ANALYSIS OF HIGH-FREQUENCY QRS POTENTIALS OBSERVED DURING ACUTE MYOCARDIAL-INFARCTION

The value of high frequency QRS potentials (HFQRS) during acute myocar dial infarction (AMI) was assessed to define infarct size and prognosi s. HFQRS were recorded by signal-averaged ECG with 150-250 Hz frequenc y ranges, using X, Y, Z orthogonal leads. Recordings were obtained in surviving AMI patients (n = 33, 12 inferior, 11 anterior, 10 anterior- inferior) on the first and tenth days, but in non-survived patients (n = 5, 2 inferior, 1 anterior, 2 anterior-inferior) only on the first d ay. Additionally, the frequency of ventricular tachycardia (VT) was ev aluated by 24-h Holter monitoring in all patients at the same days. Th e control group consisted of 11 healthy people. In surviving AMI patie nts, RMS voltage of vector magnitude reduced in anterior and anterior- inferior MI but filtered QRS duration was longer in inferior MI than n ormals (P < 0.05, < 0.05, < 0.01, respectively). In nonsurvived patien ts, RMS voltages of leads X, Y, Z and vector magnitude were lower than normals (P < 0.01, < 0.05, < 0.01, < 0.01, respectively) and survivin g AMI patients (P < 0.01, < 0.05, < 0.05, < 0.05, respectively), the f iltered QRS duration was found to be longer than normals and survived patients (P < 0.01, < 0.01). In patients who had VT on Holter monitori ng, filtered QRS duration was significantly longer than in patients wi thout VT (P < 0.05). As a result, HFQRS was important for defining inf arct size but not malignant ventricular arrythmias. VT was related to filtered QRS duration. HFQRS may offer significant prognostic informat ion and contribute to early risk stratification of AMI patients.