Angiographic Coronary Slow Flow Is Not a Valid Surrogate for Invasively Diagnosed Coronary Microvascular Dysfunction.

BACKGROUND: Ischemia with no obstructive coronary arteries is frequently caused by coronary microvascular dysfunction (CMD). Consensus diagnostic criteria for CMD include baseline angiographic slow flow by corrected TIMI (Thrombolysis In Myocardial Infarction) frame count (cTFC), but correlations between slow flow and CMD measured by invasive coronary function testing (CFT) are uncertain. OBJECTIVES: The aim of this study was to investigate relationships between cTFC and invasive CFT for CMD. METHODS: Adults with ischemia with no obstructive coronary arteries underwent invasive CFT with thermodilution-derived baseline coronary blood flow, coronary flow reserve (CFR), and index of microcirculatory resistance (IMR). CMD was defined as abnormal CFR (<2.5) and/or abnormal IMR (≥25). cTFC was measured from baseline angiography; slow flow was defined as cTFC >25. Correlations between cTFC and baseline coronary flow and between CFR and IMR and associations between slow flow and invasive measures of CMD were evaluated, adjusted for covariates. All patients provided consent. RESULTS: Among 508 adults, 49% had coronary slow flow. Patients with slow flow were more likely to have abnormal IMR (36% vs 26%; P = 0.019) but less likely to have abnormal CFR (28% vs 42%; P = 0.001), with no difference in CMD (46% vs 51%). cTFC was weakly correlated with baseline coronary blood flow (r = -0.35; 95% CI: -0.42 to -0.27), CFR (r = 0.20; 95% CI: 0.12 to 0.28), and IMR (r = 0.16; 95% CI: 0.07-0.24). In multivariable models, slow flow was associated with lower odds of abnormal CFR (adjusted OR: 0.53; 95% CI: 0.35 to 0.80). CONCLUSIONS: Coronary slow flow was weakly associated with results of invasive CFT and should not be used as a surrogate for the invasive diagnosis of CMD.

Left Ventricular Pressure Ratio Predicts In-Hospital Outcomes in Hospitalized Heart Failure With Reduced Ejection Fraction.

BACKGROUND: Given the risk of hemodynamic compromise in heart failure with reduced ejection fraction (HFrEF) patients undergoing left heart catheterization (LHC), there is a need for a simple parameter that can predict clinical outcomes. We hypothesize that left ventricular pressure ratio (LVPR), calculated as left ventricle systolic/left ventricle end-diastolic pressure, is a strong predictor of hemodynamic collapse in these patients. METHODS: Retrospective analysis of consecutive hospitalized HFrEF patients undergoing combined LHC and right heart catheterization (RHC) at a single institution from 2015-2017 was performed. LVPR was compared with standard RHC hemodynamic variables. The primary outcome was in-hospital escalation of therapy, defined as ≥40 mm Hg drop in systolic blood pressure (SBP), SBP ≤90 mm Hg for ≥15 minutes, start or escalation of vasoactive medications, cardiopulmonary resuscitation, or in-hospital death. Receiver-operating characteristic (ROC) analysis and Kaplan-Meier survival analysis were performed for prediction of the primary outcome. RESULTS: A total of 176 patients were included in this study. ROC analysis determined an optimal cut-off value of ≤3.96, which correlated with an area under the curve (AUC) of 0.65 (sensitivity, 45.9%; specificity, 83.2%; correctly classified, 64.9%). AUC was similar to other variables obtained using RHC. In-hospital survival free of escalation of therapy was lower in the low LVPR group vs the high LVPR group (0% vs 33%, respectively; P<.01). CONCLUSION: LVPR is an easily measured index obtained during LHC that can risk stratify hospitalized patients with HFrEF at the time of LHC.

The relationship between coronary microvascular dysfunction, atrial fibrillation and heart failure with preserved ejection fraction.

OBJECTIVE: Coronary microvascular dysfunction (CMD) is a new frontier in cardiovascular disease and an important contributor to myocardial ischemia. A high prevalence of CMD is shown in heart failure, however, the cause-and-effect relationship between CMD and atrial fibrillation (AF) is unknown. We hypothesize that CMD is associated with AF and increases susceptibility to the co-existence of AF and heart failure with preserved ejection fraction (HFpEF). METHODS: Our study examined the relationship between CMD, AF, and HFpEF in all patients who underwent invasive coronary physiology studies for assessment of chest pain or dyspnea. CMD was defined as impaired coronary flow reserve (CFR) without obstructive coronary disease. RESULTS: A total of 80 patients (mean age 60±12 years, 68.8% female, median follow up of 2.2 years) were studied. Patients with AF (61%) or HFpEF (62%), or both (71%) were more likely to have CMD than those patients without these conditions. Of the patients with AF and abnormal CFR, 91% had HFpEF. CMD was a predictor of AF with concomitant HFpEF (OR 4.38, P=0.02). Our clinical outcome analysis demonstrated that patients with CMD, AF or HFpEF had lower survival free of HF hospitalization than those patients without (P<0.05). AF (OR 5.5, P=0.02), diabetes, older age, female gender, and higher heart rate were predictors of CMD. CONCLUSION: CMD is highly prevalent in patients with AF with or without HFpEF. CMD is associated with poor clinical outcomes and the co-existence of AF and HFpEF. Understanding of the association between CMD and AF is important for developing an effective treatment strategy and the risk stratification for the prevention of AF in patients with CMD and vice versa.