Additive Beneficial Effects of Beta-Blockers to Angiotensin-Converting Enzyme Inhibitors in the Survival and Ventricular Enlargement (SAVE) Study fn1fn1This study was supported by a University-Industry grant from the Medical Research Council, Ottawa, Ontario, Canada and Bristol Myers Squibb, Montreal, Quebec, Canada.

AbstractObjectives. This study assessed whether treatment with a beta-adrenergic blocking agent in addition to the use of the angiotensin-converting enzyme (ACE) inhibitor captopril decreases cardiovascular mortality and morbidity in patients with asymptomatic left ventricular dysfunction after myocardial infarction (MI) and whether the presence of neurohumoral activation at the time of hospital discharge predicts the effects of beta-blocker treatment in these patients.Background. Both beta-blockers and ACE inhibitors have been shown to have beneficial effects in patients with left ventricular dysfunction but no overt heart failure after MI. These patients often have persistent neurohumoral activation at the time of hospital discharge, and one would expect that patients with activation of the sympathetic nervous system derive the most benefit from treatment with beta-blockers. However, beta-blockers are underutilized in this high risk group of patients, and it is unknown whether their beneficial effects are additive to those of ACE inhibitors.Methods. We performed a retrospective analysis of data from the Survival and Ventricular Enlargement (SAVE) study and its neurohumoral substudy. The relations between beta-blocker use at the time of randomization and neurohumoral activation and the subsequent development of cardiovascular events were analyzed by use of Cox proportional hazards models controlling for covariates.Results. After adjustment for baseline imbalances, beta-blocker use was associated with a significant reduction in risk of cardiovascular death (30%, 95% confidence interval [CI] 12% to 44%) and development of heart failure (21%, 95% CI 3% to 36%), but the reduction in recurrent MI (11%, 95% CI 13% to 31%) was not significant. These reductions were independent of the use of captopril. Beta-blockers were not found to have a greater effect in patients with neurohumoral activation at the time of hospital discharge.Conclusions. The beneficial effects of beta-blocker use at the time of hospital discharge in patients with asymptomatic left ventricular dysfunction after MI appear to be additive to those of captopril and other interventions known to improve prognosis. Neurohumoral activation at the time of hospital discharge fails to identify those patients who will derive the greatest benefit from treatment with beta-blockers.(J Am Coll Cardiol 1997;29:229–36

Transstenotic coronary pressure gradient measurement in humans:in vitro and in vivo evaluation of a new pressure monitoring angioplasty guide wire

\u3cp\u3eObjectives. The present study was designed to investigate 1) the feasibility and accuracy of coronary pressure measurements with a novel 0.015-in. (0.038 cm) fluid-filled guide wire, and 2) the effect of the guide wire itself on stenosis hemodynamics. Background. To assess the functional results of coronary angioplasty, measurements of the transstenotic pressure gradient have been advocated. However, this is no longer routinely measured because it is not reliable when determined with the angioplasty catheter. Methods. A fluid-filled 0.015-in. guide wire to be connected to a conventional pressure transducer was developed. Five wires were tested for their frequency response characteristics and for their accuracy in measuring hydrostatic pressure. In an in vitro model of stenosis (reference diameter 4 mm), the pressure gradient was determined at incremental flow levels for varying stenosis severity with and without a 0.015-in. guide wire through the narrowing. In 37 patients, the transstenotic pressure gradient was measured before and after angioplasty and compared with obstruction area and percent area stenosis as determined by quantitative coronary angiography. Results. The correlation between the actual pressure and the pressure recorded by the guide wire was excellent (r = 0.98) despite a slight underestimation (-3 ± 5%). Phasic pressure recordings were precluded by a long time constant of 16 ± 4 s. The presence of the guide wire produced a significant overestimation (>20%) of the pressure decrease only in cases of tight stenosis (>90% area reduction). Furthermore, a theoretic model based on the fluid dynamic equation predicted that this overestimation was inversely proportional to the reference diameter of the vessel, yet was only slightly influenced by the flow. The lesion was crossed in all but one (97%) and pressure gradient was recorded throughout the study in 34 (94%) of 36 patients. The mean pressure gradient decreased from 30 ± 19 before to 3 ± 5 mm Hg after angioplasty (p < 0.01). A curvilinear relation was found between the pressure gradient and both percent area stenosis (r\u3csup\u3e2\u3c/sup\u3e = 0.67) and obstruction area (r\u3csup\u3e2\u3c/sup\u3e = 0.72). A sharp increase in pressure gradient was noted once the stenosis exceeded 75% area reduction. Conclusions. Mean transstenotic pressure gradients can be easily and reliably recorded with a 0.015-in. fluid-filled guide wire. This ability should facilitate the functional assessment of coronary stenoses of intermediate severity and of immediate postangioplasty results.\u3c/p\u3