Effects of six-month afterload reduction therapy with hydralazine in chronic aortic regurgitation

Current Management of Patients with Severe Aortic Regurgitation

OPINION STATEMENT

Chronic aortic regurgitation can result from various congenital and acquired anomalies and can be associated with proximal aortic disease. As the number of aortic valve procedures is growing, the incidence of post-procedural regurgitation also increases with associated morbidity. Typical evolution is characterized by a clinically silent phase of variable duration followed by a rather rapid decline with high incidence of adverse events. A challenge remains to find the optimal timing for an intervention: Patients are exposed to unnecessary surgical risks if treated prematurely, but peri- and post-operative prognosis is worse when the intervention is performed too late. Clinical evaluation and serial imaging tests can optimize the timing for intervention. Clinical follow-up should try to elucidate associated symptoms, with quantitative measurement of functional capacity as needed. Serial imaging examinations are required to identify sub-clinical left ventricular dysfunction or severe dilatation that should prompt a surgery. At least in selected cases, newer imaging modalities (MRI, 3D echocardiography) and/or biomarkers can help for the management of these patients, and more research is needed to determine if their systematic use can be beneficial. Medical treatment with vasodilators and anti-remodeling drugs can be helpful in some patients but should not replace or delay aortic valve surgery when indicated. Most patients will eventually be treated with surgical aortic valve replacement. Although possible in selected cases, transcatheter aortic valve replacement is not commonly used for patients with pure aortic regurgitation. For patients with prior aortic valve replacement and aortic regurgitation (paravalvular or intravalvular), emerging percutaneous approaches can be considered when available, especially for those at high surgical risk.

Favorable effects of vasodilators on left ventricular remodeling in asymptomatic patients with chronic moderate-severe aortic regurgitation and normal ejection fraction: a meta-analysis of clinical trials

BACKGROUND

The role of vasodilator therapy in asymptomatic patients with chronic moderate to severe aortic regurgitation (AR) and normal left ventricular (LV) function is uncertain. We assessed the effects of vasodilator therapy (hydralazine, calcium channel blockers, and angiotensin-converting enzyme inhibitors) in this subgroup of patient population.

HYPOTHESIS

Vasodilators have favorable effects on LV remodelling in asymptomatic patients with chronic moderate to severe aortic regurgitation and normal LV function.

METHODS

We performed a systematic literature search for randomized clinical trials using long-term vasodilator therapy in asymptomatic patients with chronic severe AR and normal LV function. The magnitude of difference between the vasodilator and nonvasodilator groups was assessed by computing the mean difference (MD). Heterogeneity of the studies was analyzed by Cochran Q statistics. The MD for LV ejection fraction, LV end systolic volume index, and LV end diastolic volume index were computed by random effects model. The MD for LV end-systolic diameter and LV end-diastolic diameter were computed by fixed effects model. A 2-sided alpha error <0.05 was considered to be statistically significant.

RESULTS

Seven studies with 460 patients were included. Meta-analysis of the studies revealed a significant increase in LVEF (MD: 5.32, 95% confidence interval [CI]: 0.37 to 10.26, P = 0.035), a significant decrease in LV end diastolic volume index (MD: -16.282, 95% CI: -23.684 to -8.881, P < 0.001), and a significant decrease in LV end diastolic diameter (MD: -2.343, 95% CI: -3.397 to -1.288, P < 0.001) in the vasodilator group compared with the nonvasodilator group. However, there was no significant decrease in LV end systolic volume index (MD: -6.105, 95% CI: -12.478 to 0.267, P = 0.060) or in LV end systolic diameter (MD: 0.00, 95% CI: -0.986 to 0.986, P = 1.0) in the vasodilator group compared with the nonvasodilator group.

CONCLUSIONS

In asymptomatic patients with chronic severe AR and normal LV function, vasodilators have favorable effects on LV remodeling.

Hydralazine for essential hypertension

BACKGROUND

Hypertension is associated with an increased risk of stroke, myocardial infarction and congestive heart failure. Hydralazine is a direct-acting vasodilator which has been used for the treatment of hypertension since the 1950's. Although it has largely been replaced by newer antihypertensive drugs with more acceptable tolerability profiles, hydralazine is still widely used in developing countries due to its lower cost. A review of its relative effectiveness compared to placebo on surrogate and clinical outcomes is justified.

OBJECTIVES

To quantify the effect of hydralazine compared to placebo in randomized controlled trials (RCTs) on all cause mortality, cardiovascular mortality, serious adverse events, myocardial infarctions, strokes, withdrawals due to adverse effects and blood pressure in patients with primary hypertension.

SEARCH METHODS

We searched the following databases: Cochrane Central Register of Controlled Trials (2011, Issue 3), MEDLINE (1948-August 2011), International Pharmaceutical Abstracts (1970-June 2009) and EMBASE (1980-August 2011). Bibliographic citations from retrieved studies were also reviewed. No language restrictions were applied.

SELECTION CRITERIA

We selected RCTs studying the effect of oral hydralazine compared to oral placebo in patients with primary hypertension. We excluded studies of patients with secondary hypertension or gestational hypertension.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed trial quality using the risk of bias tool. Data synthesis and analysis was performed using RevMan 5.

MAIN RESULTS

The search strategy did not yield any randomized controlled trials comparing hydralazine to placebo for inclusion in this review. There is insufficient evidence to conclude on the effects of hydralazine versus placebo on mortality, morbidity, withdrawals due to adverse effects, serious adverse events, or systolic and diastolic blood pressure. Some of the adverse effects related to hydralazine that have been reported in the literature include reflex tachycardia, hemolytic anemia, vasculitis, glomerulonephritis, and a lupus-like syndrome.

AUTHORS' CONCLUSIONS

Hydralazine may reduce blood pressure when compared to placebo in patients with primary hypertension, however this data is based on before and after studies, not RCTs. Furthermore, its effect on clinical outcomes remains uncertain.

Hydralazine for essential hypertension

BACKGROUND

Hypertension is associated with an increased risk of stroke, myocardial infarction and congestive heart failure. Hydralazine is a direct-acting vasodilator which has been used for the treatment of hypertension since the 1950's. Although it has largely been replaced by newer antihypertensive drugs with more acceptable tolerability profiles, hydralazine is still widely used in developing countries due to its lower cost. A review of its relative effectiveness compared to placebo on surrogate and clinical outcomes is justified.

OBJECTIVES

To quantify the effect of hydralazine compared to placebo in randomized controlled trials (RCTs) on all cause mortality, cardiovascular mortality, serious adverse events, myocardial infarctions, strokes, withdrawals due to adverse effects and blood pressure in patients with primary hypertension.

SEARCH STRATEGY

We searched the following databases: Cochrane Central Register of Controlled Trials (to Second Quarter 2009), MEDLINE (2005-June 2009), International Pharmaceutical Abstracts (1970-June 2009) and EMBASE (2007-June 2009). Bibliographic citations from retrieved studies were also reviewed. No language restrictions were applied.

SELECTION CRITERIA

We selected RCTs studying the effect of oral hydralazine compared to oral placebo in patients with primary hypertension. We excluded studies of patients with secondary hypertension or gestational hypertension.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed trial quality using the risk of bias tool. Data synthesis and analysis was performed using RevMan 5.

MAIN RESULTS

The search strategy did not yield any randomized controlled trials comparing hydralazine to placebo for inclusion in this review. There is insufficient evidence to conclude on the effects of hydralazine versus placebo on mortality, morbidity, withdrawals due to adverse effects, serious adverse events, or systolic and diastolic blood pressure. Some of the adverse effects related to hydralazine that have been reported in the literature include reflex tachycardia, hemolytic anemia, vasculitis, glomerulonephritis, and a lupus-like syndrome.

AUTHORS' CONCLUSIONS

Hydralazine may reduce blood pressure when compared to placebo in patients with primary hypertension, however this data is based on before and after studies, not RCTs. Furthermore, its effect on clinical outcomes remains uncertain.

Vasodilator therapy with hydralazine induces angiotensin AT receptor-mediated cardiomyocyte growth in mice lacking guanylyl cyclase-A

BACKGROUND AND PURPOSE

Recent clinical guidelines advocate the use of the isosorbide dinitrate/hydralazine combination in treatment for heart failure. However, clinical and laboratory evidence suggest that some vasodilators may induce cardiac hypertrophy under uncertain conditions. This study investigated the effects and underlying mechanism of action of the vasodilator hydralazine on cardiac growth.

EXPERIMENTAL APPROACH

Wild-type mice and animals deficient in guanylyl cyclase-A (GCA) and/or angiotensin receptors (AT(1) and AT(2) subtypes) were treated with hydralazine ( approximately 24 mg.kg(-1).day(-1) in drinking water) for 5 weeks. Cardiac mass and/or cardiomyocyte cross-sectional area, fibrosis (van Giessen-staining) and cardiac gene expression (real-time RT-PCR) were measured.

KEY RESULTS

Hydralazine lowered blood pressure in mice of all genotypes. However, this treatment increased the heart and left ventricular to body weight ratios, as well as cardiomyocyte cross-sectional area, and cardiac expression of atrial natriuretic peptide mRNA in mice lacking GCA. Hydralazine did not affect cardiac hypertrophy in wild-type mice and mice lacking either AT(1) or AT(2) receptors alone. However, the pro-hypertrophic effect of hydralazine was prevented in mice lacking both GCA and AT(2), but not GCA and AT(1) receptors. However, hydralazine did decrease cardiac collagen deposition and collagen I mRNA (signs of cardiac fibrosis) in mice that were deficient in GCA, or both GCA and AT(2) receptors.

CONCLUSIONS AND IMPLICATIONS

The vasodilator hydralazine induced AT(2) receptor-mediated cardiomyocyte growth under conditions of GCA deficiency. However, attenuation of cardiac fibrosis by hydralazine could be beneficial in the management of cardiac diseases.

Vasodilator therapy in patients with aortic insufficiency: a systematic review

BACKGROUND

The use of vasodilators to improve long-term outcomes in asymptomatic patients with chronic aortic insufficiency (AI) is controversial.

METHODS

We reviewed MEDLINE, PREMEDLINE, Current Contents, and Cochrane databases to identify relevant clinical trials on asymptomatic patients with chronic AI of at least moderate severity. We included those studies that involved long-term vasodilator therapy (including hydralazine, calcium-channel blockers, and angiotensin-converting enzyme inhibitors) and assessed either hemodynamic and structural parameters or clinical outcomes. Data on patient demographics, study protocols, and outcomes were abstracted.

RESULTS

Ten studies with 544 asymptomatic patients with chronic AI were identified. Treatment duration with vasodilators ranged from 12 weeks to 7 years. Of these, 8 studies compared vasodilators with placebo or no therapy, with 5 demonstrating improvements in at least 1 hemodynamic or structural parameter with vasodilators and 3 showing little or no apparent benefit. The remaining 2 studies directly compared outcomes between 2 different vasodilators. Both of these studies demonstrated greater improvements in hemodynamic and structural parameters with angiotensin-converting enzyme inhibitors compared with hydralazine and nifedipine. Clinical outcomes were primarily reported in only 2 of the 10 studies. Although one study suggested that the use of vasodilators slowed the rate of progression to surgery for aortic valve replacement, another showed no difference.

CONCLUSIONS

Vasodilators inconsistently improve hemodynamic and structural parameters in asymptomatic patients with chronic AI. In addition, the impact of vasodilators on clinical outcomes is largely uncertain and requires further study.

Are vasodilators still indicated in the treatment of severe aortic regurgitation?

Aortic regurgitation (AR) is a valve disease that causes severe complications and reduces life expectancy. Surgical correction is required in the late stages of the disease. In less advanced forms, treatment with vasodilators is a consideration. The available evidence suggests that this type of treatment has a favorable effect on the consequences of AR, particularly left ventricular remodeling. However, the impact of vasodilators on clinical endpoints complicating the course of AR remains in doubt. The limited evidence supporting or opposing the utilization of vasodilators in AR hinders drawing firm conclusions and emphasizes the process of individualized interpretation of the clinical presentation of patients with the disease.

Operative contractility: A functional concept of the inotropic state

1. Initial unsuccessful attempts to evaluate ventricular function in terms of the 'heart as a pump' led to focusing on the 'heart as a muscle' and to the concept of myocardial contractility. However, no clinically ideal index exists to assess the contractile state. The aim of the present study was to develop a mathematical model to assess cardiac contractility. 2. A tri-axial system was conceived for preload (PL), afterload (AL) and contractility, where stroke volume (SV) was represented as the volume of the tetrahedron. Based on this model, 'operative' contractility ('OperCon') was calculated from the readily measured values of PL, AL and SV. The model was tested retrospectively under a variety of different experimental and clinical conditions, in 71 studies in humans and 29 studies in dogs. A prospective echocardiographic study was performed in 143 consecutive subjects to evaluate the ability of the model to assess contractility when SV and PL were measured volumetrically (mL) or dimensionally (cm). 3. With inotropic interventions, OperCon changes were comparable to those of ejection fraction (EF), velocity of shortening (Vcf) and dP/dt-max. Only with positive inotropic interventions did elastance (Ees) show significantly larger changes. With load manipulations, OperCon showed significantly smaller changes than EF and Ees and comparable changes to Vcf and dP/dt-max. Values of OperCon were similar when AL was represented by systolic blood pressure or wall stress and when volumetric or dimensional values were used. 4. Operative contractility is a reliable, simple and versatile method to assess cardiac contractility.

Valvular Heart Disease

Aortic regurgitation (AR) is characterized by diastolic reflux of blood from the aorta into the left ventricle (LV). Acute AR typically causes severe pulmonary edema and hypotension and is a surgical emergency. Chronic severe AR causes combined LV volume and pressure overload. It is accompanied by systolic hypertension and wide pulse pressure, which account for peripheral physical findings, such as bounding pulses. The afterload excess caused by systolic hypertension leads to progressive LV dilation and systolic dysfunction. The most important diagnostic test for AR is echocardiography. It provides the ability to determine the cause of AR and to assess the severity of AR and its effect on LV size, function, and hemodynamics. Many patients with chronic severe AR may remain clinically compensated for years with normal LV function and no symptoms. These patients do not require surgery but can be followed carefully for the onset of symptoms or LV dilation/dysfunction. Surgery should be considered before the LV ejection fraction falls below 55% or the LV end-diastolic dimension reaches 55 mm. Symptomatic patients should undergo surgery unless there are excessive comorbidities or other contraindications. The primary role of medical therapy with vasodilators is to delay the need for surgery in asymptomatic patients with normal LV function or to treat patients in whom surgery is not an option. The goal of vasodilator therapy is to achieve a significant decrease in systolic arterial pressure. Future therapies may focus on molecular mechanisms to prevent adverse LV remodeling and fibrosis.

Aortic insufficiency: defining the role of pharmacotherapy

Major advances in the diagnostic, evaluation, and particularly surgical treatment of aortic regurgitation (AR) have redefined the role of medical treatment. In acute AR, aortic valve replacement (AVR) is the only life-saving treatment. Medical treatment may improve the hemodynamic state temporarily before surgery. Rationale of medical treatment in chronic AR is based on the natural history and pathophysiology of the disease. The primary goal is to optimize the time of the AVR. If there is any symptom and/or left ventricular (LV) dysfunction, early AVR is required. Vasodilators should only be considered as a short-term treatment before surgery if there is evidence of severe heart failure or as a long-term treatment if AVR is contraindicated because of cardiac or noncardiac factors. In asymptomatic patients with severe chronic AR and normal LV function (even if the left ventricle is moderately dilated), vasodilators may prolong the compensated phase of chronic AR, although proof of their efficacy in delaying AVR is limited. Nifedipine is the best evidence-based treatment in this indication. ACE inhibitors are particularly useful for hypertensive patients with AR. beta-Adrenoceptor antagonists (beta-blockers) may be indicated to slow the rate of aortic dilatation and delay the need for surgery in patients with AR associated with aortic root disease. Furthermore, they may improve cardiac performance by reducing cardiac volume and LV mass in patients with impaired LV function after AVR for AR.

Vasodilatation with felodipine in chronic asymptomatic aortic regurgitation

BACKGROUND

Afterload reduction decreases volume overload on the left ventricle and may thereby delay the need for valve replacement in chronic asymptomatic aortic regurgitation. The aims of this randomized double-blind, placebo-controlled trial were to examine short- and long-term hemodynamic effects of felodipine in chronic asymptomatic aortic regurgitation.

METHODS

Sixteen patients were randomly assigned to an intravenous infusion of either felodipine 0. 3 mg or placebo followed by 3 months' treatment with felodipine 10 mg or placebo orally once daily. Magnetic resonance imaging was performed at baseline, immediately after intravenous treatment, and after 3 months of oral treatment.

RESULTS

Intravenous felodipine caused a statistically significant reduction in the systemic vascular resistance from (mean +/- SD) 1160 +/- 400 to 970 +/- 320 dynes. s. cm(-5) (P <.05), in the regurgitant volume index from 1.5 +/- 0.8 to 1.3 +/- 0.8 L. min(-1). m(-2) (P <.05), and in the regurgitant fraction from 0.31 +/- 0.15 to 0.26 +/- 0.14 (P <.05). The forward cardiac output index increased significantly from 3.2 +/- 0.9 to 3.5 +/- 0.7 L. min(-1). m(-2) (P <.05). Three months of oral treatment with felodipine caused a corresponding but more pronounced decrease in systemic vascular resistance of 880 +/- 330 dynes. s. cm(-5) (P <.05), regurgitant volume index of 1.2 +/- 0.7 L. min(-1). m(-2) (P <.05), and regurgitant fraction 0.25 +/- 0.11 (P <.05), whereas the forward cardiac output index increased to 3.6 +/- 0.7 L. min(-1). m(-2) (P <.05). No significant changes were found in the placebo group. Left ventricular volumes and ejection fraction remained unaffected by treatment, but compared with the placebo group left ventricular myocardial mass decreased significantly from 137 +/- 24 to 132 +/- 21 g. m(-2) (P <.01).

CONCLUSION

In chronic asymptomatic aortic regurgitation, felodipine causes beneficial hemodynamic effects that may postpone the need for valve replacement.

Vasoactive drugs in chronic regurgitant lesions of the mitral and aortic valves

This review examines the results of vasodilator therapy in patients with chronic regurgitant lesions of the aortic and mitral valves. The analysis includes those studies which provide data on hemodynamic measurements, left ventricular systolic function, ventricular volumes and regurgitant flow. In patients with chronic aortic or mitral regurgitation, the short-term administration of nitroprusside, hydralazine, nifedipine or an angiotensin-converting enzyme (ACE) inhibitor produces salutary hemodynamic effects. The major difference in the response to combined preload and afterload reduction (i.e., nitroprusside) in patients with aortic versus mitral regurgitation was that forward stroke volume generally increased and ejection fraction remained unchanged in mitral regurgitation, whereas ejection fraction generally increased and forward stroke volume remained unchanged in aortic regurgitation. These observations suggest that a reciprocal relation between regurgitant and forward flow characterizes the response to preload and afterload reduction in mitral regurgitation (through a preload-dependent dynamic regurgitant orifice), whereas correction of afterload mismatch dominates the response in aortic regurgitation. In studies of long-term vasodilator therapy in patients with chronic aortic regurgitation, a reduction in left ventricular volumes and regurgitant fraction, with or without an increase in ejection fraction, has been observed during treatment with hydralazine, nifedipine and ACE inhibitors. Patients with the largest, sickest hearts generally benefit the most from treatment with vasoactive drugs. Nonetheless, favorable ventricular remodeling has been reported in asymptomatic patients, and long-term nifedipine use has delayed the need for operation in asymptomatic patients with chronic aortic regurgitation. For patients with chronic mitral regurgitation, definition of the etiology of the lesion is a prerequisite for choosing appropriate therapy. Excluding patients with obstructive hypertrophic cardiomyopathy and mitral valve prolapse, and some with fixed-orifice (i.e., rheumatic) mitral regurgitation, the signal importance of preload reduction suggests that the preferred long-term therapy for symptomatic chronic mitral regurgitation is an ACE inhibitor. There are no long-term studies that support the use of vasodilator therapy in asymptomatic patients with chronic mitral regurgitation.

Angiotensin-converting enzyme inhibition and beta-adrenoceptor blockade regress established ventricular remodeling in a canine model of discrete myocardial damage

OBJECTIVES

This study was designed to assess the effect of angiotensin-converting enzyme inhibition and beta-adrenoreceptor blockade on established ventricular remodeling.

BACKGROUND

Angiotensin-converting enzyme inhibitor therapy attenuates the development of ventricular remodeling when given shortly after myocardial infarction. However, regression of established ventricular remodeling after infarction has received little attention.

METHODS

The relative effects of angiotensin-converting enzyme inhibitor therapy and beta-adrenoceptor blockade on established ventricular remodeling were assessed in a canine model characterized by increased left ventricular mass and chamber dilation as a result of localized myocardial necrosis produced by transmyocardial direct current shock. Dogs were randomly assigned to 3 months of therapy with captopril (25 mg twice daily, n = 7) or metoprolol (100 mg twice daily, n = 7) or to a control group with no intervention (n = 6), 11 +/- 4 (mean +/- SD) months after acute myocardial damage.

RESULTS

Compared with the control group, dogs in both the captopril and metoprolol groups had reduced left ventricular mass as measured by magnetic resonance imaging (-8.1 +/- 3.8 vs. 1.7 +/- 2.8 g, p = 0.003 and -9.6 +/- 5.6 vs. 1.7 +/- 2.8 g, p = 0.001), respectively. Captopril and metoprolol also produced a reduction in left ventricular end-diastolic volume (-7.6 +/- 6.0 and -6.0 +/- 5.8 ml, respectively) compared with the control value (-1.6 +/- 3.8 ml) (p = 0.14 [NS]). Both agents reduced mean arterial pressure but had disparate effects on pulmonary wedge pressure and right atrial pressure. There was no significant correlation between change in ventricular mass or volume and change in any measured hemodynamic or neurohormonal variable.

CONCLUSIONS

These data suggest that pharmacologic intervention with angiotensin-converting enzyme inhibition or beta-adrenoceptor blockade can result in regression of established ventricular remodeling. The mechanism of this response will require further study, but these data did not support a close association between regression of remodeling and hemodynamic unloading of the ventricle or systemic neuroendocrine factors.

Vasodilator therapy in chronic asymptomatic aortic regurgitation: enalapril versus hydralazine therapy

OBJECTIVES

This study attempted to evaluate the long-term efficacy of enalapril versus hydralazine therapy on left ventricular volume, mass and function as well as on the renin-angiotensin system in chronic asymptomatic aortic regurgitation.

BACKGROUND

We tested the hypothesis that early administration of a vasodilator drug might be able to reduce left ventricular dilation and mass expansion. Because the renin-angiotensin system may be activated in chronic aortic regurgitation, early enalapril therapy might be beneficial.

METHODS

Between 1990 and 1993, 76 asymptomatic nonrheumatic patients with mild to severe chronic aortic regurgitation were enrolled in a randomized, double-blind trial comparing enalapril with hydralazine. All patients underwent serial noninvasive studies. Seventy patients completed the 12-month follow-up.

RESULTS

At 1 year, patients receiving enalapril had a significant reduction in left ventricular end-diastolic and end-systolic volume indexes (124 +/- 15 vs. 108 +/- 17 ml/m2, p < 0.01; 50 +/- 12 vs. 40 +/- 14 ml/m2, p < 0.01, respectively) and mass index (131 +/- 16 vs. 113 +/- 19 g/m2, p < 0.01), whereas hydralazine therapy showed no significant changes. Both regimens not only had a significant reduction in left ventricular mean wall stress but also had a mild increase in exercise duration. Only enalapril therapy achieved a significant inhibition of the renin-angiotensin system, in contrast to hydralazine therapy. Moreover, the multiple r2 value from the analysis for end-diastolic volume index using the two variables of age and treatment drugs was 72.1% (p < 0.01).

CONCLUSIONS

Both regimens decrease left ventricular mean wall stress. Enalapril therapy achieves significant left ventricular mass regression, left ventricular end-diastolic and end-systolic volume index reduction and renin-angiotensin system suppression. These findings suggest that early unloading enalapril therapy has the potential to favorably influence the natural history of chronic aortic regurgitation.

Comparison of single-dose nifedipine and captopril for chronic severe aortic regurgitation

The effects of a single dose of either nifedipine 20 mg (n = 10) or captopril 50 mg (n = 10) were compared in 20 patients with symptomatic, chronic severe aortic regurgitation using angiography and micromanometer left ventricular pressure measurements. At 90 minutes, mean arterial pressure was reduced comparably after both drugs (86 +/- 15 to 76 +/- 18 mm Hg for nifedipine vs 95 +/- 19 to 77 +/- 18 mm Hg for captopril, p = NS between groups by analysis of variance), as was wedge pressure (11 +/- 5 to 9 +/- 4 mm Hg vs 13 +/- 9 to 9 +/- 5 mm Hg for captopril). Systemic vascular resistance was reduced more (p = 0.01) after nifedipine than after captopril (1,549 +/- 468 to 1,067 +/- 291 dynes s cm-5 vs 1,632 +/- 559 to 1,436 +/- 392 dynes s cm-5). Heart rate declined after captopril (84 +/- 14/min to 75 +/- 15/min, p = 0.002) but not after nifedipine (78 +/- 13 min to 80 +/- 14 min). Forward stroke volume increased after nifedipine (58 +/- 14 to 70 +/- 16 ml, p < 0.001) but not after captopril (58 +/- 17 to 59 +/- 16 ml). Thus, cardiac output increased after nifedipine (4.4 +/- 0.9 to 5.5 +/- 1.2 liters/min, p < 0.001) but decreased after captopril (4.8 +/- 1.2 to 4.3 +/- 1.0, p = 0.004).(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term nifedipine unloading therapy in asymptomatic patients with chronic severe aortic regurgitation

Vasodilating agents acutely reduce regurgitant volume and improve left ventricular performance in aortic regurgitation, but more information is necessary about their long-term efficacy. To evaluate the effects of 12 months of therapy with nifedipine, a randomized, double-blind, placebo-controlled trial was performed in 72 asymptomatic patients with severe aortic regurgitation. At 12 months, patients receiving nifedipine had a significant reduction in left ventricular end-diastolic volume index (110 +/- 19 versus 136 +/- 22 ml/m2, p less than 0.01) and mass (115 +/- 19 versus 142 +/- 16 g/m2, p less than 0.01) measured by two-dimensional echocardiography. They also had a reduction in left ventricular mean wall stress (360 +/- 27 versus 479 +/- 36 kdyne/cm2, p less than 0.001) and an increase in ejection fraction (72 +/- 8% versus 60 +/- 6%, p less than 0.05). These data show that the long-term unloading action of nifedipine is able to reverse left ventricular dilation and hypertrophy and suggest that such therapy has the potential to delay the need for valve replacement in asymptomatic patients.

Effect of digoxin and vasodilators on left ventricular function in aortic regurgitation

In order to assess the relative value of digoxin, nifedipine and hydralazine on left ventricular performance at rest and during exercise, we studied 10 men with moderately severe chronic aortic regurgitation using two-dimensional echocardiography. Digoxin after one month at therapeutic serum levels increased resting ejection fraction as compared to control [0.54 +/- 0.08 (SD) vs 0.47 +/- 0.08, respectively, P less than 0.03]. Ejection fraction decreased during exercise but the difference between digoxin and control was maintained. Stroke volume also was higher on digoxin than control at rest (93 +/- 15 vs 83 +/- 17 ml, P less than 0.02) and the larger stroke volume on digoxin was maintained during exercise. By contrast, stroke volume was reduced by one month of therapy with maximally tolerated nifedipine doses compared to control (74 +/- 8 vs 83 +/- 17 ml, P = 0.03) and this difference was maintained during exercise. Hydralazine in doses up to 225 mg/day for one month produced no significant changes in left ventricular performance compared to control at rest or during exercise. However, compared to digoxin ejection fraction at peak exercise was significantly less on hydralazine (0.39 +/- 0.9 vs 0.52 +/- 10, P less than 0.02). These data suggest that digoxin improved left ventricular performance and may be of benefit in the treatment of patients with chronic aortic regurgitation.

Long-term vasodilator therapy of chronic aortic insufficiency. A randomized double-blinded, placebo-controlled clinical trial

Although vasodilator drugs acutely reduce regurgitation and improve cardiac performance in aortic insufficiency, their long-term effects on left ventricular size and function are uncertain. Consequently, we performed a double-blinded, placebo-controlled trial using hydralazine in 80 minimally symptomatic patients who had clinically stable, moderate-to-severe aortic insufficiency. Patients randomized to hydralazine displayed a progressive reduction in left ventricular end-diastolic volume index (LVEDVI) measured by radionuclide angiography, the predetermined end point of the study. At 24 months, mean LVEDVI had been reduced by 30 +/- 38 ml/m2, an 18% reduction from baseline. In contrast, LVEDVI changed minimally in patients randomized to placebo, and the intergroup differences over time were statistically significant (p less than 0.03). The hydralazine group also experienced reductions in left ventricular end-systolic volume index and increases in ejection fraction that were significantly different (both p less than 0.01) from changes in placebo-treated patients. These findings show that long-term treatment with hydralazine reduces the volume overload in aortic insufficiency and suggest that such therapy may have a beneficial effect on the natural history of the disease.

Vasodilators and regression of left ventricular hypertrophy. Hydralazine versus prazosin in hypertensive humans

Long-term treatment of hypertensive rats with arterial vasodilators may further increase left ventricular hypertrophy. Since left ventricular hypertrophy may be an important determinant of outcome in hypertension, the long-term effects of arterial vasodilation with hydralazine on left ventricular mass and function were compared with those of an alternative third-line drug, the alpha1 blocker prazosin, in patients still hypertensive despite combined diuretic and beta blocker therapy. A single-blind, randomized, two-group parallel design was employed. Both treatments induced a sustained antihypertensive effect, with hydralazine showing more effect on supine blood pressure, and prazosin having more effect on standing pressure. Heart rate, cardiac output, and volume status showed only minor changes. Plasma norepinephrine showed a sustained increase when measured in both the supine and standing positions, but the increases were similar for the two treatments. Supine and standing plasma renin activity increased only during long-term treatment with hydralazine. Prazosin induced a progressive decrease in left ventricular mass over time (-34 +/- 15 g/m2 at 12 months), but hydralazine did not (-9 +/- 10 g/m2 after 12 months). Stepwise regression indicated that a decrease in systolic blood pressure was associated with a decrease in left ventricular mass with both treatments, but an increase in plasma norepinephrine was associated with an increase in left ventricular mass only with hydralazine, suggesting that increased sympathetic activity may affect left ventricular mass via cardiac alpha1 receptors. Thus, if regression of left ventricular hypertrophy is a worthwhile therapeutic goal, hydralazine and analogous arterial vasodilators are not drugs of choice.