C-29 | Utility of invasive bolus thermodilution method in diagnosis of coronary microvascular dysfunction (CMD): Real World data

Coronary Microvascular dysfunction (CMD) is the most common etiology of chest pain in patients with no obstructive coronary artery disease (CAD). CMD is associated with a 4-fold increase in mortality and a 5-fold increase in major cardiovascular events. CFR (coronary flow reserve) and IMR (Index of Microcirculatory Resistance) can be measured invasively as adjunct to coronary angiography. We aimed to assess the utility of the new invasive bolus thermodilution technology in the diagnosis of CMD. Retrospective chart review of the patients referred for invasive workup for CMD between June 2022 to February 2023 was conducted. A descriptive analysis of the patients undergoing invasive workup of CMD was performed. Safety outcomes including in-hospital and 30- days post-op complications were also analyzed. During the study duration, 47 patients were referred, of which 36 patients met criteria for a workup of CMD. Mean age was 66 years with 67% females. Most common co-morbidities were hypertension (72%), hyperlipidemia (72%) and diabetes (27%). 47% of patients were found to have microvascular dysfunction, of which 53% were females. Procedural success was 97% (failed in one patient due to slow flow). Radial access was used in 89% of the patients. The mean procedure time (44 mins), contrast use (79 ml) and fluoroscopy time (6 mins) were similar to a diagnostic coronary angiogram. No complications in including major bleeding, post-op TIA/CVA, post-op MI or procedure-related mortality were noted in the peri-operative period and 30-day follow-up. Access site complication (hematoma) were noted in two cases. CMD is often misdiagnosed as non-cardiac chest pain due to a lack of a well-established diagnostic modality. We present the largest retrospective study analyzing bolus thermodilution technology as a diagnostic modality for CMD. It is an invasive test with a very high procedural success and low risk of complications as noted in our study.