Influence of right coronary artery stenosis on exercise test responses and survival in patients with left main or left main equivalent disease
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T Kawaguchi1, J Myers, P M Ribisl
1Palo Alto, VA Medical Center, CA 94304.
Insights
Right coronary artery involvement in patients with left main or equivalent coronary artery disease significantly worsens exercise test responses and survival. This indicates RCA disease should be considered in treatment decisions for severe coronary artery disease.
Area of Science:
- Cardiology
- Clinical Medicine
- Exercise Physiology
Background:
- Left main coronary artery (LM) disease and left main equivalent (LMEQ) disease represent severe forms of coronary artery disease.
- Right coronary artery (RCA) involvement is common in these patient groups.
- The impact of RCA disease on clinical outcomes and exercise responses in LM/LMEQ patients is not fully elucidated.
Purpose of the Study:
- To investigate the role of right coronary artery (RCA) involvement in patients with left main (LM) or left main equivalent (LMEQ) coronary artery disease.
- To determine the influence of RCA stenosis on exercise test responses and patient survival.
Main Methods:
- Study included 42 patients with LM disease and 30 patients with LMEQ disease.
- Patients were assessed for the presence and severity of RCA stenosis.
- Exercise test responses and long-term survival rates were analyzed in relation to RCA involvement.
Main Results:
- No significant differences in clinical or exercise variables or survival were found between LM and LMEQ groups.
- Patients with LM/LMEQ disease and significant RCA stenosis showed greater ischemic responses during exercise.
- The presence of RCA stenosis was associated with increased ST-segment depression, prolonged ST-segment recovery, and worse annual survival rates (7.5% vs 1.0%).
Conclusions:
- Left main (LM) and left main equivalent (LMEQ) coronary artery disease patients exhibit similar survival and exercise responses.
- Right coronary artery (RCA) stenosis in LM/LMEQ patients is linked to more severe ischemic responses and significantly reduced survival.
- RCA involvement should be a critical factor in the medical and surgical management decisions for patients with severe coronary artery disease.
Abstract:
Forty-two patients with angiographically documented left main coronary artery (LM) disease (luminal occlusion > or = 50%) and 30 patients with left main equivalent (LMEQ) disease (> or = 70% luminal occlusion of both the proximal left anterior descending artery and proximal left circumflex artery) were studied to determine the role of right coronary artery (RCA) involvement on exercise test responses and survival. Significant (> or = 70%) RCA stenosis was present in 30 (72%) of the 42 LM patients and 16 (53%) of the 30 LMEQ patients. No significant differences were observed between LM and LMEQ patients in any clinical or exercise variables or survival. Thus both groups were combined for analysis of the influence of RCA involvement (i.e., LM/LMEQ with RCA versus LM/LMEQ without RCA disease). Greater ischemic responses were observed in the LM/LMEQ group with significant stenosis of the RCA. The presence of RCA stenosis was associated with significantly greater horizontal or downsloping ST-segment depression during exercise (2.4 +/- 1.2 mm vs 1.3 +/- 1.4 mm; p < 0.001), and prolonged recovery time until normalization of the ST segment (3.2 +/- 1.4 min vs 2.0 +/- 1.9 min; p < 0.01). The LM/LMEQ without RCA disease group behaved like the subgroup with two-vessel disease, and responses of the LM/LMEQ group with RCA disease were similar to the group with three-vessel disease. The annual survival in LM/LMEQ with RCA disease was worse than that in LM/LMEQ without RCA disease (average annual mortality rates = 7.5% vs 1.0%, respectively; p = 0.05). Infarct-free survival in LM/LMEQ with RCA disease was also lower than that in LM/LMEQ without RCA disease. Thus although patients with LM and LMEQ were similar in terms of survival and exercise responses, the presence of RCA stenosis was associated with significantly greater ST-segment depression, a prolonged recovery time until normalization of the ST segment, a fivefold increase in the death rate, and higher morbidity from myocardial infarction over a 5-year period of follow-up. Involvement of the RCA should be considered when making decisions concerning medical-surgical management of patients with severe coronary artery disease.