Paradoxical response to exercise in asymptomatic hypertrophic cardiomyopathy: a new description of outflow tract obstruction dynamics.

The purpose of this study was to analyze left ventricular obstruction in patients with hypertrophic cardiomyopathy (HCM) during exercise echocardiography. Despite the association of symptoms with left ventricular outflow tract obstruction in HCM, there exist paradoxical situations in which significant intraventricular gradients (>50 mm Hg) at rest occur in conjunction with excellent exercise tolerance. To examine this phenomenon, we performed exercise echocardiography and analyzed the clinical status of 107 HCM patients with and without resting obstruction. At rest, 69 patients had no obstruction and 38 exhibited an intraventricular gradient, 9 of whom exhibited a decrease in gradient of at least 30 mm Hg (99.4 ± 35.5 mm Hg to 30.2 ± 14.3 mm Hg, p < 0.001) during exercise (paradoxical response to exercise [PRE]). The PRE patients presented with a significantly lower New York Heart Association clinical class and higher left ventricular volumes and arterial pressure both at rest and during exercise than HCM patients in whom the gradient increased or did not change during stress echocardiography. Finally, PRE patients exhibited a trend toward a reduced rate of cardiac events. Our study reports a subgroup of HCM patients, designated PRE based on a decreased intraventricular gradient during exercise. The reduced exertional obstruction may account for the better functional class and trend toward fewer clinical events in PRE patients.

Lafitte S ，Reant P ，Touche C ，Pillois X ，Dijos M ，Arsac F ，Peyrou J ，Montaudon M ，Ritter P ，Roudaut R ，Demaria A ... -  《-》

Hypertrophic cardiomyopathy is predominantly a disease of left ventricular outflow tract obstruction.

Maron MS ，Olivotto I ，Zenovich AG ，Link MS ，Pandian NG ，Kuvin JT ，Nistri S ，Cecchi F ，Udelson JE ，Maron BJ ... -  《-》

Relation between left ventricular outflow tract obstruction and left ventricular shape in patients with hypertrophic cardiomyopathy: a cardiac magnetic resonance imaging study.

Hypertrophic cardiomyopathies (HCM) are often associated with left ventricular (LV) outflow tract obstruction, which can explain symptoms and impact prognosis. To better understand the mechanisms that link obstruction and LV shape in HCM. Patients with HCM who underwent cardiac magnetic resonance (CMR) imaging were included retrospectively. Obstructive HCM was defined as LV outflow gradient more than 30 mm Hg at rest by transthoracic echocardiography. The LV shape and mitral angle were assessed by CMR. Results were compared with control subjects. Mean LV-mitral angle was smaller in patients with obstructive HCM (n=29) than in patients with non-obstructive HCM (n=15) or control subjects (n=15) (80 ± 5° vs 87 ± 7° [P=0.0002] and 89 ± 2° [P<0.0001]). Mean mitral papillary muscles angle was greater in patients with non-obstructive HCM than in patients with obstructive HCM or control subjects (136 ± 17° vs 123 ± 16° [P=0.007] and 118 ± 10° [P=0.002]). Patients with non-obstructive HCM had a greater mean LV-aortic root angle than patients with obstructive HCM or control subjects (139 ± 6° vs 135 ± 7° [P=0.04] and 133 ± 7° [P=0.03]). There is a relation between morphological and functional parameters in HCM within which the mitral valve is probably part of pathophysiogenesis.

Martin R ，Lairez O ，Boudou N ，Méjean S ，Lhermusier T ，Dumonteil N ，Berry M ，Cognet T ，Massabuau P ，Elbaz M ，Rousseau H ，Galinier M ，Carrié D ... -  《-》

[Comparison of dobutamine stress echocardiography and exercise echocardiography in evaluating left ventricular outflow tract obstruction in patients with hypertrophic cardiomyopathy].

Shao CL ，Duan FJ ，Qiao SB ，You SJ ，Hu FH ，Yuan JS ，Yang WX ... -  《-》

Exercise echocardiography in asymptomatic HCM: exercise capacity, and not LV outflow tract gradient predicts long-term outcomes.

This study sought to assess long-term outcomes in asymptomatic or minimally symptomatic patients with hypertrophic cardiomyopathy (HCM) who underwent exercise echocardiography, without invasive therapies for relief of left ventricular outflow tract (LVOT) obstruction. Many HCM patients present with LVOT obstruction, mitral regurgitation (MR), and diastolic dysfunction, often requiring invasive therapies for symptomatic relief. However, a significant proportion of truly asymptomatic patients can be closely monitored. In HCM patients, exercise echocardiography has been shown to be a useful assessment of functional capacity and risk stratification. We included 426 HCM patients (44 ± 14 years; 78% men) undergoing exercise echocardiography, excluding hypertensive heart disease of elderly, ejection fraction <50% and invasive therapy (myectomy or alcohol ablation) during follow-up. Clinical, echocardiographic (LV thickness, LVOT gradient, and MR) and exercise variables (percent of age-sex predicted metabolic equivalents [METs] and heart rate recovery [HRR] at 1 min post-exercise) were recorded. A composite endpoint of death, appropriate internal defibrillator discharge, and admission for congestive heart failure was recorded. Patients were asymptomatic or minimally symptomatic on history, but 82% of patients achieved <100% of age-sex predicted METs, and 43% had ≥II+ post-stress MR. The mean LV septal thickness, post-exercise LVOT gradient, and HRR were 2.0 ± 0.5 cm, 62 ± 47 mm Hg, and 31 ± 14 beats/min, respectively. During a mean follow-up of 8.7 ± 3 years, there were 52 events (12%). Patients achieving >100% of age-sex predicted METs had 1% event rate versus 12% in those achieving <85%. On stepwise multivariate survival analysis, percent of age-sex predicted METs (hazard ratio [HR]: 0.76; 95% confidence interval [CI]: 0.64 to 0.90), abnormal HRR (HR: 0.89; 95% CI: 0.82 to 0.97), and atrial fibrillation (HR: 2.73; 95% CI: 1.30 to 5.74) (overall, p < 0.001) independently predicted outcomes. In asymptomatic or minimally symptomatic HCM patients, exercise stress testing provides excellent risk stratification, with a low event rate in patients achieving >100% of predicted METs.

Desai MY ，Bhonsale A ，Patel P ，Naji P ，Smedira NG ，Thamilarasan M ，Lytle BW ，Lever HM ... -  《-》