Hemodynamic and metabolic responses to pacing in patients with chest pain and normal coronary arteriograms

Area of Science:

• Cardiology
• Clinical Physiology

Background:

• Chest pain with normal coronary arteriograms presents a diagnostic challenge.
• Hemodynamic and metabolic assessments are crucial for evaluating cardiac function.

Purpose of the Study:

• To investigate hemodynamic and metabolic responses to atrial and coronary sinus pacing in patients with chest pain and normal coronary arteriograms.
• To differentiate patient groups based on their responses to pacing.

Main Methods:

• Evaluated 41 patients with chest pain and normal coronary arteriograms.
• Utilized atrial and coronary sinus pacing.
• Monitored hemodynamic parameters including pulmonary capillary pressure and left ventricular end-diastolic pressure.
• Assessed metabolic responses, specifically lactate production.

Main Results:

• Patients with angina, lactate production, or ST depression (group II) exhibited significantly higher pulmonary capillary pressure during peak pacing compared to normal responders (group I).
• Abnormal left ventricular end-diastolic pressure responses were observed in 6 of 9 group II patients.
• Patients with prolapsing mitral valve (group III) also showed elevated pulmonary capillary pressure, with a significantly lower stroke index during peak pacing.
• Lactate production was common in group II, but less so in group III, suggesting distinct pain mechanisms.

Conclusions:

• Pacing can reveal abnormal hemodynamic and metabolic responses in patients with chest pain and normal coronary arteriograms.
• Elevated pulmonary capillary pressure and abnormal left ventricular pressures during pacing are indicative of underlying cardiac dysfunction.
• Distinct responses in patients with angina versus mitral valve prolapse suggest different pathophysiological mechanisms for chest pain.