An innovative noninvasive respiratory stress test indicates significant coronary artery disease.

BACKGROUND: Respiratory maneuvers can uncover manifestations of myocardial ischemia. Some pulse wave characteristics are strongly associated with significant coronary artery disease (S-CAD). An innovative test using the respiratory stress response (RSR) has been developed for the detection of S-CAD. It is based on spectral analysis of finger pulse wave oscillations measured by photoplethysmography during deep, paced breathing at a rate of six breaths per minute (0.1 Hz) over 70 s. METHODS: RSR was assessed, prior to the procedure, in 150 consecutive patients referred for coronary angiography. It was calculated by analyzing the relative spectral power of the respiratory peak area at 0.1 Hz, using proprietary software. The coronary angiograms were analyzed by quantitative coronary angiography by 1 cardiologist who was blinded to the RSR results. S-CAD was defined as luminal stenosis >70% of > or = 1 coronary artery with a diameter > or = 2 mm, or left main stenosis >50%. A valid RSR was obtained in 150 of 153 patients (98%) with a mean age of 58.7 + or - 10.6 years (67% males). RESULTS: S-CAD was found in 36 patients (24%). S-CAD patients had significantly lower RSR compared to patients without S-CAD (6.7% + or - 5.1 vs. 17.4% + or - 10.6; P<.001, respectively). Multivariate logistic regression analysis, adjusted for known CAD risk factors, showed that RSR is a strong independent indicator of S-CAD (odds ratio 41.2, 95% CI 12.2-139.3; P<.001). CONCLUSION: The innovative RSR test is a simple, noninvasive bedside or office-based tool for the detection of S-CAD.

Prevalence of aspirin and clopidogrel resistance among patients with and without drug-eluting stent thrombosis.

Drug-eluting stent (DES) thrombosis has a multifactorial etiology. Variable responsiveness to antiplatelet therapy likely contributes to its pathogenesis. We aimed to determine whether patients who had experienced DES thrombosis compared with a cohort of patients who had not would exhibit greater platelet reactivity and a greater prevalence of aspirin and clopidogrel resistance. The effect of aspirin and clopidogrel on platelet reactivity was determined after angiographically proven DES thrombosis in 26 patients and in 21 patients who had not experienced stent thrombosis (ST) > or =18 months after DES implantation. Aspirin effect was assessed using the VerifyNow Aspirin Assay, and the effect of clopidogrel was assessed using the VerifyNow P2Y12 Assay and vasodilator-stimulated phosphoprotein phosphorylation (VASP-P). Aspirin resistance was present in 23% of patients with ST and 5% of controls (p = NS). Clopidogrel resistance was present in 40% of patients with ST and 14% of controls using the P2Y12 assay (p = 0.02) and 90% of patients with ST and 67% of controls using the VASP-P assay (p = NS). Mean aspirin reaction units were significantly greater among all patients with ST and those with early ST compared with controls (477 +/- 89 vs 429 +/- 58, p = 0.04; and 485 +/- 84 vs 429 +/- 58, p = 0.02, respectively). Mean P2Y12 reaction units were significantly greater among patients with early ST compared with controls (265 +/- 102 vs 184 +/- 76, p = 0.01). The results of the VASP-P assay did not correlate with the presence of ST. In conclusion, patients who experienced DES thrombosis demonstrated significantly greater rates of clopidogrel resistance as determined by P2Y12 reaction units, but not VASP-P, compared with patients without DES thrombosis. Aspirin reaction units were significantly greater in the DES thrombosis population. Point-of-care testing with the VerifyNow Aspirin and P2Y12 Assays has the potential to identify patients at increased risk of ST, particularly early ST, after DES deployment.

The potential clinical utility of intravascular ultrasound guidance in patients undergoing percutaneous coronary intervention with drug-eluting stents.

AIMS: To assess the impact on clinical outcomes of intravascular ultrasound (IVUS) guidance during drug-eluting stent (DES) implantation. IVUS guidance during percutaneous coronary intervention (PCI) has been demonstrated to be useful in optimizing stent deployment. However, it is not proved that routine use of IVUS guidance with DES implantation can prevent stent thrombosis or restenosis. METHODS AND RESULTS: The clinical outcomes of 884 patients undergoing IVUS-guided intracoronary DES implantation from April 2003 to May 2006 were compared with the outcomes of a propensity-score matched population undergoing DES implantation with angiographic guidance alone. The primary endpoint of the study was definite stent thrombosis at 12 months. The secondary endpoint was major adverse cardiac events (MACE). After propensity-score matching, the two groups were well matched for clinical and angiographic characteristics. Patients undergoing IVUS-guided DES implantation underwent less direct stenting, more post-dilation, and had greater cutting balloon and rotational atherectomy use. At 30 days and at 12 months, a higher rate of definite stent thrombosis was seen in the No IVUS group (0.5 vs. 1.4%; P = 0.046) and (0.7 vs. 2.0%; P = 0.014), respectively. There were no major differences in late stent thrombosis and MACE (14.5 vs. 16.2%; P = 0.33) at 12 month follow-up between the groups. Rates of death and Q-wave myocardial infarction were similar, and there was no significant difference between groups in target vessel revascularization. However, a trend was seen in favour of the IVUS group in target lesion revascularization (5.1 vs. 7.2%; P = 0.07). IVUS guidance was an independent predictor of freedom from cumulative stent thrombosis at 12 months (adjusted HR 0.5, CI 0.1-0.8; P = 0.02). CONCLUSION: IVUS guidance during DES implantation has the potential to influence treatment strategy and reduce both DES thrombosis and the need for repeat revascularization.