Clinical role of post-angioplasty hyperemic microvascular resistances in chronic ischemic left ventricular dysfunction

Prognostic impact and clinical outcomes of coronary flow reserve and hyperaemic microvascular resistance

BACKGROUND

Most studies dichotomise indices of coronary microvascular function to assess their prognostic values.

AIMS

We aimed to investigate whether coronary flow reserve (CFR) and hyperaemic microvascular resistance (HMR) as continua predict major adverse cardiovascular events (MACE), comprising all-cause death, myocardial infarction, revascularisation, and stroke in patients with ischaemia and non-obstructive coronary artery disease.

METHODS

A total of 610 patients were included and followed up over a median of 8.0 years (199 individual MACE in 174 patients).

RESULTS

Both CFR and HMR as continua predicted MACE with an odds ratio (OR) of 0.70 (per 1-unit increase, 95% confidence interval [CI]: 0.53, 0.92; p=0.01) and 1.63 (per 1 mmHg/cm/s, 95% CI: 1.20, 2.21; p=0.002), respectively. This relationship remained significant after adjustment for age and sex with an adjusted OR of 0.66 (per 1 unit increase, 95% CI: 0.49, 0.89; p=0.01) and 1.42 (per 1 mmHg/cm/s, 95% CI: 1.03, 1.94; p=0.03). HMR added prognostic value to CFR in predicting MACE (net reclassification index 0.17, 95% CI: 0.02, 0.31; p=0.03; integrated discrimination improvement 0.01, 95% CI: 0.0001, 0.02; p=0.046).

CONCLUSIONS

Both CFR and HMR as continuous variables predict future risk of MACE.

Risk Stratification of Patients With NonObstructive Coronary Artery Disease Using Resistive Reserve Ratio

Background Resistive reserve ratio (RRR), or the ratio of baseline to hyperemic microvascular resistance, has prognostic implications in predicting clinical outcomes in patients with obstructive coronary artery disease. However, its value in patients with angina or ischemia with nonobstructive coronary artery disease is unknown. Methods and Results We included 1692 patients with nonobstructive coronary artery disease who underwent invasive coronary vasoreactivity testing. Abnormal coronary flow reserve (CFR, the ratio of hyperemic and baseline resting flow velocities) and RRR were defined as <2.5 and <2.62, respectively. The mortality rate was marginally higher in patients with abnormal CFR (428 patients [25%]) than those with normal CFR (38 [9%] versus 81 [6%]; P=0.08), and was significantly higher in patients with abnormal RRR (716 patients [42%]) than those with normal RRR (70 [10%] versus 49 [5%], P=0.0002) over the median follow-up of 11.3 years. Patients with abnormal CFR had marginally lower survival than those with normal CFR (log-rank P=0.08). In contrast, patients with abnormal RRR had significantly lower survival than those with normal RRR (log-rank P=0.001). Abnormal RRR was associated with shorter time to death even after adjustment for other covariates (adjusted hazard ratio, 1.63; 95% CI, 1.11-2.38; P=0.01). Conclusions In patients with no obstructive coronary artery disease, RRR was superior to CFR in predicting long-term survival. An RRR <2.62 was associated with 1.6 times increased risk of death in patients with nonobstructive coronary artery disease. Indices of coronary microcirculatory resistive reserve comprising flow- and pressure-derived values may reflect underlying microvascular pathology more faithfully than flow-alone indices like CFR.

Beta-blocker therapy reduces mortality in patients with coronary artery disease treated with percutaneous revascularization: a meta-analysis of adjusted results

AIMS

The long-term impact of beta blockers on prognosis in patients treated with contemporary therapies for coronary artery disease remains to be defined.

METHODS AND RESULTS

All observational studies evaluating the impact of beta blockers in patients treated with coronary revascularization and contemporary therapies and adjusted with multivariate analysis were included. All-cause death was the primary endpoint, while Major Adverse Cardiac Events (MACE) (composite endpoint of all-cause death or myocardial infarction, MI) and MI were secondary endpoints. A total of 26 studies were included, with 863 335 patients. After 3 (1-4.3) years, long-term risk of all-cause death was lower in patients on beta blockers [odds ratio, OR 0.69 (0.66-0.72)], both for Acute Coronary Syndrome (ACS) [OR 0.60 (0.56-0.65)], and stable angina patients [OR 0.84 (0.78-0.91)], independently from ejection fraction [OR 0.64 (0.42-0.98) for reduced ejection fraction and OR 0.79 (0.69-0.91) for preserved ejection fraction]. The risk of long-term MACE was lower but NS for ACS patients treated with beta blockers [OR 0.83 (0.69-1.00)], as in stable angina. Similarly, risk of MI did not differ between patients treated with beta blockers or without beta blockers [OR 0.99 (0.89-1.09), all 95% confidence intervals]. Using meta-regression analysis, the benefit of beta blockers was increased for those with longer follow-up. The number needed to treat was 52 to avoid one event of all-cause death for ACS patients and 111 for stable patients.

CONCLUSION

Even in percutaneous coronary intervention era, beta blockers reduce mortality in patients with coronary artery disease, confirming their protective effect, which was consistent for both ACS and stable patients indifferently of preserved or reduced ejection fraction.