Spectrum of haemodynamic responses to atrial pacing in coronary artery disease.

Atrial tachy-pacing was performed in 34 patients who were divided into 3 groups as follows. Group I: 4 patients with obscure chest pain syndromes and normal coronary arteries and haemodynamics; Group 2: 25 patients with significant coronary artery disease and angina pectoris; Group 3: 5 patients with coronary artery disease, left ventricular aneurysm, and left ventricular dysfunction. Pacing produced a reduction in the left ventricular stroke work index and the left ventricular end-diastolic pressure in Group i patients, while the cardiac index and the left ventricular minute work index showed no significant change. Group 2 patients showed a variety of responses. Nine patients had a 'normal' response to atrial pacing, namely a fall in left ventricular stroke work index and left ventricular end-diastolic pressure. Of these, .5 had experienced angina during pacing and 4 did not; the other I6 had abnormal responses. When considered as a group, there was a significant decrease in the left ventricular stroke work index and an increase in the left ventricular minute work index, while the left ventricular end-diastolic pressure and cardiac index did not change significantly.