Hypertrophic Obstructive Cardiomyopathy

Effective treatment of hypertrophic cardiomyopathy with left ventricular outflow tract obstruction using a covered stent

A woman in her 60s presented with progressive exertional dyspnoea, exertional chest pressure and exertional dizziness. Echocardiogram identified a 156 mm Hg left ventricular outflow tract gradient with provocation, indicating hypertrophic cardiomyopathy with left ventricular outflow obstruction-confirmed with MRI and angiogram. An alcohol septal ablation was planned but due to communication of the second septal perforator with the right ventricle and a wire-induced mid-left anterior descending artery dissection, alcohol septal ablation was not performed. Instead, a covered stent was placed in the mid-left anterior descending artery covering the origins of the third and fourth septal perforators. The left ventricular outflow tract gradient decreased from 90 to 30 mm Hg with provocation and her symptoms improved. Follow-up showed a left ventricular outflow tract gradient of 35 mm Hg with provocation and decreased symptoms.

Unstable angina complicated with dynamic left ventricular outflow tract obstruction

Left ventricular outflow tract obstruction (LVOTO) complicated with unstable angina (uAP) has not been described widely, but patients with these two conditions have several problems. Differentiation of the two conditions is also often difficult because the chest symptoms are similar. Moreover, nitrates are commonly used for ischemic heart disease, but have the effect of worsening LVOTO. We experienced three cases of dynamic LVOTO with a sigmoid-shaped septum, and without typical hypertrophic obstructive cardiomyopathy, that were complicated with uAP. In all cases, LVOTO was improved after initial percutaneous coronary intervention (PCI) for the left anterior descending artery lesion. Next, a dobutamine stress test was performed and LVOTO was provoked again in two cases, but not in a case with small acute myocardial infarction of the basal septum during PCI. All cases remained asymptomatic with beta-blocker therapy. Therefore, PCI and beta-blocker administration for LVOTO with uAP resulted in favorable clinical courses in all three cases. These outcomes suggest that revascularization including PCI should have priority in the therapeutic strategy for a case of acute coronary syndrome with LVOTO.

Very long-term outcome of coronary covered stents: a report from the SCAAR registry

AIMS

Covered stents are mostly used for coronary perforations with a high risk of early adverse events; however, their long-term outcome is unknown. The aim of this study was to elucidate the short- and long-term outcome of patients treated with covered stents compared to all other stented patients.

METHODS AND RESULTS

The Swedish national registries from 2005-2017 disclosed 265 patients who had received 366 covered stents. Their outcomes were compared to all other stented patients (197,948) who had received 320,784 stents. Compared to regular stents, covered stents showed significant differences (p<0.001) in the short and long term in relation to in-stent restenosis (ISR), target lesion revascularisation (TLR), re-infarction (MI), re-PCI and mortality, the rates of which were all higher. The higher mortality was concentrated within the first month, as a landmark analysis at that time point, adjusted for age and procedural indication, demonstrated no future difference in mortality (HR 1.02 [0.78-1.33], p=0.877). Stent thrombosis (ST) within one year was reported to be higher in covered stents than in other stents. However, no ST was reported in equine pericardial covered stents.

CONCLUSIONS

This observational study including the entire Swedish population shows that patients receiving covered stents have a significantly higher risk of all adverse events. Reassuringly, in the long term, mortality appears to be similar to that in other stented patients.

Contemporary techniques for catheter-based intervention for hypertrophic obstructive cardiomyopathy

Hypertrophic obstructive cardiomyopathy (HOCM) is the most frequent genetic cardiovascular affection and is associated with high mortality and morbidity. Invasive treatment of symptomatic patients with HOCM refractory to drug therapy was limited to surgical myomectomy for years. In the mid 1990s, alcohol septal ablation (ASA) emerged as a new and less invasive option for septal ablation (SA) and is now considered a good alternative with excellent short- and long-term outcomes. Besides ASA, other techniques have been promoted to treat HOCM. The present review aims to summarise current practice and evidence of catheter-based techniques from the treatment of HOCM. We also detail technical points to achieve a safe and effective procedure.

Low gradient aortic stenosis

OPINION STATEMENT

Severe low-gradient (LG) aortic stenosis (AS) [aortic valve area (AVA) ≤ 1.0 cm(2), mean pressure gradient (MG) < 40 mmHg] represents a frequently encountered and challenging clinical dilemma. A systematic approach, which often requires several imaging modalities, should be undertaken to confirm the hemodynamic findings and rule out measurement error. Low-flow conditions often account for the discrepancy and can be present whether the left ventricular ejection fraction (LVEF) is depressed or normal. In patients with classical low-flow (LF), LG AS in which LVEF is reduced (<40-50 %), dobutamine stress echocardiography (DSE) should be used to distinguish patients with true severe AS and pseudo-severe AS, as well as to evaluate for the presence of left ventricular contractile or flow reserve. Surgical or transcatheter aortic valve replacement (AVR) should likely be reserved for those patients with true severe AS. Patient outcome with medical or surgical management generally relates to patient functional capacity, stenosis severity, and left ventricular functional reserve. Patients with severe LG AS with preserved LVEF can have a stroke volume that is either normal (>35 mL/m(2)) or low (<35 mL/m(2)). New data suggest that DSE can identify pseudo-severe AS in up to 30 % of patients with severe LF-LG AS with preserved LVEF. AVR should likely be restricted to those patients with true severe AS, although there is currently little data to support this strategy. Symptomatic patients with severe LG AS with preserved LVEF, whether they have normal or low flow, should be offered AVR. Transcatheter AVR provides an alternative therapeutic option in the high-risk patient.

Ejection fraction/velocity ratio identifies prosthesis-patient mismatches in patients with aortic bioprosthetic valves and left ventricular dysfunction

OBJECTIVES

Recently, a new echocardiographic nonflow corrected index (ejection fraction/velocity ratio [EFVR] = percent left ventricular ejection fraction [EF]/maximum aortic gradient) has been introduced and has shown excellent accuracy in quantifying the effective orifice area (EOA) in native aortic valves and bio-prostheses. The objective of this study was to assess the utility of the EFVR to quantify the indexed EOA in patients with an aortic bioprosthesis and left ventricular dysfunction considering an indexed EOA value of 0.85 cm(2)/m(2) or less to be indicative of a prosthesis-patient mismatch (PPM), defined as an EOA of the inserted prosthetic valve of less than that of the normal human valve.

METHODS

We studied 100 patients (62 men and 38 women; mean age +/- SD, 71 +/- 8.6 years) with an aortic bioprosthesis and left ventricular dysfunction (EF < or =49%), and we evaluated the indexed EOA by both the continuity equation (CE) and EFVR.

RESULTS

We found a significant linear correlation between the CE and EFVR (r = 0.85; P < .0001) and good agreement between the two methods in identifying patients with an indexed EOA of 0.85 cm(2)/m(2) or less; the correlation began to become nonlinear for patients with an indexed EOA of greater than 1.2 cm(2)/m(2), which was not clinically relevant. Notably, all 11 patients with a discrepancy between the indexed EOA and EFVR (ie, EFVR < or =1.0 and indexed EOA >0.85 cm(2)/m(2)) also showed an indexed EOA of greater than 0.85 but less than or equal to 1.0 cm(2)/m(2) (meaning the presence of a mild PPM).

CONCLUSIONS

The EFVR can be considered a reliable echocardiographic alternative to the CE, especially in conditions in which that is technically difficult, allowing identification of a PPM (indexed EOA < or =0.85 cm(2)/m(2)) with excellent sensitivity and specificity.

Feasibility of cardiovascular magnetic resonance to assess the orifice area of aortic bioprostheses

BACKGROUND

Prosthetic orifice area, usually calculated by transthoracic echocardiography (TTE) or transesophageal echocardiography (TEE), provides important information regarding the hemodynamic performance of aortic bioprostheses. However, both TTE and TEE have limitations; therefore accurate and reproducible determination of the orifice area often remains a challenge. The present study aimed to investigate the feasibility of cardiovascular magnetic resonance (CMR) to assess the orifice areas of aortic bioprostheses.

METHODS AND RESULTS

CMR planimetry of the orifice area was performed in 65 patients (43/22 stented/stentless prostheses; mean time since implantation, 3.1+/-2.8 years; mean orifice area [TTE], 1.70+/-0.43 cm(2); 62 normally functioning prostheses, 2 severe stenoses, and 1 severe regurgitation) in an imaging plane perpendicular to the transprosthetic flow using steady-state free-precession cine imaging under breath-hold conditions on a 1.5-T MR system. CMR results were compared with TTE (continuity equation, n=65) and TEE (planimetry, n=31). CMR planimetry was readily feasible in 80.0%; feasible with limitation in 15.4% because of stent, flow, and sternal wire artifacts; and impossible in 4.6% because of flow artifacts. Correlations of the orifice areas by CMR with TTE (r=0.82) and CMR with TEE (r=0.92) were significant. The average difference between the methods was -0.02+/-0.24 cm(2) (TTE) and 0.05+/-0.15 cm(2) (TEE). Agreement was present for stented and stentless devices and independent of orifice size. Intraobserver and interobserver variabilities of CMR planimetry were 6.7+/-5.4% and 11.5+/-7.8%.

CONCLUSIONS

The assessment of aortic bioprostheses with normal orifice areas by CMR is technically feasible and provides orifice areas with a close correlation to echocardiography and low observer dependency.

Acute hemodynamic changes in percutaneous transluminal septal coil embolization for hypertrophic obstructive cardiomyopathy

BACKGROUND

A 48-year-old man with hypertrophic obstructive cardiomyopathy (HOCM) presented with palpitations, symptoms of medically refractory class II angina, and NYHA class II-III heart failure.

INVESTIGATIONS

Physical examination revealed a grade 3 systolic murmur that increased to grade 4 with exercise. Echocardiography showed marked septal thickening (17 mm), a left ventricular outflow tract gradient (LVOTG) of 95 mmHg, and a 3+ systolic anterior motion of the mitral valve apparatus. No other pathology was noted with cardiac MRI or with coronary angiography.

DIAGNOSIS

Severe symptomatic HOCM.

MANAGEMENT

Coil embolization of the first two septal vessels resulted in a limited septal infarct (creatine kinase-MB 36.6 microg/l; troponin T 0.43 microg/l) that corresponded to a mass of 8.1 g on gadolinium contrast cardiac MRI. The LVOTG decreased immediately from 78 mmHg to 35 mmHg. On pressure-volume loops, contractile isovolemic and systolic ejectional parameters decreased, while an improvement in diastolic left ventricular function was observed.

CONCLUSION

Septal coil embolization acutely and effectively reduced the LVOTG in a patient with drug-refractory HOCM.