Comparison of treatment and outcome of acute coronary syndrome in patients with versus patients without diabetes mellitus

The aim was to evaluate management and outcomes in patients with diabetes mellitus (DM) with acute coronary syndrome (ACS). The EHS-ACS-II was a multinational survey conducted in 2004 that included 6,385 consecutive patients with ACS. The management and outcomes of patients with and without DM were compared. DM was recognized in 1,587 patients (25%) with ACS. Patients with DM had a less favorable risk-factor profile, less typical presentation, and longer delay in seeking medical attention; presented more frequently with arrhythmias, heart failure, renal failure, and major bleeding; and had higher in-hospital and 1-year mortality. They were treated more often with diuretics and inotropic agents and less often with antiaggregants (glycoprotein IIb/IIIa and clopidogrel). Insulin was administered to 53% of patients with DM during hospitalization and 31% at discharge. Patients with DM with ST-elevation (STE) myocardial infarction underwent similar primary percutaneous and coronary interventions (but received less thrombolytic therapy). Patients with DM with non-STE ACS underwent less in-hospital revascularization and had significantly higher 1-year mortality. Multivariable analyses showed DM as a predictor of 1-year mortality (odds ratio 1.37, 95% confidence interval 1.09 to 1.71), but not in-hospital mortality. In conclusion, given the current treatment, patients with and without DM with ACS had similar in-hospital adjusted mortality, but patients with DM had increased 1-year mortality. Patients with DM with non-STE ACS posed a higher risk group.

Acute myocardial infarction--a late complication of intracoronary stent placement

BACKGROUND

Myocardial infarction (MI) as the first indication of postangioplasty restenosis is extremely rare, and it has been speculated that the fibroproliferative restenotic lesion is less likely to undergo plaque rupture than the lipid-laden native atherosclerotic lesion.

HYPOTHESIS

The present study was designed to examine whether intracoronary stent implantation affects this course.

METHODS

In all, 994 consecutive patients who underwent angioplasty and intracoronary stent implantation in our hospital were reviewed retrospectively for the occurrence of MI.

RESULTS

Eight patients (0.8%), all male and hypertensive, aged 33-83 years, presented with an MI due to stent occlusion more than 30 days following stenting (range: 35-398 days). In two patients, MI occurred 3 and 5 h, respectively, following completion of a maximal high-level exercise test that was negative for ischemia. Angiography revealed complete occlusion or significant stenosis of the stent in all eight patients, with an obvious intimal dissection in either edge of the stent in six patients. Except for gender and hypertension, no correlation was found with other risk factors, vessel involved, initial angiographic results, or with stent design, diameter, or length.

CONCLUSIONS

Myocardial infarction as a late complication of successful stent implantation occurred in 0.8% of our patients. This is only the lower bound of the estimated frequency for such an event. We hypothesize that the transition point between the relatively fixed stent and the normal artery is exposed to high deformation stress which makes it vulnerable to rupture and dissection. Strenuous exercise and hypertension may increase the deformation stress and the risk of intimal rupture.

Culprit only versus complete coronary revascularization during primary PCI

BACKGROUND

Primary percutaneous intervention (PCI) is the treatment of choice for acute ST elevation myocardial infarction. Currently it is recommended to treat only the culprit artery during the acute procedure. Only few reports describe the results of simultaneous non-culprit vessel PCI. The study hypothesizes that complete revascularization during primary PCI can be achieved safely with an improved clinical outcome during the indexed hospitalization.

METHODS

One hundred and twenty consecutive patients presented with acute ST elevation myocardial infarction (STEMI) and multivessel coronary stenosis. Ninety five underwent complete revascularization (CR): the culprit artery was opened first followed by dilatation of the other significantly narrowed arteries. Twenty five had culprit only revascularization (COR): the culprit artery only was dilated and the other arteries were left untreated during the primary PCI.

RESULTS

Complete revascularization (CR) was associated with reduced incidence of major cardiac events (recurrent ischemia, reinfarction, acute heart failure and in-hospital mortality 16.7 versus 52%, P=0.0001). There was a significant lower rate of recurrent ischemic episodes (4.2% versus 32%, P=0.002), myocardial reinfarction (3.1% versus 16%, P=0.01), reintervention (7.3% versus 32%, P=0.001), acute heart failure (9.4% versus 32%, P=0.01) during the indexed hospitalization and shorter hospitalization (4.4+/-1.27 versus 9.6+/-2.3, P=0.001) in the CR group. Transient renal dysfunction was more common in CR patients (8.4% versus 4% P=0.01). In-hospital and one year mortality were similar between the two groups.

CONCLUSION

Multivessel PCI during acute myocardial infarction is feasible and safe. Complete revascularization resulted in an improved acute clinical course. These data support a policy of complete revascularization during primary PCI for STEMI.

The second Euro Heart Survey on acute coronary syndromes: Characteristics, treatment, and outcome of patients with ACS in Europe and the Mediterranean Basin in 2004

AIMS

Our study aimed to examine the management of acute coronary syndromes (ACS) in Europe and the Mediterranean basin, and to compare adherence to guidelines with that reported in the first Euro Heart Survey on ACS (EHS-ACS-I), 4 years earlier.

METHODS AND RESULTS

In a prospective survey conducted in 2004 (EHS-ACS-II), data describing the characteristics, treatment, and outcome of 6385 patients diagnosed with ACS in 190 medical centres in 32 countries were collected. ACS with ST-elevation was the initial diagnosis in 47% of patients, no ST-elevation in 48%, and undetermined electrocardiographic pattern in 5% of patients. Comparison of data collected in 2000 and 2004 showed similar baseline characteristics, but greater use of recommended medications and coronary interventions in EHS-ACS-II. Among patients with ST-elevation, the use of primary reperfusion increased slightly (from 56 to 64%), with a significant shift from fibrinolytic therapy to primary percutaneous coronary intervention (PPCI). The use of PPCI rose from 37 to 59% among those undergoing primary reperfusion therapy. Analysis of data in 34 centres that participated in both surveys showed even greater improvement with respect to the use of recommended medical therapy, interventions, and outcome.

CONCLUSION

Data from EHS-ACS-II suggest an increase in adherence to guidelines for treatment of ACS in comparison with EHS-ACS-I.

The Titanium-NO Stent:results of a multicenter registry

BACKGROUND

Contemporary stents discharge nickel, chromium and molybdenum which might contribute to restenosis. The Titan stent is coated with titanium nitride-oxide that prevents completely discharge of metal elements.

AIMS

To assess short and long term outcome of the Titan in a multi-centre registry.

METHODS

Included were all patients except those in cardiogenic shock. Titan stents were 2.0-5.0 mm in diameter and 7-28 mm in length. Clinical follow-up was performed at 30 days and 6 months.

RESULTS

Total of 333 Titan stents were implanted in 296 patients (age 68.8+/-11.8 years, 81% men). Risk factors included hypercholesterolaemia (61.3%), hypertension (51.3%), diabetes mellitus (DM) (36.6%) and current smoking (27.6%). Eighty-one percent of patients had Acute Coronary Syndrome (ACS). Sixty two percent of treated lesions were B2/C type. Lesion length was 17.5+/-14.8 mm and stent diameter was 3.0+/-2.12 mm.Procedural success was 99.7%. At 180 days, 6.3% of patients had a total of 7.6% MACE including 5.4% TLR, 0.7% MI, 0.7% stent thrombosis and 0.7% death.

CONCLUSION

The Titan stent has a remarkable safety profile. Notwithstanding the highly complicated lesion and case mix, the short- and long-term results of this registry approach those of drug-eluting stents.

Provisional stenting for multivessel PCI

BACKGROUND

Bare stents reduce acute complications and repeat revascularization following percutaneous coronary intervention (PCI), but are costly and may lead to in-stent restenosis. It remains unclear whether stents should be universally implanted or whether provisional stenting mainly to suboptimal balloon dilatation results is an acceptable approach for multivessel PCI.

OBJECTIVE

To compare the long-term clinical restenosis and target lesion revascularization (TLR) of stented and non-stented coronary artery lesions in patients who had multivessel PCI.

METHODS

We performed retrospective analysis of matched data from 129 consecutive patients who underwent multivessel PCI (at least optimal balloon angioplasty to one coronary artery segment and balloon angioplasty plus stenting to another coronary artery in the same patient, all lesions are de novo native coronary artery lesions with vessel diameter >/=2.5 mm). The study endpoint was restenosis and repeat revascularization at one-year follow-up.

RESULTS

Baseline characteristics were similar in both groups. Low in-hospital MACE (3.1%). Acute myocardial infarction, emergency revascularization via either PCI or CABG was detected and angiographic success was achieved in 99.3% of lesions in both groups. The rate of clinically driven angiographic restenosis and TLR at one-year (follow-up 100%) was similar (17.1% versus 18.6%, P=0.871, and 13.9% versus 16.3%, P=0.728, for optimal balloon angioplasty versus provisional stenting.

CONCLUSIONS

The main findings from this study are that long-term angiographic restenosis and TLR was comparable for optimal balloon angioplasty and provisional stenting, suggesting that provisional stenting is an acceptable approach for multivessel PCI.

Cutting balloons versus conventional long balloons for PCI of long coronary lesions

BACKGROUND

PCI for long coronary lesions remains a challenge because of high incidence of early complications and late restenosis. Cutting balloon angioplasty may result in reduced procedural complications and late restenosis than angioplasty with conventional long balloons (LBA) due to minimized injury to the culprit arteries.

OBJECTIVE

To compare the immediate and one-year outcomes of CBA and LBA for long coronary lesions.

METHODS

169 consecutive patients were retrospectively identified who underwent CBA or LBA for de novo lesions 20 mm in length and 2.5 mm in diameter. The primary endpoint was immediate procedural outcomes and angiographic restenosis at one year.

RESULTS

CBA was performed in 54 patients (56 lesions) and LBA in 115 patients (151 lesions). Baseline characteristics were similar in both groups with a mean lesion length of 34.89+/-11.19 mm, and vessel diameter of 3.03+/-0.54 mm. CBA resulted in reduced incidence of side branch loss (23.2% versus 41.7%, P=0.022) which was associated with less peri-procedural infarction (OR: 11.39 (95% CI: 1.34-96.53), P=0.026). It also caused less dissection (23.2% versus 38.4%, P=0.048) leading to a trend of less provisional focal stenting (32.1% versus 41.1%, P=0.264). The rate of angiographic restenosis and clinically driven target lesion revascularization at one year (follow-up 91.1%) was similar (25% versus 21.2%, and 20.4% versus 20%, for CBA versus LBA, both P=NS). The mean event-free survival was also similar (10.15+/-0.45 months for CBA versus 9.50+/-0.39 months for LBA, P=NS).

CONCLUSION

CBA demonstrated better immediate results and equivalent late results than LBA, and therefore, it may be considered a reasonable firstline approach for PCI of long coronary lesions.

Recommendations for the structure, organization, and operation of intensive cardiac care units

Two major changes in patient characteristics and management occurred recently that demand distinctive alterations in the function of the intensive cardiac care unit (ICCU). These changes include the introduction of an early invasive strategy for the treatment of acute coronary syndromes, enabling early recuperation and shorter need for intensive care on the one hand, while the number of older and sicker patients requiring prolonged and more complex intensive care is steadily increasing. A task force of the European Society of Cardiology Working Group on Acute Cardiac Care was set to give a modern updated comprehensive recommendations concerning the structure, organization, and function of the modern ICCUs and intermediate cardiac units. These include the statement that specially trained cardiologists and cardiac nurses who can manage patients with acute cardiac conditions should staff the ICCUs. The optimum number of physicians, nurses, and other personal working in the unit is included. The document indicates the desired architecture and structure of the units and the intermediate cardiac unit and their relations to the other facilities in the hospital. Specific recommendations are also included for the minimal number of beds, monitoring system, respirators, pacemaker/defibrillators, and necessary additional equipment. The desired function is discussed, namely, the patients to be admitted, the length of stay, and the relocation policy. A uniformed electronic chart for ICCUs is advised, anticipating a common European database.

Predictors for Successful Angioplasty of Chronic Totally Occluded Coronary Arteries

AIMS

Reevaluation of clinical and angiographic predictors for percutaneous recanalization of coronary chronic total occlusion (CTO) using current techniques with conventional PTCA wires and balloons.

METHODS AND RESULTS

We studied 253 consecutive patients with 283 lesions who underwent attempted PTCA of CTO (mean time since occlusion 33 months, range 3-150 month). Immediate procedural success rate was 84.8% (95% CI = 80.3%-88.6%). Multiple clinical and angiographic characteristics were evaluated as possible predictors of success/failure. Multiple logistic regression analysis revealed that a tapered morphology (P < 0.001, OR = 6.1; 95% CI = 2.1-18.2), </=45 degree of angulations of the target artery (P < 0.03, OR = 4.5; 95% CI = 1.2-17.2), length of occlusion <15 mm (P < 0.001, OR = 3.4; 95% CI = 1.6-7.0), and the presence of multiple lesions in the target artery (P < 0.03, OR = 2.2; 95% CI = 1.1-4.4) were statistically significant independent predictors of procedural success. According to absence or presence of the various identified determinants of outcome, predicted procedural success rates varied between 26 and 98%.

CONCLUSIONS

Although the probability of immediate procedural success with percutaneous recanalization of coronary CTO using conventional PTCA is now high, a number of characteristics of the occlusive lesion represent significant modulators of success or failure. These factors should be utilized in the process of patients or lesions selection.

Short- and long-term outcomes of the titanium-NO stent registry

BACKGROUND

Five to 15% of the population have allergy to nickel, chromium, or molybdenum, which is a potential cause for in-stent restenosis. The Titan stent is made of stainless steel and is coated with titanium-nitride oxide (TiNOX), which completely prevents the discharge of metal elements. We performed a real-life multicenter registry to assess the short- and long-term characteristics of the Titan stent.

METHODS AND RESULTS

A total of 103 Titan stents was implanted in 100 patients. Patients were 61.4+/-12.6 years old (81 men). Risk factors included hypercholesterolemia (63%), hypertension (53%), diabetes mellitus (DM; 35%), and current smoking (23%). Indications for PCI (percutaneous coronary intervention) were acute coronary syndromes (ACS) in 68% [acute ST elevation myocardial infarction (MI) in 8%], stable AP (angina pectoris) in 25%, and silent ischemia in 7% of the patients. Fifty-two percent of the treated lesions were of Type B2 or C. Lesion length was 14.3+/-2.9 mm and stent diameter was 3.06+/-0.36 mm. Indications for stenting were prevention of restenosis in 66%, residual stenosis in 33%, dissection in 13%, acute MI in 13%, and in-stent restenosis in 7% of the patients. Procedural success was 100%, with no complications. At 30 days, there were no major adverse cardiac events (MACE), including death, MI, and revascularization. At 180 days, only three patients had TVR (target vessel revascularization); two had TLR (target lesion revascularization) (one PCI and one CABG [coronary artery bypass grafting]), and one patient had a new narrowing proximal to the stent and underwent CABG due to multivessel disease.

CONCLUSIONS

The Titan stent has a remarkable safety profile in high-risk patients and complex coronary lesions and excellent short- and long-term outcome with a very low clinical TLR rate.

[Out-of-hospital resuscitation in Israel 2000]

The aim of the study was to evaluate the impact of pre-hospital cardio-pulmonary resuscitation, performed by mobile intensive cardiac care units of Magen David Adom (MDA) teams in the framework of a national survey conducted in the period February and March 2000. During the survey, MDA performed 539 resuscitations, 485 of which were performed by mobile intensive care units of MDA, and they constitute the study population of the present analysis. The average age of the patients was 70.5 years, and 68% were men. The mean response time of the mobile intensive care units was 10.3 minutes. In 14% of the cases, a bystander initiated basic cardiac life support before the arrival of the MDA team. Upon arrival of the resuscitation team, 242 patients (50%) had asystole, 19% ventricular tachycardia (VT)/ventricular fibrillation (VF), 13% pulseless electrical activity (PEA), and 18% had other severe arrhythmias. One hundred and ninety-nine patients (41%) were transferred alive to the hospital after successful resuscitation. Hospital summaries were obtained for 148 of these patients. The cause of cardiac arrest was cardiac in 64% of the cases and 48% of the patients who reached the hospital had a previous history of heart disease. Fifty-three patients (11%) were discharged alive from the hospital. Patients discharged alive were younger, more promptly resuscitated, 78% had a cardiac cause of death and 38% of them were in ventricular tachycardia/fibrillation when first seen by the resuscitation team. The rate of successful resuscitation to discharge in the sub-group with VT/VF was 21%, and only 4% for patients in asystole, which is in line with other studies. However, the rate of initiation of resuscitation by bystanders is low in Israel. These data may help the medical staff and the health policy providers in Israel.

The opposing effects of endothelin-1 and C-type natriuretic peptide on apoptosis of neonatal rat cardiac myocytes

C-type natriuretic peptide (CNP) and endothelin-1 are paracrine peptides with opposing effects on cardiac myocyte contraction and intracellular cGMP production. Elevated levels of both endothelin-1 and CNP are found in patients with congestive heart failure. These factors may be related to positive and negative regulation of cell apoptosis in the failing heart. To evaluate the effect of CNP and endothelin-1 on apoptosis of cardiac myocytes and the possible mechanisms involved, primary cardiac myocytes were prepared from neonatal Sabra rats. Cardiomyocyte apoptosis was evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and Annexin V in situ staining. The TUNEL method was used to measure the apoptotic index. CNP and the cGMP derivative, 8-br-cGMP, induced apoptosis of cardiac myocytes. CNP-induced apoptosis could be blocked by HS 142-1 (a mixture of 20-30 kinds of linear beta-1, 6-glucan esterified by capronic acid, an antagonist of type A and B natriuretic peptide receptors), and KT 5823 (C29H25N3O5), the inhibitor of cGMP-dependent protein kinase). Alpha-difluoromethylornithine (DFMO), the irreversible inhibitor of ornithine decarboxylase, also induced apoptosis to a similar extent. CNP and 8-br-cGMP caused a marked reduction of intracellular ornithine decarboxylase expression, as determined by Western blot analysis and immunohistochemical assay. Preincubation with endothelin-1 attenuated CNP- and 8-br-cGMP-induced cardiomyocyte apoptosis. Endothelin-1 also antagonized the CNP- and 8-br-cGMP-induced reduction of intracellular ornithine decarboxylase expression. These results suggest that CNP has a proapoptotic effect on neonatal rat cardiac myocytes. The effect is mediated via natriuretic peptide receptors and is due to an elevation of intracellular cGMP, which reduces the expression of intracellular ornithine decarboxylase and probably the production of polyamines. Endothelin-1 protects cardiac myocytes against CNP-induced apoptosis by influencing the cGMP-dependent pathway, and this effect is probably mediated through both a reduction of cGMP and antagonism of the CNP-induced reduction of intracellular ornithine decarboxylase expression.

Outcome of myocardial infarction in patients treated with aspirin is enhanced by pre-hospital administration

OBJECTIVE

Reducing time to reperfusion therapy is one of the goals in the management of acute myocardial infarction (AMI). We assessed the association between timing of aspirin administration and outcome of patients with AMI.

PATIENTS

We studied 922 consecutive AMI patients with ST-segment elevation in Killip class I-III on admission. Patients were divided into two groups based upon the timing of emergency aspirin administration: before (early aspirin users) or after (late aspirin users) hospital admission.

RESULTS

Early aspirin users (n = 338; 37%) were younger, less likely to be women, and more likely to smoke (p < 0.006) than late users (n = 584; 63%). Other baseline and clinical characteristics were similar. Early aspirin users were more likely to be treated with thrombolysis or primary percutaneous transluminal coronary angioplasty. Compared with late users, early aspirin users had significantly lower in-hospital complications and lower mortality rates at 7 (2.4 vs. 7.3%, p = 0.002) and 30 days (4.9 vs. 11.1%, p = 0.001). By multivariate adjustment, pre-hospital aspirin was an independent determinant of survival at 7 (odds ratio 0.43; 95% confidence interval 0.18-0.92) and at 30 days (odds ratio, 0.60; 95% confidence interval 0.32-1.08). Survival benefit associated with aspirin persisted for subgroups treated or not with reperfusion therapy.

CONCLUSIONS

Outcome of AMI patients treated with aspirin is improved by pre-hospital administration. Our findings suggest that emergency pre-hospital aspirin might facilitate early reperfusion.

A prospective national survey of management and clinical outcome of acute myocardial infarction in Israel, 2000

BACKGROUND

Little information is available on the clinical practice and implementation of guidelines for treating acute myocardial infarction patients in Israel.

OBJECTIVE

To assess patient characteristics, hospital course, management, and 30 day clinical outcome of all AMI patients hospitalized in Israel during a 2 month period in 2000.

METHOD

We conducted a prospective 2 month survey of consecutive AMI patients admitted to 82 of 96 internal medicine departments and all 26 cardiac departments operating in Israel in 2000. Data were collected uniformly by means of a hospital and 30 day follow-up form.

RESULTS

During the survey 1,683 consecutive patients with a discharge diagnosis of AMI were included. Their mean age was 66 years; 73% were male. The electrocardiographic pattern on admission revealed ST elevation, non-ST elevation and an undetermined ECG in 63%, 34% and 4% of patients respectively. Aspirin and heparin were given to 95% of patients. Beta-blockers and angiotensin-converting enzyme inhibitors were given to 76% and 65% of patients respectively. Among hospital survivors, 45% received lipid-lowering drugs. Thrombolytic therapy was administered in 28% of patients, coronary angiography was used in 45%, and 7% of patients underwent primary percutaneous coronary intervention. The 7 and 30 day mortality rates were 7% and 11% respectively.

CONCLUSIONS

This nationwide survey shows that one-third of the AMI patients in Israel are elderly (> or = 75 years). The survey suggests that clinical guidelines for the management of patients with AMI are partially implemented in the community. Data from large surveys representing the "real world" practice are of utmost importance for the evaluation of clinical guidelines, research and educational purposes.

The Cutting Balloon--a new technology?

The Cutting Balloon consists of a standard balloon dilatation catheter with four microtome-sharp blades that incise the plaque and minimize arterial wall trauma. It was used in 31 patients; nine had calcified arteries, ten had non-compliant lesions, three had in-stent restenosis and nine had aorto-ostial lesions. Seventeen lesions were predilated, 28 were post-dilated and 18 required stent implantation. The procedure was very effective in aorto-ostial lesions, non-compliant lesions that were not responsive to high-pressure balloon dilatation, and was partially successful in calcified arteries. It has a very specific niche in selected lesions.

Cardiovascular effects of natriuretic peptides and their interrelation with endothelin-1

The natriuretic peptides are a group of structurally related but genetically distinct peptides. Four types of natriuretic peptides have been found thus far: atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), C-type natriuretic peptide (CNP) and Dendroaspis natriuretic peptide (DNP). ANP and BNP are secreted mainly from the heart and function as hormones with vasodilatory and natriuretic effects. CNP originates mainly from endothelial cells with a paracrine effect to induce vasodilation. Other effects of natriuretic peptides including negative inotropy, antimitogenic and anticoagulation have been described. Three types of natriuretic peptide receptors mediate their functions, and among them two are cGMP-coupled. Clearance of natriuretic peptides is via its clearance receptor through the action of neutral endopeptidases. Natriuretic peptides interact with other vasoactive peptides including endothelin. The putative role of natriuretic peptides in the pathophysiology of various cardiovascular diseases including congestive heart failure, hypertension, ischemic heart disease, and cardiomyopathy are discussed. Natriuretic peptide plasma levels are used for the diagnosis and therapeutic follow-up of congestive heart failure patients. Increasing the levels of natriuretic peptides by natriuretic peptide mimetics and neutral endopeptidase inhibitors may provide a new therapeutic strategy for the treatment of cardiovascular diseases such as congestive heart failure and hypertension.

Heat acclimation-induced elevated glycogen, glycolysis, and low thyroxine improve heart ischemic tolerance

Based on our observations of energy sparing in heat-acclimated (AC) rat hearts, we investigated whether changes in preischemic glycogen level, glycolytic rate, and plasma thyroxine level mediate cardioprotection induced in these hearts during ischemia-reperfusion insults. Control (C) (24 degrees C), AC (34 degrees C, 30 days), acclimated-euthyroid (34 degrees C + 3 ng/ml l-thyroxine), and control hypothyroid (24 degrees C + 0.02% 6-n-propyl-2-thiouracil) groups were studied. Preischemic glycogen was higher in AC than in C hearts [39.0 +/- 8.5 vs. 19.2 +/- 4.2 (SE) micromol glucose/g wet wt; P < 0.0006], and the lactate produced vs. glycogen level during total ischemia ((13)C-NMR spectroscopy) was markedly slower (AC: -0.82x, r = 0.98 vs. C: -4.7x, r = 0.9). Time to onset of ischemic contracture was lengthened, and the fraction of hearts experiencing ischemic contracture was lowered. Pulse pressure recovery was improved in AC compared with C animals before, but not after, absolute sodium iodoacetate-induced glycolysis inhibition. Acclimated-euthyroid hearts exhibited decreased ischemic tolerance, whereas induced hypothyroidism in C improved cardiotolerance. Thus higher preischemic glycogen and slowed glycolysis are associated with hypothyroidism and are likely important mediators of the improved ischemic tolerance exhibited by AC hearts.