Validity and correlation of quantitative flow ratio with fractional flow reserve for assessment of intermediate coronary lesions

BACKGROUND

The angiographic percent diameter stenosis (%DS) do not assess the physiological significance of epicardial coronary stenosis. The currently practised physiological indices require pressure wires with or without adenosine-induced hyperaemia. Quantitative flow ratio (QFR) is an angiography-based method to determine the functional significance of coronary stenosis. The present study aimed to analyse the diagnostic performance of QFR in comparison to fractional flow reserve (FFR) in intermediate coronary lesions.

MATERIALS AND METHODS

It was a single centre retrospective study to analyse the diagnostic performance of offline QFR with the previously performed FFR in the last six years. A total of 56 interrogated vessels were included for the analysis. Offline QFR analysis was performed and correlated with FFR values in the intermediate coronary stenoses.

RESULTS

The mean age of the study population was 62.4 ± 9.1 years, including 81% men. The left anterior descending artery (50%) was the most common analysed vessel followed by left circumflex (27%) and right coronary (21%) arteries. The mean % DS and % area stenosis were 45.25 ± 11.22% and 57.45% ± 16.25%, respectively. The mean FFR and QFR values were 0.83 ± 0.06 and 0.82 ± 0.10, respectively. A strong positive correlation was found between FFR and QFR with a Spearman correlation coefficient of 0.56. Receiver operating curve analysis for QFR and %DS with a FFR cut off value <0.80 showed an area under the curve of 0.97 and 0.77, respectively. The sensitivity, specificity and diagnostic accuracy of QFR were 87.5%, 95% and 92.8%, respectively. There was a discordance in four vessels (7.1%) between QFR and FFR.

CONCLUSION

QFR has a good diagnostic performance in comparison to the gold standard FFR for physiological assessment of intermediate lesions. Its performance is significantly better than the anatomical % DS (p < 0.001).

Hemopneumothorax due to subacute right ventricular perforation by a pacemaker lead with subtle clinical presentation

Subacute right ventricular perforation by a pacemaker lead is a rare complication. Although occasionally asymptomatic, complicated cases are usually evidently symptomatic. Here, we report a 70-year-old man presented with mild left-sided chest pain three days after permanent pacemaker implantation. Suspected of ventricular perforation by the pacemaker lead on chest X-ray, device interrogation revealed non-corroborative parameters. This warranted a computed tomography (CT) scan, which confirmed the diagnosis, detected hemopneumothorax, and helped plan surgical intervention. The patient underwent surgical management with the placement of an epicardial pacemaker lead and was discharged after five days. Our case illustrates a rare report of subtle clinical presentation in a patient with subacute right ventricular perforation by a pacemaker lead complicated by hemopneumothorax. It further recapitulates the role of CT scan in providing definitive diagnostic information in managing such a patient. Anticipation of such a presentation is essential for primary care physicians, who are often a first contact point for a patient in the community. This requires a high index of suspicion in such patients presenting with minimal symptoms. Early recognition and timely referral by a family physician may prevent untoward consequences of device-related complications.