A 74-year-old man with an old inferior myocardial infarction, chronic atrial fibrillation and recent episodes of pulmonary oedema is admitted to the intensive care unit. A grade II/VI systolic ejection murmur is heard at the base of the heart. The echocardiographic examination shows a hypertrophic left ventricle (LV) with mildly reduced systolic function and moderate-to-severe aortic stenosis (peak pressure drop 70 mmHg; mean 42 mmHg) (Fig. 1) . Coronary arteriography shows a significant

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... s in the right coronary artery and non-significant irregularities in the left coronary artery. The angiographic LV ejection fraction was 40%. Doppler tracings are shown in Fig. 2 . What is the LV filling pressure? Comments This patient has LV hypertrophy with mildly depressed systolic function. In addition he is in atrial fibrillation which makes the estimation of PCWP from mitral and pulmonary venous flow velocities troublesome. The mitral flow velocity waveform is monophasic because of the absence of atrial contraction, and the E wave varies from cycle to cycle (Fig. 2) . The variability of the E wave velocity, however, is rather limited. It has been shown that this is a sign of elevated left atrial pressure (which tends to minimize the variation due to the length of the cycle). In addition, the deceleration rates of both the E wave of transmitral flow and the D wave of pulmonary venous flow are rapid, which are other markers of elevated PCWP in patients with atrial fibrillation [1] . E velocity of mitral annulus is low and indicates abnormal LV relaxation (Fig. 2) [2] . The high E/E ratio indicates elevated PCWP. This is the most reliable parameter to use for the estimation of LV filling pressures in patients with atrial fibrillation particularly when the LV systolic function is not moderately-to-severely impaired. In atrial fibrillation, however, it is necessary to use an average of measurements obtained from five cardiac cycles. Teaching Corner 299