/-3%.

CONCLUSION

The surprisingly high rate of early failure due to calcific stenosis and of thromboembolic events of the Pericarbon valve implanted in the aortic position in the elderly made us discontinue its use in our institution.

Accuracy and feasibility of contrast echocardiography for detection of perfusion defects in routine practice: comparison with wall motion and technetium-99m sestamibi single-photon emission computed tomography. The Nycomed NC100100 Investigators

OBJECTIVES

We sought to assess the feasibility and accuracy of myocardial contrast echocardiography (MCE) using standard imaging approaches for the detection of perfusion defects in patients who had a myocardial infarction (MI).

BACKGROUND

Myocardial contrast echocardiography may be more versatile than perfusion scintigraphy for identifying the presence and extent of perfusion defects after MI. However, its reliability in routine practice is unclear.

METHODS

Fundamental or harmonic MCE was performed with continuous or triggered imaging in 203 patients with a previous MI using bolus doses of a perfluorocarbon-filled contrast agent (NC100100). All patients underwent single-photon emission computed tomography (SPECT) after the injection of technetium-99m (Tc-99m) sestamibi at rest. Quantitative and semiquantitative SPECT, wall motion and digitized echocardiographic data were interpreted independently. The accuracy of MCE was assessed for detection of segments and patients with moderate and severe sestamibi-SPECT defects, as well as for detection of patients with extensive perfusion defects (>12% of left ventricle).

RESULTS

In segments with diagnostic MCE, the segmental sensitivity ranged from 14% to 65%, and the specificity varied from 78% to 95%, depending on the dose of contrast agent. Using both segment- and patient-based analysis, the greatest accuracy and proportion of interpretable images were obtained using harmonic imaging in the triggered mode. For the detection of extensive defects, the sensitivity varied from 13% to 48%, with specificity from 63% to 100%. Harmonic imaging remained the most accurate approach. Time since MI and SPECT defect location and intensity were all determinants of the MCE response. The extent of defects on MCE was less than the extent of either abnormal wall motion or SPECT abnormalities. The combination of wall motion and MCE assessment gave the best balance of sensitivity (46% to 55%) and specificity (82% to 83%).

CONCLUSIONS

Although MCE is specific, it has limited sensitivity for detection of moderate or severe perfusion defects, and it underestimates the extent of SPECT defects. The best results are obtained by integration with wall motion. More sophisticated methods of acquisition and interpretation are needed to enhance the feasibility of this technique in routine practice.