POLARIS

Multi-Modality Guidance System

Resting Indices

All resting indices—including Pd/Pa, diastolic pressure ratio (dPR) and iFR— provide clinically equivalent results and all indices in the dPR class are numerically identical and verified by clinical evidence.

How dPR Measures Up

  1. Measuring different parts of diastole yields numerically identical results to iFR using the 0.89 cutoff
  2. dPR is as accurate to iFR as two iFR measurements are to each other
  3. Due to class effect, the DEFINE-FLAIR and iFR-Swedeheart studies provide clinical evidence for dPR. All studies, cutoffs and clinical recommendations for iFR can be applied 1:1 to dPR.

Class Effect Among Resting Indices

Class Effect Among Resting Indices
Watch Prof. Keith Oldroyd, Dr. Ziad Ali, and Dr. Luis Raposo discuss the class effect among all resting indices on PCRTV. Learn about new options in resting indices, including dPR, that were presented at EuroPCR and why measuring different parts of diastole yields numerically identical results to iFR.

Key Resources

Explore our coronary physiology products Explore our IVUS products available

What is dPR?

dPR is a diastolic pressure ratio. Measuring different parts of diastole yields results that are numerically identical.

30% of Diastole*

dPR: 0.86
iFR: 0.86
30% of Diastole*

65% of Diastole*

dPR: 0.86
iFR: 0.86
65% of Diastole*

90% of Diastole*

dPR: 0.86
iFR: 0.86
90% of Diastole*
 

dPR = iFR - 6 Definitions of Proof1,2

Selecting the wave-free period is not necessary for calculating results numerically identical to iFR.

 
 

Which Physiology Test to Use When and Why?

Which Physiology Test to Use When and Why?
Watch Ziad A. Ali, MD at CRT18 present the choices in coronary physiology and discuss when to use FFR, dPR (iFR) or Pd/Pa.

Evolution of Resting Physiology with Nils P. Johnson

Evolution of Resting Physiology with Nils P. Johnson
Watch Nils P. Johnson, MD at CRT18 discuss the history of resting physiology including an overview and comparison of the new diastolic pressure ratio (dPR) measurement with iFR and Pd/Pa.
 

COMPARISON OF DIFFERENT DIASTOLIC RESTING INDEXES TO IFR1

Read the latest JACC publication that compares different diastolic resting indexes to iFR and learn why all diastolic resting indexes tested were identical to iFR, both numerically and with respect to their agreement with FFR.  

Read Now

Boston Scientific’s Diastolic Pressure Ratio Definition

Methodology

  • dPR values were compared to iFR values using 893 waveform tracings from 833 patients pooled from the VERIFY 2 and CONTRAST studies
  • The dPR window uses two criteria: Pa < mean Pa and down-sloping Pa
  • Does not require ECG signal
  • No need to identify dicrotic notch

Intermediate Lesion

dPR: 0.90
iFR: 0.90
Intermediate Lesion

Severe Lesion

dPR: 0.71
iFR: 0.71
 

dPR is as Accurate to iFR as Two iFR Measurements are to Each Other

VERIFY 2: dPR is within the Intra-iFR Variation of ~0.01*,3

CONTRAST + VERIFY 2 Pooled Analysis: dPR = iFR

dPR COMING IN 2018 to the POLARIS MULTI-MODALITY GUIDANCE SYSTEM

What is Pd/Pa?

Pd/Pa calculates the entire cardiac cycle at rest.

Pd/Pa = iFR, like °C = °F

“Pd/Pa seems to offer a universal resting physiological metric with equivalent agreement to iFR. Although not numerically identical, 1 index can be linearly transformed into the other, much like the conversion of units of temperature. Using the binary cutoff of iFR ≤0.89 as a reference standard, Pd/Pa showed excellent agreement according to ROC curve analysis and the best cutoff value of Pd/Pa was ≤0.91.”

-Kobayashi Y, et al. JACC Oct 2017.

How do Pd/Pa and iFR compare?

Unlike iFR and FFR which only contain 66% of the same information, Pd/Pa and iFR contain 95% of the same information. Therefore, a Pd/Pa cutoff of 0.91 = an iFR cutoff of 0.89 as shown in Resolve, Verify 2 and Kobayashi et al.4,5  

Pd/Pa and iFR contain 95% of the same information

 
 

Pd/Pa

iFR

Single Cutoff6

≤0.91

≤0.89

Hybrid Algorithm7,8

0.88-0.97

0.86-0.93

FDA-Cleared9

✔

✔

Inclusion in Appropriate Use Criteria10,11

✔

✔

SCAI/ACC Reimbursement Recommendation12

✔

✔

Equivalent Correlation to FFR13,14,15,16

✔

✔

Equivalent Correlation to CFR17

✔

✔

Results Integrate into All Major Hemodynamic Systems

✔

X

ECG-free Algorithm Widely Available18

✔

X

Workhorse Pressure Guidewires Available

✔

X
 

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