Thomas P. Gavaghan

Immediate postoperative aspirin improves vein graft patency early and late after coronary artery bypass graft surgery. A placebo-controlled, randomized study.

BackgroundThe efficacy of aspirin for prevention of thrombotic graft occlusion after coronary artery bypass grafting (CABG) depends both on the dosage and time window of administration. Early and late graft patency were therefore assessed in a prospective, double-blind, randomized, placebo-controlled trial of aspirin, 324 mg daily, given within 1 hour of CABG. Methods and ResultsAngiographic graft patency was determined at 1 week (231 patients) and year (219 patients) after CABG. The early vein graft occlusion rate was 1.6% on aspirin and 6.2% on placebo (p = 0.004), and late graft occlusion rate was 5.8% on continued aspirin and 11.6% on placebo (p = 0.01). New graft occlusion between 1 week and 1 year was less common in patients on aspirin than on placebo (4.3% versus 7.4%, p = 0.013). The protective effect of aspirin against occlusion persisted in most subgroups of graft type, graft flow, diameter of recipient artery, location of grafted artery, and endarterectomy. Mean chest tube blood loss for the first 24 hours was 571 ml for the aspirin group and 563 ml for the placebo group. Red cell transfusion requirements were 902 ml in the aspirin group and 934 ml in the placebo group (p=NS). The reoperation rate was 4.8% in the aspirin group and 1% in the placebo group (p = 0.1). ConclusionsImmediate postoperative administration of aspirin (324 mg) improves early graft patency and, with continued usage, protects against further occlusion up to 1 year after CABG. Postoperative blood loss was similar in the two groups; however, aspirin was associated with a nonsignificant higher rate of reoperation.

Contribution of left ventricular contraction to the generation of right ventricular systolic pressure in the human heart.

To determine whether left ventricular (LV) contraction contributes to the generation of right ventricular (RV) systolic pressure in humans, LV and RV pressures and their first derivative (dP/dt) were recorded simultaneously with micromanometer-tipped catheters in 11 conscious subjects. Seven subjects had normal LV and coronary angiograms. Four subjects had moderate LV dysfunction (resting ejection fraction 0.40 to 0.50), and three of these had coronary artery disease. During normal sinus rhythm, LV contraction slightly preceded RV contraction (mean 20 msec), and LV and RV dP/dt recordings showed single positive systolic peaks that were coincident. During endocardial pacing of the RV free wall, RV contraction preceded LV contraction (mean 23 msec) and two systolic RV dP/dt peaks were recorded, the first (peak I) occurring significantly before (mean +/- SD = 67 +/- 23 msec, p less than .01), and the second (peak II) coincident with the single systolic LV dP/dt peak. RV ectopic beats produced a similar RV dP/dt pattern, with peak I occurring 63 +/- 11 msec (p less than .01) before, and peak II coincident with the single LV dP/dt peak. Conversely, during LV ectopic beats, LV contraction preceded RV contraction (mean 63 msec) and two systolic RV dP/dt peaks were recorded, but peak I was coincident with the single LV dP/dt peak, while peak II occurred significantly later (63 +/- 26 msec, p less than .01). In two subjects right bundle branch block produced similar findings. In three subjects left bundle branch block produced little ventricular asynchrony (mean 14 msec), but did delay the development of peak LV dP/dt after LV contraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Intravenous sotalol for the treatment of atrial fibrillation and flutter after cardiopulmonary bypass. Comparison with disopyramide and digoxin in a randomised trial.

The efficacy of sotalol in treating acute atrial fibrillation and flutter after open heart surgery was compared with that of a digoxin/disopyramide combination. Forty adult patients with postoperative atrial arrhythmias were randomised into either group 1 (sotalol 1 mg/kg bolus intravenously plus 0.2 mg/kg intravenously over 12 hours) or group 2 (digoxin 0.75 mg intravenously, then two hours later disopyramide 2 mg/kg intravenous bolus and 0.4 mg/kg/h intravenously for 10 hours). In each group, 17 out of 20 patients reverted to sinus or junctional rhythm within 12 hours. The time to reversion in group 1 was significantly shorter than in group 2. Systolic blood pressure fell by greater than or equal to 20 mm Hg or to less than or equal to 90 mm Hg during drug administration in 17 out of 20 patients in group 1 (sotalol withdrawn in two) and in none out of 20 in group 2. Two patients in group 1 developed transient bradycardia (sotalol withdrawn in one). None of 17 patients in group 1 and two of 17 in group 2 relapsed temporarily into atrial fibrillation during the 12 hours of intravenous treatment. On continued oral treatment, one late relapse occurred in group 1 and five in group 2, and five patients in group 2 had disopyramide withdrawn because of anticholinergic side effects (acute urinary retention in four). Sotalol was as effective as the digoxin/disopyramide combination and acted significantly faster. Sensitivity to beta blockade in these patients may be related to high plasma catecholamine concentrations known to occur after cardiopulmonary bypass.

Flecainide compared with a combination of digoxin and disopyramide for acute atrial arrhythmias after cardiopulmonary bypass

Fifty six adult patients were randomised to treatment with flecainide (group 1, n = 29) or a combination of digoxin and disopyramide (group 2, n = 27) for acute atrial fibrillation and flutter after cardiac surgery. Intravenous flecainide was given as a 2 mg/kg bolus over 20 minutes followed by an infusion (0.2 mg/kg per hour) for 12 hours. Group 2 were given digoxin (0.75 mg) intravenously followed two hours later by an intravenous bolus of disopyramide (2 mg/kg) and an infusion (0.4 mg/kg per hour) for 10 hours. Within 12 hours sinus rhythm was restored in 86% of the group 1 (25 patients) and 89% of the group 2 (24 patients). The median time to reversion was significantly shorter in group 1 (80 minutes, range 30-180 minutes) than group 2 (220 minutes, range 138-523 minutes). None of the patients in group 1 and four of the patients in group 2 had transient relapses into atrial fibrillation during the 12 hours of intravenous treatment. There were five late relapses in group 1 and seven in group 2 during subsequent oral treatment. Two group 1 patients and two group 2 patients showed adverse drug effects. Intractable ventricular arrhythmias occurred after five days of oral treatment in one patient (group 1) who had poor left ventricular function, hepatic impairment, and toxic concentrations of drugs at the time of death. Flecainide was as effective as the combination of digoxin and disopyramide and it acted significantly faster and was associated with fewer relapses. Monitoring of blood concentrations of flecainide is essential in patients with poor left ventricular function and hepatic impairment.

Increased plasma beta-thromboglobulin in patients with coronary artery vein graft occlusion : response to low dose aspirin

The therapeutic effect of aspirin on vein graft patency was studied in patients undergoing coronary artery bypass graft surgery. The study design enabled the prospective evaluation of the relation of platelet activation, as measured by plasma beta-thromboglobulin concentration, to subsequent coronary vein graft occlusion. Serial beta-thromboglobulin levels were measured in 105 patients randomized to receive aspirin (324 mg/day) or placebo beginning within 1 h after surgery. Graft patency was assessed angiographically at 1 week and 1 year after surgery. Of 49 patients receiving placebo, 17 (34.7%) had one or more graft occlusions, 6 early, 10 late and 1 with both early and late occlusion. Of 56 patients receiving aspirin, 7 (12.5%) had one or more occlusions, 3 early and 4 late (p less than 0.01). Preoperatively, the beta-thromboglobulin level in surgical patients (29 +/- 13.5 ng/ml) was significantly higher than that of 51 control subjects (22.6 +/- 11.1 ng/ml) (p less than 0.004). Plasma beta-thromboglobulin levels remained comparatively constant at 3 and 12 months after surgery in the 43 patients who had both samples available (p less than 0.001, r = 0.65). The reduction in beta-thromboglobulin concentration from the preoperative level to 12 months postoperatively was greater in the aspirin-treated group (p less than 0.001). Multivariate logistic regression analysis demonstrated a significant association between preoperative beta-thromboglobulin concentration and graft occlusion (p less than 0.02), and aspirin treatment was effective in preventing occlusion when adjusted for the preoperative beta-thromboglobulin level (p less than 0.005). Plasma beta-thromboglobulin concentrations are elevated in patients with coronary artery disease, suggesting ongoing platelet activation.(ABSTRACT TRUNCATED AT 250 WORDS)

Intracoronary stenting without intravascular ultrasound guidance followed by antiplatelet therapy with aspirin alone in selected patients

One hundred selected patients with 103 lesions were treated with the deployment of 117 Palmaz-Schatz stents without the use of intravascular ultrasound, followed by antiplatelet therapy with aspirin alone. Angiographic and clinical follow-up revealed 2 stent thromboses; 3 stents required redilation, and 3 patients required intervention for disease progression elsewhere, suggesting that this approach can be applied effectively in selected patients.