Symptoms and left ventricular size and function in patients with chronic aortic regurgitation

When Aortic Stenosis Is Not Alone: Epidemiology, Pathophysiology, Diagnosis and Management in Mixed and Combined Valvular Disease

Aortic stenosis (AS) may present frequently combined with other valvular diseases or mixed with aortic regurgitation, with peculiar physio-pathological and clinical implications. The hemodynamic interactions between AS in mixed or combined valve disease depend on the specific combination of valve lesions and may result in diagnostic pitfalls at echocardiography; other imaging modalities may be helpful. Indeed, diagnosis is challenging because several echocardiographic methods commonly used to assess stenosis or regurgitation have been validated only in patients with the single-valve disease. Moreover, in the developed world, patients with multiple valve diseases tend to be older and more fragile over time; also, when more than one valvular lesion needs to address the surgical risk rises together with the long-term risk of morbidity and mortality associated with multiple valve prostheses, and the likelihood and risk of reoperation. Therefore, when AS presents mixed or combined valve disease, the heart valve team must integrate various parameters into the diagnosis and management strategy, including suitability for single or multiple transcatheter valve procedures. This review aims to summarize the most critical pathophysiological mechanisms underlying AS when associated with mitral regurgitation, mitral stenosis, aortic regurgitation, and tricuspid regurgitation. We will focus on echocardiography, clinical implications, and the most important treatment strategies.

Size matters! Impact of age, sex, height, and weight on the normal heart size

BACKGROUND

Therapeutic decisions in cardiology are determined frequently by cardiac chamber size. To decide whether cardiac dimensions are still in the normal range, reliable reference values are needed. However, published reference values mostly refer to historical cohorts using motion-mode measurements and have not been adjusted for sex or age. The impact of body size was only vaguely addressed. The importance of such adjustments is illustrated by studies, which show that smaller individuals and women are at risk of delayed treatment and impaired outcome when currently used reference values are applied. The aim of the present study was to assess the impact of body size, sex, and age on the normal heart size.

METHODS AND RESULTS

We prospectively studied 622 individuals (52.7% women; 17-91 years; 143-200 cm; 32-240 kg) without cardiac disease by standard transthoracic echocardiography. Multivariable linear regression analyses of the impact of sex, age, height, and weight on cardiac chamber size were performed. By multivariable regression analysis (n=500), all 4 variables independently influenced cardiac chamber size. The validity of cardiac dimensions predicted by the regression model was tested prospectively in a validation cohort (n=122). A calculator is proposed that estimates cardiac dimensions on the basis of the regression analysis.

CONCLUSIONS

Sex, height, weight, and age significantly affect the normal heart size. These parameters need to be considered when cutoff values indicating the need for treatment or even surgery are established.

Role of vasodilators in regurgitant valve disease

Vasodilator therapy is designed to reduce regurgitant volume and improve left ventricular function. Acute administration reduces vascular resistance and decreases regurgitant volume and left ventricular filling pressure. These effects may be clinically useful in acute regurgitations, but less consistent results have been reported in long-term therapy. In chronic mitral functional regurgitation, vasodilator therapy has proved to have clinical or prognostic benefit only when heart failure or poor ventricular function is present. The indication of vasodilator treatment in aortic regurgitation has raised significant controversy. Several studies with small series have shown beneficial effects on regurgitant volume, ejection fraction, and mass of the left ventricle. Nevertheless, in the only two randomized long-term follow-up studies, results differed completely. In our experience, both nifedipine and enalapril failed to reduce the need for valvular surgery or show benefits in echocardiographic parameters. Vasodilator therapy would be indicated only in patients with severe aortic regurgitation and systemic hypertension, or when surgery is contraindicated.

Long-term vasodilator therapy in patients with severe aortic regurgitation

BACKGROUND

Vasodilator therapy can reduce the left ventricular volume and mass and improve left ventricular performance in patients with aortic regurgitation. Accordingly, it has been suggested that such therapy may reduce or delay the need for aortic-valve replacement.

METHODS

We randomly assigned 95 patients with asymptomatic severe aortic regurgitation and normal left ventricular function to receive open-label nifedipine (20 mg every 12 hours), open-label enalapril (20 mg per day), or no treatment (control group) to identify the possible beneficial effects of vasodilator therapy on left ventricular function and the need for aortic-valve replacement.

RESULTS

After a mean of seven years of follow-up, the rate of aortic-valve replacement was similar among the groups: 39 percent in the control group, 50 percent in the enalapril group, and 41 percent in the nifedipine group (P=0.62). In addition, there were no significant differences among the groups in aortic regurgitant volume, left ventricular size, left ventricular mass, mean wall stress, or ejection fraction. One year after valve replacement, the left ventricular end-diastolic diameter and end-systolic diameter had decreased to a similar degree among the patients who underwent surgery in each of the three groups, and all the patients had a normal ejection fraction.

CONCLUSIONS

Long-term vasodilator therapy with nifedipine or enalapril did not reduce or delay the need for aortic-valve replacement in patients with asymptomatic severe aortic regurgitation and normal left ventricular systolic function. Furthermore, such therapy did not reduce the aortic regurgitant volume, decrease the size of the left ventricle, or improve left ventricular function.

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.