Prolonged QT interval at onset of acute myocardial infarction in predicting early phase ventricular tachycardia.

The prospectively assessed time course of changes in ventricular repolarization during acute myocardial infarction (AMI) is reported in 32 patients admitted 2.0 +/- 1.8 (SD) hours after AMI onset. The initial corrected QT interval (QTc) upon hospitalization was longer (0.52 +/- 0.07 seconds) in the 14 patients developing ventricular tachycardia (VT) within the first 48 hours as compared to QTc (0.47 +/- 0.03 seconds) in the eight patients with frequent ventricular premature beats (VPBs) and to QTc (0.46 +/- 0.03 seconds) in the 10 patients with infrequent VPBs (p less than 0.001; analysis of variance). By the fifth day after AMI onset, the QTc shortened significantly only in the VT group, suggesting a greater initial abnormality of repolarization in these patients. All 32 patients had coronary angiography, radionuclide ventriculography, and myocardial perfusion scintigraphy before hospital discharge. Significant discriminating factors related to early phase VT in AMI included initially longer QT and QTc intervals, faster heart rate, higher peak serum levels of creatine kinase, acute anterior infarction, angiographically documented proximal stenosis of the left anterior descending coronary artery, and scintigraphic evidence of hypoperfusion of the interventricular septum. Prior infarction, angina pectoris, hypertension, multivessel coronary artery disease, and depressed left ventricular ejection fraction did not provide discrimination among the three different ventricular arrhythmia AMI groups. We conclude that (1) the QT interval is frequently prolonged early in AMI, (2) the initial transiently prolonged ventricular repolarization facilitates and predicts complex ventricular tachyarrhythmias within the first 48 hours of AMI, (3) jeopardized blood supply to the interventricular septum frequently coexists, and (4) therapeutic enhancement of rapid recovery of the ventricular repolarization process merits investigation for prevention of VT in AMI.

Antibody responses to influenza immunization of children with acute lymphoblastic leukemia.

Antibody responses of two doses of a bivalent influenza vaccine containing A/Victoria/75 (A/Vic/75) and A/New Jersey/76 (A/NJ/76) viral antigens were studied in 22 children receiving maintenance chemotherapy for acute lymphoblastic leukemia (ALL), 16 children no longer receiving therapy for ALL, and 50 sibling controls. Before immunization, the three groups showed no difference in titer of antibody to either antigen. After the first immunization, children off therapy showed significantly higher titers to A/NJ/76 than did either sibling controls of children receiving therapy (P less than 0.01). After the second immunization, children off therapy showed significantly higher antibody titers to both antigens than did children receiving therapy or controls (P less than 0.01 for both A/NJ/76 and A/Vic/75). Antibody titers of children receiving therapy were not significantly different from those of controls. A year later, there were no significant differences in antibody titers among the groups. Thus, children with ALL who are receiving chemotherapy respond normally to two doses of influenza vaccine, whereas children off therapy manifest abnormally high titers of antibody to both influenza virus antigens.