Related Experiment Videos
[The noninvasive identification of patients with angina and normal coronary arteries]
G Rusticali1, D Di Clemente, A Ruggeri
1Istituto di Patologia Speciale Medica e Metodologia Clinica, Università degli Studi di Bologna.
Insights
Verapamil effectively improves exercise capacity in Syndrome X patients with angina and normal coronary arteries, unlike isosorbide dinitrate. This response helps identify these patients, potentially avoiding invasive coronary angiography.
Area of Science:
- Cardiology
- Clinical Medicine
- Pharmacology
Background:
- Syndrome X (angina with normal coronary arteries) and coronary artery disease share symptoms but have different prognoses.
- Coronary atherosclerosis is progressive, while Syndrome X generally has a benign prognosis.
- Current practice often involves coronary angiography for suspected coronary artery disease, even with normal arteries.
Purpose of the Study:
- To evaluate non-invasive testing for identifying coronary artery anatomy and prognosis in patients with effort-induced angina.
- To assess the influence of isosorbide dinitrate and verapamil on coronary flow reserve and exercise stress testing in Syndrome X.
Main Methods:
- 48 patients with effort angina underwent randomized crossover testing with isosorbide dinitrate or verapamil before and after exercise stress tests.
- Efficacy was measured by preventing ST depression, improving ischemic thresholds, and increasing time to peak exercise.
- Coronary angiography was performed within 3 months.
Main Results:
- Verapamil improved exercise capacity in 13/15 Syndrome X patients; isosorbide dinitrate was largely ineffective.
- In coronary artery disease patients, both drugs showed variable effectiveness.
- A positive response to verapamil (but not isosorbide dinitrate) was highly sensitive (86%) and specific (100%) for Syndrome X.
Conclusions:
- Verapamil, not isosorbide dinitrate, enhances exercise capacity in Syndrome X.
- This drug response differentiates Syndrome X from stable angina.
- Non-invasive testing with verapamil can identify Syndrome X patients, potentially guiding decisions about coronary angiography.
Background:
Although patients with syndrome X (angina and normal coronary arteries, in absence of coronary spasm, cardiomyopathy or valvulopathy) and those with stable angina as well as documented coronary artery disease share a similar clinical presentation (effort related symptoms, positive exercise stress testing and reversible perfusion defects), their prognosis is markedly different. Coronary atherosclerosis is usually progressive relative to morbidity and mortality. Conversely prognosis both in terms of persistence of pain and mortality appears to be benign in syndrome X. Most cardiologists favor proceeding with coronary angiography in all patients presenting with exercise induced ST depression and reversible perfusion defects. However, it should not be assumed that this strategy will remain the preferred one. The aim of this study was to assess whether non invasive testing could identify underlying coronary artery anatomy, thus prognosis in the above subset of patients. The approach was selected on a clearly stated objective of how isosorbide dinitrate and verapamil may influence coronary flow reserve, thus exercise stress testing in syndrome X. Nitrates have been shown to reduce coronary flow reserve during stress tachycardia. The opposite occurs with calcium blockers.
Methods:
We studied 48 patients with effort angina referred to our laboratory for diagnostic evaluation. All patients underwent two separate sessions at one-day interval. Each session consisted of exercise stress testing before and after isosorbide dinitrate (s.l.; 5-10 mg) or verapamil (i.v.; 10 mg), given in a randomized crossover fashion. Angiography was performed within 3 months from testing. Efficacy of drugs in terms of exercise capacity was assessed by using the following criteria: 1) prevention of significant (> or = 0.1 mV) ST depression while reaching same workload levels attained during baseline testing; 2) improvement in the ischemic thresholds, that is an increase in: time to 0.1 mV ST depression > or = 120 sec., with heart rate (> or = 10 bpm) and rate pressure product (> or = 2 U x 1000) greater than those attained during baseline testing; 3) increase in time to peak exercise (> or = 120 sec).
Results:
In syndrome X, both drugs resulted ineffective in one patient, one patient showed a favourable response to isosorbide dinitrate whereas the remaining 13/15 patients improved exercise capacity following verapamil, but not isosorbide dinitrate. The opposite occurred in coronary artery disease patients: both isosorbide dinitrate and verapamil were effective in 21/33 patients, and ineffective in 8/33 patients. The remaining 4 patients responded to isosorbide dinitrate but not to verapamil.
Conclusions:
1) Verapamil, but not isosorbide dinitrate, improves exercise capacity in syndrome X; 2) this does not apply to patients with stable angina; 3) a favourable response to verapamil but not to isosorbide dinitrate is both a sensitive (86%) and specific (100%) method for identifying patients with angina and normal coronary arteries; 4) non invasive testing may select those effort angina patients who have to proceed directly to coronary angiography; 5) some patients with effort related angina may not require further investigation.