Effect of Permanent Right Internal Mammary Artery Closure on Coronary Collateral Function and Myocardial Ischemia

Abstract

Background—The objective of this study is to test the effect of permanent right internal mammary artery device closure on coronary collateral function and myocardial ischemia.Methods and Results—This was a prospective, open-label clinical trial in 50 patients with coronary artery disease. The primary study end point was coronary collateral flow index as obtained during a 1-minute proximal right coronary artery (RCA) and left coronary artery balloon occlusion at baseline before and at follow-up examination 6 weeks after distal right internal mammary artery device closure. Collateral flow index is the ratio between simultaneously recorded mean coronary occlusive pressure divided by mean aortic pressure, both subtracted by central venous pressure. Secondary study end points were fractional flow reserve during vessel patency, the quantitative intracoronary ECG ST-segment elevation, and angina pectoris during the same 1-minute coronary occlusion. Collateral flow index in the untreated RCA and left coronary artery changed from 0.071±0.082 at baseline to 0.132±0.117 (P<0.0001) at follow-up examination and from 0.106±0.092 to 0.081±0.079 (P=0.29), respectively. RCA fractional flow reserve increased significantly (P=0.0029) from baseline to follow-up examination, despite deferral of coronary intervention in all patients. There was a decrease in intracoronary ECG ST-elevation during RCA occlusion from baseline to follow-up examination (P=0.0015); it did not change in the left coronary artery. Angina pectoris during RCA occlusion tended to occur in fewer patients at follow-up versus baseline examination (P=0.06).Conclusions—Permanent right internal mammary artery device closure seems to augment extracardiac ipsilateral coronary supply to the effect of reducing ischemia in the dependent myocardial region.Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT02475408.

Neoangiogenesis connecting a left internal mammary artery proximal stump to an ischemic area of the heart after bypass occlusion

“…Recently investigated have been the function of mammary‐to‐coronary artery anastomoses and their effects on myocardial ischemia in humans by occluding the IMAs with an angioplasty balloon. In the presence versus absence of IMA occlusion, the collateral flow index was significantly higher, intracoronary ECG ST elevation significantly less, and angina diminished while occluding the right IMA for 3 weeks even improved fractional flow reserve . Hence, these studies have confirmed the theory that a functional ischemia‐reducing extracardiac coronary artery supply exists via naturally‐occurring IMA anastomoses.…”

Therapeutic occlusion of the internal mammary arteries to relieve refractory angina

“…[ 5 ] The collateral flow index, fractional flow reserve, intracoronary ECG, and anginal symptoms have all been recently demonstrated to improve when the ipsilateral IMA is occluded. [ 6 ] These recent findings confirm that the old principle of IMA occlusion had a strong rationale, and suggest that it would be worthwhile further studying its effects in RA.…”

The effect of pegylated granulocyte colony‐stimulating factor on collateral function and myocardial ischaemia in chronic coronary artery disease: A randomized controlled trial

“…In comparison, the absolute change in CFI during short‐term treatment with G‐CSF was +0.049 ± 0.062 (−0.010 ± 0.060 in the placebo group), whereby the CFI responses during follow‐up were more consistent, and thus, statistically more relevant in the previous than the actual study. The average CFI response to other forms of coronary arteriogenesis, such as heart rate reduction by ivabradine, physical exercise, external counterpulsation, or extracardiac coronary collateral supply augmentation via the native internal mammary artery compares as follows: +0.059 ± 0.050, +0.069 ± 0.050, and +0.067 ± 0.064, respectively. Thus, the effects appear more sizeable and less variable than the response induced by pegfilgrastim, both of which may be related to a possible fading effect of the pro‐arteriogenic action of pegfilgrastim linked to a longer period of administration over 6 months vs only 6 weeks to 3 months.…”