QFR vs. perfusion imaging to predict abnormal FFR in patients with prior coronary artery disease

Background

In patients with suspected obstructive coronary artery disease (CAD) and a high pre-test probability, myocardial perfusion imaging (MPI) or referral for invasive coronary angiography (ICA) are viable diagnostic strategies. The present study compared the diagnostic performance of quantitative flow ratio (QFR) and MPI by single-photon emission computed tomography (SPECT), positron emission tomography (PET), and cardiac magnetic resonance imaging (CMR).

Methods

In this PACIFIC-II substudy, 189 patients with prior MI/PCI who were suspected of having symptoms related to myocardial ischemia and underwent SPECT, PET, and CMR before ICA were evaluated for inclusion. ICA was obtained with (109 patients) and without (80 patients) adherence to a QFR acquisition protocol. All major coronary arteries were interrogated by FFR, except for vessels with a subtotal/total occlusion. An FFR ≤0.80 was used to define significant epicardial CAD. QFR analyses (v2.0) were performed based on ICA by a corelab in vascular territories (N=487) in which FFR was obtained. MPI modalities were assessed for presence of ischemia by corelabs, uninterpretable scans were omitted from the diagnostic comparison analyses.

Results

QFR analysis success rate was higher (81%) among vessels acquired using the QFR acquisition protocol compared to vessels obtained without the protocol (52%, p<0.001). Overall, a QFR result was available in 334 (69%) vessels. Among these vessels, QFR had a higher sensitivity (72%) and accuracy (84%) compared to SPECT (46%, p=0.001 and 66%, p<0.001), PET (58%, p=0.032 and 65%, p<0.001), and CMR (33%, p<0.001 and 72%, p<0.001). Whereas specificity of QFR (87%) was similar to CMR (83%, p=0.123) but higher than that of SPECT (71%, p<0.001) and PET (67%, p<0.001). Lastly, QFR exhibited a higher area under the receiver operating characteristic curve (0.89) than SPECT (0.57, p<0.001), PET (0.66, p<0.001), and CMR (0.60, p<0.001).

Conclusions

Provided QFR was analyzable (69% of the vessels), QFR correlated better with FFR (both as measures of epicardial CAD) than MPI as reflected in the diagnostic performance measures for detecting vessels-specific significant epicardial CAD as defined by FFR.

Funding Acknowledgement

Type of funding sources: None.

Left atrial strain for predicting arrhythmia recurrence after atrial fibrillation ablation: cardiac magnetic resonance rapid strain vs. feature tracking strain

Background

Global left atrial (LA) strain is a predictor of atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI). Recently, novel rapid LA strain assessment approaches have emerged: LA long axis strain and LA AV junction strain. Currently, it remains unknown whether these rapid strain approaches can predict AF recurrence after AF ablative therapy and hence may be a simple alternative for the cumbersome LA feature tracking strain analysis.

Purpose

The present study focusses on the predictive value of different atrial strain quantification methods in relation to AF recurrence after PVI. Rapid LA strain analysis is compared to LA feature tracking strain in AF patients.

Methods

A total of 58 AF patients (78% paroxysmal AF, 64% male, mean age 61±7 years) undergoing first radiofrequency PVI ablation were included. Prior to ablation, all patients underwent cardiac magnetic resonance imaging being in sinus rhythm. LA rapid strain (long axis strain and AV junction strain) and LA feature tracking strain were derived from 2-chamber and 4-chamber cine CMR images. All patients were routinely followed up for arrhythmia recurrence through 12-lead ECGs, mobile-based one-lead ECGs, and/or Holter monitoring.

Results

After one year follow-up, arrhythmia recurrence (after the 90-day blanking period) was observed in 21 patients (36%), occurring after a median of 159 (119–320) days. LA long axis strain, AV junction strain, and feature tracking strain were all significantly reduced in patients with AF recurrence compared to patients without AF recurrence (long axis strain: −19.96±11.03% vs. −28.18±9.93%, P=0.005; AV junction strain: −18.08±9.69% vs. −25.60±8.79%, P=0.004; feature tracking strain: −12.54±4.16% vs. −15.94±3.50%, P=0.002, respectively, figure A to C). ROC analysis identified LA feature tracking strain as having the highest area under the curve (AUC) for predicting AF recurrence after ablative therapy (AUC: 0.75 for LA feature tracking strain, 0.71 for LA long axis strain, 0.70 for AV junction strain, figure D). Both LA rapid strain methods had a significant correlation with LA feature tracking strain (LA long axis strain vs. LA feature tracking strain, r=0.76, P<0.001 and LA AV junction strain vs. LA feature tracking strain, r=0.77, P<0.001).

Conclusion

LA rapid strain and LA feature tracking strain both have clinically relevant predictive power for prediction of AF recurrence after index PVI in AF patients. Considering the ease of LA rapid strain analysis, this method may be a valuable parameter to assess in clinical practice.

Funding Acknowledgement

Type of funding sources: None. Figure 1