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Ivor L. Gerber
Dept of Cardiology, Auckland City Hospital, Auckland, New Zealand

The mainstay of therapy for all patients with coronary artery disease includes acetylsalicylic acid and the statins. For symptomatic patients, traditional therapeutic options include pharmacological agents such as beta blockers, calcium channel blockers, and nitrates, and revascularization measures such as percutaneous coronary artery interventions and coronary artery bypass grafting¹. Potential therapeutic options for patients with angina refractory to standard medical therapy and unsuitable for revascularization procedures (intractable angina) are described below.

Laser transmyocardial revascularization may be performed surgically or percutaneously using a holmium:YAG laser. The goal with both techniques is to create a series of transmural endomyocardial channels to improve myocardial revascularization. While the precise mechanism for the improvement in angina is uncertain, the clinical benefits may be due to the healing response to injury which is associated with myocardial vascularity, or due to the destruction of afferent nerves². Despite early enthusiasm, these procedures are not commonly performed due to the relatively high morbidity and mortality rates and the variable clinical results. Spinal cord stimulation modifies the neurological input and output of the heart by delivering a very low dose of electric current to the dorsal columns of the high thoracic spinal cord. The mechanisms of action are likely related to the inhibition of pain transmission and the anti-ischemic properties of the therapy³. This therapy is generally effective, safe, and cost-effective. Enhanced external counterpulsation uses non-invasive pneumatic compression of the legs to improve diastolic filling of the coronary vessels and promote development of collateral flow. Each treatment period requires thirty-five hours of therapy over a seven-week treatment period. Recently published studies found the treatment to be well tolerated and effective with an improvement of anginal symptoms in the majority of patients⁴. Metabolic agents include perhexiline, trimetazidine, ranolazine, and etomoxir⁵. These drugs exert their anti-ischemic effects primarily by altering myocardial metabolism. They increase glucose metabolism at the expense of free-fatty-acid metabolism, enhancing oxygen efficiency during myocardial ischemia. Randomized studies have generally shown favourable results and larger long-term studies are on-going. Perhexiline has been available for many years but initial enthusiasm for its use was dampened by reports of hepatic toxicity. Therapeutic angiogenesis is a recent addition to therapeutic options for patients with intractable angina and studies are ongoing to determine the safety and efficacy of this modality⁶. This technique requires injection of cytokines to promote neovascularization and improve myocardial perfusion into the regions affected by chronic ischemia.

While angina refractory to standard medical therapy and unsuitable for revascularization procedures remains a clinical challenge, there is an increasing array of therapeutic options that may allow significant symptom benefit.

Time of Presentation
Saturday 7 May 2005 - 1030-1200

References

1. Gibbons R.J., et al. ACC/AHA 2002 guideline update for the management of patients with chronic stable angina - summary article. Circulation. 2003; 107:149-158.