Perry M. Elliott

925-41 Coronary Sinus pH During Dipyridamole Infusion in Patients with Angina and Hypertrophic Cardiomyopathy

Typical angina pectoris and myocardial scarring suggestive of ischemia are common in patients with hypertrophic cardiomyopathy (HCM). However, the clinical evaluation of myocardial ischemia in HCM remains problematic as baseline ECG abnormalities are frequent and thallium-201 perfusion abnormalities correlate poorly with anginal symptoms. Similarly, coronary sinus lactate studies are subject to sampling errors. Coronary sinus pH measurement using a catheter mounted pH electrode is a validated, sensitive technique for the detection of myocardial ischemia. The change in coronary sinus pH during i.v. dipyridamole was determined in 10 patients with HCM and typical exertional chest pain (7 male, mean age 35xa0±xa011 years, range 19–53). Eight patients had ST segment depression of xa0≥xa01 mm in 2 or more leads of the baseline ECG at rest and 4 had reversible perfusion defects during stress thallium-201 scintigraphy. The pH electrode was introduced into the coronary sinus via the subclavian vein and dipyridamole (0.5xa0mg/kg) administered by slow i.v. injection. All patients experienced typical chest pain associated with a fall in coronary sinus pH (mean 0.08xa0±xa00.04, range: 0.020.15 units). Eight patients had changes xa0≥xa00.04 units. ST depression (xa0≥xa01 mm from baseline) occurred in 3 patients. Peak heart rate Imean 95.5xa0±xa012 bpm, range 80xa0–xa0115) correlated with the maximal pH change (rxa0=xa00.7, Pxa0=xa00.02). There was no association between maximum pH change and left ventricular dimensions or outflow tract gradient. Conclusion Chest pain during dipyridamole infusion in patients with HCM is caused by myocardial ischemia. Coronary sinus pH electrodes can be used successfully in the evaluation of myocardial ischemia risk in patients with HCM.