Infective Endocarditis in Obstructive Hypertrophic Cardiomyopathy: A Case Series and Literature Review
Infective endocarditis (IE) is a rare but potentially fatal complication of hypertrophic cardiomyopathy (HCM), particularly in cases involving left ventricular outflow tract obstruction. This article presents a detailed analysis of three cases of hypertrophic obstructive cardiomyopathy (HOCM) complicated by IE, highlighting the clinical challenges, diagnostic approaches, and therapeutic strategies employed. The discussion is supplemented by a comprehensive review of the relevant literature, providing insights into the epidemiology, risk factors, and management of IE in HOCM patients.
Case Presentations
The first case involved a 42-year-old woman with a history of HOCM who presented with a low-grade fever, chest distress, shortness of breath, and worsening edema for one month. Two months prior to admission, she had undergone cosmetic surgery (fat filling). Despite being diagnosed with HOCM several years earlier, she had not undergone alcohol septal ablation or myomectomy due to the presence of multiple branches of the first septal artery and high surgical risk. She had been managed with an oral beta-blocker. Blood cultures on the third day of admission grew Gram-positive streptococci, which were sensitive to linezolid, penicillin, ceftriaxone, and vancomycin. Due to a penicillin allergy, the bacteremia was uncontrolled, leading to IE. Echocardiography revealed severe mitral regurgitation with multiple patchy and echodense vegetations on the anterior and posterior mitral valve (MV) leaflets. The patient underwent urgent mitral valve replacement (MVR) and septal myectomy (SM) due to worsening heart failure. Postoperative pathology confirmed the presence of multiple vegetations on the MV. Her symptoms resolved significantly after surgery, and she was discharged following 25 days of parenteral treatment with amikacin and linezolid.
The second case was a 34-year-old woman with previously diagnosed HOCM who complained of worsening chest stiffness, dyspnea on exertion, and a low-grade fever for 10 days. Echocardiography identified multiple hypoechoic masses adherent to the anterior and posterior MV leaflets, the largest measuring 2.0 cm by 1.3 cm. Blood cultures were sterile as she had received short courses of antibiotics before admission. Despite empiric antibiotic therapy, her heart failure worsened, necessitating MVR and SM. Intraoperative findings included abundant vegetations on the MV leaflets, anterior MV leaflet perforation, and severe mitral insufficiency. Postoperatively, her symptoms were completely relieved, and she was discharged with improved observation.
The third case involved an 86-year-old woman admitted for recurrent fever, chest stiffness, and dyspnea on exertion for over one month. She had a 10-year history of exertional dyspnea and chest discomfort but was only diagnosed with HOCM one year prior. She had received a dual-chamber pacemaker for severe symptoms but experienced recurrent pouch infections, leading to surgical debridement and eventual pacemaker removal. Blood cultures before admission were negative. Echocardiography showed mobile isoechoic vegetations on the right ventricular pacing electrode. After two weeks of medical treatment without improvement, her family transferred her to a local hospital for palliative care due to her advanced age and surgical ineligibility.
Discussion
The incidence of IE in HOCM is relatively low, with Spirito et al. reporting a 10-year occurrence rate of 4.3%. They identified a subgroup of HCM patients with both obstruction and atrial dilatation as being particularly prone to IE. Among 640 IE patients at the authors’ institution since 2009, only three (0.5%) were diagnosed with HCM. These patients exhibited both left outflow tract obstruction and atrial enlargement, consistent with previous literature. However, recent studies by Dominguez et al. and Sims et al. have shown similar IE incidence rates in HCM patients with or without obstruction. The small sample size in these studies may limit their generalizability, underscoring the need for larger retrospective and prospective studies to clarify the true prevalence and risk factors for IE in HCM.
The management of IE in HOCM is complex and often requires a multidisciplinary approach. In cases where antibiotic therapy fails to control the infection or when there is severe valvular regurgitation or worsening heart failure, surgical intervention becomes necessary. MVR and SM were performed in two of the three cases presented, with both patients experiencing significant symptom relief and improved functional class postoperatively. A long-term study has shown that SM and MVR are safe procedures associated with low mortality and symptomatic improvement in the 1-5 years following surgery. MVR alone, however, has been correlated with poorer outcomes and less symptomatic benefit.
Prophylactic antibiotic therapy is an important consideration for HCM patients at high risk of bacteremia, particularly those with intracardiac devices. The increasing use of such devices in HCM management necessitates careful attention to infection prevention strategies. Despite advances in diagnosis and treatment, IE continues to carry high in-hospital mortality, and many patients require surgery due to uncontrollable sepsis, severe valvular regurgitation, or recurrent embolic complications.
Conclusion
IE is a rare but serious complication of HOCM that poses significant diagnostic and therapeutic challenges. The cases presented illustrate the importance of timely and aggressive management, including surgical intervention when necessary. The combined approach of MVR and SM appears to offer substantial benefits for patients with HOCM complicated by IE, particularly in cases refractory to medical therapy. Further research is needed to better understand the epidemiology and risk factors for IE in HCM and to optimize prevention and treatment strategies for this high-risk population.
doi.org/10.1097/CM9.0000000000001265
Was this helpful?
0 / 0