Schaff, Hartzell V.

Background— Few studies have compared long-term status of bypass grafts between patients with and without diabetes, and uncertainty exists as to whether diabetes independently predicts poor clinical outcome after CABG. Methods and Results— Among 1526 patients in BARI who underwent CABG as initial revascularization, 99 of 292 (34%) with treated diabetes mellitus (TDM) (those on insulin or oral hypoglycemic agents) and 469 of 1234 (38%) without TDM had follow-up angiography. Angiograms with the longest interval from initial surgery and before any percutaneous graft intervention (mean 3.9 years) were reviewed. An average of 3.0 grafts were placed at initial CABG for patients with TDM (n=297; internal mammary artery [IMA], 33%) and 2.9 grafts for patients without TDM (n=1347; IMA, 34%). Patients with TDM were more likely than those without to have small (<1.5 mm) grafted distal vessels (29% versus 22%) and vessels of poor quality (9% versus 6%). On follow-up angiography, 89% of IMA grafts were free of stenoses ≥50% among patients with TDM versus 85% among patients without TDM ( P =0.23). For vein grafts, the corresponding percentages were 71% versus 75% ( P =0.40). After statistical adjustment, TDM was unrelated to having a graft stenosis ≥50% (adjusted odds ratio, 0.87; 95% CI, 0.58 to 1.32). Conclusions— Despite diabetic patients’ having smaller distal vessels and vessels judged to be of poorer quality, diabetes does not appear to adversely affect patency of IMA or vein grafts over an average of 4-year follow-up. Previously observed differences in survival between CABG-treated patients with and without diabetes may be largely a result of differential risk of mortality from noncardiac causes.

Background— Left ventricular dysfunction is an indication for aortic valve replacement (AVR) in patients with severe aortic regurgitation (AR). However, the postoperative outcome of patients with severe AR and a markedly low ejection fraction (EF) is not known. Methods and Results— The study group consisted of a total of 450 patients who had AVR for isolated AR between 1980 and 1995. Patients with markedly reduced left ventricular function (EF <35%, LoEF, n=43) were compared with those with moderate reduction in left ventricular function (EF 35% to 50%, MedEF, n=134) and those with normal left ventricular function (EF ≥50%, Nl EF, n=273). The operative mortality rate was higher with LoEF (14%) than with MedEF and Nl EF (6.7% and 3.7%, respectively, P =0.02). At 10 years, 41%±9% of LoEF patients had survived compared with 56%±5% and 70%±3% of MedEF and Nl EF patients, respectively ( P <0.0001). Congestive heart failure occurred at 10 years in 25%±9% with LoEF compared with 17%±4% and 9%±2% with MedEF and NL EF, respectively ( P <0.003). Postoperative EF improved by 4.9%±13.8% in the LoEF group and by 4%±11.9% in the MedEF group compared with −2.3%±10.9% in the Nl EF group ( P <0.002 and P <0.0001, respectively). Conclusions— Patients with severe AR and markedly low EF incur excess operative mortality rates, postoperative mortality rates, and congestive heart failure after AVR. However, postoperative EF improves markedly, and most patients enjoy a long postoperative survival without recurrence of heart failure after AVR; thus they should not be denied the benefits of AVR.

Objective— C-reactive protein (CRP) is a sensitive marker of inflammation and a prognostic marker in cardiovascular disease. Evidence suggests direct biological activities of CRP within the vascular wall. The study was designed to examine the vasoreactive effects of CRP. Methods and Results— Human internal mammary artery rings were obtained during cardiovascular bypass surgery and suspended in an organ bath chamber. The rings were precontracted with endothelin-1, and response to cumulative concentrations of CRP was obtained. Experiments were repeated after initial incubation with 20, 40, and 60 mmol/L KCl, the potassium channel blockers BaCl, tetraethylammonium chloride, and glibenclamide, and the NO synthase inhibitor N -monomethyl- l -arginine and also after removal of the endothelium. CRP caused dose-dependent relaxation of human internal mammary artery rings, which was not affected by preincubation with N -monomethyl- l -arginine or removal of the endothelium. Maximum relaxation response to CRP (79.5±10%) was attenuated by KCl (2.5±11.5%, P <0.001), BaCl (24.5±7.5%, P <0.001), and tetraethylammonium chloride (34.9±8.25%, P <0.01) but not by glibenclamide. Conclusions– The present study demonstrates that CRP exerts an endothelium-independent vasorelaxing effect via potassium channels. Thus, the study suggests a role of CRP in the regulation of vascular tone.

Background— Although aortic valve replacement can be performed at an acceptable risk level in selected patients with left ventricular systolic dysfunction and low-output, low-gradient aortic stenosis, not all patients presenting with these hemodynamics will benefit from the operation. Some patients may have only mild aortic stenosis, despite a small calculated valve area. We report on the clinical utility of diagnostic dobutamine stimulation during cardiac catheterization in these diagnostically challenging patients. Methods and Results— Thirty-two patients with low-output, low-gradient aortic stenosis and an ejection fraction <40% had dobutamine infusion in the catheterization laboratory. On the basis of the results of the dobutamine test, 21 patients underwent aortic valve replacement. All patients with a final aortic valve area ≤1.2 cm 2 at peak dobutamine infusion and a mean gradient of >30 mm Hg were found to have severe calcific aortic stenosis at operation. In the 15 patients in whom contractile reserve was identified during dobutamine challenge (increase in stroke volume >20%), 1 patient died perioperatively (7% mortality) and 12 patients were alive in New York Heart Association class I or II status at follow-up. Conclusions— In patients with left ventricular systolic dysfunction and aortic stenosis with a low output and a low mean gradient, dobutamine challenge may aid in selecting those who would benefit from an aortic valve operation.