From coronary artery disease to heart failure: role of the hibernating myocardium

PFAS and their association with the increased risk of cardiovascular disease in postmenopausal women

Cardiovascular diseases (CVDs) are one of the major causes of death globally. In addition to traditional risk factors such as unhealthy lifestyles (smoking, obesity, sedentary) and genetics, common environmental exposures, including persistent environmental contaminants, may also influence CVD risk. Per- and polyfluoroalkyl substances (PFASs) are a class of highly fluorinated chemicals used in household consumer and industrial products known to persist in our environment for years, causing health concerns that are now linked to endocrine disruptions and related outcomes in women, including interference of the cardiovascular and reproductive systems. In postmenopausal women, higher levels of PFAS are observed than in premenopausal women due to the cessation of menstruation, which is crucial for PFAS excretion. Because of these findings, we explored the association between perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and perfluorobutanesulfonic acid in postmenopausal women from our previously established CVD study. We used liquid chromatography with tandem mass spectrometry, supported by machine learning approaches, and the detection and quantification of serum metabolites and proteins. Here, we show that PFOS can be a good predictor of coronary artery disease, whereas PFOA can be an intermediate predictor of coronary microvascular disease. We also found that the PFAS levels in our study are significantly associated with inflammation-related proteins. Our findings may provide new insight into the potential mechanisms underlying the PFAS-induced risk of CVDs in this population. This study shows that exposure to PFOA and PFOS is associated with an increased risk of cardiovascular disease in postmenopausal women. PFOS and PFOA levels correlate with amino acids and proteins related to inflammation. These circulating biomarkers contribute to the etiology of CVD and potentially implicate a mechanistic relationship between PFAS exposure and increased risk of cardiovascular events in this population.

Acquisition, Processing, and Interpretation of PET 18F-FDG Viability and Inflammation Studies

PURPOSE OF REVIEW

This article reviews the acquisition protocols and image interpretation for ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) imaging with positron emission tomography (PET) applied to the evaluation of myocardial viability and inflammation.

RECENT FINDINGS

Cardiac PET with ¹⁸F-FDG provides essential information for the assessment of myocardial viability and inflammation and is usually combined with PET perfusion imaging using ⁸²Rb or ¹³N-ammonia. Viable myocardium maintains glucose metabolism which can be detected via the uptake of ¹⁸F-FDG by PET imaging. The patient is prepared for viability imaging by shifting the metabolism of the heart to maximize the uptake of glucose and hence of ¹⁸F-FDG. Comparison of the ¹⁸F-FDG and myocardial perfusion images allows distinction between regions of the myocardium that are hibernating and thus may recover function with intervention, from those that are infarcted. Increased glucose utilization in the inflammatory cells also makes ¹⁸F-FDG a useful imaging technique in conditions such as cardiac sarcoidosis. Here, suppression of normal myocardial uptake is essential for accurate image interpretation. ¹⁸F-FDG PET broadens the scope of information potentially available through a cardiac PET study. With careful patient preparation, it provides valuable insights into myocardial viability and inflammatory processes such as sarcoidosis.

What we know about cardiomyocyte dedifferentiation

Cardiomyocytes (CMs) lost during cardiac injury and heart failure (HF) cannot be replaced due to their limited proliferative capacity. Regenerating the failing heart by promoting CM cell-cycle re-entry is an ambitious solution, currently vigorously pursued. Some genes have been proven to promote endogenous CM proliferation, believed to be preceded by CM dedifferentiation, wherein terminally differentiated CMs are initially reversed back to the less mature state which precedes cell division. However, very little else is known about CM dedifferentiation which remains poorly defined. We lack robust molecular markers and proper understanding of the mechanisms driving dedifferentiation. Even the term dedifferentiation is debated because there is no objective evidence of pluripotency, and could rather reflect CM plasticity instead. Nonetheless, the significance of CM transition states on cardiac function, and whether they necessarily lead to CM proliferation, remains unclear. This review summarises the current state of knowledge of both natural and experimentally induced CM dedifferentiation in non-mammalian vertebrates (primarily the zebrafish) and mammals, as well as the phenotypes and molecular mechanisms involved. The significance and potential challenges of studying CM dedifferentiation are also discussed. In summary, CM dedifferentiation, essential for CM plasticity, may have an important role in heart regeneration, thereby contributing to the prevention and treatment of heart disease. More attention is needed in this field to overcome the technical limitations and knowledge gaps.

Myocardial revascularization in chronic coronary syndromes: does viability matter?

Coronary artery disease (CAD) is the leading cause of death worldwide and improving the prognosis and survival of patients with ischemic heart disease remains a priority of cardiovascular specialists. This article will review the principles of myocardial viability, present the noninvasive imaging tests available to clinicians, as well as critically appraise the latest literature on myocardial viability, coronary revascularization and outcome with a final outlook at studies in the pipelines and future evidence in myocardial viability that will be soon available.

Myocardial Viability Testing by Positron Emission Tomography: Basic Concepts, Mini-Review of the Literature and Experience From a Tertiary PET Center

Ischemic heart disease ranges in severity from slightly reduced myocardial perfusion with preserved contractile function to chronic occlusion of coronary arteries with myocardial cells replaced by acontractile scar tissue-ischemic heart failure (iHF). Progression towards scar tissue is thought to involve a period in which the myocardial cells are acontractile but still viable despite severely reduced perfusion. This state of reduced myocardial function that can be reversed by revascularization is termed "hibernation." The concept of hibernating myocardium in iHF has prompted an increasing amount of requests for preoperative patient workup, but while the concept of viability is widely agreed upon, no consensus on clinical testing of hibernation has been established. Therefore, a variety of imaging methods have been used to assess hibernation including morphology based (MRI and ultrasound), perfusion based (MRI, SPECT, or PET) and/or methods to assess myocardial metabolism (PET). Regrettably, the heterogeneous body of literature on the subject has resulted in few robust prospective clinical trials designed to assess the impact of preoperative viability testing prior to revascularization. However, the PARR-2 trial and sub-studies has indicated that >5% hibernating myocardium favors revascularization over optimized medical therapy. In this paper, we review the basic concepts and current evidence for using PET to assess myocardial hibernation and discuss the various methodologies used to process the perfusion/metabolism PET images. Finally, we present our experience in conducting PET viability testing in a tertiary referral center.

Exercise and Coronary Heart Disease

Coronary artery disease (CAD) can be obstructive or nonobstructive. Patients with nonobstructive and stable angina pectoris are usually women. Nonobstructive CAD is caused by endothelial dysfunction at the microvascular level, such as cardiac syndrome X and coronary slow flow syndrome. Even if coronary anatomy is nonobstructive, the presence of myocardial ischemia is a major determinant for the exercise program. CAD is a chronic inflammatory disease, and the progression of the disease can lead to a rapid change in the functional capacity of CAD patients. Exercise training is a major component of cardiac rehabilitation and reduces cardiovascular mortality, morbidity, and rehospitalization as well as improves psychological stress and controls risk factors of CAD, such as diabetes mellitus, hypertension, and obesity. It is possible that the quality of life of patients with CAD can be improved by using appropriate exercise therapy. However, the exercise programs among CAD patients are highly underutilized. This chapter will summarize the research progress of exercise in the prevention and treatment of CAD as well as how to create safe exercise programs and the importance of exercise for patients with CAD. In addition, exercise training has fundamental beneficial effects on ischemic and nonischemic heart failure.

Off-pump versus on-pump coronary artery bypass surgery in patients with triple-vessel disease and enlarged ventricles

BACKGROUND AND OBJECTIVES

Off-pump coronary artery bypass grafting (OPCAB) is a popular treatment for patients with ischemic heart disease, especially for high-risk patients. However, whether OPCAB can lead to better clinical outcomes than on-pump coronary artery bypass grafting (ONCAB) in patients with enlarged ventricles remains controversial. This prospective randomized study was designed to characterize comparison of early clinical outcome and mid-term follow-up following ONCAB versus OPCAB in patients with triple-vessel disease and enlarged ventricles.

DESIGN AND SETTINGS

Prospective randomized trial of patients treated at The First Affiliated Hospital, China Medical University, over a 3-year period (2007-2010).

METHODS

A total of 102 patients with triple-vessel disease and enlarged ventricles (end-diastolic dimension >=6.0 cm) were randomized to OPCAB or ONCAB between July 2007 and December 2010. The in-hospital out.comes were analyzed. The study included a mid-term follow-up, with a mean follow-up time of 49.40 (12.88 months).

RESULTS

No significant differences were recorded in the baseline clinical characteristics of ONCAB and OPCAB groups. A statistical difference was found between the two groups at the time of extubation, intensive care unit stay, hospital stay, blood requirements, incidence of intra-aortic balloon pump support, pulmonary complications, stroke, reoperation for bleeding, and inotropic requirements > 24 hours (P < .05). The number of anastomoses performed per patient, the incidence of postoperative ventricular arrhythmia, myocardial infarction, new-onset atrial fibrillation, hemodialysis, infective complications, recurrent angina, and percutaneous reintervention were similar between the 2 groups (P > .05). The left ventricular end-diastolic dimension was significantly smaller at 6 months' follow-up in the 2 groups than it was before operation ( < .05). No differences in hospital mortality and mid-term mortality between OPCAB and ONCAB groups were found. During the follow-up, no patient in either group had undergone repeat coronary artery bypass grafting.

CONCLUSION

No differences in early and mid-term mortality were found between OPCAB and ONCAB in patients with triple-vessel disease and enlarged ventricles. However, OPCAB seems to have a beneficial effect on postoperative complications.

High-definition electrocardiography potential in identifying the reasons for unstable clinical course of coronary heart disease

Aim. To investigate the correlation between clinical and morphological characteristics of coronary heart disease (CHD) and high-definition electrocardiography (HD-ECG) parameters. Material and methods. In total, 85 patients with unstable angina and ST segment depression (ST-UA) underwent HD-ECG during the angina attack, with late ventricular potential (LVP) analysis. One-year survival data were also analysed. Post-mortem histological examination of cardiac tissue was performed in 6 patients with ST-UA. Results. The important morphologic features of ST-UA included cardiomyocyte (CMC) dystrophy, due to acute and chronic myocardial ischemia, and acute injury in the cardiac conduction areas. LVPs were registered in 27 % of the ST-UA patients, mostly among people with transient myocardial ischemia (69,57 %). In patients who previ-ously underwent myocardial infarction, LVP prevalence was lower (28,57 %). At the early stages of hospitalization, LVP were registered in 14 patients (60,87 %), while pharmacotherapy and clinical course stabilization were associated with decreased LVP prevalence (21,74 %). The study results suggest that in patients with acute coronary syndrome, LVP registration predicts not an adverse outcome, but a better prognosis. Conclusion. ST-UA is characterised by typical changes of CMC and myocardial stroma in posterior septal area, which result in metabolic, energetic, and electrical myocardial instability. LVPs could be used as a marker of functional (ischemic) myocardial heterogeneity in patients with ST-UA. LVP registration could be associated with a better prognosis in this clinical group.

Five-year follow-up of a randomized comparison between off-pump and on-pump stable multivessel coronary artery bypass grafting. The MASS III Trial

BACKGROUND

Coronary artery bypass graft surgery with cardiopulmonary bypass is a safe, routine procedure. Nevertheless, significant morbidity remains, mostly because of the body's response to the nonphysiological nature of cardiopulmonary bypass. Few data are available on the effects of off-pump coronary artery bypass graft surgery (OPCAB) on cardiac events and long-term clinical outcomes.

METHODS AND RESULTS

In a single-center randomized trial, 308 patients undergoing coronary artery bypass graft surgery were randomly assigned: 155 to OPCAB and 153 to on-pump CAB (ONCAB). Primary composite end points were death, myocardial infarction, further revascularization (surgery or angioplasty), or stroke. After 5-year follow-up, the primary composite end point was not different between groups (hazard ratio 0.71, 95% CI 0.41 to 1.22; P=0.21). A statistical difference was found between OPCAB and ONCAB groups in the duration of surgery (240±65 versus 300±87.5 minutes; P<0.001), in the length of ICU stay (19.5±17.8 versus 43±17.0 hours; P<0.001), time to extubation (4.6±6.8 versus 9.3±5.7 hours; P<0.001), hospital stay (6±2 versus 9±2 days; P<0.001), higher incidence of atrial fibrillation (35 versus 4% of patients; P<0.001), and blood requirements (31 versus 61% of patients; P<0.001), respectively. The number of grafts per patient was higher in the ONCAB than the OPCAB group (2.97 versus 2.49 grafts/patient; P<0.001).

CONCLUSIONS

No difference was found between groups in the primary composite end point at 5-years follow-up. Although OPCAB surgery was related to a lower number of grafts and higher episodes of atrial fibrillation, it had no significant implications related to long-term outcomes. Clinical Trial Registration-URL: http://www.controlled-trials.com. Unique identifier: ISRCTN66068876.

Relation between regional and global systolic function in patients with ischemic cardiomyopathy after beta-blocker therapy or revascularization

BACKGROUND

To assess the relationship between improved regional and global myocardial function in patients with ischemic cardiomyopathy in response to beta-blocker therapy or revascularization.

MATERIALS AND METHODS

Cardiovascular magnetic resonance (CMR) was performed in 32 patients with ischemic cardiomyopathy before and 8 +/- 2 months after therapy. Patients were assigned clinically to beta-blocker therapy (n = 20) or revascularization (n = 12). CMR at baseline was performed to assess regional and global LV function at rest and under low-dose dobutamine. Wall thickening was analyzed in dysfunctional, adjacent, and remote segments. Follow-up CMR included rest function evaluation.

RESULTS

Augmentation of wall thickening during dobutamine at baseline was similar in dysfunctional, adjacent and remote segments in both patient groups. Therefore, baseline characteristics were similar for both patient groups. In both patient groups resting LV ejection fraction and end-systolic volume improved significantly (p < 0.05) at follow-up. Stepwise multivariate analysis revealed that improvement in global LV ejection fraction in the beta-blocker treated patients was significantly related to improved function of remote myocardium (p < 0.05), whereas in the revascularized patients improved function in dysfunctional and adjacent segments was more pronounced (p < 0.05).

CONCLUSION

In patients with chronic ischemic LV dysfunction, beta-Blocker therapy or revascularization resulted in a similar improvement of global systolic LV function. However, after beta-blocker therapy, improved global systolic function was mainly related to improved contraction of remote myocardium, whereas after revascularization the dysfunctional and adjacent regions contributed predominantly to the improved global systolic function.

Cardiac positron emission tomography: current clinical practice

In the last two decades, the field of nuclear cardiology has experienced significant progress. The introduction of positron emission tomography (PET) imaging represented a major breakthrough that has significantly contributed to a better understanding of physiology and pathophysiology of several heart diseases. Currently, PET imaging is recognized as a well-established method to assess cardiac perfusion, function, metabolism, and viability. This article summarizes the main clinical applications of state-of-the art cardiac PET technology.

Reperfusion normalizes motor activation patterns in large-vessel disease

OBJECTIVE

Hemodynamic impairment in one hemisphere has been shown to trigger ipsilateral motor activation in the opposite hemisphere on functional imaging. We hypothesized that reversing the hypoperfusion would normalize the motor activation pattern.

METHODS

We studied four patients with high-grade stenosis and impaired vasomotor reactivity (VMR) but no stroke. Functional magnetic resonance imaging motor activation pattern before and after VMR normalization was compared with seven healthy control subjects scanned at an interval of 3 months using voxel-wise statistical parametric maps and region of interest analysis. Subjects performed a repetitive hand closure task in synchrony with 1Hz metronome tone. We used repeated-measures analysis of variance to compute the interaction between group (patients/control subjects) and time by obtaining the average blood oxygen level dependent signal of three motor regions of interest in each hemisphere.

RESULTS

Two patients normalized their VMR after spontaneous resolution of dissection, and two after revascularization procedures. Both voxel-wise statistical maps and region of interest analysis showed that VMR normalization was associated in each case with a reduction in the atypical activation in the hemisphere opposite to the previously hypoperfused hemisphere (p < 0.001).

INTERPRETATION

In the presence of a physiological stressor such as hypoperfusion, the brain is capable of dynamic functional reorganization to the opposite hemisphere that is reversible when normal blood flow is restored. These findings are important to our understanding of the clinical consequences of hemodynamic failure and the role of the ipsilateral hemisphere in maintaining normal neurological function.

Tachycardia-induced Cardiomyopathy (Tachycardiomyopathy)

The term tachycardia-induced cardio-myopathy or tachycardiomyopathy refers to impairment in left ventricular function secondary to chronic tachycardia, which is partially or completely reversible once the tachyarrhythmia is controlled. Tachycardia-induced cardiomyopathy has been shown to occur both in experimental models and in patients with incessant tachyarrhythmia. Data from several studies and from case reports have shown that rate control by means of cardioversion, negative chronotropic agents, and surgical or catheter-based atrio-ventricular node ablation, resulted in significant improvement of systolic function. The diagnosis of tachycardia-induced cardiomyopathy is usually made following observation of marked improvement in systolic function after normalization of heart rate. Clinicians should be aware that patients with unexplained systolic dysfunction may have tachycardia-induced cardiomyo-pathy, and that controlling the arrhythmia may result in improvement of systolic function.

Identification of the ischemic etiology of heart failure by cardiovascular magnetic resonance imaging: diagnostic accuracy of late gadolinium enhancement

BACKGROUND

A large proportion of patients with heart failure (HF) have a large and poorly contracting left ventricle. The noninvasive recognition of the ischemic etiology of such patients is difficult, and for this purpose, usually patients undergo coronary angiography. It has been shown that cardiovascular magnetic resonance (CMR) imaging can detect myocardial scarring by evaluating late gadolinium enhancement (LGE). The diagnostic accuracy of such method in differentiating the etiology of HF has not been previously tested in an unselected HF ambulatory population.

METHODS

We studied 60 ambulatory patients consecutively enrolled from a specialized HF clinic. We included HF patients who were found to have increased left ventricular (LV) dimensions and reduced function. CMR was performed in these patients by operators who were unaware of patients' history and clinical conditions. LV dimensions and global and regional function, as well as the pattern of LGE, were obtained in each subject. Coronary angiography was subsequently performed in all the patients. The diagnostic accuracy of clinical history and electrocardiographic patterns, as well as regional wall motion abnormalities, wall thinning, and LGE, in differentiating coronary artery disease (CAD) from non-CAD patients were evaluated.

RESULTS

The majority of CAD patients (98%) showed LV contrast hyperenhancement with respect to non-CAD HF subjects (16%). The detection of LGE by CMR had a sensitivity of 98% and a specificity of 84% and an overall accuracy of 93% in detecting CAD etiology among HF patients.

CONCLUSIONS

LGE is able to accurately differentiate CAD from non-CAD etiology of HF and may represent a clinically useful noninvasive tool for this purpose. As it provides relevant functional information as well as insight into the etiology, CMR may be included among the most important diagnostic tools in the workup of patients with HF.

Pulsed-wave tissue Doppler quantification of systolic and diastolic function of viable and nonviable myocardium in patients with ischemic cardiomyopathy

BACKGROUND

Detection of myocardial viability is crucial for clinical treatment of patients with ischemic cardiomyopathy. Currently, quantitative information for the evaluation of systolic and diastolic function of viable tissue is limited. Our aim was to compare quantitatively systolic and diastolic function in viable and nonviable dysfunctional myocardium in patients with ischemic cardiomyopathy.

METHODS

A total of 93 patients (mean age, 62 +/- 10 years) underwent dobutamine stress echocardiography to assess myocardial viability. Pulsed-wave tissue Doppler imaging (TDI) was used to assess systolic ejection velocity (V(S)) and early (V(E)) and late (V(A)) diastolic velocities at rest and at low-dose dobutamine infusion (10 microg/kg per minute) in viable and nonviable dysfunctional regions. Analysis was repeated after dividing study population in patients >or=65 years old (n = 40) and <65 years old (n = 53).

RESULTS

Pulsed-wave TDI demonstrated that V(S) was comparable in dysfunctional viable and nonviable regions at rest (V(S), 6.3 +/- 1.9 cm/s vs 6.3 +/- 2.0 cm/s, respectively, P = .93). However, at low-dose dobutamine challenge, V(S) was significantly higher in viable regions (8.5 +/- 2.7 cm/s vs 7.8 +/- 2.4 cm/s, P = .002). Viable regions had higher V(E) at rest compared with nonviable regions (8.4 +/- 2.5 cm/s vs 7.5 +/- 2.8 cm/s, P = .003). Myocardial velocities were significantly higher in patients >or=65 years old, both in viable and nonviable regions.

CONCLUSIONS

Quantification of myocardial motion by pulsed-wave TDI demonstrates that at low-dose dobutamine stress, systolic velocity is markedly improved in viable myocardium, indicating the presence of contractile reserve in viable regions. A superior early diastolic filling at rest can also differentiate viable from nonviable myocardium.

An echocardiogram-based 16-segment model for predicting left ventricular ejection fraction improvement

An important goal of cardiac revascularization is to improve the left ventricular ejection fraction, which is an important clinical determinant of the long-term outcome for patients with coronary artery disease. Regional myocardium function improvement may be expected from revascularization when viable myocardium is detected using non-invasive cardiac imaging. However, the quantitative relation between regional myocardial function recovery and global heart function improvement has not been determined and there is no tool to predict the amount of ejection fraction improvement prior to revascularization. A 16 segment biomechanical model of the left ventricle is proposed to establish the relationship between the ejection fraction improvement and the viable segments detected by echocardiography. With the assumption that the viable segments would potentially improve contractility after revascularization, the ejection fraction improvement is estimated for all possible wall motion score improvement in viable segments. The model shows that the ejection fraction improvement is linearly related to the contractility in the normal segments and a weighted sum of the numbers of viable segments that recover to normal or hypokinetic contractility. The predictive value of the model is illustrated for a group of patients reported in the literature. The model predictions of the post-revascularization ejection fraction are very close to the follow-up data with a very strong correlation (R2 = 0.92). By predicting the ejection fraction improvement, the model may provide a tool for evaluating the efficacy of revascularization and for selecting patients who would benefit from revascularization.

Perioperative enoximone infusion improves cardiac enzyme release after CABG

OBJECTIVE

To assess whether routine postoperative enoximone infusion compared with dobutamine improved clinical and biochemical results after coronary artery bypass grafting with cardiopulmonary bypass.

DESIGN

Prospective nonrandomized study. Data collection was blinded to the choice of inotrope.

SETTING

Double-institutional clinical investigation.

PARTICIPANTS

Two hundred sixteen consecutive patients undergoing myocardial revascularization between May 2000 and December 2002.

INTERVENTIONS

Seventy-two patients underwent myocardial revascularization and were treated with enoximone, 5 microg/kg/min (group A). They were compared in a ratio of 1:2 to 144 patients treated with dobutamine at the same dose (group B) after aortic cross-clamp removal. The groups proved to be homogenous in preoperative and intraoperative characteristics.

MEASUREMENTS AND MAIN RESULTS

Hospital outcome, electrocardiogram, echocardiography, further inotropic support, and biochemical markers of ischemia were compared. Subsets of patients with comorbidities and total arterial revascularization were analyzed. Perioperative myocardial infarction, postoperative low-output syndrome, intra-aortic balloon pump, atrial fibrillation, ST-segment changes, postoperative echocardiographic findings, and intensive care and hospital durations were similar between groups. In the postoperative course, more patients belonging to group A maintained low-dose inotropic support, whereas more patients belonging to group B required higher doses. Troponin I and creatine kinase-MB values were higher in patients of group B, especially when subgroups with diabetes, left ventricular hypertrophy, or total arterial revascularization were included.

CONCLUSION

Postoperative enoximone reduced troponin I release and need for inotropic support in patients undergoing on-pump myocardial revascularization. Subgroup data were confirmed in diabetes, left ventricular hypertrophy, and total arterial revascularization.

Pulsed wave tissue Doppler imaging for the quantification of contractile reserve in stunned, hibernating, and scarred myocardium

OBJECTIVES

To assess whether quantification of myocardial systolic velocities by pulsed wave tissue Doppler imaging can differentiate between stunned, hibernating, and scarred myocardium.

DESIGN

Observational study.

SETTING

Tertiary referral centre.

PATIENTS

70 patients with reduced left ventricular function caused by chronic coronary artery disease.

METHODS

Pulsed wave tissue Doppler imaging was done close to the mitral annulus at rest and during low dose dobutamine; systolic ejection velocity (Vs) and the difference in Vs between low dose dobutamine and the resting value (DeltaVs) were assessed using a six segment model. Assessment of perfusion (with Tc-99m-tetrofosmin SPECT) and glucose utilisation (by 18F-fluorodeoxyglucose SPECT) was used to classify dysfunctional regions (by resting cross sectional echocardiography) as stunned, hibernating, or scarred.

RESULTS

253 of 420 regions (60%) were dysfunctional. Of these, 132 (52%) were classified as stunned, 25 (10%) as hibernating, and 96 (38%) as scarred. At rest, Vs in stunned, hibernating, and scar tissue was, respectively, 6.3 (1.8), 6.6 (2.2), and 5.5 (1.5) cm/s (p = 0.001 by ANOVA). There was a gradual decline in Vs during low dose dobutamine infusion between stunned, hibernating, and scar tissue (8.3 (2.6) v 7.8 (1.5) v 6.8 (1.9) cm/s, p < 0.001 by ANOVA). DeltaVs was higher in stunned (2.1 (1.9) cm/s) than in hibernating (1.2 (1.4) cm/s, p < 0.05) or scarred regions (1.3 (1.2) cm/s, p = 0.001).

CONCLUSIONS

Quantitative tissue Doppler imaging showed a gradual reduction in regional velocities between stunned, hibernating, and scarred myocardium. Dobutamine induced contractile reserve was higher in stunned regions than in hibernating and scarred myocardium, reflecting different severities of myocardial damage.

Predictors of new malignant ventricular arrhythmias after coronary surgery

OBJECTIVES

We sought to investigate the relationship between perioperative factors and the occurrence of ventricular tachycardia (VT) and ventricular fibrillation (VF), as well as the impact of VT/VF on early and late mortality.

BACKGROUND

Both VT and VF are rare but serious complications after coronary artery bypass graft surgery (CABG), and their etiology and implications remain uncertain.

METHODS

Data on 4,411 consecutive patients undergoing CABG (1,154 [25.8%] had off-pump surgery) between April 1996 and September 2001 were extracted from a prospective database and analyzed. Odds ratios (ORs) describing associations between possible risk factors and VT/VF were estimated separately. Factors observed to be significantly associated with VT/VF were further investigated using multivariate logistic regression.

RESULTS

Sixty-nine patients suffered VT/VF (1.6%). There were 61 (1.4%) in-hospital/30-day deaths, 15 among patients who had postoperative VT/VF (21.7%). Patient factors independently associated with an increase in the odds of VT/VF included age <65 years, female gender, body mass index <25 kg/m(2), unstable angina, moderate or poor ejection fraction, and the need for inotropes and an intra-aortic balloon pump (OR 1.72 to 4.47, p < 0.05). After adjustment, off-pump surgery was associated with a substantial but nonsignificant protective effect against VT/VF (OR 0.53, 95% confidence interval [CI] 0.25 to 1.13; p = 0.10). Actuarial survival at two years was 98.2% among patients who had VT/VF and who survived to discharge/30 days, compared with 97.0% for the control group (adjusted hazard ratio 0.96 (95% CI 0.40 to 2.31, p = 0.92).

CONCLUSIONS

The incidence of VT/VF is low in patients undergoing coronary surgery but is associated with high in-hospital mortality. The late survival of the discharged VT/VF patients compares favorably with that of controls.

Application of tissue Doppler imaging in cardiology

Tissue Doppler imaging (TDI) is a new echocardiographic technique employing the Doppler principle to measure the velocity of myocardial segments and other cardiac structures. It is well suited for the measurement of long-axis ventricular function. Impairment of longitudinal myocardial fiber motion is a sensitive marker of early myocardial dysfunction and ischaemia, and TDI might therefore become an important tool in routine echocardiography. The technique allows truly quantitative measurement of regional myocardial function both at rest and during stress echocardiography. TDI has great potential in the diagnosis of diastolic left ventricular dysfunction, overcoming the load-dependence of conventional Doppler techniques. Right ventricular function, intracardiac and pulmonary artery pressures, transplant rejection and intraventricular dyssynchrony can also be assessed. This article reviews the current and evolving applications of TDI in cardiology.

Demographics and concomitant disorders in heart failure

Chronic heart failure is an increasingly common cause of premature death and poor quality of life. Community-based epidemiological studies have provided much-needed information on the demography of chronic heart failure, providing insight into its influence on public health. In most patients, chronic heart failure is accompanied by a range of concomitant disorders that both contribute to the cause of the disease and have a key role in its progression and response to treatment. Information on the most common comorbidities in chronic heart failure--ischaemic heart disease, hypertension, and diabetes mellitus--is presented for prespecified subgroups in the reports of many large-scale, multicentre trials; despite their limitations, these subanalyses provide guidance in therapeutic decision-making. Similarly, because chronic heart failure is commonly an endpoint in intervention trials of both hypertension and diabetes, such studies afford important information on the prevention of chronic heart failure in these common diseases.

Single photon emission computed tomography perfusion imaging for assessment of myocardial viability and management of heart failure

In the setting of coronary artery disease, some areas of dysfunctional myocardium may realize significant improvement in function as a consequence of revascularization. These areas represent viable myocardium, encompassing a spectrum of pathophysiology ranging from chronic stunning, in which resting blood flow is preserved, to hibernating myocardium, in which resting blood flow is decreased. The accurate preoperative evaluation of viable myocardium helps identify those patients with left ventricular dysfunction who will most benefit from coronary revascularization. Of the various modalities available for viability assessment, the nuclear medicine techniques (201)Thallium and (18)Fluorodeoxyglucose positron emission tomography have emerged as the most sensitive. It has been consistently shown that in patients with a significant amount of viable myocardium, there is a substantial survival benefit in revascularization versus medical therapy. The likelihood of affecting a significant improvement decreases with time to revascularization, however, particularly in the setting of an enlarged left ventricle secondary to ventricular remodeling.

Off-pump coronary artery bypass grafting: not a flash in the pan

During the past decade, technical improvements have made off-pump coronary artery bypass operations a routine procedure. During this time, off-pump coronary artery bypass has been audited against conventional techniques by many observational, case-matched, and prospective randomized studies. There is evidence in the literature suggesting that off-pump coronary artery bypass operations reduce postoperative morbidity, organ dysfunction, and costs, without compromising midterm outcome compared with conventional coronary operations. The available evidence also supports the view that high-risk patients might benefit the most from revascularization on the beating heart. High quality follow-up data are still needed to assess the impact of off-pump coronary artery bypass operations on long-term clinical outcome.

Assessment of residual myocardial viability in regions with chronic electrocardiographic Q-wave infarction

BACKGROUND

Q waves on the electrocardiogram are often considered to be reflective of irreversibly scarred myocardium due to antecedent transmural myocardial infarction. However, there are some indications that residual viable tissue may be present in Q-wave-infarcted regions. It is clinically relevant to know how many Q-wave regions contain viable tissue because these patients may benefit from revascularization in terms of improvement of function and long-term survival.

METHODS

Patients (n = 150) with chronic electrocardiographic Q-wave infarction, heart failure symptoms, and chronic coronary artery disease underwent dobutamine-atropine stress echocardiography to assess myocardial viability. Residual viability in regions with Q-wave infarction was considered present when the end-diastolic wall thickness (EDWT) was >6 mm and the response during dobutamine infusion indicated viable tissue.

RESULTS

Baseline echocardiography revealed 517 dysfunctional myocardial regions; 202 of the dysfunctional regions were related to Q waves on the electrocardiogram and the other 315 dysfunctional regions were not. EDWT was < or =6 mm in 13 regions with a Q wave on the electrocardiogram, with only 1 region exhibiting viable tissue during dobutamine stress echocardiography. EDWT was >6 mm in 189 regions with a Q wave, with 118 (62%) having viable tissue on dobutamine stress echocardiography. In 6 dysfunctional regions without a Q wave, EDWT was < or =6 mm, with all being nonviable on dobutamine stress echocardiography; of the 309 regions without a Q wave and EDWT >6 mm, 204 (66%) exhibited viability on dobutamine stress echocardiography.

CONCLUSIONS

Fifty-eight percent of dysfunctional regions related to chronic Q waves were viable according to the combined information of EDWT and dobutamine stress echocardiography. EDWT </=6 mm virtually excludes viability; regions with EDWT >6 mm need additional testing to detect or exclude viability.

Is there a long-term predictive value of intraoperative low-dose dobutamine echocardiography in patients who have coronary artery bypass graft surgery with cardiopulmonary bypass?

In patients with coronary artery disease, chronic regional left ventricular systolic dysfunction at rest may be caused by hibernating or by infarcted myocardium. Intraoperative low-dose dobutamine (LDD) echocardiography reliably predicts the immediate recovery of regional myocardial function after coronary artery bypass graft (CABG) surgery. We sought to determine whether intraoperative LDD echocardiography would also predict recovery of regional function after 1 yr. Twenty-five patients with coronary artery disease who underwent CABG surgery with intraoperative LDD echocardiography were evaluated 1 yr later with a follow-up transthoracic echocardiogram. The covariates of left ventricular ejection fraction, old myocardial infarction, and diabetes mellitus were considered in an analysis of regional wall motion (RWM). A 16-segment model and a 1-5-point scoring system were used to evaluate 350 myocardial segments. Multiple logistic regression analysis was performed to determine whether response to intraoperative LDD echocardiography (5 microg. kg(-1). min(-1)) predicted changes in regional function at 1 yr. A segment was defined as stunned if the RWM score obtained during LDD infusion deteriorated after cardiopulmonary bypass but recovered in the 1-yr follow-up echocardiogram. A response to intraoperative LDD predicted changes in regional function at 1 yr. The overall odds of improvement in regional function were 2.22 times greater (95% confidence interval = 1.29, 3.82; P = 0.0039) with a positive response to intraoperative LDD. The positive predictive value of intraoperative LDD echocardiography for improvement in myocardial function was 0.81 and the negative predictive value was 0.34. The predictive values did not vary with the examined covariates. Of segments with unexpected deterioration of RWM immediately after cardiopulmonary bypass, 87% recovered at the time of the 1-yr follow-up echocardiogram. Contractile reserve demonstrated by intraoperative LDD echocardiography predicts regional function at 1 yr; however, the test cannot predict which segment will not recover. Most of unexpected regional ventricular systolic dysfunction immediately after CABG surgery can be attributed to myocardial stunning.

IMPLICATIONS

In patients undergoing coronary artery bypass graft surgery, intraoperative low-dose dobutamine echocardiography has only limited value for the prediction of regional myocardial function at 1 yr. Small-dose dobutamine echocardiography predicts regional myocardial function at 1 yr when baseline regional wall motion abnormalities improve with dobutamine; however, the test cannot be used to predict which segment will not recover at 1 yr.

Subsystem organ function during coronary surgery

Conventional coronary artery bypass grafting (CABG) carries a mortality rate of 1% to 2% in elective patients. However, despite advances in perfusion, anaesthetic, and surgical techniques cardiopulmonary bypass (CPB) is still associated with subsystem dysfunction. Off-pump coronary artery bypass grafting (OPCAB) has recently gained popularity as a potentially more physiological method to maintain the functional integrity of major organ systems. The review of observational reports, case-matched studies and prospective randomized trials seems to suggest that OPCAB surgery reduces postoperative subsystem organ dysfunction when compared with conventional coronary revascularisation.

Statins and chronic heart failure: do we need a large-scale outcome trial?

Hydroxymethylglutaryl-coenzyme A reductase inhibitors (statins) are of proven clinical benefit in coronary heart disease, at least in those patients who do not have overt chronic heart failure (CHF). However, as there have been no prospective clinical trials of statins in CHF patients, the question arises as to whether the benefits observed in the absence of CHF can be necessarily inferred in those patients in whom CHF is established. In this review, the evidence base stating support of the use of statins in CHF is presented, as well as theoretical considerations as to why these agents may not necessarily be of benefit in this setting. The beneficial potential of statins clearly relates to their plaque stabilization properties and associated improvements in endothelial function, which together should reduce the risk of further infarction and, perhaps, the ischemic burden on the failing ventricle. Furthermore, these agents may have beneficial effects independent of lipid lowering. These include actions on neoangiogenesis, downregulation of AT(1) receptors, inhibition of proinflammatory cytokine activity and favorable modulation of the autonomic nervous system. The potential adverse effects of statins in CHF include reduction in levels of coenzyme Q10 (which may further exacerbate oxidative stress in CHF) and loss of the protection that lipoproteins may provide through binding and detoxifying endotoxins entering the circulation via the gut. In support of these possibilities are epidemiologic data linking a lower serum cholesterol with a poorer prognosis in CHF. These uncertainties indicate the need for a definitive outcome trial to assess the efficacy and safety of statins in CHF, despite their current widespread, non-evidence based use in this population.

Simultaneously monitoring both T(1) and T(2)* signal intensities on a bolus injection of Gd-DTPA may distinguish infarcted myocardium

PURPOSE

To determine whether injured myocardium may be identified by simultaneously monitoring contrast-induced T(1) and T(2)* signal intensity time-course changes with an interleaved T(1)-T(2)* imaging sequence.

MATERIALS AND METHODS

Gadolinium-diethylene triamine pentaacetic acid (0.05 mmol/ kg) was injected as a bolus into ex vivo pig hearts, and simultaneous T(1) and T(2)* time-courses were obtained during the first pass.

RESULTS

Observing contrast-enhanced R(1) or R(2)* rates (1/T(1) or 1/T(2)* times, respectively) early after contrast injection did not fully differentiate viable from nonviable myocardium. T(2)* recovery at maximal T(1) signal intensity, measured using simultaneous T(1) and T(2)* imaging, displayed a significantly different percentage recovery (P < 0.05) among normal (30.5 +/- 2.4% of baseline value), reperfused infarcted (63 +/- 7.2%), and low-reflow infarcted (90 +/- 2.8%) myocardium.

CONCLUSION

Simultaneously monitoring both T(1) and T(2)* signal intensities may help in the assessment of myocardial injury.

The prevalence of impaired left ventricular diastolic filling is related to the extent of coronary atherosclerosis in patients with stable coronary artery disease

AIMS

The relation between abnormal left ventricular (LV) diastolic filling and the extent of coronary atherosclerosis per se has not been described. We aimed to investigate the prevalence of impaired LV diastolic filling in patients with stable coronary artery disease (CAD) and its relationship to the number and location of coronary lesions visualized at coronary angiography.

METHODS AND RESULTS

In 170 consecutive patients with stable CAD and an abnormal coronary angiogram we assessed LV diastolic filling by Doppler evaluation of the transmitral early to atrial peak flow velocity (E/A) and the systolic to diastolic ratio of the pulmonary venous peak inflow to the left atrium (S/D). Abnormal diastolic filling was defined as E/A < or =0.75, or E/A >1.0 combined with S/D < or =1.0, and was present in 41% of the patients. In patients with one-, two- and three-vessel disease the prevalence of impaired diastolic filling was 27, 30 and 49%, respectively (P = 0.026). In multiple logistic regression analysis diastolic filling was independently correlated with the number of stenotic coronary vessel areas.

CONCLUSION

In patients with stable angiographically verified CAD, the prevalence of impaired diastolic filling was 41%. The prevalence increased with an increasing number of stenotic coronary artery areas independent of other variables tested, including prior myocardial infarction, LV systolic function and mitral regurgitation.

Neuro-fuzzy systems for computer-aided myocardial viability assessment

This paper describes a multimodality framework for computer-aided myocardial viability assessment based on neuro-fuzzy techniques. The proposed approach distinguishes two main levels: the modality-independent inference level and the modality-dependent application level. This two-level distinction releases the hard constraint of multimodality image registration. An abstract description template is used to describe the different myocardial functions (contractile function, perfusion, metabolism). Parameters extracted from different image modalities are combined to derive a diagnostic image. The neuro-fuzzy techniques make our system transparent, adaptive and easily extendable. Its effectiveness and robustness are demonstrated in a positron emission tomography/magnetic resonance imaging data fusion application.

Apoptosis and the systolic dysfunction in congestive heart failure. Story of apoptosis interruptus and zombie myocytes

Although previously it was believed that apoptosis could not occur in the terminally differentiated tissue, such as adult heart muscle cells, recent studies in endomyocardial biopsies from patients with dilated cardiomyopathy and in explanted hearts from patients with end-stage heart failure undergoing cardiac transplantation have demonstrated histologic evidence of apoptosis. Whereas neurohormonal activation during heart failure leads to compensatory hemodynamic alterations, coupled with ventricular dilatation, it induces transcription factors and myocyte hypertrophy. Persistent growth stimulation in terminally differentiated cells may lead paradoxically to apoptotic cell death. The apoptosis in cardiomyopathic hearts is associated with cytochrome c release from mitochondria to cytoplasm and activation of proteolytic caspase-8 and -3. Although the caspases are duly processed, the fragmentation of the nuclear proteins (including DNA) is completed less frequently, and only a variable degree of fragmentation of cytoplasmic proteins (including contractile proteins) is observed. It is hypothesized that release of cytochrome c from mitochondria should interfere with energy production and lead to functional impairment and variable loss of contractile proteins in a living heart muscle cell should contribute to systolic dysfunction. Because a nuclear blueprint is retained, however, the dysfunctional cell may continue to exist and in favorable conditions, such as with LVAD support, the apoptotic process may subside. Potential feasibility of reversal of heart failure should renew efforts to develop more targeted pharmaceutical intervention within the apoptotic cascade and allow newer paradigm for the management of heart failure.

Enhanced 99Tc(m)-MIBI SPECT detection of hibernating myocardium following the use of sub-lingual nitroglycerine

The purpose of this study was to assess the feasibility of detecting hibernating myocardium using 99Tc(m)-MIBI SPECT imaging following the use of sublingual glyceryl trinitrate (GTN). Thirty-eight subjects were studied, five asymptomatic and 33 with a history of myocardial ischaemia or myocardial infarction (MI). The study was conducted on two separate days, both at rest, one under controlled basal conditions and the other 20 min following the sublingual administration of GTN. A total of 190 cardiac segments were qualitatively analysed and 72 segments with fixed defects were compared to the study following the use of GTN for evidence of improved radionuclide uptake. Following GTN, 73.6% of fixed segment defects showed no change in uptake, 5.5% showed probable improvement whilst in 20.8% a definite enhanced uptake was demonstrated. In 3.7% of segments, worsening of radionuclide uptake was observed.

Usefulness of low-dose dobutamine stress echocardiography in predicting recovery of poor left ventricular function in atrial fibrillation dilated cardiomyopathy

Assessment of contractile reserve was performed in 16 patients with dilated cardiomyopathy and chronic atrial fibrillation. In this prospective study, low-dose dobutamine echocardiography could predict recovery of left ventricular dysfunction and could identify tachycardiomyopathy before restoration of sinus rhythm.

Concept and evaluation of hibernating myocardium

Hibernating myocardium is a state of persistently impaired myocardial and left ventricular function at rest due to reduced coronary blood flows. It can be defined as an exquisitely regulated tissue successfully adapting its activity to prevailing circumstances. It has been documented in patients with angina (chronic stable and/or unstable), acute myocardial infarction, heart failure and/or severe left ventricular dysfunction, and anomalous left coronary artery from the pulmonary artery. The diagnosis of hibernating myocardium involves (a) documenting left ventricular dysfunction at rest and (b) documenting that there is viable myocardium in the area of dysfunction. Tests commonly used for the latter are dobutamine echocardiography, 201Tl isotope studies, and positron image tomography. Revascularization, either by surgery or by interventional catheter techniques, has been shown to improve or normalize the abnormal left ventricular function at rest.

Prolonged myocardial hibernation exacerbates cardiomyocyte degeneration and impairs recovery of function after revascularization

OBJECTIVES

We sought to define the effects of time on contractile function, morphology and functional recovery after coronary revascularization in patients with dysfunctional but viable (hibernating) myocardium.

BACKGROUND

Functional recovery after coronary artery bypass graft surgery in patients with chronic myocardial hibernation is incomplete or delayed. The proposed cause is a progressive temporal degeneration of cardiomyocytes.

METHODS

In 32 patients with multivessel coronary disease, regional wall motion analysis was performed in hypoperfused but metabolically active areas before and 6 months after bypass surgery. During bypass surgery, transmural biopsy samples were obtained from the center of the hypokinetic zone for light and electron microscopic analyses. The proposed duration of myocardial hibernation was retrospectively assessed.

RESULTS

Patients with a subacute hibernating condition (<50 days) demonstrated a higher preoperative ejection fraction (EF, 50+/-8%), and a better preserved wall motion (WM) in the supraapical wall (-1.4+/-0.4) than did patients with intermediate-term (>50 days, EF 37+/-9%, p < 0.05; WM -2.4+/-1.5, p = 0.08) or chronic (>6 months, EF 40+/-14%, WM -2.7+/-0.9, p < 0.005) ischemia. Structural degeneration correlated with the duration of ischemia (r = 0.56, p < 0.05). Postoperative recovery of function was enhanced in patients with a short history of hibernation compared with patients with an intermediate-term or chronic condition (EF 60+/-10% vs. 40+/-10%, p < 0.001, and vs. 47+/-14%, p < 0.05).

CONCLUSIONS

Hibernating myocardium exhibits time-dependent deterioration due to progressive structural degeneration with enhanced fibrosis. Early revascularization should be attempted to salvage the jeopardized tissue and improve postoperative outcome.

Structural changes of atrial myocardium due to sustained atrial fibrillation in the goat

BACKGROUND

After cardioversion of sustained atrial fibrillation (AF), the electrical and contractile functions of the atria are impaired, and recurrences of AF frequently occur. Whether remodeling of the structure of atrial myocardium is the basis for this problem is not known.

METHODS AND RESULTS

Sustained AF was induced by electrical pacing in 13 goats instrumented long-term. The goats were killed after 9 to 23 weeks, and the atrial myocardium was examined by light and electron microscopy. The changes were quantified in left and right atrial free walls, appendages, trabeculae, the interatrial septum, and the bundle of Bachmann. A substantial proportion of the atrial myocytes (up to 92%) revealed marked changes in their cellular substructures, such as loss of myofibrils, accumulation of glycogen, changes in mitochondrial shape and size, fragmentation of sarcoplasmic reticulum, and dispersion of nuclear chromatin. These changes were accompanied by an increase in size of the myocytes (up to 195%). There were virtually no signs of cellular degeneration, and the interstitial space remained unaltered. The duration of sustained AF did not significantly affect the degree of myolytic cell changes.

CONCLUSIONS

Sustained AF in goats leads to predominantly structural changes in the atrial myocytes similar to those seen in ventricular myocytes from chronic hibernating myocardium. These structural changes may explain the depressed contractile function of atrial myocardium after cardioversion. This goat model of AF offers a new approach to study the cascade of events leading to sustained AF and its maintenance.

Contractile reserve of dysfunctional myocardium after revascularization: a dobutamine stress echocardiography study

OBJECTIVES

We sought to investigate the effects of revascularization on the contractile reserve of dysfunctional myocardium.

BACKGROUND

The improvement in dysfunctional but viable myocardium after revascularization is frequently less than expected from the amount of contractile reserve detected on dobutamine stress echocardiography. The fate of the contractile reserve, when it does not result in an adequate contractile recovery, is unknown.

METHODS

Basal contraction and contractile reserve of infarct zones were assessed by dobutamine stress echocardiography in 21 postinfarction male patients before and > 3 months after revascularization (30 infarct zones; mean +/- SD left ventricular ejection fraction 35 +/- 8%). An infarct zone wall motion score index (WMSI) was calculated.

RESULTS

Before revascularization, contractile reserve was present in 14 infarct zones (12 patients) and absent in 16 (9 patients). After revascularization, ejection fraction increased by 5 +/- 4% (p < 0.01) in patients classified as positive for contractile reserve and remained unchanged in those classified as negative. New York Heart Association classification improved in 58.3% and 22.2% of patients, respectively. Basal contraction improved in eight zones with previous contractile reserve (57.1%) and in one zone without (6.3%) (p < 0.01). Contractile reserve was still evident in 13 zones with previous contractile reserve (93%; 8 with contractile recovery), and it developed in 6 zones without (38%; none with contractile recovery). WMSI values after revascularization were decreased from values before revascularization during low dose dobutamine in zones with and without previous contractile reserve (p < 0.01 and < 0.05, respectively).

CONCLUSIONS

After revascularization, contractile reserve is maintained or even increases in viable infarct zones that do not recover as expected. It may also develop in some infarct zones judged not to be viable before revascularization. This increased contractile reserve may play a role in the functional improvement of patients after revascularization.

Hibernating myocardium: clinical and functional response to revascularisation

OBJECTIVE

We assessed the effects of coronary bypass grafting on left ventricular (LV) function, exercise capacity and symptom profile in patients with LV impairment and evaluated the role of identifying myocardial hibernation in a prospective non-randomised study.

METHODS

Of 120 patients screened, 47 patients with LV ejection fraction < 35% and three vessel coronary artery disease were studied. All underwent stress/redistribution and separate day rest/redistribution T1-201 imaging together with cine MRI at enrolment, and cine MRI at follow-up. Group 1, 30 patients undergoing bypass surgery, underwent symptom limited treadmill exercise testing with peak VO2 measurement, and symptom profile evaluation less than 3 months before, and 3-6 months after operation. Revascularisation was assessed by post-operative T1-201 imaging and repeat coronary angiography. Group 2, 17 patients treated on medical therapy alone underwent symptom profile assessment at enrolment and follow-up for those who survived. Segmental hibernation was defined as the equivalent of greater than 50% of maximal T1-201 uptake where wall motion was severely impaired on resting imaging. Patients were considered to be hibernating where two of nine LV segments fulfilled these criteria.

RESULTS

In group 1, five patients died (17%), peri-or post-operatively, two defaulted and 23 attended follow-up studies. In group 2, three patients died prior to follow-up (18%). In the surgical group there was an increase in mean LVEF from 24.0 +/- 8% to 29.7 +/- 11% (P < 0.05) while in the medical group there was a fall from 25.7 +/- 10% to 20.6 +/- 8% (P < 0.05). In group 1, the mean NYHA dyspnoea grade improved from 2.7 to 1.4 while in the medical group it was unchanged, 2.6 to 2.5. In patients with myocardial hibernation identified pre-operatively, 18/19 (95%) improved LVEF after CABG compared with 2/4 (50%) of patients without hibernation. 17/19 (86%) patients with hibernation improved NYHA dyspnoea class compared with 2/4 (50%) of patients without. 60/93 (65%) of hibernating segments improved function after revascularisation while 47/53 (89%) hibernating segments showed no improvement on medical therapy alone.

CONCLUSION

In patients with severe LV impairment with myocardial hibernation, coronary artery bypass grafting improves both global and regional systolic LV function, and symptom profile. Medical treatment of patients with LV impairment and myocardial hibernation does not improve LV contractile function or symptoms. Both surgical and medical therapy carry a high mortality rate.

Causes of congestive heart failure. Prompt diagnosis may affect prognosis

Congestive heart failure (CHF) is a progressive disease with multiple possible causes. Systolic heart failure, defined as contractile failure of the myocardium leading to a reduced ejection fraction, is the most common type. Systolic heart failure may result from coronary artery disease, hypertension, a metabolic disorder, infection, or an infiltrative or other disease, or it may be idiopathic. Recognition of CHF can be difficult, especially in elderly patients with several medical conditions. An early clinical sign may be dyspnea on exertion. The extent of workup needed is often indicated by findings on history taking and physical examination. In all patients suspected of having new-onset CHF, a chest film, an electrocardiogram, and left ventricular ejection fraction should be obtained and a search for complicating and causative factors undertaken. Early treatment may halt the otherwise inevitable decline in cardiac function and improve prognosis.