Nonculprit Lesion Severity and Outcome of Revascularization in Patients With STEMI and Multivessel Coronary Disease

BACKGROUND

In the COMPLETE (Complete vs Culprit-only Revascularization to Treat Multi-vessel Disease After Early PCI for STEMI) trial, angiography-guided percutaneous coronary intervention (PCI) of nonculprit lesions with the aim of complete revascularization reduced major cardiovascular (CV) events in patients with ST-segment elevation myocardial infarction (MI) and multivessel coronary artery disease.

OBJECTIVES

The purpose of this study was to determine the effect of nonculprit-lesion stenosis severity measured by quantitative coronary angiography (QCA) on the benefit of complete revascularization.

METHODS

Among 4,041 patients randomized in the COMPLETE trial, nonculprit lesion stenosis severity was measured using QCA in the angiographic core laboratory in 3,851 patients with 5,355 nonculprit lesions. In pre-specified analyses, the treatment effect in patients with QCA stenosis ≥60% versus <60% on the first coprimary outcome of CV death or new MI and the second co-primary outcome of CV death, new MI, or ischemia-driven revascularization was determined.

RESULTS

The first coprimary outcome was reduced with complete revascularization in the 2,479 patients with QCA stenosis ≥60% (2.5%/year vs. 4.2%/year; hazard ratio [HR]: 0.61; 95% confidence interval [CI]: 0.47 to 0.79), but not in the 1,372 patients with QCA stenosis <60% (3.0%/year vs. 2.9%/year; HR: 1.04; 95% CI: 0.72 to 1.50; interaction p = 0.02). The second coprimary outcome was reduced in patients with QCA stenosis ≥60% (2.9%/year vs. 6.9%/year; HR: 0.43; 95% CI: 0.34 to 0.54) to a greater extent than patients with QCA stenosis <60% (3.3%/year vs. 5.2%/year; HR: 0.65; 95% CI: 0.47 to 0.89; interaction p = 0.04).

CONCLUSIONS

Among patients with ST-segment elevation MI and multivessel coronary artery disease, complete revascularization reduced major CV outcomes to a greater extent in patients with stenosis severity of ≥60% compared with <60%, as determined by quantitative coronary angiography.

Spontaneous coronary artery dissection: the management dilemma continues

Spontaneous coronary artery dissection (SCAD) is an increasingly recognised cause of acute coronary syndrome, particularly in women. A 36-year-old Caucasian woman presented to our hospital with sudden onset chest pain and was diagnosed with a non-ST elevation myocardial infarction. Coronary angiography revealed mid and distal left anterior descending artery (LAD) dissection with distal LAD occlusion. A short segment of apical LAD filled late with incomplete opacification (Thrombolysis In Myocardial Infarction (TIMI) 1 flow). A decision was made to treat the patient conservatively, with subsequent resolution of dissection over the next 3 months. Our patient made a good clinical recovery with healing of her affected coronary vasculature on subsequent angiogram. The case illustrates that SCAD can be managed conservatively with antiplatelet agents, β-blockers, heparin and statins, if the patient is haemodynamically stable and coronary flow is adequate.

Comparison of procedural complications with versus without interventional cardiology fellows-in-training during contemporary percutaneous coronary intervention

Despite increasing complexity of contemporary procedures at tertiary care hospitals, the relationship between interventional cardiology fellows-in-training (ICFITs) and complications of percutaneous coronary intervention (PCI) has not been reported. We compiled logbooks of 6 ICFITs at an academic hospital and evaluated patient and procedural characteristics of PCIs performed with and without presence of an ICFIT. The primary end point was the composite of all in-hospital PCI complications defined by the American College of Cardiology's National Cardiovascular Data Registry: (1) catheterization laboratory events such as no-reflow and dissection/perforation, (2) general clinical events such as stroke or cardiogenic shock, (3) vascular and bleeding complications, and (4) miscellaneous complications such as peak troponin or creatinine levels. Logistic regression adjusted for differences in measured confounders between patients treated with and without presence of an ICFIT. All analyses were repeated after excluding PCI for ST-elevation myocardial infarction. Of 2,605 PCI procedures at the academic hospital between July 2007 and April 2010, an ICFIT was present for 1,638 procedures (63%). Despite having worse clinical and procedural characteristics, patients in the ICFIT group experienced similar rates of the composite end point (12.9% vs 14.5% without ICFIT, p = 0.27). Longer mean fluoroscopy times and greater number of stents were noted in the ICFIT group; however, hospital length of stay was shorter and no individual adverse events were increased in the ICFIT procedures. Presence of an ICFIT remained unrelated to the composite end point after multivariable adjustment (odds ratio 0.92, 95% confidence interval 0.71 to 1.20; p = 0.53), and findings were similar after excluding PCI for ST-elevation myocardial infarction. In conclusion, in contemporary practice at a large academic medical center, PCI complication rates were not adversely affected by the presence of an ICFIT.

Quantifying improvement in symptoms, functioning, and quality of life after peripheral endovascular revascularization

BACKGROUND

Patients with peripheral arterial disease often undergo peripheral endovascular revascularization (PER) to alleviate symptoms. Despite the growth of PER, little information exists quantifying the health status benefits after the procedure.

METHODS AND RESULTS

From February 2001 to August 2004, 477 consecutive patients underwent PER for symptomatic peripheral arterial disease. Of these, 300 consented to participate in a longitudinal follow-up study of their health status. Health status was quantified with the disease-specific Peripheral Artery Questionnaire and the generic Short Form-12 and the EuroQol 5 Dimensions (EQ5D)questionnaire. Scores range from 0 to 100; higher scores represent fewer symptoms and better health status. The average age of the cohort was 68+/-11 years (mean+/-SD); 186 (62%) were male, 288 (96%) were white, and 118 (39%) were diabetic. Clinical follow-up was attained in 99% of patients; health status assessments were made in 86%. Mean Peripheral Artery Questionnaire summary scores improved significantly after revascularization from 31+/-19 to 62+/-27 at 1 year (P<0.0001). Generic health status scores also improved significantly (P<0.001 for all). Despite a technically successful procedure in 98% of patients, 21% of patients did not achieve the minimal clinically important improvement of an 8-point change in Peripheral Artery Questionnaire Summary score after PER (35+/-19 at baseline versus 31+/-16 at 1 year; P=0.09).

CONCLUSIONS

For most patients, significant and sustained improvements in symptoms, functioning, and quality of life occur after PER. Identifying and counseling patients less likely to benefit from PER is an important future research direction.

Functional and clinical outcomes of nitinol stenting with and without abciximab for complex superficial femoral artery disease: A randomized trial

OBJECTIVE

To evaluate the effect of glycoprotein IIb/IIIa inhibition during nitinol stenting, of superficial femoral occlusive disease.

BACKGROUND

Stent implantation in the superficial femoral artery has been associated with suboptimal results while Glycoprotein IIb/IIIa inhibitors have shown improved procedural results during coronary intervention. We evaluated abciximab infusion during (Smart Stent) implantation in superficial femoral obstructions.

METHODS

We conducted a randomized placebo controlled trial. The two primary end points include: (1) 9-month restenosis defined as a decrease in ankle brachial index and in-stent duplex ultrasound restenosis: (2) adverse events defined as death (30 days) or repeat revascularization within 9 months.

RESULTS

Twenty-seven patients were randomized to abciximab and 24 patients to control (placebo). The primary end point of cumulative restenosis occurred in 15.4% of patients administered abciximab and in 12% administered placebo (P = 0.873). The primary restenosis endpoint in diabetics and total occlusions were similar at 14.3% and 15.4% respectively. The composite end point of 30-day mortality and 9-month revascularization occurred in 5.8% abciximab and 0% (P = 0.274) placebo with no 30-day deaths. Graded treadmill time and Rutherford class were all significantly improved in both groups, but the abciximab group did not appear to demonstrate any identifiable effect.

CONCLUSION

(Smart Stent) nitinol stenting of the superficial femoral artery was associated with favorable functional outcomes at 9 months. Adjunctive abciximab did not appear to demonstrate any identifiable effect.

Usefulness of optical coherent reflectometry with guided radiofrequency energy to treat chronic total occlusions in peripheral arteries (the GRIP trial)

Optical coherent reflectometry, a forward-looking, fiberoptic-guided device was used in 72 patients to direct radiofrequency energy across the central intraluminal portion of 75 chronic total occlusions in peripheral arteries (iliac, femoral, and popliteal) that failed attempts with conventional guidewires. The system was successful in crossing 76% of the chronic total occlusions with no clinical perforations or distal embolizations, and complications consisted of a single dissection greater than or equal to grade C.

Multivessel percutaneous coronary intervention in patients with multivessel disease and acute myocardial infarction

BACKGROUND

The optimal percutaneous interventional strategy for dealing with significant non-culprit lesions in patients with multivessel disease (MVD) with acute myocardial infarction (AMI) at presentation remains controversial.

METHODS

A total of 820 patients treated with primary angioplasty for AMI between 1998 and 2002 were classified in groups of patients with single vessel disease (SVD) or MVD (> or =70% stenosis of > or =2 coronary arteries). Patients with MVD were subdivided in 3 groups on the basis of the revascularization strategy: 1) patients undergoing percutaneous coronary intervention (PCI) of the infarct-related artery (IRA) only; 2) patients undergoing PCI of both the IRA and non-IRA(s) during the initial procedure; and 3) patients undergoing PCI of the IRA followed by staged, in-hospital PCI of the non-IRA(s). Procedural, 30-day, and 1-year outcomes are reported.

RESULTS

At 1 year, compared with patients with SVD, patients with MVD had a higher incidence of re-infarction (5.9% vs 1.6%, P =.003), revascularization (18% vs 9.6%, P <.001), mortality (12% vs 3.2%, P <.001), and major adverse cardiac events (MACEs; 31% vs 13%, P <.001). In patients with MVD, compared with PCI restricted to the IRA only, multivessel PCI was associated with higher rates of re-infarction (13.0% vs 2.8%, P <.001), revascularization (25% vs 15%, P =.007), and MACEs (40% vs 28%, P =.006). Multivessel PCI was an independent predictor of MACEs at 1 year (odds ratio = 1.67, P =.01).

CONCLUSIONS

These data suggest that in patients with MVD, PCI should be directed at the IRA only, with decisions about PCI of non-culprit lesions guided by objective evidence of residual ischemia at late follow-up. Further studies are needed to confirm these findings.

Improving in-hospital mortality in the setting of an increasing risk profile among patients undergoing catheter-based reperfusion for an acute myocardial infarction without cardiogenic shock

Prompt myocardial reperfusion is the therapeutic goal for patients presenting with acute myocardial infarction (AMI). However, there remains a paucity of clinical data from single centers solely dedicated to a catheter-based reperfusion strategy. Therefore, we sought to identify significant predictors of in-hospital mortality, to determine the changing profile of patient demographics and to identify the mortality trend over time.

METHODS

Consecutive patients who underwent percutaneous coronary intervention (PCI) for an AMI between January of 1982 and December of 1999 were included in this multivariable analysis (excluding cardiogenic shock). AMI was defined as an evolving myocardial infarction within the preceding 24 hours. The primary endpoint for this analysis was in-hospital mortality.

RESULTS

There were 2,745 patients identified in this study, of which 8.3% (n = 228) were non-survivors. The significant multivariable predictors of in-hospital mortality included creatinine > 1.5 mg/dl [relative risk (RR), 5.7; 95% confidence interval (CI) 4.0 8.1], ejection fraction < 40% (RR, 6.6; 95% CI, 4.3 10.0), multivessel disease (RR, 2.8; 95% CI, 1.9 4.2), female (RR, 2.3; 95% CI, 1.6 3.1) and age > 70 years (RR, 1.6; 95% CI, 1.1 2.2). The incidence of patients with these high-risk characteristics increased in recent years; thus, the unadjusted slope of the mortality trend over 20 years was not significant. However, following adjustment for the temporal shift in high-risk variables, there was a significant reduction in the adjusted in-hospital mortality rate (RR, 0.89; 95% CI 0.8 0.98; p = 0.017). Despite the changing risk profile, the short-term mortality continues to improve for patients undergoing AMI PCI.

Diabetes mellitus is associated with a shift in the temporal risk profile of inhospital death after percutaneous coronary intervention: an analysis of 25,223 patients over 20 years

BACKGROUND

Numerous studies have demonstrated that patients with diabetes have higher rates of restenosis, late myocardial infarction, and late death after percutaneous coronary interventions (PCI). However, it remains unclear whether patients with diabetes mellitus also have an increased hazard for early death after either elective or urgent PCI.

METHODS

Patients undergoing PCI at the Mid American Heart Institute between 1980 and 1999 were identified. The main end point was inhospital death. Patients were stratified both by diabetes status and whether they underwent elective or urgent PCI.

RESULTS

There were 17,341 nondiabetic patients and 4308 patients with diabetes who underwent elective PCI. There were 2946 nondiabetic patients and 628 patients with diabetes who underwent urgent PCI. Multivariate analysis demonstrated that diabetes was associated with increased inhospital mortality rate after any PCI (odds ratio 1.4, 95% CI 1.1-1.8, P =.003). The unadjusted inhospital mortality rates for the nondiabetic patients and patients with diabetes were 0.8% and 1.4%, respectively (P <.001), after elective PCI. The mortality rate was 6.9% for the nondiabetic patients and 12.7% for the patients with diabetes (P <.001) after urgent PCI. The inhospital mortality rates among diabetic patients appear to be decreasing over time among the elective cohort (elective PCI diabetes-time interaction, P =.007) but not in the urgent cohort (urgent PCI-diabetes-time interaction, P =.68).

CONCLUSIONS

There has been an improvement in the inhospital survival rate among patients with diabetes in the elective PCI cohort. This improved hospital survival has yet to be realized among patients with diabetes undergoing urgent PCI.

Procedural outcomes and long-term survival among patients undergoing percutaneous coronary intervention of a chronic total occlusion in native coronary arteries: a 20-year experience

OBJECTIVES

The study compared procedural outcomes and long-term survival for patients undergoing percutaneous coronary intervention (PCI) of a chronic total coronary artery occlusion (CTO) with a matched non-CTO cohort to determine whether successful PCI of a CTO is associated with improved survival.

BACKGROUND

Percutaneous coronary intervention of a CTO is a common occurrence, and the long-term survival for patients with successful PCI of a CTO has not been clearly defined.

METHODS

Between June 1980 and December 1999, a total of 2,007 consecutive patients underwent PCI for a CTO. Utilizing propensity scoring methods, a matched non-CTO cohort of 2,007 patients was identified and compared to the CTO group. The cohorts were stratified into successful and failed procedures.

RESULTS

The in-hospital major adverse cardiac event (MACE) rate was 3.8% in the CTO cohort. Technical success has improved over the last 10 years (overall 74.4%, slope 1.0%/yr, p = 0.02, R2 = 49.9%) as did procedural success (overall 69.9%, slope 1.2%/yr, p = 0.02, R2 = 51.5%) without a concomitant increase in in-hospital MACE rates (slope 0.1%/yr, p = 0.7). There was a distinct 10-year survival advantage for successful CTO treatment compared with failed CTO treatment (73.5% vs. 65.1%, p = 0.001). The CTO versus non-CTO 10-year survival was the same (71.2% vs. 71.4%, p = 0.9). Diabetics in the CTO cohort had a lower 10-year survival compared with nondiabetics (58.3% vs. 74.3%, p < 0.0001).

CONCLUSIONS

These data represent follow-up of the largest reported series of patients undergoing PCI for a CTO. The 10-year survival rates for matched non-CTO and the CTO cohorts were similar. Success rates have continued to improve without an accompanying increase in MACE rates. A successfully revascularized CTO confers a significant 10-year survival advantage compared with failed revascularization.

Incidence and importance of thrombolysis in myocardial infarction grade 3 flow after primary percutaneous transluminal coronary angioplasty for acute myocardial infarction

We analyzed angiographic flow and myocardial salvage in 180 patients who underwent primary percutaneous transluminal coronary angioplasty (PTCA) without antecedent thrombolytic therapy for acute myocardial infarction. Thrombolysis in Myocardial Infarction (TIMI) flow grade was analyzed visually before and after PTCA. All patients underwent paired baseline (before angioplasty) and predischarge quantitative tomographic perfusion imaging with technetium-99m (Tc-99m) sestamibi techniques for assessment of the initial area at risk and final infarct size. The myocardial salvage index was defined as the proportion of jeopardized myocardium that was salvaged. After primary PTCA, TIMI grade 3 flow was obtained in 163 patients (91%), TIMI grade 2 flow in 13 patients (7%), and TIMI grade 0 or 1 flow in 4 patients (2%). There was a significant association between TIMI flow and both infarct size and salvage index. Infarct size was significantly smaller in patients with TIMI grade 3 flow than in those with TIMI grade 2 flow (15 +/- 16% vs 29 +/- 21% of left ventricular mass, p = 0.007). The salvage index was 55 +/- 41% of the area at risk in the TIMI 3 group and 27 +/- 38% of the area at risk in the TIMI 2 group (p = 0.04). After primary PTCA, restoration of TIMI grade 3 flow was necessary for optimal myocardial salvage. TIMI grade 2 flow was associated with a larger final infarct size and a lower salvage index.

Results of direct percutaneous transluminal coronary angioplasty in octogenarians

Direct percutaneous transluminal coronary angioplasty (PTCA) has emerged as effective reperfusion therapy for acute myocardial infarction; however, few data exist on its use in octogenarians. Thrombolytic therapy in this age group has reduced early mortality from approximately 30% to 20%, but is associated with an increased risk of stroke and major hemorrhage. We analyzed the acute and long-term results of direct PTCA performed on patients aged > or = 80 years at our institution between 1980 and 1993. The study group consisted of 55 patients (mean patient age 83.3 +/- 2.3 years). Infarcts were anterior in 27 patients (49%). Cardiogenic shock was present in 6 patients (11%). The mean time to reperfusion was 4.3 +/- 2.8 hours. Direct PTCA was successful in 53 patients (96%). There were no emergent bypass operations. In-hospital death occurred in 9 patients (16%), including 4 of 6 (67%) presenting in cardiogenic shock and 5 of 49 (10%) who were hemodynamically stable on presentation. Repeat PTCA for recurrent ischemia was performed in 6 patients (11%). There were no strokes during hospitalization. Bleeding complications requiring blood transfusion were present in 4 patients (7%). Thirty-day mortality was 16% and 1-year actuarial survival was 67%. Direct PTCA in patients aged > or = 80 years can be performed safely with a high procedural success rate. The clinical outcome with PTCA in this high risk subset of patients compares favorably with that reported previously for both thrombolytic and medical therapy.

Directional atherectomy of left main stenoses

Balloon angioplasty (PTCA) of left main (LM) stenoses is limited by frequent clinical restenosis. Directional coronary atherectomy (DCA) may be an effective alternative to PTCA due to its ability to achieve a greater postprocedural luminal diameter when treating bulky, eccentric plaques and aorto-ostial lesions. We analyzed the acute and long-term results following 24 DCA procedures in 22 patients with "protected" LM lesions. Acute success (residual stenosis < or = 40%, no major ischemic complications) was 88% overall, 100% in 13 planned procedures, and 73% in 11 adjunctive DCA procedures that followed suboptimal PTCA. Mean LM stenosis was reduced from 86% to 13% (P < 0.01). There were no procedural complications directly attributed to DCA. At a mean of 24 +/- 3 months, the clinical restenosis rate was 16%, survival was 100%, and event-free survival (freedom from death, MI, or repeat lesion-related interventions) was 89%. We conclude that DCA in protected LM lesions (1) can achieved excellent angiographic results with low procedural complication rates, (2) may succeed where PTCA yields suboptimal results, and (3) may provide late clinical outcomes superior to those of balloon angioplasty.

Effects of reperfusion on ischemic right ventricular dysfunction. Disparate mechanisms of benefit related to duration of ischemia

BACKGROUND

Right ventricular free wall (RVFW) ischemia impairs global RV performance and may result in acute hemodynamic compromise. However, RV function and hemodynamic performance typically improve spontaneously over time. This study was designed to determine whether reperfusion facilitates recovery of function in the ischemic right ventricle.

METHODS AND RESULTS

Closed chest dogs underwent right coronary balloon occlusion for 1 hour (n = 9), 4 hours (n = 6), or 8 hours (n = 7). In all animals, occlusion depressed RVFW function and global RV performance. After 1 hour of ischemia, reperfusion led to immediate improvement in RVFW function and consequently global RV performance, with complete recovery over 4 weeks and scar in < 1% of total RVFW area. Reperfusion after 4- and 8-hour occlusions resulted in acute improvement in global RV performance but to a lesser extent and by different mechanisms, since RVFW contraction remained severely impaired. This disproportionate recovery of global RV function was attributable to diminished RVFW dyskinesis associated with reperfusion-induced increments in RVFW diastolic thickness (characterized histopathologically in 6 additional animals subjected to 4-hour occlusions but killed 1 hour after reperfusion by interstitial edema, contraction band necrosis, and hemorrhage). Although later reperfusion was associated with a slower pace and lesser extent of recovery, RVFW contraction improved markedly over time. At 4 weeks, there was trivial RVFW scar in 4-hour animals (2% of total RVFW area), and, although fibrosis was significantly greater in 8-hour animals (7% of RVFW area), infarction was minimal relative to the extent of jeopardized myocardium.

CONCLUSIONS

The responses of ischemic RV myocardium to reperfusion are complex, with disparate effects according to the duration of preceding ischemia. Early reperfusion results in prompt improvement in and subsequent complete recovery of RVFW contraction and global RV performance, with trivial or no RVFW scar. Late reperfusion leads to little acute recovery of RVFW function, but global performance improves owing to diminished RVFW dyskinesis associated with reperfusion-induced increments in RVFW diastolic thickness. Nevertheless, RVFW function improves over time, with minimal evidence of infarction. Therefore, reperfusion facilitates recovery of RV function and minimizes the extent of infarction even after prolonged ischemia.

Feasibility of intraoperative coronary angiography during hypothermic cardioplegic arrest

Although intraoperative coronary angioplasty has the potential to enhance revascularization in selected patients undergoing coronary bypass, this technique is only rarely performed, due in part to the lack of angiographic monitoring. Accordingly, to develop angiographic techniques potentially applicable to intraoperative angioplasty, 6 conditioned dogs were placed on full cardiopulmonary bypass, the aorta was cross-clamped, and the heart arrested with cold cardioplegia solution. After 45 minutes of arrest, selective coronary angiography was performed employing catheters introduced through a proximal aortotomy. Small-volume contrast injections resulted in excellent opacification; however, the contrast agent stagnated within the coronary tree. Fortunately, intracoronary flush injection of the saline-cardioplegia solution resulted in immediate and complete contrast washout. After discontinuation of bypass, echocardiography revealed normal left and right ventricular function. Histopathologic analysis of tissue specimens from animals in which contrast was flushed documented the presence of normal coronary arteries and myocardium. These findings demonstrate methods by which intraoperative coronary angiography can be performed in the arrested heart without having adverse effects on either the cardiac function or histologic appearance. These techniques may have application for the performance of intraoperative angioplasty.

Determinants of the recovery of right ventricular performance following experimental chronic right coronary artery occlusion

BACKGROUND

Patients with acute ischemic right ventricular dysfunction often develop hemodynamic compromise, yet most manifest spontaneous early clinical improvement and later recovery of global right ventricular performance. This study was designed to delineate the determinants of right ventricular performance following chronic right coronary artery occlusion.

METHODS AND RESULTS

Thrombotic right coronary artery occlusion was induced in 16 closed-chest dogs. Acute occlusion depressed right ventricular free wall motion (motion score, 1.0 +/- 0.0 to 3.4 +/- 0.1*) and global performance (right ventricular fractional area change, 29.2 +/- 1.8% to 2.3 +/- 1.9%*). There was right ventricular dilatation and reversed septal curvature, with elevated and equalized diastolic filling pressures. At 5 days, despite persistent severe right ventricular free wall dysfunction (motion score, 3.4 +/- 0.1 to 2.7 +/- 0.1*), global right ventricular performance improved (fractional area change, 2.3 +/- 1.9% to 17.0 +/- 3.8%*), in part due to reduced right ventricular free wall dyskinesis associated with increased right ventricular free wall end-diastolic thickness. At 7 weeks, collateral flow had restored right ventricular free wall perfusion to baseline values. The increased right ventricular free wall thickness had resolved, right ventricular free wall motion was improved (2.7 +/- 0.1 to 1.6 +/- 0.1*), and global right ventricular performance had recovered further (17.0 +/- 3.8 to 20.9 +/- 0.9). Right ventricular dilatation was reduced, septal curvature normalized, and there was resolution of equalized filling pressures. Histopathological analysis demonstrated minimal right ventricular infarction.

CONCLUSIONS

Acute right coronary artery occlusion results in right ventricular free wall dyskinesis and depressed global right ventricular performance. Global right ventricular function improves early, in part due to reduced right ventricular free wall dyskinesis associated with increased right ventricular free wall diastolic thickness. Collateral restoration of perfusion facilitates late recovery of right ventricular free wall function (*P < .05).

Reduced aerobic metabolic efficiency in globally "stunned" myocardium

Post-ischemic "stunned" myocardium appears to be metabolically inefficient, since oxygen consumption is preserved, while mechanical work is depressed. The present study investigated whether this metabolic inefficiency represents a basal functional abnormality present in the quiescent myocardium (e.g. abnormal mitochondrial coupling) or is specifically related to muscle contraction. Isolated perfused rabbit hearts (n = 7) were exposed to 20 min zero-flow ischemia to produce post-ischemic myocardial stunning. After 10 min of reperfusion, mean rate-pressure product (mmHg/min), was reduced to 56.1% of baseline in stunned hearts, while mean oxygen consumption (mumol O2/min/g LV) was reduced to only 71.8% of baseline. The ratio of oxygen consumption to rate-pressure product remained significantly elevated throughout 40 min of reperfusion when compared with non-ischemic controls (P less than 0.01). Despite inappropriately high oxygen consumption in the beating stunned heart, basal oxygen consumption measured after KCl arrest was not significantly different from controls (1.07 +/- 0.07 vs. 1.03 +/- 0.04, respectively). These results indicate that the metabolic inefficiency found in stunned myocardium is not a basal abnormality, but rather is related specifically to abnormalities in contraction or electromechanical coupling.