Global impairment of coronary blood flow in the setting of acute coronary syndromes (a RESTORE substudy). Randomized Efficacy Study of Tirofiban for Outcomes and Restenosis

Impact of nonculprit vessel myocardial perfusion on outcomes of patients undergoing percutaneous coronary intervention for acute coronary syndromes: analysis from the ACUITY trial (Acute Catheterization and Urgent Intervention Triage Strategy)

OBJECTIVES

This study evaluated the impact of nonculprit vessel myocardial perfusion on outcomes of non-ST-segment elevation acute coronary syndromes (NSTE-ACS) patients.

BACKGROUND

ST-segment elevation myocardial infarction patients have decreased perfusion in areas remote from the infarct-related vessel. The impact of myocardial hypoperfusion of regions supplied by nonculprit vessels in NSTE-ACS patients treated with percutaneous coronary intervention (PCI) is unknown.

METHODS

The angiographic substudy of the ACUITY (Acute Catheterization and Urgent Intervention Triage Strategy) trial included 6,921 NSTE-ACS patients. Complete 3-vessel assessments of baseline coronary TIMI (Thrombolysis In Myocardial Infarction) flow grade and myocardial blush grade (MBG) were performed. We examined the outcomes of PCI-treated patients according to the worst nonculprit vessel MBG identified per patient.

RESULTS

Among the 3,826 patients treated with PCI, the worst nonculprit MBG was determined in 3,426 (89.5%) patients, including 375 (10.9%) MBG 0/1 patients, 475 (13.9%) MBG 2 patients, and 2,576 (75.2%) MBG 3 patients. Nonculprit MBG 0/1 was associated with worse baseline clinical characteristics. Patients with nonculprit MBG 0/1 versus MBG 3 had increased rates of 30-day (3.0% vs. 0.7%, p < 0.0001) and 1-year (4.4% vs. 1.0%, p < 0.0001) death. Similar results were found among patients with pre-procedural TIMI flow grade 3 in the culprit vessel, where nonculprit vessel MBG 0/1 (hazard ratio: 2.81 [95% confidence interval: 1.63 to 4.84], p = 0.0002) was the strongest predictor of 1-year mortality.

CONCLUSIONS

Reduced myocardial perfusion in an area supplied by a nonculprit vessel is associated with increased short- and long-term mortality rates in NSTE-ACS patients undergoing PCI. Furthermore, worst nonculprit MBG is able to risk-stratify patients with normal baseline flow of the culprit vessel.

Right ventricular dysfunction and exercise capacity after inferior (posterior) wall acute myocardial infarction

Tissue Doppler echocardiography is a novel technique that can be used to diagnose right ventricular (RV) systolic dysfunction. Until recently, there have been no data on the influence of tissue Doppler-derived RV systolic dysfunction on exercise capacity after inferior (posterior) myocardial infarction (MI). We studied 90 consecutive patients (76% men, mean age 61 ± 10 years) with first inferior ST-segment elevation MI and left ventricular ejection fraction ≥45%. RV systolic dysfunction was defined as RV systolic myocardial velocity <11.5 cm/s at the basal segment of the RV free wall assessed by pulse tissue Doppler. Patients were categorized as with or without RV systolic dysfunction (RV systolic myocardial velocity 9.34 ± 1.36 and 13.74 ± 1.58 cm/s, respectively). A cardiopulmonary exercise test was performed before or soon after discharge (day 14 ± 10). Patients with RV systolic dysfunction had lower oxygen consumption assessed as percent predicted oxygen uptake in liters per minute and milliliters per kilogram per minute at their anaerobic threshold (61 ± 11% vs 69 ± 17%, p = 0.007; 53 ± 12% vs 61 ± 19%, p = 0.012, respectively) and at peak exercise (71 ± 12% vs 83 ± 16%, p = 0.0001; 62 ± 14% vs 74 ± 21%, p = 0.002, respectively). Multivariate regression analysis revealed that the following independent factors negatively influenced exercise capacity: RV systolic dysfunction, female gender, age, lower body mass index, current smoking, and maximal troponin I concentration. In conclusion, we found decreased exercise capacity in patients with systolic RV dysfunction assessed by pulse tissue Doppler in patients with inferior (posterior) wall acute MI despite preserved left ventricular function.

Use of the TIMI frame count in the assessment of coronary artery blood flow and microvascular function over the past 15 years

Since its introduction, the TIMI frame count method has contributed to the understanding of the pathophysiology of coronary artery disease. In this article, the evolution of the TFC method and its applicability in the assessment of various therapeutic modalities are described.

Relationship between infarct artery location, epicardial flow, and myocardial perfusion after primary percutaneous revascularization in acute myocardial infarction

BACKGROUND

The association between infarct artery location, reperfusion success, and clinical outcomes after primary percutaneous coronary intervention (PCI) has not been characterized. We examined the infarct artery-specific impact of epicardial and myocardial flow and reperfusion after primary PCI for acute myocardial infarction.

METHODS

Among 2082 patients undergoing primary PCI in the CADILLAC trial, myocardial blush grade, TIMI flow grade, ST-segment resolution, and clinical outcomes were analyzed according to the infarct artery.

RESULTS

Baseline clinical characteristics did not significantly differ between patients experiencing infarction in the left anterior descending (LAD, 37%) versus left circumflex (18%) and right coronary artery (46%) distributions. Baseline left ventricular function was reduced, and collateral flow was less commonly present in patients with infarction involving the LAD. Achievement of final TIMI-3 flow, grade 3 myocardial blush, and ST-segment resolution >70% was also significantly less common in anterior infarction. Patients with anterior versus nonanterior infarction had significantly higher mortality at 30 days (3.4% vs 1.3%, P = .0006) and 1 year (6.5% vs 2.9%, P < .0001) and had increased 1-year rates of reinfarction (3.6% vs 1.7%, P = .009) and ischemic target vessel revascularization (16.1% vs 11.7%, P = .006). By multivariate analysis, LAD infarction was a powerful independent predictor of 1-year mortality (odds ratio 2.45, P = .009).

CONCLUSIONS

Acute myocardial infarction involving the LAD distribution is associated with reduced left ventricular function, less frequent collateral flow, impaired myocardial perfusion and decreased reperfusion success, findings associated with reduced survival, and increased major adverse cardiac events compared with other vascular territories. These data provide mechanistic insights to the adverse prognosis of patients with anterior infarction.

Effect of rescue or adjunctive percutaneous coronary intervention of the culprit artery after fibrinolytic administration on epicardial flow in nonculprit arteries

We hypothesized that blood flow in noninfarct arteries would improve after percutaneous coronary intervention of the culprit artery in the setting of ST-elevation myocardial infarction (STEMI). The corrected Thrombolysis In Myocardial Infarction (TIMI) frame count was measured in 94 patients (102 arteries) enrolled in the INTEGRITI, ENTIRE, and FASTER trials of reduced dose fibrinolytic and glycoprotein IIb/IIIa inhibition. The corrected TIMI frame count in nonculprit arteries improved by 3.4 +/- 13.4 frames after percutaneous coronary intervention but remained significantly slower than flow in normal arteries.

Frame count reserve

BACKGROUND

The Doppler wire-derived (relative) coronary flow velocity reserve (CVR) that is used to evaluate functional significance of a coronary stenosis is a method performed only by interventional cardiologists. An angiographic method would be useful in the diagnostic catheterization laboratory. For this purpose, we investigated the relation between TIMI frame count reserve (FCR) and CVR.

METHODS AND RESULTS

In 38 patients, (relative) FCR of left anterior descending (LAD) and left circumflex coronary artery (LCx) was calculated by using manual, synchronized contrast agent injections and compared with (relative) CVR. In addition, vessel length was measured with an intracoronary guidewire and frame count flow velocity was calculated and compared with average peak velocity. There was a strong correlation between FCR and CVR (r=0.62, P<0.001) and between relative FCR and relative CVR (r=0.84, P<0.001). The LAD was significantly longer than the LCx (mean, 14.3+/-1.6 cm versus 11.4+/-1.8 cm, P<0.001), and, therefore, TIMI frame count of LAD was significantly higher than of LCx (mean basal 32.5+/-15.1 versus 23.6+/-9.1 and hyperemic 12.1+/-6.6 versus 8.7+/-3.2, both P<0.02). However, all flow velocity measurements and estimations of volume flow were not different for LAD compared with LCx. There were also no differences between mean FCR and CVR of LAD or LCx, of both vessels compared with each other and between mean relative FCR and relative CVR.

CONCLUSIONS

The (relative) frame count reserve can be used to estimate (relative) coronary flow velocity reserve.

Can the premises of the spasm of resistance vessel concept permit improvement in the treatment and prevention of ischemic heart disease?

In this communication, the spasm of resistance vessel (S-RV) concept of ischemic heart disease (IHD) and other ischemic will be reviewed and updated, and evidence will be presented that principles of the hypothesis might improve the treatment and prevention of IHD. The S-RV concept provides a different basic pathogenetic framework for IHD, and suggestions for treatment and prevention stem from its different basic conceptualization of this disorder. The concept asserts that S-RV directly induces symptoms in IHD, and this position challenges the accepted pathogenetic mechanism for this disorder, i.e., that symptoms in IHD are due directly to obstructive occlusions of epicardial arteries secondary to coronary artery disease. The S-RV concept avers that ischemia-induced S-RV is a major factor in IHD, and evidence supporting this position is provided. Another major position of the hypothesis is that no-reflow (reduced flow after infarction and severe myocardial ischemia in the absence of infarction) is due to ischemic injury-induced S-RV, and a variety of evidences to support this position are offered.Proposed improvement in the treatment of IHD is based mainly on treating ischemia-induced S-RV. alpha-Adrenergic sympathetic blockade reverses ischemia-induced S-RV, and alpha-adrenergic blockade is suggested as therapy for acute coronary syndromes and to prevent complications of percutaneous coronary interventions. Also, angiotensin-converting enzyme inhibition, which has actions similar to alpha-adrenergic blockade, is also suggested. Proposals for the prevention of IHD are based the prevention of S-RV, and special emphasis is given to preventing exercise- and stress-related IHD.