Left ventricular outflow tract planimetry by cardiovascular magnetic resonance differentiates obstructive from non-obstructive hypertrophic cardiomyopathy.

The relation to the pressure gradient as assessed by echocardiography and the CMR-derived planimetry of the LVOT is not known, no values for the differentiation of obstruction exist. We studied 37 patients with hypertrophic cardiomyopathy and 14 healthy controls using standard sequences with 3D coverage of the left ventricular outflow tract. A cutoff value of 2.7 cm2 identified obstruction as defined by echocardiography with 100% accuracy. CMR planimetry at rest is a promising tool to evaluate patients with hypertrophic cardiomyopathy.