George Michael Deeb

Clinical outcome of patients with advanced coronary artery disease after viability studies with positron emission tomography

OBJECTIVE The aim of this study was to determine the prognostic significance of perfusion-metabolism imaging in patients undergoing positron emission tomography for myocardial viability assessment. BACKGROUND Positron emission tomography using nitrogen-13 ammonia and 18fluorodeoxyglucose to assess myocardial blood flow and metabolism has been shown to predict improvement in wall motion after coronary artery revascularization. The prognostic implications of metabolic imaging in patients with advanced coronary artery disease have not been investigated. METHODS Eighty-two patients with advanced coronary artery disease and impaired left ventricular function underwent positron emission tomographic imaging between August 1988 and March 1990 to assess myocardial viability before coronary artery revascularization. RESULTS Forty patients underwent successful revascularization. Patients who exhibited evidence of metabolically compromised myocardium by positron emission tomography (decreased blood flow with preserved metabolism) who did not undergo subsequent revascularization were more likely to experience a myocardial infarction, death, cardiac arrest or late revascularization due to development of new symptoms than were the other patient groups (p less than 0.01). Concordantly decreased flow and metabolism in segments of previous infarction did not affect outcome in patients with or without subsequent revascularization. Those with a compromised myocardium who did undergo revascularization were more likely to experience an improvement in functional class than were patients with preoperative positron emission tomographic findings of concordant decrease in flow and metabolism. CONCLUSIONS Positron emission tomographic myocardial viability imaging appears to identify patients at increased risk of having an adverse cardiac event or death. Patients with impaired left ventricular function and positron emission tomographic evidence for jeopardized myocardium appear to have the most benefit from a revascularization procedure.

Relation of regional function, perfusion and metabolism in patients with advanced coronary artery disease undergoing surgical revascularization

BACKGROUND Imaging of myocardial glucose metabolism using [18F]fluorodeoxyglucose (FDG) with positron emission tomography (PET) has been proposed for identification of tissue viability in patients with advanced coronary artery disease. This study was designed to evaluate the predictive value of flow and metabolic imaging for functional recovery after revascularization in myocardial segments of varying degrees of dysfunction. METHODS AND RESULTS Thirty-seven patients (mean age, 59 +/- 11 years) with coronary artery disease and impaired left ventricular function (ejection fraction, 34 +/- 10%) were studied with PET using FDG and [13N]ammonia before surgical coronary revascularization (3 +/- 1 grafts per patient). Tissue was scintigraphically characterized as normal, nonviable (concordant reduction of perfusion and FDG uptake), viable without discordance of perfusion and metabolism (mildly reduced perfusion and metabolism), or ischemically compromised (mismatch of reduced perfusion and maintained FDG uptake). Functional outcome was assessed by serial radionuclide ventriculography before and at 13 +/- 13 weeks (median interval of 8 weeks) after coronary revascularization. Preoperatively impaired regional wall motion improved significantly in ischemically compromised (mismatch) revascularized segments but not in nonviable myocardium or in viable myocardium without discordance of perfusion and metabolism. The negative predictive value of PET for functional recovery was 86%, whereas the positive predictive value in revascularized regions ranged from 48% to 86% depending on severity of baseline wall motion abnormalities. CONCLUSIONS PET identifies metabolically active tissue, which benefits from revascularization. Although the negative predictive value of PET for recovery was high, functional improvement of viable but ischemically compromised tissue was less frequent than previously reported. The predictive value of PET was highest in left ventricular segments with severe dysfunction and a mismatch or reduced perfusion but preserved metabolism. Integration of PET, angiographic, and functional data is necessary for the optimal selection of patients with advanced coronary artery disease and impaired left ventricular function for revascularization.

Resolution of large azygos vein aneurysm following stent-graft shunt placement in a patient with Ehlers-Danlos syndrome type IV.

Ehlers-Danlos syndrome (EDS) type IV is a rare connective tissue disorder associated with thin-walled, friable arteries and veins predisposing patients to aneurysm formation, dissection, fistula formation, and vessel rupture. Azygos vein aneurysm is an extremely rare condition which has not been reported in association with EDS in the literature. We present a patient with EDS type IV and interrupted inferior vena cava (IVC) with azygos continuation who developed an azygos vein aneurysm. In order to decrease flow through the azygos vein and reduce the risk of aneurysm rupture, a stent-graft shunt was created from the right hepatic vein to the azygos vein via a transhepatic, retroperitoneal route. At 6 month follow-up the shunt was open and the azygos vein aneurysm had resolved.

Visceral Malperfusion in Aortic Dissection: The Michigan Experience

One of the most dreaded complications of acute aortic dissection is end-organ malperfusion. We summarize current evidence and describe our treatment paradigm in the setting of malperfusion in aortic dissection. Given the difficulty with identifying isolated visceral malperfusion in aortic dissection, both in the literature as well as in our practice, we have broadened the discussion to include data examining the presentation complex of malperfusion, particularly if mesenteric ischemia is identified. The approach to treating malperfusion syndrome is different depending on whether the patient presents with type A dissection vs type B dissection with malperfusion. Although thoracic endovascular aortic repair has emerged as the dominant strategy for resolving malperfusion for complicated type B dissection, fenestration may still have a role in its treatment. In contrast, for type A aortic dissection presenting with visceral malperfusion, the concept of operative repair after restoration of end-organ perfusion has been proposed with increasing frequency in recent reports. At the University of Michigan, we apply a patient-specific algorithm, based on the presence of malperfusion with end-organ dysfunction. In those patients presenting with visceral malperfusion, we prefer to first fenestrate, await resolution of the malperfusion syndrome and then perform central aortic repair. We recognize that other groups have implemented similar algorithms to reduce the dismal results of operative procedures in this cohort. However, the most appropriate period of delay remains unknown and there is a persistent risk of rupture before repair is performed. Future studies should be performed to determine whether these various treatment paradigms have merit.

Mortality Predictors in Patients Referred for but Not Undergoing Transcatheter Aortic Valve Replacement

Although transcatheter aortic valve replacement (TAVR) has expanded the proportion of patients with aortic stenosis (AS) who are candidates for valve replacement, some patients remain untreated, and their outcomes are not clear. We evaluated 172 consecutive patients with severe symptomatic AS referred for TAVR who declined (n = 55) or were not candidates for (n = 117) intervention. We examined clinical and echocardiographic variables associated with mortality. There were 77 deaths, and mean follow-up was 17.9 ± 10.9 months for survivors. Mortality rate at 1 and 2 years was 39.2% and 52.6%, respectively. There was a significant difference in mortality rate between patients who declined the procedure and those who were not candidates (p = 0.001), with 1-year mortality rates of 20.6% and 48.4%, respectively. On multivariate analysis, 4 variables were independently associated with all-cause mortality: New York Heart Association Class IV heart failure (hazard ratio [HR] 2.6, 95% confidence interval [CI] 1.6 to 4.2, p <0.001), glomerular filtration rate <48 ml/min (HR 2.1, 95% CI 1.3 to 3.4, p = 0.002), albumin <3.9 g/dl (HR 1.9, 95% CI 1.2 to 3.1, p = 0.007), and ejection fraction <50% (HR 1.9, 95% CI 1.4 to 3.0, p = 0.01). In this new era with expanded treatment options, patients with severe symptomatic AS who remain untreated after referral for TAVR experience a mortality rate of 39% at 1 year. The presence of advanced heart failure, renal dysfunction, low albumin, and/or left ventricular dysfunction identifies patients at higher risk of mortality.

Evolving trends in aortic valve replacement: A statewide experience

Transcatheter aortic valve replacement (TAVR) is an alternative to surgical aortic valve replacement (SAVR) for the treatment of aortic stenosis in patients at intermediate, high, and extreme risk for mortality from SAVR. We examined recent trends in aortic valve replacement (AVR) in Michigan.

Outcomes of Patients Presenting With Acute Type A Aortic Dissection in the Setting of Prior Cardiac Surgery An Analysis From the International Registry of Acute Aortic Dissection

Background— Prior cardiac surgery (PCS) can complicate the presentation and management of patients with type A acute aortic dissection (TAAAD). This report from the International Registry of Acute Aortic Dissection examines this hypothesis. Methods and Results— A total of 352 of 2196 patients with TAAAD (16%) enrolled in the International Registry of Acute Aortic Dissection had cardiac surgery before dissection, including coronary artery bypass grafting (34%), aortic or mitral valve surgery (36%), aortic surgery (42%), and other cardiac surgery (16%). Those with PCS were older, had a higher frequency of diabetes mellitus, hypertension, and atherosclerosis, and presented later from symptom onset to hospital presentation and diagnosis (all P<0.05). In-hospital mortality was significantly higher for PCS patients (34% versus 23%; P<0.001). Five-year mortality was independently predicted by PCS (hazard ratio [HR], 2.04; 95% confidence interval [CI], 1.05–3.95), age >70 years (HR, 2.65; 95% CI, 1.40–5.05), medical management (HR, 5.10; 95% CI, 2.43–10.71), distal communication (HR, 2.64; 95% CI, 1.35–5.14), and coma (HR, 9.50; 95% CI, 2.05–44.05). Among patients with PCS, in-hospital (43% medical versus 30% surgical; P=0.033) and intermediate-term mortality was higher in patients with medical versus surgical management. Propensity-matched analysis revealed significant increase in mortality with medical management, but not with PCS. Conclusions— PCS delays presentation, diagnosis, and treatment of TAAAD and is an important adverse risk factor for early and intermediate-term mortality. This effect may be because of increased medical management in this patient population.