Leukotrienes C4 and D4 (LTC4 and LTD4), possible mediators of cardiac dysfunction during inflammatory injury, may depress cardiac function by reducing coronary flow or by exerting a negative effect directly on the myocardium. We used an isovolumic rat heart preparation perfused at constant pressure and measured left ventricular developed pressure (mmHg), coronary flow (ml.min-1), oxygen extraction, and myocardial oxygen consumption and delivery (mumol O2.[gramme dry weight]-1.min-1) during infusion of five doses of angiotensin II, LTC4, LTD4 (approximately 10 to approximately 300 pmol.min-1), and noradrenaline (400 to 2000 pmol.min-1), or perfusion with medium which contained calcium at half-concentration. LTC4 and LTD4 were equipotent with angiotensin. At low effective doses, increased oxygen extraction offset the decrease in oxygen delivery, maintaining a stable level of oxygen consumption and left ventricular developed pressure. At the highest doses, angiotensin, LTC4 and LTD4 reduced coronary flow from 21 to 15, 21 to 13, and 21 to 13 ml.min-1, respectively. And, despite greater oxygen extraction of 59%, 58% and 65% for angiotensin, LTC4 and LTD4, left ventricular developed pressure fell from a baseline of 120 mmHg to 113, 106 and 92, respectively. In contrast, low calcium perfusion reduced left ventricular developed pressure (126 to 92) and oxygen extraction (46 to 30%) without changing coronary flow or oxygen delivery. These results suggest that LTC4 and LTD4 are potent coronary vasoconstricting agents which depress cardiac function by limiting oxygen delivery.

1 and Stent Restenosis (STRESS) 2 studies (Aug. 25 issue) raise important questions about strategies for coronary-stent placement. Should coronary stents be considered for all patients with new focal lesions in large coronary arteries that have a high likelihood of dissection, 3 or should they be used only on a conditional basis if balloon angioplasty does not achieve the desired degree of dilation?Although the randomized studies 1,2 showed that coronarystent placement reduced the rate of clinical restenosis, the only component of the composite end point that was favorably affected was the need for a second intervention involving the original coronary lesion. Coronary-stent placement did not reduce the risk of death or major complications such as myocardial infarction, because stent thrombosis occurred in 3 to 4 percent of patients up to two weeks after treatment and was usually associated with death or myocardial infarction. Other drawbacks of coronary-stent placement included major hemorrhage in 7 to 14 percent of patients 1,2 and rates of angiographic restenosis 1,2 that fell short of the values needed to produce a cost savings. 4 An intraprocedural strategy of conditional stent placement for patients with stenoses of more than 25 to 30 percent after balloon angioplasty should be considered. Such a strategy is reasonable because dilation with balloon angioplasty is re-quired in all patients before they undergo coronary-stent placement, and the rate of angiographic restenosis depends on the luminal diameter at the time of the procedure, not on the dilating procedure itself. 2,5 If dilation with balloon angioplasty can achieve a "stent-like" result, the benefits of a large postprocedural luminal diameter should be conferred without the need for coronary-stent placement. The safety of the conditional approach is suggested by the results of the Benestent study, in which no complications occurred in patients undergoing elective bypass surgery who underwent bailout coronary-stent placement after failed balloon angioplasty. 1 Brigham and Women's Hospital 1. Serruys PW, de Jaegere P, Kiemeneij F, et al. A comparison of balloonexpandable-stent implantation with balloon angioplasty in patients with coronary artery disease. N Engl J Med 1994;331:489-95. 2. Fischman DL, Leon MB, Baim DS, et al. A randomized comparison of coronary-stent placement and balloon angioplasty in the treatment of coronary artery disease. N Engl J Med 1994;331:496-501. 3. Topol EJ. Caveats about elective coronary stenting. N Engl J Med 1994;331: 539-41. 4. Cohen DJ, Breall JA, Ho KK, et al. Evaluating the potential cost-effectiveness of stenting as a treatment for symptomatic single-vessel coronary disease: use of a decision-analytic model. Circulation 1994;89:1859-74. 5. Kuntz RE, Gibson CM, Nobuyoshi M, Baim DS. Generalized model of restenosis after conventional balloon angioplasty, stenting and directional atherectomy. J Am Coll Cardiol 1993;21:15-25.To the Editor: The two recently published studies comparing the implantation of a Palmaz-Scha...

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