Stress testing patients on oral dipyridamole Dr Parthi Arumugam Consultant Nuclear Physician Nuclear Medicine Centre Manchester Royal Infirmary

Parthi Arumugam Case history  71 year old male  Typical angina  Peripheral vascular disease  Risk factors for CAD Hypertension Diabetic Current Smoker Raised BMI

Parthi Arumugam What is the next line of investigation ?  Exercise testing  Myocardial perfusion imaging  Dobutamine stress echo  CT Coronary angiogram  Invasive Coronary angiogram

Parthi Arumugam  Based on NICE guidelines on chest pain of recent onset 1, this patient has a high pre test likelihood of CAD so invasive coronary angiogram should be considered.  The patient decided to have a functional test, so based on local availability, MPS was ordered. CTCA is also a suitable alternative.  So all responses are potentially correct. 1.NICE clinical guidelines 95

Parthi Arumugam  He was booked for an Adenosine Rubidium PET perfusion study.  He turned up for his appointment having forgotten to stop oral Dipyridamole.

Parthi Arumugam What is the most appropriate stress modality?  Exercise  High dose Adenosine  Dobutamine  Dipyridamole  Cancel the test and rebook

Parthi Arumugam  Either exercise or Dobutamine stressing could be employed but there are practical issues when used in conjunction with Rubidium imaging.  Cancelling the test is an option but would inconvenience the patient.  IV Dipyridamole was used.

Parthi Arumugam  IV Dipyridamole is a safe and efficacious in patients who are on oral dipyridamole 2.  The protocol was completed without any significant side effects or ischaemic symptoms. 2 ASNC guidelines pdf

Parthi Arumugam Stress Rest Stress Rest

Parthi Arumugam  Scans shows extensive inducible ischaemia in the inferior, inferolateral and inferoseptal myocardium (involving 8/20 segments).

Parthi Arumugam Absolute Blood Flow Measurement

Parthi Arumugam  Flow measurement showed global ischaemia with significantly reduced flow reserve in the RCA and LCx (normal flow reserve should be more than 2.0),with probable steal phenomena – resting flow more than stress.  Note there is reduced flow in the LAD territory where relative perfusion was ‘normal’.

Parthi Arumugam Coronary Angiogram  Coronary angiogram showed occluded RCA, tightly stenosed LCx and moderate LAD disease, which correlates with the flow reserve measurement.  Patient has been referred for CABG.

Parthi Arumugam Teaching points  IV Dipyridamole can be used in patients on oral dipyridamole.  Relative perfusion assessment can underestimate extent of ischaemia in patients with multivessel disease.