Measurement of atrial volumes by magnetic resonance imaging in healthy volunteers and in patients with myocardial infarction

Magnetic resonance imaging was used to measure atrial volumes and emptying fractions in healthy volunteers to establish normal ranges and also in patients with myocardial infarction. Fourteen healthy volunteers (age mean +/- SD, 47 +/- 13 years) and 14 patients (age 56 +/- 9) with previous myocardial infarction were studied. All patients were in sinus rhythm, had competent cardiac valves and no heart failure. Atrial and ventricular volumes were measured from a set of cardiac gated transverse spin echo images (TE 40 ms) covering the heart and acquired at the end of ventricular systole and diastole. Ventricular ejection fractions and atrial emptying fractions were calculated. In patients with myocardial infarction, left atrial end-diastolic and systolic volumes were significantly higher (P < 0.001), and the emptying fraction significantly lower (P < 0.001) than in the control group. The right atrial end-diastolic volume was also significantly higher (P < 0.05) and the emptying fraction significantly lower (P < 0.01) than those in the control group. These findings are likely to be due to abnormal left ventricular long axis dynamics caused by damage to the myocardium, and reflect the abnormal systolic and diastolic functions of the left ventricle which contribute to atrial filling and emptying, respectively. Changes in atrial volumes can be measured non-invasively by magnetic resonance imaging. Using this method we have studied the normal ranges and demonstrated abnormalities in patients with myocardial infarction. Thus this imaging method may prove to be useful for studying atrial function under different physiological and pathological conditions and for evaluating the effect of therapeutic interventions on atrial function.