Reversal of chronic ischemic myocardial dysfunction after transluminal coronary angioplasty

Pharmacologic Management of Chronic Heart Failure: A Review

Standard drug therapy of systolic heart failure has been evaluated in large-scale randomized clinical trials and includes angiotensin-converting enzyme (ACE) inhibi tors, which should be used as first-line therapy, diuret ics for the management of extracellular fluid volume excess, and digoxin. In combination with ACE inhibitors and diuretics, with or without digoxin, some β-adrener gic receptor blockers attenuate disease progression and improve outcome in mild-to-moderate systolic heart failure. The pharmacologic management of chronic dia stolic heart failure is largely empirical and directed at reducing symptoms. Symptoms caused by increased ventricular filling pressures may be diminished by diuret ics and nitrovasodilators. Some calcium channel antago nists and most β-blockers prolong diastolic filling time by slowing heart rate, thereby improving the symptoms of diastolic heart failure.

Evaluation of left ventricular function three years after percutaneous recanalization of chronic total coronary occlusions

We investigated early and late effects of percutaneous revascularization for chronic total coronary occlusion on left ventricular (LV) function and volumes. Magnetic resonance imaging was performed in 21 patients before and 5 months and 3 years after recanalization. Global LV function and volumes and segmental wall thickening (SWT) were quantified on cine images. The 2 viability indexes used were the transmural extent of infarction (TEI) on delayed contrast enhancement images and end-diastolic wall thickness at baseline. Significant decreases in mean end-diastolic (86 +/- 14 to 78 +/- 15 ml/m2; p = 0.02) and mean end-systolic volume indexes (35 +/- 13 to 30 +/- 13 ml/m2; p = 0.03) were observed 3 years after recanalization. Mean ejection fraction tended to improve (60 +/- 9% to 63 +/- 11%; p = 0.11). SWT significantly increased at 5-months' follow-up (p <0.001), and an additional improvement was found at 3 years' (p = 0.04) follow-up in segments with TEI <25%. In segments with TEI of 25% to 75%, SWT was unchanged at 5-month follow-up (p = 0.89), but improved at 3 years (p = 0.04). SWT was unchanged in segments with transmural scars. For segmental functional recovery, TEI was a better predictor than end-diastolic wall thickness at baseline (odds ratio 5.6, 95% confidence interval 1.5 to 21.1, p = 0.01 vs odds ratio 2.5, 95% confidence interval 0.7 to 8.3, p = 0.14). In conclusion, a positive effect on LV remodeling and ejection fraction was observed up to 3 years after recanalization. Both early and late improvements in regional LV function were observed in the perfusion territory of chronic total coronary occlusion and were related to the transmural extent of infarction on pretreatment magnetic resonance imaging.

[Predictors of improved left ventricular systolic function after surgical revascularization in patients with ischemic cardiomyopathy]

INTRODUCTION AND OBJECTIVES

Although it is known that the presence of myocardial viability predicts an increase in ejection fraction after revascularization in patients with ischemic cardiomyopathy, little is known about other predictive factors. The aim of this study was to identify variables that can predict an increase in ejection fraction after coronary revascularization surgery in patients with ischemic cardiomyopathy and a viable myocardium.

METHODS

The study included 30 patients (mean age 61.6 [11] years, one female) with ischemic cardiomyopathy (ejection fraction <or=40%) who fulfilled criteria for myocardial viability. All underwent ECG-gated single-photon emission computed tomography before and after surgery.

RESULTS

An increase in ejection fraction >or=5% occurred after surgery in 17 of the 30 patients (56.6%). These patients were characterized by the presence of left main coronary artery disease (P< .004), a large number of grafts (P< .03), a high perfusion summed difference score (P< .012), a low end-diastolic volume (P< .013), and a low end-systolic volume (P< .01). An end-systolic volume <148 mL and a summed difference score >or=4 gave the best predictive model (P=.001, R2=0.73) for an increase in ejection fraction.

CONCLUSIONS

In patients with ischemic cardiomyopathy and a viable myocardium, the main determinants of an increase in ejection fraction after revascularization surgery were low levels of left ventricular remodeling and myocardial ischemia.

Coronary blood flow, metabolism, and function in dysfunctional viable myocardium before and early after surgical revascularisation

OBJECTIVES

To assess the link between perfusion, metabolism, and function in viable myocardium before and early after surgical revascularisation.

DESIGN

Myocardial blood flow (MBF, thermodilution technique), metabolism (lactate, glucose, and free fatty acid extraction and fluxes), and function (transoesophageal echocardiography) were assessed in patients with critical stenosis of the left anterior descending coronary artery (LAD) before and 30 minutes after surgical revascularisation.

SETTING

Tertiary cardiac centre.

PATIENTS

23 patients (mean (SEM) age 57 (1.7) years with LAD stenosis: 17 had dysfunctional viable myocardium in the LAD territory, as shown by thallium-201 rest redistribution and dobutamine stress echocardiography (group 1), and six had normally contracting myocardium (group 2).

RESULTS

LAD MBF was lower in group 1 than in group 2 (58 (7) v 113 (21) ml/min, p < 0.001) before revascularisation and improved postoperatively in group 1 (129 (133) ml/min, p < 0.001) but not in group 2 (105 (20) ml/min, p = 0.26). Group 1 also had functional improvement in the LAD territory at intraoperative echocardiography (mean regional wall motion score from 2.6 (0.85) to 1.5 (0.98), p < 0.01). Oxidative metabolism, with lactate and free fatty acid extraction, was found preoperatively and postoperatively in both groups; however, lactate and free fatty acid uptake increased after revascularisation only in group 1.

CONCLUSIONS

MBF is reduced and oxidative metabolism is preserved at rest in dysfunctional but viable myocardium. Surgical revascularisation yields immediate perfusion and functional improvement, and increases the uptake of lactate and free fatty acids.

Prospective Evaluation of Clinical Outcomes After Acute ST-Elevation Myocardial Infarction in Patients Who Are Ineligible for Reperfusion Therapy: Preliminary Results From the TETAMI Registry and Randomized Trial

Background— Treatment with lytics or primary percutaneous coronary interventions (PCI) reduces the mortality rate of patients with ST-elevation myocardial infarction (STEMI) presenting within 12 hours. Patients presenting >12 hours are generally considered to be ineligible for reperfusion therapy, and there are currently no specific treatment recommendations for this subgroup.

Methods— All patients with STEMI <24 hours were included in the Treatment with Enoxaparin and Tirofiban in Acute Myocardial Infarction (TETAMI) randomized trial or registry. Those patients who were ineligible for acute reperfusion, had no cardiogenic shock, and were not planned for revascularization within 48 hours were randomized to 1 of 4 antithrombotic regimens involving enoxaparin or unfractionated heparin (UFH), in combination with tirofiban or placebo for 2 to 8 days. A concurrent registry tracked STEMI patients coming in within <12 hours, and who underwent reperfusion. This registry also tracked the remaining STEMI patients who neither received reperfusion nor were enrolled in the TETAMI randomized trial. The demographics and clinical outcomes of all three groups (received reperfusion therapy, too late for reperfusion and enrolled in the randomized trial, neither received reperfusion therapy nor were enrolled in the randomized trial) were prospectively tracked.

Results and Conclusion— There were 2,737 patients who presented with STEMI or a new left branch bundle block (LBBB), of which 1,654 (60%) presented ≤12 hours. There were 1,196 (72%) of 1,654 patients who received reperfusion therapy. There were 458 (28%) of the 1,654 patients deemed “ineligible” for reperfusion, mostly because of a contraindication to lytics or for being “too old.” In contrast, 1,083 (40%) of 2,737 patients presented >12 hours. Apart from 34 of these patients who had a stuttering infarction and were referred for reperfusion, the remaining patients did not receive reperfusion therapy.

Registry patients who received reperfusion therapy, compared with TETAMI randomized patients (all of whom received antithrombotic therapy) and registry patients who did not receive reperfusion, were younger (61 years versus 63 years and 67 years), were more likely to be male (78% versus 73% and 63%), and had persistent ST-segment elevation as opposed to LBBB or Q waves. Registry patients who received reperfusion therapy had better clinical outcomes, even after adjusting for admission Killip class, compared with TETAMI randomized patients and registry patients who did not receive reperfusion therapy. TETAMI randomized patients had better outcomes than registry patients who did not receive reperfusion therapy.

The major obstacle to expanding the delivery of reperfusion therapy to patients with STEMI is the large fraction of patients who present too late for reperfusion therapy. Examination of prospectively gathered data on STEMI patients who are ineligible for reperfusion may help optimize their treatment.

[Comparison of dobutamine echocardiography and rest-redistribution 201-thallium SPECT in the assessment of myocardial viability taking PET as gold standard]

BACKGROUND AND AIM

To compare Tl-201 SPECT and dobutamine stress echocardiography for the detection of myocardial viability in patients with severe left ventricular dysfunction using metabolic imaging by positron emission tomography as the standard reference.

MATERIAL AND METHODS

We studied 25 consecutive patients with severe coronary artery disease and left ventricular dysfunction that underwent two different diagnostic modalities for evaluating myocardial viability: stress echocardiography with incremental doses of dobutamine from 5 up to 40 g/kg/min in 3 min stages, and 201 Tl SPECT using a rest-redistribution protocol with delayed images obtained at 4 hours. Fluorodeoxyglucose uptake by PET was used as the gold standard. Viability criteria were as follows, for 201Tl SPECT imaging: normal uptake at rest and presence of redistribution in the delayed images, for dobutamine stress echocardiography: sustained improvement and biphasic response.

RESULTS

Sensitivity of thallium redistribution was 46%, for normal uptake, plus redistribution 82%, 34% for dobutamine biphasic response and 58% for sustained improvement plus biphasic response. Specificity of biphasic response was 82% and that of redistribution 67%. Stepwise logistic regression indicated that biphasic wall motion response during dobutamine stress echocardiography (2.01 CI 95%; 1.10 to 3.99) and the presence of redistribution plus normal uptake at rest with thallium imaging (2.68 CI 95%; 1.42 to 5.13) were the best predictors of viability. These results were the same when both techniques were analyzed together.

CONCLUSIONS

Biphasic wall motion response during dobutamine stress echocardiography and the normal uptake plus presence of redistribution with thallium imaging were the best pre

Medical management of mild-to-moderate heart failure before the advent of beta blockers

Clinical trials of beta blockers in heart failure have generally required that patients be receiving optimal drug therapy before randomization to the study medication. Therefore, because beta blockers are used in addition to conventional drug therapy, review of the standard drug therapy of mild-to-moderate heart failure before the advent of beta blockade is essential to understanding the role of beta blockers in the treatment of heart failure. The conventional medical management of systolic heart failure includes angiotensin-converting enzyme (ACE) inhibitors, which should be used as first-line therapy; diuretics, for the management of body fluid-volume excess; digoxin; and some other vasodilators. These therapies have been evaluated in large-scale, randomized, controlled trials. ACE inhibitors have been shown to significantly attenuate disease progression and improve outcome (ie, morbidity and mortality) in patients with mild-to-moderate systolic heart failure. Controversial or unproven therapies include nonglycoside inotropic agents, angiotensin II receptor antagonists, antiarrhythmic agents, anticoagulants, and calcium channel blockers. The pharmacologic management of diastolic heart failure is largely empirical and is directed at reducing symptoms. Symptoms caused by increased ventricular filling pressures may be treated with diuretics and long-acting nitrates. Some calcium channel blockers and most beta blockers prolong diastolic filling time by slowing heart rate, thereby potentially improving the symptoms of diastolic heart failure. Calcium antagonists, beta blockers, diuretics, and ACE inhibitors may also promote regression of left ventricular hypertrophy and thus improve ventricular compliance, possibly preventing the development of diastolic dysfunction. Because randomized controlled trials of diastolic heart failure are lacking, this review focuses on the conventional management of mild-to-moderate systolic heart failure before the advent of beta blockade.

Heart failure in women

Heart failure affects more than 5 million Americans. Each year, about 400,000 individuals develop heart failure, making it the nation's most rapidly growing cardiac problem. Almost one third of these individuals have New York Heart Association Functional Class III or IV heart failure and are faced with progressive clinical deterioration and frequent hospital admissions. These figures will continue to escalate as the population ages. The success of interventional procedures and pharmacologic therapies in the management of coronary artery disease has enabled this population to survive acute events, at the same time creating a population with chronic disease. Common etiologies of heart failure in women include coronary artery disease, myocardial infarction, and valvular disease. However, women are at especially high risk for developing heart failure due to diastolic dysfunction associated with hypertension and diabetes. Heart failure in women is best managed across the care continuum, incorporating pharmacologic agents, interventional procedures when appropriate, dietary restrictions, self-monitoring, and psychosocial support. Much of the recent literature has focused on women and heart disease. This emphasis is partly due to public misconception about women's health problems and the growing body of research distinguishing gender differences. Significant advances in therapy have been made to improve the quality and span of life for people with heart disease. Despite therapeutic advances, however, women have high mortality rates from heart disease, including heart failure due to ischemic causes. In fact, women with heart failure present differently than men and have different etiologies and treatment options. As we learn more about women and heart disease, the distinguishing differences unfold and become helpful in establishing a plan of care.

[Thallium-201 scintigraphy and dobutamine echocardiography in the assessment of myocardial viability]

BACKGROUND

The possibility of differentiating viable from non-viable tissue among patients with severe coronary artery disease and severe left ventricular impairment entails relevant clinical and therapeutic implications since it may influence the indication of patient revascularization. To evaluate the presence of myocardial viability two techniques are available in the clinical setting: echocardiography with intravenous infusion of dobutamine and scintigraphy with myocardial perfusion with thalliem-201 by means of single-photon emission tomography.

OBJECTIVE

To compare prospectively the value of these techniques for detecting viable myocardium.

MATERIAL AND METHODS

Thirty-five patients with severe coronary disease and severe left ventricular dysfunction were included in the study. All patients underwent an echocardiogram using incremental doses of dobutamine, from 5 up to 40 micrograms/kg/min in three-minute periods. For thallium-201 scintigraphy the rest redistribution protocol with delayed images at 4 hours was used. The criteria for detecting viability were: a) for thallium-201, the presence of redistribution in delayed images and normal uptake at rest, and b) for dobutamine echocardiography, a sustained improvement in regional motion, biphasic response, and worsening.

RESULTS

By considering the segmental improvement post-revascularization as "gold standard" of viability, the statistically significant variables in a logistic regression model and, therefore, predictors of segmental functional recovery were the biphasic response and the sustained response for dobutamine echocardiography and normal uptake at rest and redistribution in the delayed images for thallium-201. Taken together, the result was significant for the biphasic response of dobutamine echocardiography.

CONCLUSIONS

The biphasic response with dobutamine echocardiography is the echocardiographic pattern that best predicts the functional recovery of the ischemic myocardium. A normal uptake and redistribution at four hours is the only scintigraphic pattern that can predict functional improvement. Of both patterns, the biphasic response is the best predictor of the functional recovery of the dysfunctional myocardium.

Percutaneous transluminal coronary angioplasty performed 24-48 hours after the onset of acute myocardial infarction improves chronic-phase left ventricular regional wall motion

The authors investigated the capacity of percutaneous transluminal coronary angioplasty (PTCA) performed 24-48 hours after the onset of acute myocardial infarction (AMI) to improve regional left ventricular wall motion. Twenty-four patients were divided into two groups: a PTCA group who received successful PTCA (14 cases) and a non-PTCA group (10 cases) who did not receive PTCA. Left ventricular end-diastolic volume (LVEDV) increased significantly (p<0.01) from 57+/-14 mL/m2 during the acute phase to 83+/-16 mL/m2 during the chronic phase in the non-PTCA group, whereas no significant change in LVEDV was seen in the PTCA group (69+/-26 vs. 76+/-16 mL/m2). In addition, in patients with 99% stenosis/thrombolysis in myocardial infarction (TIMI) grade 3 flow, increases in regional left ventricular wall motion (delta(sd)/chord) at the infarcted site between the acute and chronic phases were significantly greater in the PTCA group than in the non-PTCA group (2.49+/-1.05 vs. 0.67+/-0.65, p<0.01). PTCA performed 24-48 hours after the onset of AMI improved wall motion at the infarcted site.

Hypoxic Hypoperfusion Fails to Induce Myocardial Hibernation in Anesthetized Swine

BACKGROUND: Congenital origin of the left coronary artery from the pulmonary artery (ALCAPA) results in chronically dysfunctional myocardium with the partial ability to recover after revascularization. We attempted to establish an ALCAPA syndrome in anesthetized pigs for 24 hours and to compare it with stunned and infarcted myocardium. METHODS AND RESULTS: In group 1 (n = 12), a bypass graft was interposed between the pulmonary artery and the left anterior descending coronary artery (LAD). Reduction of flow in the LAD with gradual increases in flow from the pulmonary artery resulted in an incremental reduction of segment shortening (8.9 +/- 5.3% at 24 hours vs 26.6 +/- 10% at baseline, P <.005). In group 3 (n = 5), 2 cycles of 10-minute LAD occlusion resulted in decreased segment shortening with slow recovery (at 24 hours 18.7 +/- 1.3% vs 24.2 +/- 4% at baseline, segment shortening with slow recovery (at 24 hours 18.7 +/- 1.3% vs 24.2 +/- 4% at baseline, P <.05). In group 3 (n = 6), 1-hour LAD occlusion reduced segment shortening at 24 hours to 4.7 +/- 5.2% (P <.005 vs baseline). Histological analysis of the LAD territory revealed severe degeneration, myolysis, and alteration of the chromatin structure in group 1 comparable to ischemic cell death in group 3, whereas control areas and the LAD area in group 2 showed only minor structural alterations. Infarct size/risk area, as measured by tetrazolium staining, was 49.8 +/- 11.2% in group 1, 9.3 +/- 8.1% in group 2 (P <.005), and 60.3 +/- 9% in group 3. CONCLUSION: Hypoxic myocardial hypoperfusion from the pulmonary artery results in myocardial necrosis in anesthetized pigs. These findings are in contrast to the concept of myocardial hibernation in the ALCAPA syndrome because in this model, hypoxic hypoperfusion failed to induce adaptation to preserve myocardial structure.

Stress-induced reversible and mild-to-moderate irreversible thallium defects: are they equally accurate for predicting recovery of regional left ventricular function after revascularization?

BACKGROUND

In patients with coronary artery disease, stress-redistribution-reinjection thallium scintigraphy provides important information regarding myocardial ischemia and viability. Although both reversible and mild-to-moderate irreversible thallium defects retain metabolically active, viable myocardium, we hypothesized that stress-induced reversible thallium defects may better differentiate reversible from irreversible regional left ventricular dysfunction after revascularization.

METHODS AND RESULTS

Twenty-four patients with chronic coronary artery disease underwent prerevascularization and postrevascularization exercise-redistribution-reinjection thallium single photon emission CT, gated MRI, and radionuclide angiography. After revascularization, mean left ventricular ejection fraction increased from 30+/-9% to 37+/-13% at rest (P<0.001). Before revascularization, abnormal contraction at rest was observed in 56 of 110 reversible and 20 of 37 mild-to-moderate irreversible thallium defects (51% and 54%, respectively). After revascularization, regional contraction improved in 44 of 56 reversible compared with 6 of 20 mild-to-moderate irreversible thallium defects (79% and 30%, respectively; P<0.001). The final thallium content (maximum tracer uptake on redistribution-reinjection images) was significantly higher in regions with reversible defects that improved than in those that did not improve after revascularization (86+/-16% versus 66+/-9%, P<0.001). In contrast, final thallium content was similar in regions with mild-to-moderate irreversible defects that improved and in those that did not improve after revascularization (69+/-9% versus 65+/-10%, P=NS). Furthermore, when asynergic regions were grouped according to the final thallium content, at 60% threshold value, functional recovery was observed in 83% of regions with reversible defects compared with 33% of regions with mild-to-moderate irreversible defects (P<0.001).

CONCLUSIONS

These findings suggest that although both reversible and mild-to-moderate irreversible thallium defects after stress retain viable myocardium, the identification of reversible thallium defect on stress in an asynergic region more accurately predicts recovery of function after revascularization. Even at a similar mass of viable myocardial tissue (as reflected by the final thallium content), the presence of inducible ischemia is associated with an increased likelihood of functional recovery.

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.

Does dobutamine stress echocardiography induce damage during viability diagnosis of patients with chronic regional dysfunction after myocardial infarction?

Experimental hibernating-model investigations of animals have shown that myocardial necrosis can be induced by longer-term intracoronary dobutamine infusion. This study was designed to determine whether myocardial infarction could be ascertained in patients with chronic regional wall motion abnormalities and greater than 75% stenosis in the supplying coronary artery through dobutamine stress echocardiography. Twenty patients with coronary artery disease and regional resting wall motion abnormalities were examined with a standard dobutamine protocol (5 to 50 microg/kg/min). Exclusion criteria were an acute coronary syndrome, severe heart failure, and severe hypertension. Creatine kinase (CK, CKMB), myoglobin, and troponine-I were measured before and at each of the first 7 hours after beginning of infusion. Fourteen of these 20 patients exhibited viable myocardium. The serum markers CK, CKMB, myoglobin, and troponin-I demonstrated no increase beyond the reference range, suggesting that with this protocol, no myocardial necrosis was induced.

Coronary recanalization by elective angioplasty prevents ventricular dilation after anterior myocardial infarction

OBJECTIVES

In a prospective study we evaluated whether late recanalization of the left anterior descending coronary artery (LAD) affects ventricular volume and function after anterior myocardial infarction.

BACKGROUND

Persistent coronary occlusion after anterior myocardial infarction leads to ventricular dilation and heart failure.

METHODS

We studied 73 consecutive patients with acute anterior myocardial infarction as a first cardiac event; all had an isolated lesion or occlusion of the proximal LAD. Six patients died before hospital discharge. The 67 survivors were classified into two groups: group I (patent LAD and good distal flow, n = 40) and group II (LAD occlusion or subocclusion, n = 27). The 20 patients in group I who had significant residual stenosis and all patients in group II underwent elective percutaneous transluminal coronary angioplasty (PTCA) within 18 days of myocardial infarction. The procedure was successful in 17 patients in group I (group IB) and in 16 patients in group II (group IIA): in the remaining 11 patients of group II, patency could not be reestablished (group IIB). Left ventricular volumes, ejection fraction and a dysfunction score were measured by echocardiography on admission, before PTCA, at discharge and after 3 and 6 months.

RESULTS

Although cumulative ST segment elevation was similar in groups I and II, ejection fraction and dysfunction score were significantly worse in group II. However, ventricular function and volumes progressively improved in group IIA, whereas group IIB exhibited progressive deterioration of function (dysfunction score [mean +/- SD] increased from 21 +/- 6 to 25 +/- 8, p < 0.05; ejection fraction decreased from 43 +/- 10% to 37 +/- 11%, p < 0.05); and end-systolic volume increased from 34 +/- 10 to 72 +/- 28 ml/m2, p < 0.05). Patients in group IIB also had worse effort tolerance, higher heart rate at rest, lower blood pressure and significantly greater prevalence of chronic heart failure.

CONCLUSIONS

Delayed PTCA of an occluded LAD can frequently restore vessel patency. Success appears to be associated with better ventricular function and a lack of chronic dilation. Large randomized studies are warranted to evaluate the effect of delayed PTCA on late mortality.

Recovery of regional left ventricular dysfunction after coronary revascularization. Impact of myocardial viability assessed by nuclear imaging and vessel patency at follow-up angiography

OBJECTIVES

This study sought to evaluate an imaging approach using technetium-99m sestamibi scintigraphy and positron emission tomography with fluorine-18 fluorodeoxyglucose for assessment of myocardial viability proved by serial quantitative left ventricular angiography. Furthermore, the influence of successful long-term revascularization on functional recovery was studied.

BACKGROUND

Previous studies using positron emission tomography of myocardial perfusion and metabolism have demonstrated accurate identification of myocardial viability. However, most of these studies used a qualitative or semiquantitative wall motion analysis approach.

METHODS

Nuclear imaging with semiquantitative analysis of tracer uptake was performed in 193 patients with regional wall motion abnormalities. Regions were categorized as normal, viable with perfusion/metabolism mismatch, viable without mismatch (intermediate) and scar. Seventy-two of 103 patients with subsequent revascularization underwent follow-up angiography. In 52 of 72 patients, changes in regional wall motion were measured by the centerline method from serial angiography.

RESULTS

Wall motion improved in mismatch regions from -2.2 +/- 1.0 to -1.1 +/- 1.4 SD (p < 0.001). In contrast, regions with an intermediate pattern and those with scar did not improve. Restenosis or graft occlusion influenced functional outcome because regions with preoperative mismatch and successful long-term revascularization improved at follow-up (from -2.3 +/- 1.0 to -0.8 +/- 1.4 SD, p < 0.001), whereas wall motion did not change with recurrent hypoperfusion. Metabolic imaging added diagnostic information, particularly in regions with mild and moderate perfusion defects.

CONCLUSIONS

This imaging approach allows detection of viability in regions with myocardial dysfunction. Wall motion benefits most in myocardium with perfusion/metabolism mismatch and successful long-term revascularization.

Myocyte degeneration and cell death in hibernating human myocardium

OBJECTIVES

The aim of this study was to analyze the morphologic characteristics of myocyte degeneration leading to replacement fibrosis in hibernating myocardium by use of electron microscopy and immunohistochemical techniques.

BACKGROUND

Data on the ultrastructure and the cytoskeleton of cardiomyocytes in myocardial hibernation are scarce. Incomplete or delayed functional recovery might be due to variable degree of cardiomyocyte degeneration in hibernating myocardium.

METHODS

In 24 patients, regional wall motion abnormalities were analyzed by use of the centerline method before and 6 +/- 1 months after coronary artery bypass surgery. Preoperative technetium-99m sestamibi uptake was measured by single-photon emission computed tomography for assessing regional perfusion. Fluorine-18 fluorodeoxyglucose uptake was measured by positron emission tomography to assess glucose metabolism. Transmural biopsy specimens were taken during coronary artery bypass surgery from the center of the hypocontractile area of the anterior wall.

RESULTS

The myocytes showed varying signs of mild-to-severe degenerative changes and an increased degree of fibrosis. Immunohistochemical analysis demonstrated disruption of the cytoskeletal proteins titin and alpha-actinin. Electron microscopy of the cell organelles and immunohistochemical analysis of the cytoskeleton showed a similarity in the degree of degenerative alterations. Group 1 (n = 11) represented patients with only minor structural alterations, whereas group 2 (n = 13) showed severe morphologic degenerative changes. Wall motion abnormalities showed postoperative improvements, and nuclear imaging revealed a perfusion-metabolism mismatch without significant differences between the groups.

CONCLUSIONS

Long-term hypoperfusion causes different degrees of morphologic alterations leading to degeneration. Preoperative analysis of regional contractility and perfusion-metabolism imaging does not distinguish the severity of morphologic alterations nor the functional outcome after revascularization. The insufficient act of self-preservation in hibernating myocardium may lead to a progressive structural degeneration with an incomplete and delayed recovery of function after restoration of blood flow.

Clinical importance of viability assessment in chronic ischemic heart failure

BACKGROUND AND HYPOTHESIS

Revascularization has provided an effective treatment of depressed left ventricular function in patients with chronically ischemic or "viable" myocardium. Assessment of viable myocardium can be achieved by several noninvasive techniques including dobutamine stress echo or radionuclides such as flurodeoxyglucose (F18DG). F18DG uptake studies are based on the assumption that enhanced glucose uptake in areas of diminished blood flow provides evidence of viable myocardium. To determine the clinical utility of viability assessment in the management of chronic ischemic left ventricular dysfunction, we reviewed the findings and short-term treatment of a series of patients referred for heart failure evaluation who had subsequent F18DG uptake scans.

METHODS

We retrospectively reviewed 59 consecutive F18DG viability studies in a series of patients who had documented coronary artery disease and depressed left ventricular function. Single photon emission computerized tomography (SPECT) with F18DG was performed in the patients and these images were compared to SPECT images of resting myocardial perfusion using thallium, sestamibi, or teboroxime. Clinical decisions based on the results of these scans were obtained from chart review. Thirty-day mortality was determined from chart review or contact with the patient's physician. The patients were divided into those without and with F18DG uptake consistent with viable ischemic myocardium. Further analysis included subgroups of patients who were advised to undergo transplantation, revascularization, or to continue medical therapy.

RESULTS

Of 34 patients referred for cardiac transplantation, 18 had viable myocardium and 13 underwent revascularization. In the entire study group, 34 of 59 (58%) had evidence of viable myocardium and 29 had subsequent revascularization procedures. Thirty-day survival for all revascularization patients was 86%.

CONCLUSION

Assessment of myocardial viability with F18DG SPECT imaging in patients with ischemic left ventricular dysfunction led to a clinical decision for revascularization in approximately half the patients with severe coronary disease and left ventricular dysfunction who were evaluated for myocardial viability in our institution.

Assessment of hibernating myocardium by dobutamine stimulation in a canine model

OBJECTIVES

The purpose of this study was to 1) develop an animal model of hibernating myocardium, and 2) evaluate the ability of dobutamine stimulation to detect hibernating myocardium using both qualitative and quantitative assessment of regional myocardial function.

BACKGROUND

Left ventricular dysfunction may be due to chronic ischemia with or without myocardial infarction and may improve after coronary blood flow is enhanced by revascularization procedures. This condition has been coined "hibernating myocardium" and variably defined in recent years. The results of recent clinical studies suggest that dobutamine echocardiography may be useful for detecting viable myocardium in patients with left ventricular dysfunction.

METHODS

Twenty-one dogs underwent initial operation. Sonomicrometer crystals were implanted, and baseline measurements of segment shortening and wall thickening (by echocardiography) were made. A coronary artery was ligated; the chest was closed; and measurements were repeated. Dobutamine was incrementally infused with determination of wall thickening and segment shortening at baseline and on days 3 and 7 and weeks 2 and 4 after coronary artery occlusion. Finally, the chest was reopened; the ligated vessel was bypassed; and measurements were repeated.

RESULTS

Of the 10 dogs that completed the entire protocol, 7 had varying degrees of nontransmural myocardial infarction (group 1), and 3 had complete transmural myocardial infarction (group 2). In group 1, baseline function was significantly impaired compared with preligation function but increased during dobutamine infusion. When reperfused after 4 weeks, both wall thickening and segment shortening increased significantly. In group 2, significant changes were not seen during the dobutamine studies or after reperfusion. Myocardial perfusion during dobutamine infusion increased in group 1 but did not change in group 2.

CONCLUSIONS

We demonstrated improvement in chronically dysfunctional myocardium after restoration of previously interrupted myocardial blood flow in dogs after nontransmural myocardial infarction, thus validating a canine model of hibernating myocardium. As assessed by two independent methods, dobutamine infusion identified hibernating myocardium in an animal model.

Results of revascularization in patients with severe left ventricular dysfunction

BACKGROUND

In patients with coronary artery disease and poor ventricular function (ejection fraction, < 20%), bypass grafting remains a surgical challenge. This study evaluates experience with isolated revascularization in such patients.

METHODS AND RESULTS

In 79 consecutive patients (69 men, 10 women; average age, 59 +/- 9 years), preoperative ejection fraction was 18 +/- 5%. Indications for surgery were congestive heart failure (CHF) in 5 of 79 patients (6%), CHF and angina in 19 (24%), angina in 41 (52%), ventricular arrhythmias (VAs) in 8 (10%), and critical anatomy in 6 (8%). Some patients had prior VAs (23 of 79; 29%) or mitral regurgitation (18; 23%) and required emergent surgery (25; 32%). At surgery, temperature mapping ensured adequate distribution of antegrade cold cardioplegia, with 3.6 +/- 0.7 grafts per patient, including left internal mammary artery graft in 60 of 79 (76%) and endarterectomy in 14 (18%). Hospital mortality was 3.8%. Perioperative support included intra-aortic balloon pump in 18 of 79 (23%) and drugs for VAs in 28 (35%). Morbidity included myocardial infarction in 2 of 79 (2.5%) and stroke in 2 (2.5%). During follow-up, there were 19 late deaths. Actuarial survival was 94%, 82%, and 68% at 1, 2, and 5 years, respectively, and was similar in patients with severe angina, CHF, mitral regurgitation, or VAs. Freedom from sudden death was 100%, 98%, and 91% at 1, 2, and 5 years, respectively. Among survivors, angina improved in 84% and heart failure improved in 26%.

CONCLUSIONS

These data support bypass graft surgery in patients with severe LV dysfunction. With careful cardioplegic techniques, hospital mortality was low (3.8%). Long-term survival is encouraging, with good relief of symptoms in most patients. Perioperative VAs are frequent but respond to medical treatment, with only 23% of patients discharged on antiarrhythmic drugs. Five-year freedom from sudden death is 91%, with only 3 late sudden deaths in this series.

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

Hibernating myocardium is defined as persistently impaired myocardial and left ventricular (LV) function at rest resulting from reduced myocardial blood flow. It may occur in unstable angina and chronic stable angina, acute myocardial infarction, and LV dysfunction and congestive heart failure. Recovery of the hibernating myocardium has clearly been shown to occur with the establishment of successful revascularization either by coronary bypass surgery or by percutaneous transluminal coronary angioplasty. It may be possible to show recovery of the viable myocardium by reducing myocardial oxygen demand and/or by increasing coronary blood flow with pharmaceutical agents.

Maximal myocardial perfusion by videodensitometry in the assessment of the early and late results of coronary angioplasty: relationship with coronary artery measurements and left ventricular function at rest

In the assessment of the acute results of percutaneous transluminal coronary angioplasty (PTCA), myocardial perfusion at maximal vasodilatation theoretically has fewer limitations than the coronary flow reserve measurements and quantitative coronary angiography. The purpose of this study was to compare the myocardial perfusion to the measurements of the severity of the lesion (minimal luminal diameter and percent area stenosis) and to relate it to the changes of left ventricular function after PTCA. Regional myocardial perfusion was assessed during intracoronary papaverine, using the inverse mean transit time of contrast medium (1/Tmn), before, 15 min after, 18-24 hr after, and 6 months after successful single-vessel PTCA in 14 patients with stable angina. Left ventricular angiography (before angioplasty, 18-24 hr after, and 6 months later) was analysed by area-length and centerline methods. Immediately after PTCA, 1/Tmn increased from 0.14 +/- 0.07 sec-1 to 0.21 +/- 0.09 sec-1 (P = .001). Maximal myocardial perfusion remained higher than the pre-PTCA value the day after angioplasty (1/Tmn of 0.23 +/- 0.09 sec-1), while it reduced to near pre-PTCA values at follow-up (1/Tmn of 0.16 +/- 0.05 sec-1). Before PTCA, three out of ten patients had ejection fraction of < 65%, and seven had mild-to-moderate hypokinesis. The day after PTCA the ejection fraction and the regional dysfunction improved significantly. The change in ejection fraction 18-24 hr after PTCA did not correlate with minimal luminal diameter and percent area stenosis and correlated slightly with the improvement of perfusion (r = 0.54, P = .10). At follow-up left ventricular function deteriorated in the whole group, despite the persistence of angiographic success of PTCA, possibly because of changes in the loading condition. Coronary artery stenosis measurements and 1/Tmn failed to correlate with the left ventricular function. Given the difficulties in routine application of the analysis of time-density curves, the measurement of minimal luminal diameter remains a more practical assessment of the results of the intervention. However, the improvement of myocardial perfusion may give more information than coronary artery dimensions of the early recovery of left ventricular function.

Rest technetium 99m-sestamibi tomoscintigraphy in hibernating myocardium

The myocardial uptake of rest-injected technetium 99m sestamibi on single-photon-emission computed tomographic images was assessed in 25 patients. All had an area of myocardial dysfunction that could be related to a coronary artery stenosis. None of the patients had clinical evidence of a myocardial infarction. Three months after revascularization, viability was demonstrated by contrast angiography and center-line analysis in 21 (78%) of the 27 formerly hibernating territories. Among these, none had a transmural defect, and 38% had a normal technetium 99m-sestamibi uptake. The four transmural preoperative defects were located in territories without viability. Eight of the 9 territories that were normal at scintigraphy proved to be viable postoperatively. It is concluded that as long as some residual technetium 99m-sestamibi uptake is present, viable myocardium is also present.

Myocardial hibernation

From available results, the following schematic can be drawn: Reductions in perfusion pressure are not associated with impaired ventricular function as long as they take place within the autoregulatory range. Additional reductions in perfusion pressure that moderately diminish coronary blood flow will result in a particular ischemia with decreased but stable function: perfusion and contraction match, the myocardium hibernates. The process responsible for this new equilibrium could be termed down regulation of function. The trigger inducing hibernation is so far unknown. The strategy, however, is similar to that used by hibernating animals. Likewise, myocardial hibernation is a protective mechanism. As hibernators recover initial function after unfavourable periods are terminated, hibernating myocardium recovers after institution of physiologic perfusion. It is under debate, whether function quickly recovers or remains temporarily depressed. As hibernating animals might finally even die, if unfavourable periods last too long, myocardium might become irreversibly injured due to ischemia lasting too long. Additional reductions in perfusion pressure and oxygen supply below the hibernating range produce ischemia in the more classical sense, because oxygen supply and demand no longer match. Damage will become irreversible in case the situation persists longer than about 20 min. After onset of reperfusion, the myocardial function would remain depressed, however, for a considerable period: myocardial stunning. Considering the regional heterogeneities of myocardial blood flow, distinct differentiation between moderate and severe ischemia is difficult. Ischemia will induce more articulate damage in subendocardial than in subepicardial layers. Similarly, damage in the ischemic core will be more pronounced than in the border zone.(ABSTRACT TRUNCATED AT 250 WORDS)

Discrepancy between pre- and post-transplant diagnosis of end-stage dilated cardiomyopathy

A pretransplant diagnosis was compared with the diagnosis made after macroscopic and microscopic examination of the explanted hearts in 112 cardiac transplant recipients. A coronary angiogram was recorded in 87.5% and endomyocardial biopsy was performed in 12.5% of patients within 1 year of the transplant. Echocardiograms were obtained in all patients. Before transplantation, 57.1% of patients were classified as having ischemic cardiomyopathy and 33.9% were classified as having idiopathic dilated cardiomyopathy (IDC). At explantation, severe coronary artery disease was found in all patients with a pretransplant diagnosis of ischemic cardiomyopathy, in 9 patients with a pretransplant diagnosis of IDC (6 of them had a "normal" pretransplant angiograms), and in 3 of the 4 patients with presumptive alcoholic cardiomyopathy. Left ventricular hypertrophy, undetected on echocardiography, was found at autopsy in 11 patients with presumed IDC, and acute myocarditis was found in 3 patients with a pretransplant diagnosis of IDC. A correct pretransplant diagnosis can lead to different management (e.g., bypass surgery rather than transplant), and may also portend different pre- and post-transplant prognoses. The results of this study suggest that an "in-depth" search for a cause should be conducted in all patients with heart failure, regardless of their clinical presentation. Our study also emphasizes the limitations of coronary angiography and echocardiography in patients with IDC and the need for improving current diagnostic techniques in these patients.

Dobutamine echocardiography and resting-redistribution thallium-201 scintigraphy predicts recovery of hibernating myocardium after coronary revascularization

The value of dobutamine echocardiography and resting thallium-201 scintigraphy to predict reversal of regional left ventricular wall motion dysfunction after revascularization in patients with chronic coronary artery disease was assessed. Improvement in wall motion during dobutamine echocardiography and normal or mildly decreased uptake on thallium-201 scanning are strong predictors of reversible left ventricular dysfunction. Dobutamine echocardiography and resting thallium-201 scanning are simple and safe methods of assessing hibernating myocardium.

Electrocardiographic and segmental wall motion abnormalities in pancreatitis mimicking myocardial infarction

Transient electrocardiographic changes in patients with acute cholecystitis, pancreatitis, and pneumonia have been reported in the past. These changes usually are in the form of T-wave inversion, ST-segment depression, and rarely ST-segment elevation in the absence of coronary artery disease. To the authors' knowledge, this is the first report documenting both left ventricular segmental wall motion abnormality and electrocardiographic changes of myocardial injury in the presence of acute pancreatitis.

Current status of myocardial perfusion imaging after percutaneous transluminal coronary angioplasty

Controversy exists with regard to the diagnostic accuracy and optimal technique of myocardial perfusion imaging after coronary angioplasty. Exercise treadmill testing is inexpensive, with adequate predictive value for restenosis and clinical events in patients with single-vessel coronary angioplasty with a normal rest electrocardiogram (ECG). Myocardial tomography has advantages for assessing patients with multivessel coronary angioplasty. Exercise stress imaging is generally preferable to pharmacologic stress in patients without physical limitations after angioplasty. Delayed thallium-201 imaging and reinjection protocols may be useful to reconcile whether residual ischemia exists in "fixed" perfusion defects. Appropriately timed stress myocardial perfusion imaging 2 to 4 weeks after procedurally successful coronary angioplasty can document improved cardiac functional capacity and reduced ECG and imaging evidence of myocardial ischemia. Although routine serial postangioplasty evaluations cannot be recommended, stress myocardial imaging may be valuable in subjects with defective anginal nociception or extensive myocardium at risk in the area subtended by the angioplasty vessel.

Effects of coronary angioplasty on left ventricular function

It is well known that myocardial revascularization after successful coronary bypass surgery results in improved left ventricular function. Coronary angioplasty also results in successful revascularization, favorably affecting both stunned and hibernating myocardium. We studied 22 patients with chronic stable angina who underwent successful angioplasty for an isolated narrowing of the proximal or midportion of the left anterior descending artery. These patients also performed isometric exercises before and after angioplasty, which can be used to characterize left ventricular function. Revascularization after angioplasty induced an immediate improvement in left ventricular function in those patients with dysfunction secondary to hibernating myocardium. Further studies are needed to assess the possibility of the myocardial stunning phenomenon occurring after angioplasty in those patients without left ventricular improvement.

Coronary bypass with ejection fraction of 0.20 or less using centigrade cardioplegia: long-term follow-up

Forty-two patients with an ejection fraction of 0.20 or less underwent coronary artery bypass grafting from 1986 to 1990 using a method of myocardial protection we term "centigrade cardioplegia," combining single-dose, cold, crystalloid cardioplegia, systemic hypothermia, and local hypothermia. Thirty-day mortality was 4.8% (2/42). Perioperative morbidity included two myocardial infarctions (4.8%) and one stroke (2.4%), which fully resolved. Postoperative left ventricular function improved (left ventricular ejection fraction, 0.157 +/- 0.028 to 0.226 +/- 0.085; p < 0.0002), as did New York Heart Association class (3.4 +/- 0.73 to 1.8 +/- 0.63; p < 0.0001) and Canadian class (3.3 +/- 0.81 to 0.61 +/- 0.92). Survival, 88% at 1 year, declined to 68% at 3 years and 34% at 6 years. This high-risk group had very acceptable short-term results, indicating adequate intraoperative myocardial protection. Four clinical variables were associated with long-term survival: (1) chief complaint of pain only (p = 0.05), (2) history of unstable angina (p = 0.04), (3) Canadian class less than IV (p = 0.05), and (4) New York Heart Association class less than IV (p = 0.05). Reduced survival, although not statistically significant (p = 0.07), was noted for right ventricular ejection fraction of 0.30 or less. These factors may help predict which patients with severe left ventricular dysfunction will benefit from revascularization.

Benefit of late coronary reperfusion on ventricular morphology and function after myocardial infarction

OBJECTIVES

This study was designed to examine the relation between the timing and adequacy of perfusion of the infarct bed and changes in ventricular size and the extent of abnormal wall motion after acute myocardial infarction.

METHODS

A validated echocardiographic mapping technique was used to measure the left ventricular endocardial surface area index and the extent of abnormal wall motion over a 3-month period in 91 patients who had either 1) no anterograde or collateral flow to the infarct bed (n = 14), 2) only collateral flow to the infarct bed (n = 18), 3) restoration of anterograde flow to the infarct bed within hours of chest pain (early [n = 43]), or 4) restoration of anterograde flow to the infarct bed within a mean of 5 days after acute myocardial infarction (late [n = 16]).

RESULTS

Over the follow-up period, a progressive and significant increase in endocardial surface area index was observed only in the group of patients without anterograde or collateral flow to the infarct bed (entry 64 +/- 3.4 cm2/m2 vs. 3 months 75.9 +/- 6.4 cm2/m2, p < 0.005). In contrast, a progressive reduction in the extent of abnormal wall motion was evident in the group of patients in whom anterograde flow to the infarct bed was restored within hours (entry 26.7 +/- 2.5 cm2 vs. 3 months 11.8 +/- 2.9 cm2, p < 0.001) or days (entry 22.1 +/- 3.6 cm2 vs. 3 months 11.8 +/- 3.3 cm2, p < 0.001) of coronary occlusion. Multiple stepwise linear regression analysis confirmed that by 3 months, 1) ventricular size was independently related to endocardial surface area index and abnormal wall motion at entry (p < 0.0001) and to the change in abnormal wall motion over the follow-up period (p < 0.0001), and 2) the change in abnormal wall motion was related to the presence of anterograde flow to the infarct bed (p < 0.0001) independent of the timing of reperfusion, infarct site or the extent of abnormal wall motion on admission.

CONCLUSIONS

After myocardial infarction, the process of ventricular remodeling is influenced by changes in the extent of abnormal wall motion, which in turn are related to the adequacy rather than the timing of perfusion of the infarct bed.

Resting thallium-201 scintigraphy for identifying viable myocardium in a patient with severe left ventricular dysfunction

Recognizing patients with coronary artery disease in whom severe left ventricular dysfunction is attributed to a chronic decrease in myocardial blood flow without infarction is often difficult but important because such patients may benefit from surgical revascularization. Herein we describe a patient with severe left ventricular dysfunction who had appreciable resting wall motion abnormalities; tomographic thallium-201 myocardial scintigraphy performed while the patient was resting identified viable myocardium. Subsequent revascularization improved regional and global left ventricular function considerably.

Myocardial hibernation in the infarcted region cannot be assessed from the presence of stress-induced ischemia: usefulness of delayed image of exercise thallium-201 scintigraphy

To examine the relationship between the improvement of wall motion in infarcted regions after percutaneous transluminal coronary angioplasty (PTCA) and thallium-201 uptake in the delayed image of exercise thallium-201 scintigraphy before PTCA, 14 patients with anterior old myocardial infarction were studied. Exercise thallium-201 scintigraphy was performed before PTCA of left anterior descending artery, and mean percent thallium-201 uptake of abnormal segments was calculated in the initial and 4-hour delayed images. Left ventricular angiography was performed during catheterization, before, and 4 to 13 months after PTCA; and regional ejection fraction of anterior wall was calculated. Atrial pacing stress test with the measurement of lactate concentration of aorta and great cardiac vein was performed during catheterization before PTCA. In five patients with mean percent thallium-201 uptake in the delayed image < or = 50% (group I), regional ejection fraction did not increase after PTCA (23% +/- 9% to 24% +/- 12%). In the other nine patients with mean percent thallium-201 uptake > 50% (group II), regional ejection fraction increased significantly after PTCA (39% +/- 18% to 47% +/- 14%; p < 0.05). There was no significant difference in regional ejection fraction, lactate extraction ratio during maximal pacing, and the redistribution of exercise thallium-201 scintigraphy between the two groups before PTCA. Thus the delayed image before PTCA is useful to detect reversible nonfunctioning viable myocardium (hibernating myocardium) in the infarcted region. However, the wall-motion abnormality and the degree of stress-induced ischemia in the infarcted region before PTCA may not be necessarily useful for the detection of hibernating myocardium.

Ischemic cardiomyopathy: endomyocardial biopsy and ventriculographic evaluation of patients with congestive heart failure, dilated cardiomyopathy and coronary artery disease

OBJECTIVES

This study was designed to define clinical and pathophysiologic similarities and differences between patients with ischemic and idiopathic dilated cardiomyopathy.

BACKGROUND

Significant coronary artery disease in patients with new onset congestive heart failure due to dilated cardiomyopathy has important prognostic and therapeutic implications.

METHODS

Clinical, histologic, ventriculographic and hemodynamic features of patients with dilated cardiomyopathy who underwent coronary angiography were reviewed.

RESULTS

Patients with ischemic cardiomyopathy (n = 21) compared with those with idiopathic cardiomyopathy (n = 40) had similar presenting symptoms, durations of illness, and coronary risk factor profiles, with the exception of a greater prevalence of cigarette smoking (71% vs. 39%, p = 0.028) and male gender (100% vs. 70%, p = 0.014). Endomyocardial biopsy specimens from patients with ischemic cardiomyopathy demonstrated a greater prevalence of replacement fibrosis (48% vs. 8%, p = 0.001) and a lesser degree of histologically assessed myocyte hypertrophy (mean grade 0.5 +/- 0.7 vs. 1.3 +/- 1.3, p = 0.015). Although ventriculographically determined regional dyskinesia was present in both groups, there was a higher prevalence of two or more adjacent segments in the ischemic cardiomyopathy group (50% vs. 10%, p = 0.03). This ischemic group had hemodynamic variables associated with a worse prognosis: higher pulmonary artery wedge pressure (23 +/- 10 vs. 15 +/- 9 mm Hg, p = 0.006) and lower cardiac index (2.0 +/- 0.5 vs. 2.3 +/- 0.5 liters/min per m2, p = 0.044). Also, in this group, patients had a mean of 2.6 +/- 0.7 diseased vessels; 15 (71%) of 21 patients had triple-vessel disease and 18 (86%) of 21 had at least one occluded or suboccluded artery.

CONCLUSIONS

1) Patients with ischemic and idiopathic cardiomyopathy may be clinically indistinguishable unless coronary angiography is performed. 2) A greater prevalence of replacement fibrosis and a lesser degree of myocardial hypertrophy in patients with ischemic cardiomyopathy may account for the greater extent of hemodynamic decompensation observed at presentation.

Increase in serum cardiac myosin light chain I associated with elective percutaneous transluminal coronary angioplasty in patients with ischemic heart disease

Changes in serum myosin light chain I (MLCI) due to elective percutaneous transluminal coronary angioplasty (PTCA) were studied after PTCA (0, 8 and 48 hours) in 57 patients with old myocardial infarction (MI group) and 20 patients with angina pectoris (AP group). The AP group showed no increase after PTCA. In contrast, in the MI group there were 16 patients in whom MLCI at 48 hours was increased by 1.0 ng/ml or more (MI1 group) and another group of 41 patients who showed no increase in MLCI (MI2 group). The MI1 group had a significantly higher incidence of (1) non-Q wave myocardial infarction (62.5% vs. 17.1%, p < 0.01), (2) 99% stenosis of a coronary artery (50.0% vs. 12.2%, p < 0.01), and (3) redistribution in a hypoperfusion area found in the delayed image of resting thallium-201 (201Tl) myocardial scintigraphy (85.7% vs. 15.8%, p < 0.01). The left ventricular ejection fraction (LVEF) was significantly improved in the MI1 group, 3 to 4 months later (from 0.49 +/- 0.12 to 0.58 +/- 0.11, p < 0.01), in contrast to the patient of MI2 group who did not show any improvement. The AP group was not considered to have a bulk of myocardium impaired enough to show a release of MLCI due to PTCA-associated transient coronary occlusion. In the MI1 group, however, MLCI was probably released from the chronically under-perfused, but still salvageable, portion of the myocardium. This is consistent with the improvement in LVEF observed 3 to 4 months after the relief of severe coronary stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial hibernation identified by hyperbaric oxygen treatment and echocardiography in postinfarction patients: comparison with exercise thallium scintigraphy

To evaluate the potential for hyperbaric oxygen (HBO) to produce transient improvement in function in areas of myocardium ischemic at rest (hibernating myocardium), 24 patients were studied within 1 week of acute myocardial infarction. Results were compared with single-photon emission computed tomography (SPECT) thallium-201 exercise scintigraphy. Echocardiography demonstrated improved contraction following HBO in 20 of 62 damaged left ventricular segments in 12 of 24 patients. Thirteen of the 28 segments and 9 of the 14 patients showing reversible ischemia on SPECT imaging showed improvement with HBO. There were eight segments with apparently normal resting contraction that showed a reversible thallium defect. Of 42 segments with fixed contraction abnormalities following HBO, eight had reversible thallium defects, four had normal thallium kinetics, and 30 had fixed thallium defects. Thus hyperbaric oxygen can demonstrate improvement in function in some segments of left ventricle after infarction. There is some overlap with viability as determined by thallium studies, but the two techniques may be complementary in describing myocardial ischemia.

Frequency and predictors of left ventricular segmental dysfunction in patients with recent rest angina

The relation between coronary artery lesion morphology and associated segmental left ventricular (LV) dysfunction in patients with unstable angina is unclear. Fifty-two patients with angina occurring at rest who underwent cardiac catheterization within 3 days of the last episode of pain and had no enzymatic evidence for myocardial necrosis were evaluated. Coronary artery narrowings deemed responsible for the ischemic episodes were analyzed with regard to the artery involved, maximal diameter of the narrowing, presence of thrombus, and complex appearance. Time to catheterization, age, sex and electrocardiographic evidence of ischemia were also noted. Segmental LV dysfunction in the territory supplied by the "culprit lesion" was present in 58% of patients. It occurred significantly more often with lesion location in the left anterior descending coronary artery, and was less frequent with lesions in the left circumflex and ramus coronary arteries. Ischemic electrocardiographic changes were more sensitive in predicting LV dysfunction with culprit lesion location in the left anterior descending or right coronary artery. LV dysfunction could not be predicted by any other parameter analyzed. It is concluded that postischemic LV dysfunction occurs frequently in rest angina, especially when the severest narrowing is in the left anterior descending coronary artery.

Hibernation and myocardial ischemia: clinical detection by positron emission tomography

Regions of myocardium supplied by severely diseased epicardial arteries may develop chronic ischemia at rest and exhibit reduced contractility, contributing to a reduction in global left ventricular function. However, after revascularization, contractility in these regions may return to normal. These regions of asynergy are described as "hibernating myocardium." Such myocardium in which normal contractility may be restored often coexists with areas of infarcted, or scar, tissue, leading to the definition of hypoperfused hibernating myocardium as viable myocardium. It is important to identify viable myocardium, as revascularization of these areas should lead to the greatest improvement in left ventricular function and, thus, improvement in survival. Positron emission tomography is the best noninvasive method for quantifying regional myocardial blood flow and metabolism. Using 18F-fluorodeoxyglucose, which measures myocardial glucose utilization, it is possible to identify myocardial tissue that is hypoperfused at rest with preserved or increased glucose uptake. This mismatch of blood flow to metabolism has a high predictive accuracy in the recovery of contractile function. In order to reduce the need for metabolic imaging in documenting myocardial viability, a regional index of perfusable tissue derived from imaging with 15O water has been recently developed that also allows the quantification of tissue viability.

Hibernating myocardium in patients with coronary artery disease: identification and clinical importance

The term hibernating myocardium describes a particular outcome of myocardial ischemia in which myocytes show a chronically depressed contractile ability but remain viable. Revascularization of hibernating tissue causes a recovery of mechanical function that correlates with long-term survival. Therefore it is important clinically to distinguish hibernating from infarcted myocardium, since asynergies due to hibernation will improve on reperfusion, whilst those due to infarct will not. One suggested technique to identify hibernating myocardium is to stimulate the myocytes acutely, but briefly, by administration of inotropic agents while monitoring contractile function by echocardiography. We report our experience on the use of low dosages of dobutamine. Myocardial viability was validated by measuring the recovery in contraction of the akinetic areas after coronary artery bypass surgery by means of intraoperative epicardial echocardiography. The test has a sensitivity of 93% and a specificity of 78%. It is useful for identification of viable myocardium and also for quantification of intraoperative risk in individual patients. Limitations of this test are related to the presence of downregulation of beta receptors and to the impossibility of differentiating hibernating from stunned myocardium. Another useful technique of identifying hibernating myocardium is the use of radionuclear markers for viability. In our experience the two most important tests are (1) rest-redistribution imaging of thallium 201 (which has a high sensitivity of 93% but a low specificity of 44%) and (2) 99mTc-Sestamibi imaging, which provides information on both perfusion and function with a single injection. This latter technique allows differentiation between stunning and hibernating on the basis of coronary flow which is preserved in stunning and reduced in hibernation.

Recovery of myocardial function in the hibernating heart

Impaired contractile performance at rest is not necessarily due to irreversible tissue damage but may relate to the "hibernating" myocardium. Hibernating myocardium has been defined as potentially reversible, chronic contractile dysfunction during prolonged, painless ischemia. The extent and time course of functional recovery after restoration of flow is of major importance for clinical decision making. The existence of hibernating myocardium was first documented in patients following bypass surgery. Angiographic studies in patients undergoing coronary angioplasty revealed immediate recovery of global and regional systolic, as well as diastolic, function after revascularization. Subgroup analysis showed an improvement in patients without previous myocardial infarctions and in those with non-Q-wave infarctions, but a benefit was not consistently seen in patients with transmural infarctions. A further improvement of systolic function after 15 weeks suggests a biphasic course of recovery. Prospective studies must clarify whether the potential for improvement in function constitutes an indication for revascularization independent of clinical symptoms.

Effect on global and regional left ventricular functions by percutaneous transluminal coronary angioplasty in the chronic stage after myocardial infarction

Data are reported on 145 consecutive patients with prior myocardial infarction who had successful percutaneous transluminal coronary angioplasty (PTCA) of the infarct-related artery (5 +/- 6 months after infarction), and left ventricular (LV) angiograms before PTCA and during follow-up (7 +/- 4 months). There was a significant long-term improvement in LV function, ejection fraction increased from 60 +/- 13% to 64 +/- 13% (p less than 0.001), and regional wall motion abnormalities decreased by 40%. Multivariate discriminant analysis identified reduced LV function and a high degree of stenosis before PTCA as predictors for improvement in LV function (ejection fraction less than 60%: ejection fraction from 48 +/- 9% to 57 +/- 14%, p less than 0.001; and stenosis greater than or equal to 90%: ejection fraction from 59 +/- 15% to 66 +/- 14%, p = 0.003). Restenosis greater than or equal to 90% in patients with initial stenosis less than 90% decreased ejection fraction from 59 +/- 16% to 51 +/- 14% (p less than 0.05). Other factors tested (treatment of infarction by thrombolysis, time between infarction and PTCA, and severity of angina pectoris) had no effect on long-term changes in LV function. It is concluded that successful elective PTCA of a high-grade stenosis in an infarct-related artery may improve LV ejection fraction and regional wall motion abnormalities, especially in patients with impaired LV function.

Reperfusion of hibernating myocardium: contractile function, high-energy phosphate content, and myocyte injury after 3 hours of sublethal ischemia and 3 hours of reperfusion in the canine model

Hibernating myocardium has been defined as a persistent impairment of contractile function resulting from reduced coronary blood flow that can be partially or completely resolved once coronary perfusion is restored. In fact, recent clinical reports have documented a dramatic improvement in contractile function after relief of chronic sublethal ischemia. To investigate the phenomenon of sublethal ischemia followed by reperfusion, we assessed myocyte morphology, high-energy phosphate content, and regional contractile function in dogs undergoing (1) 3 hours of subtotal coronary artery occlusion (CO) and 3 hours of reflow or (2) 3 hours of total CO followed by reflow, in which myocyte viability was maintained by extensive collateral perfusion during ischemia (total CO/negligible necrosis). Data were compared with findings in a third group of dogs with total CO and low collateral blood flow during ischemia, in which large confluent infarcts developed. Endocardial blood flow averaged 30 +/- 6% (p less than 0.01) and 27 +/- 4% (p less than 0.01) of baseline preocclusion values during ischemia in the groups with subtotal CO and total CO/negligible necrosis, versus 3 +/- 1% of baseline values in dogs with total CO/confluent necrosis. Both the subtotal CO and total CO/negligible necrosis groups exhibited only mild-to-moderate reversible myocyte injury (assessed by electron microscopy) and had essentially no necrosis: infarct size was 1 +/- 1% (p less than 0.01) and 4 +/- 2% (p less than 0.01) of the risk region in the subtotal CO and total CO/negligible necrosis groups, versus 55 +/- 9% of the risk region in the total CO/confluent necrosis group. Furthermore, myocardial high-energy phosphate stores were in part preserved in all dogs that underwent sublethal ischemia: endocardial adenosine triphosphate (ATP) content was 55 +/- 11% (p less than 0.01) and 56 +/- 8% (p less than 0.01) versus 11 +/- 2% of baseline values in the subtotal CO, total CO/negligible necrosis, and total CO/confluent necrosis groups, respectively. At 3 hours post occlusion, segment shortening averaged +21 +/- 10% of baseline values in dogs with subtotal CO, (p less than 0.01 versus both total CO groups), -29 +/- 9% in dogs with total CO/negligible necrosis, and -36 +/- 13% in dogs with total CO/confluent necrosis. Reperfusion after sublethal ischemia produced an acute improvement in contractile function in both the subtotal CO and total CO/negligible necrosis groups.(ABSTRACT TRUNCATED AT 400 WORDS)