Invasive Cardiac Testing Made Easier With Analytical Software

Recently a close relative experienced several rather severe bouts of chest pain. She had a positive family history for coronary heart disease and was in her mid 60’s. An urgent visit to a cardiologist and GI doctor started a series of tests; upper GI endoscopy, EKG, holter monitor, echocardiogram, and finally a nuclear stress test. 

All tests were negative—but some doubt remains. Other tests being considered in the future include a coronary CT angiogram (cCTA) (which is a CT scan with dye injected into a peripheral vein) or the “gold standard” test—the invasive coronary angiogram (ICA) with fractional flow reserve (FFR) assessment where a catheter is fed through the vessels directly to the opening of the coronary arteries, dye is then injected, and flow measurements are taken. 

The doctor is actually not sure at the present time that an ICA is needed and has decided to basically wait. The planned course of care is to treat the pain with a calcium channel-blocker and nitrates and see what happens over time.

Why not just do a coronary angiogram? Well, about 1 in 1000 have an adverse event up to and including stroke, heart attack, and even death. Rather dramatic side effects can occur just from sliding a long catheter through the blood vessels and squirting dye into the arteries of the heart. Plus, a coronary angiogram is very expensive.

So, rather than go straight to an angiogram, the less dangerous—and less expensive tests are done.

A company in Redwood City, California Heartflow, may change all of that with software that uses a cCTA plus millions of calculations on the data gathered during this non-invasive test. The test is commonly referred to as a HeartFlow Analysis. Physicians more formally call the test an FFRct, which stands for fractional flow reserve CT analysis.

The FFRct is not a new test. As mentioned above, it is typically done during the ICA and the data is obtained following the direct injection of dye into the heart arteries.  But this same analysis can be done on the data received during a cCTA, at a much lower risk and much lower cost. But, will it lead to the same doubt?  A recent study; Prospective Longitudinal Trial of FFRct Outcome and Resource Impacts, (PLATFORM) compared standard diagnostic strategies with an FFRct-guided strategy in 584 patients with stable chest pain. 

PLATFORM discovered that the use of an FFRct-guided strategy resulted in the cancellation of a planned ICA in 60% of patients (117 total cancellations).  None of the 117 patients who had an ICA cancelled suffered from an adverse event in the year following, indicating that it is safe to follow an FFRct–guided strategy. FFRct also provides enough data to discriminate between those coronary lesions that would require revascularization and those that do not.

According to the Merck Manual, more than one million coronary angiograms are done each year. That number could drop by hundreds of thousands per year if this strategy was followed—saving about $2,500 for each person. 

HeartFlow FFRct demonstrates that computer technology can constructively improve upon a very disruptive approach to cardiac care.