Heart rate variability in patients with variant angina: effect of the presence of significant coronary stenosis.

BACKGROUND: The syndrome of variant angina occurs in patients with a wide spectrum of coronary disease ranging from angiographically normal coronary arteries to severe three-vessel disease. Survival and choice of therapy for these patients are determined by the extent of underlying fixed coronary obstruction. We examined whether heart rate variability (HRV) due to reduced vagal outflow may correlate with the severity of coronary stenoses in such patients. METHODS: Fifteen men and 2 women with clinically unstable variant angina underwent 24-hour Holter monitoring from which low and high-frequency power, standard deviation of mean 24-hour RR interval, proportion of adjacent RR intervals that differed by more than 50 ms, and mean root square of differences between successive RR intervals were extracted by power spectral analysis. Coronary angiography was later performed to determine coronary pathology and verify variant angina. As controls we studied an age-matched control group of 8 subjects (5 men, 3 women) with no clinical and/or electrocardiographic evidence of coronary heart disease or spasm as shown by negative treadmill exercise and hyperventilation tests. RESULTS: All measured components of HRV were significantly lower in the 9 patients with severe coronary artery disease compared to the 8 patients with normal coronary arteries or < 40% stenosis. The two groups were otherwise similar in terms of age and clinical parameters. CONCLUSIONS: These preliminary findings on a small but carefully selected group of patients with variant angina indicate that the analysis of HRV can select patients with severe disease for a more intensive approach. These findings require confirmation on a larger patient series.

An uncommon case of variant angina.

This case report describes a 48-year-old woman patient with variant angina who died because of severe myocardial ischemia and cardiogenic shock, in spite of chronic therapy with nitrates and calcium-antagonists and acute intravenous administration of nitrates, calcium-antagonists and tissue-type plasminogen activator. Her Holter monitoring showed a reduction of time domain measures of heart rate variability. The hemodynamic study exhibited a normal ventriculography and angiographically normal epicardial coronary arteries. The provocative testing, performed (during intravenous therapy with nitrates and diltiazem) by intracoronary injection of progressively increasing doses of ergonovine, induced only a mild vasoconstriction of proximal left anterior descending artery, without symptoms or ST-T segment changes. This case reminds us that variant angina can be a lethal disease, confirms that a negative result of intracoronary ergonovine testing performed during intravenous therapy with nitrates and calcium-antagonists does not assure the prevention of new episodes during chronic oral therapy with the same drugs, suggests a possible prognostic value of the reduction of heart rate variability indexes and shows an unusual response to nitrate administration.

Exercise-induced T-wave normalization predicts recovery of regional contractile function after anterior myocardial infarction.

AIMS: We investigated the ability of T-wave pseudonormalization and ST-segment elevation, which are demonstrated in infarct-related leads during submaximal exercise testing, to predict late recovery of contractile function. METHODS: We studied 88 consecutive patients (73 males, mean age 59 +/- 8 years) with anterior infarction, persistent T-wave inversion and a documented lesion of the proximal segment of the left anterior descending coronary artery. They all underwent 2D-echocardiography on admission, 4 weeks as well as 6 months after myocardial infarction to evaluate the dysfunction score and the ejection fraction. Submaximal (75% of maximal predicted heart rate) exercise testing was performed in 80 patients 2 weeks after myocardial infarction following discontinuation of treatment. RESULTS: During exercise testing, 59 of the 88 patients showing negative T-waves on the resting electrocardiogram exhibited pseudonormalization (group A) in at least three adjacent precordial leads, whilst 29 (group B) did not. Patients of group A more frequently exhibited an early creatine kinase peak (41% vs 24%, P < 0.05) and residual angiographic perfusion (97% vs 69%, P < 0.05). The dysfunction score did not change in group B (from 19 +/- 7 to 22 +/- 4), but decreased in group A (from 18 +/- 4 to 11 +/- 6 P < 0.05). The ejection fraction was similar in the two groups on admission (group A: 48 +/- 7%, group B: 45 +/- 10%), but was significantly different at 4-week (52 +/- 99 vs 42 +/- 11%, P < 0.05) and 6-month follow-up (58 +/- 9 vs 44 +/- 10%, P < 0.01). The concomitant presence of ST-segment elevation and T-wave normalization showed the highest positive predictive value for left ventricular function recovery (100%). CONCLUSIONS: T-wave normalization induced by submaximal exercise test is frequently associated with residual perfusion to the infarct area and predicts progressive improvement in regional wall motion, especially if associated with ST-segment elevation. Therefore, these electrocardiographic findings may be used as easily obtainable markers of residual viability that predict late recovery in contractile function.

Coronary collaterals reduce the duration of exercise-induced ischemia by allowing a faster recovery.

The role of collaterals in influencing postischemic recovery after exercise testing has not been investigated previously. We studied 54 patients (mean age 59 +/- 6 years) with effort-induced angina and documented coronary disease who underwent exercise testing and thallium-201 myocardial scintigraphy. On angiography, 30 patients (group A) exhibited visible collaterals (grade 2 to 3, Cohen and Rentrop classification) perfusing the ischemic zone, whereas the other 24 (group B) did not. Patients with collaterals had more severe coronary artery disease (Gensini score 46.9 +/- 16 vs 28.6 +/- 18; p less than 0.001) and more severe impairment of coronary flow reserve (time and rate-pressure product to 1 mm ST segment depression 3.5 +/- 0.8 vs 4.8 +/- 0.6 minutes, p less than 0.01; 14,189 +/- 2451 vs 16,081 +/- 2215 beats/min x mm Hg, p less than 0.04, respectively). However, in these patients the ECG returned to baseline more rapidly after exercise (5.5 +/- 1.6 vs 11.7 +/- 3.3 minutes; p less than 0.001). Therefore, although collaterals do not apparently prevent or delay the development of exercise-induced ischemia, they can limit its duration by allowing a faster recovery.

Assessment of residual tissue viability by exercise testing in recent myocardial infarction: comparison of the electrocardiogram and myocardial perfusion scintigraphy.

The assessment of residual myocardial viability in infarcted areas is relevant for subsequent management and prognosis but requires expensive technology. To evaluate the possibility that simple, easily obtainable clinical markers may detect the presence of within-infarct viable tissue, the significance of exercise-induced ST elevation occurring in leads exploring the area of a recent Q wave myocardial infarction was assessed. Twenty-five patients with recent (less than 6 months) myocardial infarction were studied. All had angiographically documented coronary artery disease, diagnostic Q waves (n = 24) or negative T waves (n = 25) on the rest 12-lead electrocardiogram and exhibited during exercise greater than or equal to 1.5 mm ST segment elevation (n = 17) or isolated T wave pseudonormalization (n = 8) in the infarct-related leads. ST-T wave changes were reproduced in all patients during thallium-201 exercise myocardial scintigraphy. A fixed perfusion defect was observed in 24 of the 25 patients. A reversible defect was seen in 16 (94%) of 17 patients who exhibited transient ST elevation during exercise but in only 4 (50%) of the 8 patients who had only T wave pseudonormalization. In conclusion, in patients with recent myocardial infarction, analysis of simple ST segment variables obtained during exercise testing may allow a first-line discrimination of those who may potentially benefit from a revascularization procedure.