Replacement of Regurgitant Bicuspid Aortic Valve in a Dilated,Non-Compacted Left Ventricle

Introduction

Bicuspid aortic valve (BAV) is the most common form of congenital heart disease, with the majority requiring some sort of intervention, most often surgery. ¹ Up to 20% of asymptomatic adults with BAV present with moderate to severe aortic valve insufficiency, ¹ while 1% to 11% of cases could present with associated left ventricular non-compaction (LVNC) syndrome. ² No guidelines exist about surgical indications and outcomes in patients with BAV with severe LV dilatation, LV systolic dysfunction, or LVNC. ³ We present a case of dilated cardiomyopathy in the setting of severe BAV regurgitation and partial LVNC syndrome and the decision to surgical intervene.

Case Report

A 32-year-old male was evaluated after a three-month history of dyspnea, worsening exertional chest pain, and palpitations. He had a healthy childhood with above average functional capacity, and no prior history of heart disease. On physical examination, vital signs were within normal limits, and there was no evidence of jugular venous distention, lung crackles, or peripheral edema. Cardiac evaluation revealed a parasternal heave, along with a systolic ejection click, and a grade 3 diastolic murmur at the left upper sternal border was appreciated. On echocardiography, the left ventricle (LV) was severely dilated with LV end-diastolic diameter (LVEDD) of 9.1 cm, and LV end-systolic diameter (LVESD) of 8.1 cm. The LV systolic function was severely reduced with an ejection fraction of 18±5%. Moreover, prominent trabeculations were noted along the apex and lateral wall of the LV. The right ventricular size and function were normal. The aortic valve was bicuspid, with a posteriorly directed aortic regurgitant jet (see Figure 1).

OPEN IN VIEWER

Figure 1.

Preoperative transthoracic echocardiogram. A, Bicuspid aortic valve (BAV) in short axis view. B, Posterior-directed regurgitant jet across aortic valve in parasternal long axis. C, Left ventricle end-diastolic diameter (LVEDD) 9.1 cm valve in parasternal long axis. D, Left ventricle end-systolic diameter (LVESD) 8.1 cm valve in parasternal long axis. E, Left ventricular end-diastolic volume 604 mL in four-chamber view, and evidence of apical trabeculations from LV non-compaction (LVNC). F, Left ventricular end-systolic volume 494 mL, LVEF 18±5%.

Once his medical regimen was optimized, he underwent a metabolic exercise stress test demonstrating peak oxygen consumption (VO₂) of 31 ml/kg/min which was 62% of the predicted value. He achieved 84% of predicted maximal heart rate (8.9 Metabolic Equivalents (METS)), with a normal blood pressure response and no significant arrhythmias or ischemic electrocardiographic changes during the test.

Cardiac magnetic resonance imaging (MRI) confirmed the dilated LV (left ventricular end-diastolic volume 923 mL with an index of 469 mL/m² and left ventricular end-systolic volume 735 mL with an index of 373 mL/m²) along with a left ventricular ejection fraction (LVEF) of 20%. The LV non-compacted and compacted ratio was 3.0, with the non-compacted tissue mass being 1.2 times bigger than the compacted LV mass at the end of diastole. The aortic valve was bicuspid, due to the fusion of the left and right coronary cusps, with severe eccentric and posteriorly directed regurgitant jet (regurgitant fraction 48%; see Figure 2).

OPEN IN VIEWER

Figure 2.

Cardiac magnetic resonance imaging (MRI). A, Magnetic resonance imaging of the left ventricle (LV) in long axis view revealing prominent myocardial trabeculations consistent with left ventricular non-compaction. Non-compacted to compacted ratio was 3.0. B, Left ventricle imaged in short axis with prominent myocardial trabeculations.

He underwent right cardiac catheterization, which revealed normal filling pressures (central venous pressure (CVP) of 7 mm Hg, mean pulmonary artery pressure of 22 mm Hg, and pulmonary capillary wedge pressure of 16 mm Hg) along with preserved cardiac output (cardiac output [CO] of 5.00 L/min and cardiac index [CI] of 2.55 L/min/m²). Coronary angiography revealed normal coronary arteries, with severe aortic regurgitation being noted on aortography.

Due to case complexity, the patient completed a multidisciplinary evaluation including consultation with cardiothoracic surgery, heart failure, and electrophysiology services. Given the presence of severe aortic regurgitation on cardiac imaging, and relatively preserved functional capacity on metabolic stress, the dilated cardiomyopathy was deemed predominantly due to the chronic volume load from the valvular disease. Consequently, cardiothoracic surgery anticipated surgical benefit and considered him to be a medium-risk surgical candidate. The heart failure team anticipated no need for backup mechanical support when taking into account patient’s age, functional capacity class, and high-peak VO₂. The electrophysiology team recommended intraoperative epicardial lead placement for primary prophylaxis therapy with implantable cardioverter defibrillator in the setting of LVEF <35% and partially non-compacted LV, as well as resynchronization therapy given low EF and left bundle branch block.

He underwent aortic valve replacement with a mechanical valve and epicardial lead implantation. Intraoperatively, he required a second bypass run due to LV distension and dysfunction. Postoperatively, several runs of nonsustained ventricular tachycardia were noted. The patient was successfully extubated on postoperative day #1 and required pressors and inotropic support for two days. Repeat transthoracic echocardiogram on postoperative day 5 demonstrated no change in the LVEF (EF ∼15%), with a decrease in left ventricular size (see Figure 3). Subsequently, he had implantation of a chronic resynchronization therapy device with implantable defibrillator (CRT-D). He was discharged home on postoperative day 14.

OPEN IN VIEWER

Figure 3.

Postoperatory transthoracic echocardiogram. A, Left ventricle end-diastolic diameter (LVEDD) of 7.5 cm on parasternal long axis. B, Left ventricle end-systolic diastolic diameter of 7.4 cm on parasternal long axis. C, Mechanical aortic valve encircled with no significant aortic regurgitation on Doppler assessment. D, Left ventricular end-diastolic volume of 423 mL, LVEF∼15%.

At three-month follow-up, he was asymptomatic with preserved functional capacity. The repeat echocardiogram showed an improved 28% LVEF, along with LVEDD of 8.9 cm and LVESD of 8.5 cm. Due to implanted CRT-D, patient was unable to undergo follow-up cardiac MRI.

Discussion

Patients with BAV complicated by significant regurgitation have an increased risk of primary cardiac events. ¹ The likelihood of symptom onset in asymptomatic cases increases by 6% per year, with a chance of LV dilatation of 3% to 4% per year. ¹ No specific recommendations exist about surgical indication and/or outcomes in patients with regurgitant BAV with either severely depressed EF and/or LV dilation. Yet, data suggest that significant reductions in LVEDD, LVESD, and aortic regurgitation might occur after BAV interventions. ⁴ Nevertheless, these data are derived from patients with preserved LVEF and only mild LV dilatation.

Furthermore, our case was complicated by partially non-compacted LV, involving the apex and lateral wall. In general, patients with non-compaction cardiomyopathy carry higher mortality when they have an enlarged LV, limited functional capacity, presence of atrial fibrillation or presence of left bundle branch block. In this subgroup of patients, automated cardioverter/defibrillator implantation and early heart transplantation are sought. ⁵ Moreover, reports for the optimal managements of patients with LVNC requiring cardiac surgery are very limited.

The best evidence about outcomes in patients with severe regurgitant BAV complicated by dilated and dysfunctional non-compacted LV comes from case reports. First, Cavusoglu ⁶ reported a case of regurgitant BAV associated with a dilated and dysfunctional non-compacted LV (EF of 25% and LVEDD of 8.3 cm). Despite optimal medical treatment, the patient rapidly progressed from asymptomatic status to symptoms at rest and died. In contrast, Wrigley and Ohki reported successful cases of aortic valve replacement (AVR) in patients with regurgitant BAV, preserved LVEF, mild LV dilatation, and LVNC syndrome. ^7,8 The decision to proceed with surgical intervention in our patient was derived from a multidisciplinary team approach taking into account the patient’s age and likelihood of further left ventricular dysfunction and dilation with potential fatal outcomes, as seen in the case reported by Cavusoglu ⁶ , along with preoperative stress testing revealing good functional capacity and preserved cardiac hemodynamics.

Our patient represents the most extreme documented case of regurgitant BAV with dilated cardiomyopathy complicated by a partially non-compacted LV. Surgical intervention resulted in an increase in systolic performance and reduction in LV dimensions. Such improvements have important repercussion on patient outcomes since it suggests regurgitant BAV as the primary cause of dilated cardiomyopathy over the non-compaction syndrome. Based on recent series on left ventricular non-compaction, 47% of the patients either died (35%) or underwent heart transplantation (12%) within two years of diagnosis. ⁵ In contrast, data on patients undergoing aortic replacement for severe aortic regurgitation complicated by low EF reported a 41% survival rate at ten years. ⁹

Further research is warranted to provide guidelines for the care of such complex patients to delineate potential surgical benefit.