Effect of enalapril on myocardial infarction and unstable angina in patients with low ejection fractions

An association between raised renin levels and myocardial infarction has been reported. We studied the effects of enalapril, an angiotensin-converting enzyme (ACE) inhibitor, on the development of myocardial infarction and unstable angina in 6797 patients with ejection fractions < or = 0.35 enrolled into the two Studies of Left Ventricular Dysfunction (SOLVD) trials. Patients were randomly assigned to placebo (n = 3401) or enalapril (n = 3396) at doses of 2.5-20 mg per day in two concurrent double-blind trials with the same protocol. Patients with heart failure entered the treatment trial (n = 2569) and those without heart failure entered the prevention trial (n = 4228). Follow-up averaged 40 months. In each trial there were significant reductions in the number of patients developing myocardial infarction (treatment trial: 158 placebo vs 127 enalapril, p < 0.02; prevention trial: 204 vs 161 p < 0.01) or unstable angina (240 vs 187 p < 0.001; 355 vs 312, p < 0.05). Combined, there were 362 placebo group patients with myocardial infarction compared with 288 in the enalapril group (risk reduction 23%, 95% CI 11-34%; p < 0.001). 595 placebo group patients developed unstable angina compared with 499 in the enalapril group (risk reduction 20%, 95% CI 9-29%, p < 0.001). There was also a reduction in cardiac deaths (711 placebo, 615 enalapril; p < 0.003), so that the reduction in the combined endpoint of deaths, myocardial infarction, and unstable angina was highly significant (20% risk reduction, 95% CI 14-26%; p < 0.0001). Enalapril treatment significantly reduced myocardial infarction, unstable angina, and cardiac mortality in patients with low ejection fractions.

Baseline quality of life as a predictor of mortality and hospitalization in 5,025 patients with congestive heart failure. SOLVD Investigations. Studies of Left Ventricular Dysfunction Investigators

This study examined the independent relation of health-related quality of life (HRQL) to mortality and congestive heart failure (CHF)-related hospitalizations in patients with an ejection fraction of < 0.35 followed for a mean of 36.5 months. A brief HRQL questionnaire was administered at baseline to patients randomized to placebo or enalapril in the Studies of Left Ventricular Dysfunction (SOLVD) trial. Participants had an ejection fraction of < 0.35 and either symptomatic CHF (treatment trial, n = 2,465) or asymptomatic CHF (prevention trial, n = 2,560). Baseline assessment of HRQL predicted mortality and CHF-related hospitalizations in symptomatic and asymptomatic patients randomized to enalapril and placebo treatment. Domains that were the stronger univariate predictors of mortality and CHF-related hospitalizations were activities of daily living (relative risk [RR] for mortality: 1.163, p < 0.000; for hospitalization: 1.215, p < 0.000), general health (RR for mortality: 1.205, p < 0.000; for hospitalization: 1.188, p < 0.000), and social functioning (RR for mortality 1.098, p < 0.000; for hospitalization: RR 1.156, p < 0.000). In the multivariate model, activities of daily living (RR for mortality 1.41, p < 0.000; for hospitalization: RR 1.43, p < 0.002), general health (RR for mortality 1.21, p < 0.000; for hospitalization RR 1.16, p < 0.013) and heart failure symptoms (RR for mortality 1.02, p < 0.025; for hospitalization RR 1.03, p < 0.004) were found to be independent risk factors. HRQL independently predicted mortality and CHF-related hospitalizations after adjustment for ejection fraction, age, treatment, and New York Heart Association classification in patients with an ejection fraction of < 0.35, randomized to enalapril and placebo treatment. HRQL provides additional clinical information regarding disease course and outcome that is not captured by traditional indexes of clinical status.

Early detection of doxorubicin cardiotoxicity: interest of Doppler echocardiographic analysis of left ventricular filling dynamics

Doxorubicin (Adriamycin) is an effective anticancer agent but its therapeutic value is limited by its myocardial cardiotoxicity. To improve early detection of doxorubicin cardiotoxicity, studies were performed in patients with long-term doxorubicin treatment using pulsed Doppler echocardiography to assess the changes in left ventricular (LV) diastolic filling dynamics. M-mode echocardiographic systolic parameters and Doppler transmitral flow velocities were analyzed in two groups of patients. In group A (45 patients, mean age 45 +/- 13 years), the results were compared with those of a control group of 35 normal subjects matched for age. In group B (19 patients, mean age 44 +/- 12 years), the pretreatment results were prospectively compared with those obtained during treatment protocol. The patients received a cumulative dosage of 253 +/- 125 mg/m2 of doxorubicin for group A and 240 +/- 135 mg/m2 for group B. After doxorubicin treatment, in the two groups there were no significant changes in LV dimensions, shortening fraction, and mean velocity of circumferential fiber shortening (VCF). In contrast, Doppler echocardiographic parameters of diastolic function were significantly modified after doxorubicin in the two groups:isovolumic relaxation period was prolonged by 32% in group A (p less than 0.001) and by 22% in group B (p less than 0.005).2+ The early peak flow velocity was reduced by 18% in group A (p less 0.002) and by 13% in group B (p less than 0.04), and the ratio early peak flow velocity/atrial peak flow velocity also decreased significantly, by 23% in group A (p less than 0.001) and by 20% in group B (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative efficacy of ranolazine versus atenolol for chronic angina pectoris

We investigated whether ranolazine therapy improves exercise-induced angina pectoris and myocardial ischemia compared with placebo or with standard doses of atenolol in patients who had chronic angina and evaluated the effects on hemodynamics at rest and during exercise. In this trial, 158 patients who had symptom-limited exercise discontinued beta-blocker therapy and were randomized into a double-blind, 3-period, crossover study of 400 mg of immediate-release ranolazine 3 times daily, 100 mg/day of atenolol, or placebo, each administered for 1 week. Exercise tests were administered at the end of each treatment period. Therapy with ranolazine or atenolol produced statistically significant improvement in all 3 exercise end points compared with placebo. Compared with atenolol therapy, ranolazine therapy resulted in significantly longer total exercise duration and was statistically indistinguishable from atenolol for time to onset of angina and ST-segment depression. Except for a modest increase in systolic blood pressure at peak exercise during ranolazine therapy, hemodynamic measurements did not differ significantly during ranolazine and placebo therapies. In contrast, atenolol significantly decreased blood pressure, heart rate, and rate-pressure product at rest and during exercise compared with placebo or ranolazine. In conclusion, ranolazine therapy prolonged exercise duration and decreased exercise-induced ischemia and angina with quantitative effects equal to or greater than those with atenolol. Unlike atenolol, the anti-ischemic and antianginal effects of ranolazine occurred without decreases in blood pressure, heart rate, or rate-pressure product.

Global ischaemia induces a biphasic response of the mitochondrial respiratory chain. Anoxic pre-perfusion protects against ischaemic damage

Studies of Langendorff-perfused rat hearts have revealed a biphasic response of the mitochondrial respiratory chain to global ischaemia. The initial effect is a 30-40% increase in the rate of glutamate/malate oxidation after 10 min of ischaemia, owing to an increase in the capacity for NADH oxidation. This effect is followed by a progressive decrease in these oxidative activities as the ischaemia is prolonged, apparently owing to damage to Complex I at a site subsequent to the NADH dehydrogenase component. This damage is exacerbated by reperfusion, which causes a further decrease in Complex I activity and also decreases the activities of the other complexes, most notably of Complex III. Perfusion for up to 1 h with anoxic buffer produced only the increase in NADH oxidase activity, and neither anoxia alone, nor anoxia and reperfusion, caused loss of Complex I activity. Perfusing for 3-10 min with anoxic buffer before 1 h of global ischaemia had a significant protective effect against the ischaemia-induced damage to Complex I.

Benefits, challenges, and registerability of the polypill

Guidelines for the management of cardiovascular disease (CVD) stress the importance of treating global risk, rather than individual risk, factors. Patients at high cardiovascular (CV) risk, for example, benefit from a combination of aspirin, antihypertensive agents, lipid-lowering drugs, and possibly folic acid. As the number of medications that a patient requires increases, adherence and compliance to therapy are likely to decrease. The use of affordable, multiple-target, fixed-combination 'polypills', which concomitantly reduce multiple risk factors without increasing the pill burden or the risk of adverse effects, has the potential to improve CV risk factor management, thereby reducing the incidence of CVD. This review discusses the benefits of the polypill and the challenges and requirements for its success and registerability. Discussions with regulatory bodies are required in order to obtain some 'balance' between an overcautious registration approach and the potentially large public health benefits that are likely to arise from the use of polypills.

Impaired early left ventricular relaxation in coronary artery disease: effects of intracornary nifedipine

It has been shown that the maximal rate of left ventricular (LV) relaxation is impaired in patients with coronary artery disease (CAD) under basal conditions. To test the hypothesis that this impaired LV relaxation could be related to viable but metabolically abnormal myocardium, we studied the time course of isovolumic LV pressure fall in 21 patients with CAD and in 13 control subjects under basal conditions. This study was repeated after intracoronary injection of the calcium antagonist nifedipine (N) in 11 patients with CAD and in eight controls. Our data showed that isovolumic pressure fall was biexponential in 20 of 21 CAD patients and in six of 13 controls. Moreover, the time constant of isovolumic pressure fall during the first 40 msec after peak (negative) dP/dt (T1) was significantly greater in CAD patients than in controls (62 +/- 3 vs 44 +/- 1 msec, p < 0.002); the time constant of pressure fall during the 40-80 msec after peak (negative) dP/dt (T2) was similar in both groups ( 42 +/- 2 vs 39 +/- 2 msec, NS). Thirty seconds after injection of nifedipine, T1 and T2, were significantly prolonged in patients with CAD (14 msec and 16 msec, respectively, p < 0.005) and in controls 12 msec and 14 msec, respectively, p < 0.05), and a negative inotropic effect was observed in both groups (peak (positive) dP/dt - 16% in controls and -23% in CAD patients, p < 0.01). At rest, impairment of isovolumic relaxation in CAD patients is mainly limited to the first 40 msec after peak (negative) dP/dt, suggesting a dyssynchronous wall motion. This impairment of LV relaxation is better identified by T1 than by peak (negative) dP/dt in individual patients, and cannot be improved by administration of a calcium antagonist.

Effects of ranolazine on left ventricular regional diastolic function in patients with ischemic heart disease

To assess the effects of ranolazine, a new antiischemic drug, on regional myocardium of the left ventricle, left ventricular (LV) hemodynamic and angiographic data were obtained in 15 patients with previous transmural myocardial infarction before and after intravenous infusion of ranolazine (200 or 500 micrograms/kg body weight). LV angiogram was analyzed by the area method and was divided into six segments. Regional LV segments were classified as normal (perfused by intact coronary vessels, n = 20), ischemic (perfused by stenotic vessels but without ECG evidence suggesting myocardial necrosis, n = 25), or infarcted (total coronary occlusion and with the ECG evidence for necrosis, n = 45). Regional area fractional shortening, peak filling rate, and segmental wall motion during isovolumic relaxation period were analyzed. After ranolazine, regional area fractional shortening was unchanged in all segments. However, regional peak filling rate was decreased in the normal segments (1499 +/- 315 to 1368 +/- 303 mm2/sec, p < 0.05). In the ischemic segments, by contrast, the administration of ranolazine significantly increased the regional peak filling rate (1050 +/- 410 to 1133 +/- 439 mm/sec, p < 0.05) and regional wall lengthening during the isovolumic relaxation period (0.9 +/- 4.1% to 2.8 +/- 5.7% of end-diastolic segmental area, p < 0.05), which indicates an improvement of regional diastolic function. Infarct segments were little affected by ranolazine. Thus, ranolazine improves diastolic function of the noninfarcted myocardium under chronic ischemic conditions and also may exert a mild negative lusitropic effect on the normal myocardium, although the former beneficial effect appears to be more clinically important.(ABSTRACT TRUNCATED AT 250 WORDS)

Progression of left ventricular dysfunction secondary to coronary artery disease, sustained neurohormonal activation and effects of ibopamine therapy during long-term therapy with angiotensin-converting enzyme inhibitor

Left ventricular function and neurohormonal status in patients with heart failure remaining symptomatic during therapy with angiotensin-converting enzyme inhibitors were assessed, and the effects of dopaminergic receptor stimulation in this setting were determined. Neurohormonal and left ventricular function (radionuclide angiography) data were obtained in 19 patients with symptomatic ischemic heart failure. Measurements were repeated after 4 to 6 weeks of therapy with the dopamine agonist ibopamine (100 mg, 3 times/day) or placebo administered in a double-blind, randomized, parallel group design. At baseline, despite therapy with enalapril, the angiotensin II levels (mean 39.4 pg/ml; p < 0.01 vs controls) were significantly increased, as were plasma norepinephrine (497 +/- 240 pg/ml; p < 0.01 vs controls), endothelin-1, atrial natriuretic peptide and arginine vasopressin. Moreover, in comparison with pretreatment values, left ventricular ejection fraction had decreased substantially (-9.1%) in patients with plasma norepinephrine > or = 600 pg/ml, but not in those with lower values of norepinephrine. With ibopamine, plasma norepinephrine decreased from 516 +/- 241 to 391 +/- 208 pg/ml (n = 8; p < 0.025 vs placebo), whereas it increased with placebo. In conclusion, the neurohormonal control provided by an angiotensin-converting enzyme inhibitor is reduced in a large subset of patients during prolonged therapy; ibopamine appears to be a potentially useful drug to improve neurohormonal control in this setting.

Dose-related efficacy of irbesartan for hypertension: an integrated analysis

Results of eight multicenter, randomized, placebo-controlled, double-blind, parallel-group studies were pooled to assess the efficacy of the angiotensin II-receptor blocker irbesartan over the dose range of 1 to 900 mg. A total of 2955 adults with a seated diastolic blood pressure of 95 to 110 mm Hg were randomized to treatment with oral irbesartan once daily or placebo for 6 to 8 weeks. Office blood pressure was measured at trough (24+/-3 hours after the last dose) and peak (3+/-1 hours after the last dose) by mercury sphygmomanometry. Demographic characteristics (mean blood pressure; 151/101 mm Hg; mean age, 54 years; 63% male; and 82% white) were similar across all dose groups. After the groups were pooled, antihypertensive efficacy was assessed by therapeutic response (trough seated diastolic blood pressure <90 mm Hg or a reduction from baseline of > or = 10 mm Hg) and by modeling of the maximum reductions in trough and peak seated diastolic and systolic blood pressure. Antihypertensive effects increased with increasing doses and reached a plateau at > or = 300 mg. Irbesartan 150 mg provided placebo-subtracted reductions in trough seated systolic and diastolic blood pressure of approximately 8 and approximately 5 mm Hg, respectively, with 56% of patients displaying a favorable response. In conclusion, irbesartan provides clinically significant blood pressure lowering, with a clear relationship between (log) dose and antihypertensive effect.

Costs and effects of enalapril therapy in patients with symptomatic heart failure: an economic analysis of the Studies of Left Ventricular Dysfunction (SOLVD) Treatment Trial

The clinical results of the Studies of Left Ventricular Dysfunction (SOLVD) Treatment Trial have been published previously, but no evaluation of cost-effectiveness based on the primary data has been reported. The authors used a decision analytic model based on primary data from SOLVD to estimate years of survival (overall, by New York Heart Association Class, and quality-adjusted) and to estimate costs of nonfatal hospitalizations, ambulatory care, therapy with enalapril, and deaths. Clinical and resource utilization data were derived from participants in SOLVD, and cost data were derived from the United States. Therapy with enalapril during the approximate 48-month follow-up period in SOLVD resulted in a gain of 0.16 year of life and savings of dollars 718. During the patient's lifetime, a survival benefit of 0.40 year, a cost per year of life saved of dollars 80, and a cost per quality-adjusted life year of dollars 115 with the use of enalapril were projected. The results indicated a net savings and gain in life expectancy during the SOLVD treatment trial. The lifetime projection suggests that therapy with angiotensin-converting enzyme inhibitors, such as enalapril, is extremely attractive when compared with many commonly used interventions in patients with cardiovascular disease or heart failure.

Effects of a cardioselective beta 1 partial agonist (corwin) on left ventricular function and myocardial metabolism in patients with previous myocardial infarction

Corwin is a new selective beta 1 partial agonist, able to stabilize the beta 1 adrenoceptors at approximately 43% of their maximal activity. The aim of the study was to determine the effects of this agent in patients with coronary artery disease (CAD) and previous myocardial infarction (MI). In a first group of 14 patients, corwin increased significantly the peak (+)dP/dt (+35%; p less than 0.005), the global ejection fraction, and the ejection fraction of abnormally contracting segments (from 20 +/- 18 to 26 +/- 19%; p less than 0.02). Corwin also induced significant decreases in mean systolic (-8%; p less than 0.05) and mean diastolic (-38%; p less than 0.001) wall stress and accelerated the relaxation rate. In a second group of 11 patients, a metabolic study indicated that neither myocardial oxygen consumption (15 +/- 7 versus 15 +/- 7 ml/min; difference not significant) nor lactate extraction was modified by the drug. In this group, increases in peak (+)dP/dt, acceleration in ventricular relaxation (-8 ms in time constant of isovolumic pressure decrease; p less than 0.01), and decreases in left ventricular end-diastolic pressure also were noted after administration of corwin, both under basal conditions and during a cold pressor test. In conclusion, corwin is a positive inotrope which, in patients with CAD and left ventricular dysfunction, improves left ventricular systolic and diastolic function without inducing myocardial ischemia.

Effects of long-term enalapril therapy on left ventricular diastolic properties in patients with depressed ejection fraction. SOLVD Investigators

BACKGROUND

The aim of the present study was to analyze the changes in left ventricular diastolic function that occur in patients with chronic severe left ventricular systolic dysfunction in the absence or presence of prolonged therapy with an angiotensin converting enzyme inhibitor.

METHODS AND RESULTS

Left ventricular function data (cineangiography plus Millar, frame-by-frame analysis) and right ventricular volumes (radionuclide angiography) were obtained at baseline and after an average follow-up of 12.4 months in 42 patients with a left ventricular ejection fraction of 35% or less. After baseline measurements, the patients were randomized to placebo (n = 16) or enalapril (10 mg BID, n = 26). In the placebo group, the changes in left ventricular function were characterized by increases in end-diastolic (159 +/- 43 to 170 +/- 44 mL/m2) and end-systolic (119 +/- 38 to 128 +/- 49 mL/m2) volumes accompanied by a downward and rightward shift of the diastolic pressure-volume relation. In contrast, decreases in end-diastolic (166 +/- 43 to 156 +/- 47 mL/m2) and end-systolic (125 +/- 43 to 111 +/- 42 mL/m2) volumes accompanied by a slight upward and leftward shift of the diastolic pressure-volume relation were noted in the enalapril group. These changes in left ventricular volumes were significantly different between groups (both P < .005) but were not attended by changes in left ventricular end-diastolic pressure, in time constant of isovolumic pressure decrease, or in right ventricular volumes. However, the chamber stiffness constant beta decreased from 0.044 +/- 0.027 to 0.032 +/- 0.019 mL-1/m2 in the placebo group, whereas it increased insignificantly in the enalapril group (0.040 +/- 0.028 to 0.041 +/- 0.028 mL-1/m2). These changes in chamber stiffness constant beta between baseline and follow-up were significantly different between placebo and enalapril groups (P < .05). Another index of chamber compliance, delta V/delta P, also confirmed the presence of opposite changes in left ventricular chamber compliance in the placebo group and in the enalapril group. The mean diastolic wall stress increased with placebo but not with enalapril (+51 versus -13 kdyn/cm2; P < .04) whereas left ventricular mass and the indexes of left ventricular sphericity tended to improve in the enalapril group. The changes in plasma levels of norepinephrine, atrial natriuretic peptide, and arginine vasopressin were, however, comparable in both groups.

CONCLUSIONS

The data indicate that in patients with severe systolic left ventricular dysfunction, the progressive left ventricular dilatation was accompanied by a decrease in left ventricular chamber stiffness; enalapril therapy was able to prevent or partially reverse these changes and tended to reduce left ventricular mass and ventricular sphericity. Those changes were suggestive of partial reversal of left ventricular remodeling by enalapril administration.

Superiority of big endothelin-1 and endothelin-1 over natriuretic peptides in predicting survival in severe congestive heart failure: a 7-year follow-up study

BACKGROUND

Plasma concentrations of atrial and brain natriuretic peptides (ANP, BNP), of their N-terminal pro-peptides, of endothelin-1 (ET-1), and big endothelin-1 (big ET-1) have diagnostic and prognostic significance in congestive heart failure (CHF). However, their respective values as a predictor of survival remain controversial and have never been directly compared in severe CHF.

METHODS AND RESULTS

We analyzed, in 47 patients with severe CHF (New York Heart Association [NYHA] class III to IV; age 66 +/- 8 years, ejection fraction 20 +/- 6%), the prognostic performance of a panel of neurohormones and assays (N-terminal pro-ANP 1-25, 68-98 by radioimmunoassay [RIA], and 1-98 by enzyme-linked immunosorbent assay [ELISA], BNP by RIA and immunoradiometric assay [IRMA], N-terminal pro-BNP by Elisa, ET-1 by RIA, and big ET-1 by RIA and Elisa. Data were compared with 40 patients with mild to moderate CHF [NYHA I-II] and 30 healthy subjects. After a follow-up of 81 +/- 15 months, there were 34 deaths and 1 heart transplant. All neurohormones were significantly higher at baseline in patients with severe than in mild to moderate CHF or healthy subjects (all P < .001). Although all neurohormones but BNP IRMA were significant predictors of survival in univariate analysis, only big ET-1 RIA and ET-1 were independent predictors of survival (improvement chi(2): 7.5 and 4.6, P < .01 and P < .05). Using medians as cutpoints of big ET-1 RIA and ET-1, 2 severe CHF populations were defined with a different outcome (5-year survival: 55 versus 18%, P < .01).

CONCLUSIONS

Big ET-1 and ET-1 are strong independent predictors of survival in patients with severe CHF and better for this purpose than natriuretic peptides or their pro-peptides. These markers allow easily to identify a population with a very high risk mortality eligible for more aggressive therapies.

Biomarkers in the prevention and treatment of atherosclerosis: need, validation, and future

Cardiovascular disease (CVD) remains one of the leading causes of morbidity and mortality in the developed world, and there is a clear need to develop novel therapeutic strategies to reduce cardiovascular risk further than is currently possible. Traditionally, the effectiveness of new cardiovascular drugs has been evaluated in clinical trials using cardiovascular outcomes as endpoints. However, such trials require large numbers of patients followed over long periods of time. Clinical trials using surrogate markers for CVD may be shorter in duration and involve fewer participants. Measurement of atherosclerotic progression is an ideal surrogate marker as it is predictive of future cardiovascular events. The "gold standard" for detecting and defining the severity, extent, and rate of atherosclerotic progression has been quantitative coronary angiography. However, this technique has fundamental limitations. More recently, measurement of carotid intima-media thickness using B-mode ultrasound and measurement of atheroma volume using intravascular ultrasound have emerged as more accurate techniques for detecting atherosclerotic progression. Both of these techniques have potential utility as surrogate endpoints in place of cardiovascular outcomes in clinical trials. Their use might facilitate the more rapid development of novel, safe, and effective therapies.

Assessment of regional left ventricular relaxation in patients with coronary artery disease: importance of geometric factors and changes in wall thickness

To assess local myocardial relaxation abnormalities in patients with coronary artery disease, local myocardial left ventricular wall stress was computed in nine normal subjects and in 22 patients with coronary artery disease. In normal left ventricles, the rate of decrease in isovolumic local stress was not significantly different from the rate of decrease in isovolumic pressure, and the residual wall stress at the end of isovolumic relaxation was uniformly low. In patients with coronary artery disease, the residual wall stress was increased both in infarcted areas and in non-infarcted areas perfused by stenosed arteries (43 +/- 31 and 30 +/- 19 kdyne/cm2, respectively, vs 9 +/- 5 kdyne/cm2 in normal areas; p less than .001). The rate of decrease in local stress in infarcted areas paralleled the rate of decrease in pressure (48 vs 49 msec; NS), but in ischemic areas the rate of decrease in stress was significantly slower than the rate of decrease in pressure (69 +/- 35 vs 48 +/- 15 msec; p less than .05). It is concluded that in patients with coronary artery disease, indexes based only on the analysis of decreases in isovolumic pressure underestimate the severity of local impairments in relaxation rate and cannot be used to predict the level of residual diastolic wall stress.

Effects of nicardipine and nisoldipine on myocardial metabolism, coronary blood flow and oxygen supply in angina pectoris

The effects of the calcium antagonists nicardipine and nisoldipine on left ventricular (LV) metabolism were analyzed in 32 patients with angina pectoris. Measurements were made at a fixed heart rate under the basal state and during a cold pressor test (CPT). After administration of the drugs, coronary blood flow increased significantly and the mean aortic pressure decreased by 10% (p less than 0.01) in the basal state and by 11% (p less than 0.01) during CPT. Despite the reduction in pressure-rate product, myocardial oxygen consumption was unchanged in the basal state (18 +/- 4 vs 19 +/- 4 ml/min, difference not significant) and during CPT (21 +/- 5 vs 21 +/- 5 ml/min, difference not significant); this discrepancy between a reduced pressure-rate product and an unchanged oxygen consumption was also noted when nicardipine was given after propranolol (0.1 mg/kg; 12 patients). Both agents also increased LV lactate uptake, particularly during CPT (+13 mumol/min, p less than 0.05 vs control CPT) and reduced LV glutamine production. In 10 patients in whom 14C-lactate was infused, the chemical LV lactate extraction ratio increased more than the 14C-lactate extraction ratio after administration of the drugs, indicating a reduction in LV lactate production. The data are consistent with the hypothesis that nicardipine and nisoldipine improve perfusion and aerobic metabolism in chronically ischemic areas, resulting in an augmented oxygen consumption and in a reduced lactate production.

Hemodynamic and cardiac effects of nicardipine in patients with coronary artery disease

The hemodynamic and cardiac effects of the calcium antagonist nicardipine, alone (n = 10 patients) or combined with propranolol (0.1 mg/kg i.v.; n = 9 patients), were assessed in patients with coronary artery disease. In the absence of beta-blockade, nicardipine (5 or 10 mg i.v.) increased heart rate (+23 and +15 beats/min after 5 and 10 mg, respectively; p less than 0.01) and cardiac output (from 4.7 +/- 1.1 to 7.4 +/- 1.3 L/min after 5 mg and from 5.1 +/- 1.1 to 8.6 +/- 1.6 L/min after 10 mg; p less than 0.005). Systemic vascular resistance decreased with both doses (-46 and -57%; p less than 0.005), whereas mean aortic pressure decreased by 14 mm Hg after 5 mg and by 28 mm Hg after 10 mg (p less than 0.004); left ventricular end-diastolic pressure was unchanged. Nicardipine also decreased significantly end-systolic left ventricular volume and increased ejection fraction (from 63 to 71% after 5 mg and from 54 to 63% after 10 mg; p less than 0.008) and velocity of shortening. Peak (+) dP/dt and (dP/dt)/DP40 (value of dP/dt at a developed pressure of 40 mm Hg) were unchanged, and Emax, the maximal left ventricular pressure/volume ratio, improved slightly (+8%; p less than 0.05). After beta-blockade, nicardipine (2.5 mg i.v.) still decreased mean aortic pressure (-16 mm Hg; p less than 0.05) and systemic vascular resistance, and improved the ejection phase indices; cardiac output and ventricular relaxation, both depressed after propranolol administration, were also normalized after infusion of nicardipine.(ABSTRACT TRUNCATED AT 250 WORDS)

Diastolic dysfunction and myocardial energetics

Myocardial relaxation is an energy-dependent process. Indeed, adenosine triphosphate (ATP) is required to pump free myoplasmic calcium back into the sarcoplasmic reticulum. It is also necessary to extrude the calcium ions which enter the cell during the plateau phase of the action potential. The calcium-sodium exchange mechanism does not seem to require energy in itself, but sodium exchanged for calcium eventually needs to be extruded via sodium/potassium ATPase and there is also an ATP-dependent calcium pump. Thus, when ATP production is limited, calcium may remain fixed to troponin for part or for the whole of diastole, resulting in a slower rate of isovolumic relaxation and reduced distensibility of the myocardium. Alterations in diastolic function caused by inadequate energy production occur in the high-demand type of myocardial ischaemia. There is also growing evidence that most forms of heart failure are accompanied by a state of energy depletion. Alterations in mitochondrial density and enzymatic activity are common in the failing myocardium and may partially explain the reduction in ATP production. Inadequate growth of the capillary network in hypertrophied myocardium, impaired subendocardial perfusion due to increased diastolic wall stress and/or coronary artery disease, probably also contribute to an imbalance between energy production and utilization. As relaxation is intrinsically a much slower process than activation and since changes in ATP concentration may also affect calcium efflux by allosteric effects, impaired relaxation and reduced diastolic distensibility are almost universal in chronic congestive heart failure. Optimal therapy of heart failure should, therefore, also aim at improving this phase of the cardiac cycle.

Force-velocity-length relations in hypertrophic cardiomyopathy: evidence of normal or depressed myocardial contractility

To assess myocardial contractility in patients with hypertrophic cardiomyopathy (HC), force-velocity-length relations were analyzed during left ventricular (LV) ejection. LV pressure, volume and wall stress data in 15 patients with HC were analyzed and compared with values from 32 normal subjects. Patients with HC had a greater LV mass than did normal subjects (272 versus 96 g/m2, p less than 0.001), elevated LV end-diastolic pressure (17.5 versus 9.8 mm Hg, p less than 0.01) and impaired LV relaxation compared with those of normal subjects. Patients with HC also had a greater ejection fraction (84 +/- 7 versus 74 +/- 8%, p less than 0.01) and mean velocity of shortening than did normal subjects. However, in patients with HC, end-systolic stress (60 +/- 29 versus 187 +/- 61 kdyne/cm2, p less than 0.001) was significantly lower. End-systolic volume and stress data were linearly related in normal subjects (r = 0.88), and values from patients with HC fell either within the lowest part of the 95% confidence interval of this normal relation or outside it in the zone of depressed contractility (11 patients with HC). In addition, the slopes of the relations between end-systolic wall stress and ejection fraction or mean velocity of shortening were abnormal in patients with HC; the slope of the stress-volume trajectory during late ejection was also depressed in 12 patients with HC (average slope 2.6 versus 5.5 kdyne/cm5/m2, p less than 0.001). Thus, there is no evidence of a hypercontractile state in patients with HC; their high values of ejection phase indexes may be explained by a reduction in myocardial afterload.

Effects of D-nebivolol and L-nebivolol on left ventricular systolic and diastolic function: comparison with D-L-nebivolol and atenolol

(D-L) Nebivolol is a new beta 1-selective adrenoceptor blocker which in normal individuals preserves rest and exercise hemodynamics. We assessed the effects of the enantiomers (L- and D-nebivolol) on left ventricular (LV) systolic and diastolic function and compared their effects with those of the racemic mixture. LV angiography (+Millar) was performed before and after intravenous (i.v.) infusion of either D- or L-nebivolol (1.25-2.5 mg, n = 22) in patients with ischemic heart disease and previous myocardial infarction. Neither L- nor D-nebivolol produced significant changes in heart rate (HR), peak (+) dP/dt, (dP/dt) DP40, cardiac index (CI) or ejection fraction (EF). Diastolic distensibility, evaluated from the shift of the pressure-volume data at the time of mitral valve opening, did not improve after D- or L-enantiomers administration. In contrast, both D-L-nebivolol 2.5 mg (n = 9) and atenolol 15 mg (n = 9) significantly reduced HR and peak (+) dP/dt, but in comparison to atenolol D-L nebivolol improved EF (+4% after D-L nebivolol vs. -4% after atenolol; p < 0.05 D-L nebivolol vs. atenolol) and maintained cardiac output CO, (+2% vs. -21%; p < 0.05 between groups). Moreover, unlike any of the other drugs in the study, the racemate shifted the diastolic pressure-volume data downward, suggesting improved LV distensibility. The beneficial effects of nebivolol on LV systolic and diastolic function appears to require the presence of both D- and L-enantiomers.

Cardiovascular and endocrine effects of endothelin-1 at pathophysiological and pharmacological plasma concentrations in conscious dogs

BACKGROUND

Increased plasma concentrations of endothelin-1, a potent vasoconstrictor produced by the endothelium, have been reported in various pathological conditions. This study was conducted to evaluate effects of endothelin-1 at pathophysiological and pharmacological plasma concentrations.

METHODS AND RESULTS

Endothelin-1 was infused at increasing doses (2.5, 5, 10, and 20 ng/kg.min for 1 hour each) in nine conscious dogs. During endothelin-1 infusion, plasma endothelin-1 rose from a basal value of 1.8 +/- 0.4 pmol/l to 5.8 +/- 1.1 (pathophysiological), 20.8 +/- 3.9 (pathophysiological), 85.4 +/- 18.9 (pharmacological), and 311.4 +/- 55.7 (pharmacological) pmol/l at each dose, respectively. Heart rate increased at 2.5 ng/kg.min (from 129 +/- 7 to 146 +/- 12 beats/min) but decreased at 20 ng/kg.min (97 +/- 7 beats/min) (p less than 0.001). Such a biphasic response was also observed for peak (+)dP/dt and (dP/dt)/DP40 (p less than 0.005). Left ventricular systolic pressures, mean aortic pressure, and left atrial pressure increased over time (p less than 0.05, p less than 0.005, and p less than 0.001, respectively). The time constant of early isovolumic relaxation rose progressively (p less than 0.001). The percent systolic shortening decreased at 10 and 20 ng/kg.min (p less than 0.005). Pressure-segment length loops showed a reduction in systolic shortening associated with an increase in left ventricular systolic pressure at 20 ng/kg.min. Atrial natriuretic factor rose after 5 ng/kg.min from 28.5 +/- 6.5 to 92.0 +/- 18.2 pmol/l (p less than 0.005). Angiotensin II and catecholamines did not change significantly. Serum urea and creatinine rose progressively (p less than 0.05), whereas glucose decreased (p less than 0.05). The above results differed significantly from measurements obtained in a time-control group of six dogs.

CONCLUSIONS

A fourfold increase of plasma endothelin-1 obtained after doubling the infusion rate suggests a reduction in endothelin-1 clearance or endothelin-1 endogenous production. The biphasic response of heart rate is consistent with baroreflex-mediated effects resulting from vasodilation at the pathophysiological level and vasoconstriction at the pharmacological level. Hemodynamic data suggest an increase followed by a decrease in contractility at both levels, respectively. Finally, endothelin-1 is a stimulator of atrial natriuretic factor.

Changes in ventricular volume, wall thickness and wall stress during progression of left ventricular dysfunction. The SOLVD Investigators

To assess the long-term changes in cardiac function in asymptomatic patients with severe left ventricular dysfunction, left ventricular (cineangiography) and right ventricular (radionuclide angiography) function were assessed at baseline in 49 patients enrolled in the prevention arm of the Studies of Left Ventricular Dysfunction. After an average follow-up period of 12.4 months, 30 patients (11 randomized to the placebo group and 19 to the enalapril group) could be restudied to assess the progression of ventricular dysfunction. After 1 year of follow-up, the changes in heart rate, left ventricular end-diastolic and systolic pressure and right ventricular volumes were comparable in both groups. However, there were modest but opposite changes in left ventricular end-diastolic volume (+9 ml/m2 with placebo vs. -10 ml/m2 with enalapril, p < 0.05) and end-systolic volume (+5 ml/m2 with placebo vs. -13 ml/m2 with enalapril, p < 0.05). Mean systolic wall stress increased insignificantly in both groups, whereas ejection fraction increased from 29% to 31% in the placebo group and from 28% to 32% with enalapril (p = NS, placebo vs. enalapril). Even in asymptomatic patients with severe left ventricular dysfunction, there was a slow progression of left ventricular dilation. Enalapril administration appeared to slow this progression, but wall stress was not normalized by the treatment at the doses used in the study, indicating that at least one of the stimuli for further remodeling remained present.