Patterns of left ventricular dilation during the six months after myocardial infarction

Changes in left ventricular volume after a first myocardial infarction were studied in 50 patients. Serial radionuclide andiograms were obtained 48 h, 10 days and 1 and 6 months after infarction and left ventricular volume measured by a nongeometric method. Left ventricular dilation (≥20% increase in end-diastolic volume) occurred within 10 days of infarction in 11 patients, who had a mean volume increase of 34 ± 15% (p = 0.002 versus 48 h) at 10 days and 61 ± 43% (p = 0.01 versus 10 days) at 6 months. Ten other patients manifested left ventricular dilation between 10 days and 6 months with a lesser volume increase of 42 ± 18% by 6 months. Among the 21 patients with ventricular dilation, progressive dilation (serial volume increases ≥20% on two or more occasions) occurred in 8 patients, who all had a large anterior infarct. Mean volume increases at 10 days and 1 and 6 months were 27 ± 20%, 49 + 40% (p = 0.03 versus 10 days) and 79 + 37% (p = 0.006 versus 1 month), respectively, in this group. In patients with progressive dilation, left ventricular ejection fraction decreased from 35 + 6% at 48 h to 24 + 10% at 1 month (p < 0.001) and 27 + 10% (p = 0.006) at 6 months. Between 1 month and 2 years after infarction six patients died, of whom four had progressive dilation. Severe left ventricular dilation can develop within the first 10 days after infarction and may progress during the next 6 months, with deterioration in ventricular function and a high likelihood of death.