Coronary microvascular dysfunction (CMD) is a prevalent cause of ischemic heart disease and is associated with poorer quality of life and worse patient outcomes. Both functional and structural abnormalities of the microcirculation can generate ischemia in the absence of epicardial stenosis or worsen concomitant obstructive coronary artery disease (CAD). The invasive assessment of CMD allows for the evaluation of the entirety of the coronary vascular tree, from the large epicardial vessels to the microcirculation, and enables the study of vasomotor function through vasoreactivity testing. The standard evaluation of CMD includes vasomotor assessment with acetylcholine, as well as flow- and resistance-derived indices calculated with either thermodilution or Doppler guidewires. Tailored treatment based upon the information gathered from the invasive evaluation of CMD has been demonstrated to reduce the burden of angina; therefore, a thorough understanding of these procedures is warranted with the aim of improving the quality of life of the patient. This review summarizes the most widespread approaches for the invasive evaluation of CMD, with a focus on patients with ischemia and non-obstructive CAD.
Background: The safety of revascularization deferral according to pressure wire examination in patients with chronic kidney disease (CKD) has not been fully established.Methods: From a retrospective cohort of 439 patients in whom revascularization was deferred after physiological assessment, we examined the incidence of patient-oriented composite endpoint (POCE: all-cause death, myocardial infarction [MI] and unplanned revascularization) in patients with CKD (estimated glomerular filtration rate [eGFR] < 60 mL/min/1.73 m 2 ) and without it.Results: At 4 years of follow-up, the primary endpoint was met by 25.0% of patients with CKD and by 14.4% of patients without CKD (hazard ratio [HR] 1.56, 95% confidence interval [CI] 0.96-2.53, p = 0.071). The incidence of POCE was even higher in patients with an eGFR < 30 mL/min/1.73 m 2 : 43.8% (HR 3.10, 95% CI 1.08-8.92, p = 0.036). However, no differences were observed in the incidence of MI (4.2% vs. 4.4% in non-CKD), target vessel revascularization (5.8% vs. 5.9%), and target vessel MI (0.8% vs. 4.6%).
Conclusions:Patients with CKD in whom pressure-wire evaluation led to deferral of coronary revascularization develop more POCE in the long term, compared to patients with normal renal function. However, the increase in POCE in patients with CKD was seldom related to deferred vessels, thus suggesting an epiphenomenon of an intrinsically higher cardiovascular risk of CKD patients.
Background
Evidence regarding the use of pressure indices for the assessment of coronary stenoses in patients with chronic kidney disease (CKD) is scarce.
Methods
We assessed the relation between eGFR, FFR and resting Pd/Pa in 1147 consecutive patients (1316 vessels) included in the International Collaboration of Comprehensive Physiologic Assessment Study. We also compared FFR and Pd/Pa against a standardized cut-off of coronary flow reserve (CFR<2.0). Finally, we examined the occurrence of vessel-oriented composite outcome (VOCO: cardiac death, vessel-specific revascularization, vessel-specific myocardial infarction) across negative/positive results of both FFR and CFR in patients with and without CKD.
Results
FFR increases as renal function worsens (beta −10.5, 95% CI −20.0 to −11.03, p=0.030), a relation that was not seen with resting Pd/Pa (beta −6.14, 95% CI −19.9 to 6.78, p=0.351). Both indices had similar diagnostic accuracies for the detection of a CFR<2.0 in the presence of CKD (AUC 0.629 for FFR vs 0.663 for resting Pd/Pa, p=0.192). However, CKD patients showed a higher proportion of vessels with negative FFR but low CFR (24.5% vs 13.4%, p=0.015).
CFR decreased linearly with deteriorating eGFR, and this was mainly driven by higher resting coronary flow in CKD patients (p=0.026), while hyperaemic coronary flow remained similar (p=0.403). IMR did not change significantly with eGFR (beta −0.02, 95% −0.09 to 0.05, p=0.557).
The incidence of VOCO was higher in patients with CKD and FFR>0.80 when compared to non-CKD patients and FFR>0.80 (12.7% vs 6.90%, p=0.062). Prognosis was worse for those with CKD, negative FFR and CFR<2.0 (20.59% vs. 8.44% in non-CKD, p=0.038).
Conclusions
The assessment of a given coronary stenosis in patients with CKD with either FFR or resting Pd/Pa is equivalent when compared to underlying coronary flow. In CKD, impaired CFR is caused by a state of increased resting flow. The assessment of CFR on top of standard pressure wire examination significantly improves prognostic stratification in CKD patients.
Funding Acknowledgement
Type of funding sources: None.
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