Platelet activation during coronary angioplasty in humans.

BACKGROUND: Previous studies have indicated that balloon angioplasty is associated with local platelet activation. In addition, different contrast media have different effects on thrombus formation during angioplasty in humans. We hypothesized that coronary angioplasty in humans is associated with activation of platelets to specific platelet agonists and that this activation may be differently modified by different angiographic contrast agents. METHODS AND RESULTS: We studied 25 patients referred for angioplasty of the left anterior descending or circumflex coronary arteries. All patients were pretreated with aspirin and received heparin. Blood samples for assessment of platelet aggregation to serotonin, ADP, epinephrine, and collagen were obtained from the coronary sinus before any contrast injection, after initial diagnostic contrast injections, and after three balloon inflations. Patients were randomized to receive iopamidol, diatrizoate, or ioxaglate. Contrast alone was not associated with altered platelet aggregation. However, balloon angioplasty was consistently associated with increased platelet aggregation to serotonin but not to ADP, epinephrine, or collagen. These effects were similar with the three contrast agents studied except that the use of iopamidol was associated with increased platelet responsiveness to all concentrations of ADP after balloon dilation. CONCLUSIONS: Coronary angioplasty in humans was associated with increased platelet aggregation in blood drawn from the coronary sinus. This effect was primarily seen when serotonin was used as an agonist.

Influence of contrast media on thrombus formation during coronary angioplasty.

The influence of contrast media on thrombus formation during percutaneous transluminal coronary angioplasty was assessed in 124 consecutive patients undergoing coronary angioplasty and receiving either ionic (n = 57) (Group I) or nonionic (n = 67) (Group II) contrast medium. The presence of thrombus was assessed by qualitative analysis of angiograms in identical pre- and postangioplasty projections by four observers who had no knowledge of other data. Quantitation of stenosis severity before and after angioplasty and qualitative analysis of lesion eccentricity and complexity and of the presence of dissection were also performed. Although the baseline clinical characteristics of the two groups (including presenting syndromes and procedural and angiographic variables) did not differ, more patients in Group II than Group I developed new thrombus during coronary angioplasty (18% vs. 4%, p less than 0.02). In particular, patients with a presenting syndrome of recent myocardial infarction or rest angina, or both, and patients with an eccentric coronary plaque were more likely to develop new thrombus if they received nonionic than if they received ionic contrast medium (p less than 0.05). Patients with new thrombus formation and patients with thrombus present both before and after angioplasty had a high incidence of acute procedural complications (36% and 23%, respectively). Patients in Groups I and II had a similar incidence of ischemic events during follow-up.

Prevalence of and variables associated with silent myocardial ischemia on exercise thallium-201 stress testing.

The prevalence of silent myocardial ischemia was prospectively assessed in a group of 103 consecutive patients (mean age 59 +/- 10 years, 79% male) undergoing symptom-limited exercise thallium-201 scintigraphy. Variables that best correlated with the occurrence of painless ischemia by quantitative scintigraphic criteria were examined. Fifty-nine patients (57%) had no angina on exercise testing. A significantly greater percent of patients with silent ischemia than of patients with angina had a recent myocardial infarction (31% versus 7%, p less than 0.01), had no prior angina (91% versus 64%, p less than 0.01), had dyspnea as an exercise test end point (56% versus 35%, p less than 0.05) and exhibited redistribution defects in the supply regions of the right and circumflex coronary arteries (50% versus 35%, p less than 0.05). The group with exercise angina had more ST depression (64% versus 41%, p less than 0.05) and more patients with four or more redistribution defects. However, there was no difference between the two groups with respect to mean total thallium-201 perfusion score, number of redistribution defects per patient, multi-vessel thallium redistribution pattern or extent of angiographic coronary artery disease. There was also no difference between the silent ischemia and angina groups with respect to antianginal drug usage, prevalence of diabetes mellitus, exercise duration, peak exercise heart rate, peak work load, peak double (rate-pressure) product and percent of patients achieving greater than or equal to 85% of maximal predicted heart rate for age. Thus, in this study group, there was a rather high prevalence rate of silent ischemia (57%) by exercise thallium-201 criteria.(ABSTRACT TRUNCATED AT 250 WORDS)