Haas, Tammy S.

Background: Marked septal hypertrophy is considered a requirement for effective myectomy in obstructive hypertrophic cardiomyopathy (HCM), with mitral valve replacement recommended as the alternative strategy in patients with minimal hypertrophy. However, it remains uncertain whether relief of obstruction can be effectively abolished without mitral valve replacement in patients with minimal septal wall thickening. Methods: Of 500 patients who underwent surgical myectomy from 2004 to January 2014, 21 (4.2%) were identified with a maximum LV wall thickness ≤ 15mm and constitute the study cohort. Results: All 21 patients (56 ± 10 years old; 62% male) were followed for advanced heart failure symptoms refractory to drug therapy with a maximal septal wall thickness of 13.6 ± 1.7 mm (range: 10-15 mm; ≤ 12 mm in 5 patients). Outflow obstruction ≥ 30 mmHg due to mitral valve-septal contact was present after exercise in 17 of 21 patients (range: 50-150 mmHg), and under resting conditions in 4 patients (range: 30-65 mmHg). In all patients, surgical relief of obstruction consisted of muscular resection of the basal septum with revision of abnormal and apically displaced papillary muscles, which were judged intraoperatively to be contributing to obstruction. In addition, in 10 patients (47%) myectomy alone was not sufficient to relieve obstruction due to the limited opportunity for septal reduction and adjunctive mitral valve repair was performed to shorten an elongated anterior leaflet. No patient required mitral valve replacement or incurred a ventricular septal defect. Post-operatively, 4 patients developed complete heart block requiring permanent pacemaker (1 patient with pre-operative right bundle branch block) and 1 had a cerebrovascular event. At most recent follow up 18 ± 19 months post-myectomy, septal thickness was reduced to 10 ± 2 mm, no patient had an outflow gradient at rest or with provocation, and all patients were alive with the majority asymptomatic (class I: n=13; 62% and class II n=8; 38%). Conclusion: In patients with minimal septal hypertrophy, outflow obstruction can be effectively abolished with surgical myectomy and adjunctive mitral valve repair with a small increased risk of heart block, but without the need for mitral valve replacement.

Background— Hypertrophic cardiomyopathy (HCM) is the most common genetic heart disease characterized by a diverse clinical and phenotypic spectrum. This study reports the prevalence, morphology, clinical course, and management of an underrecognized subgroup of HCM patients with left ventricular apical aneurysms. Methods and Results— Of 1299 HCM patients, 28 (2%) were identified with left ventricular apical aneurysms, including a pair of identical twins. Aneurysms were recognized at a wide age range (26 to 83 years), including 12 patients (43%) who were ≤50 years of age. Apical aneurysms varied considerably in size (maximum dimension, 10 to 66 mm), were dyskinetic/akinetic with thin rims, and were associated with transmural (and often more extensive) myocardial scarring identified by late gadolinium enhancement cardiovascular magnetic resonance. Apical aneurysms were recognized by echocardiography in only 16 of 28 patients (57%) but by cardiovascular magnetic resonance in the 12 patients undetected by echocardiography. Left ventricular chamber morphology varied; however, 19 patients (68%) showed an “hourglass” contour, with midventricular hypertrophy producing muscular narrowing and intracavitary gradients in 9 patients (74±42 mm Hg). Sarcomeric protein missense mutations known to cause other phenotypic expressions of HCM were present in 3 patients. Over 4.1±3.7 years of follow-up, 12 patients (43%) with left ventricular apical aneurysms experienced adverse disease complications (event rate, 10.5%/y), including sudden death, appropriate implantable cardioverter-defibrillator discharges, nonfatal thromboembolic stroke, and progressive heart failure and death. Conclusions— Patients with left ventricular apical aneurysms represent an underappreciated subset in the heterogeneous HCM disease spectrum with important clinical implications, often requiring a high index of suspicion and cardiovascular magnetic resonance for identification. Apical aneurysms in HCM are associated with substantial cardiovascular morbidity and mortality and raise novel treatment considerations.