[Clinical significance of electrocardiographic P-terminal force in V1 in patients with hypertrophic cardiomyopathy].
The clinical usefulness of P-terminal force in lead V1 (P-TF) was evaluated in 49 patients with hypertrophic cardiomyopathy. These 49 patients were categorized as 17 with an abnormal P-wave (P-TF greater than or equal to 3.0 msec.mV: group A) and 32 with a normal P-wave (P-TF less than 3.0 msec.mV: group B). Systolic blood pressure response (delta SBP) during the treadmill exercise test was significantly less in the group A than in the group B (delta SBP: 36 +/- 22 mmHg, 58 +/- 26 mmHg, respectively). Left atrial dimension measured from the M-mode echocardiogram was 37.8 +/- 5.0 mm in the group A and 31.0 +/- 5.2 mm in the group B. These differences were statistically significant (p less than 0.05). Left ventricular end-diastolic pressure averaged 19.5 +/- 7.9 mmHg in the group A and 13.5 +/- 4.0 mmHg in the group B (p less than 0.05). When comparing the group A and B, negative dp/dt / positive dp/dt of the group A was significantly less (0.69 +/- 0.14, 0.90 +/- 0.18, respectively) and the time constant T of the group A was significantly prolonged (86 +/- 30 msec, 56 +/- 10 msec, respectively). According to classifications of hypertrophic cardiomyopathy, all patients with the obstructive type had an abnormal P-wave. On the contrary, the majority of patients with apical hypertrophy had a normal P-wave.(ABSTRACT TRUNCATED AT 250 WORDS)