[Myocardial revascularization may resolve arrhythmic warm-up in patients with implantable cardioverter-defibrillator: 2 case reports]. / La rivascolarizzazione miocardica come risoluzione del riscaldamento aritmico in pazienti con cardiovertitotre-defibrillatore impiantabile: due casi clinici]

Patients with ventricular arrhythmias and coronary artery disease may have a poor clinical outcome because of an increased risk of sudden cardiac death. In these patients therapeutic approaches include two main strategies: automatic implantable cardioverter-defibrillator (ICD) and antiarrhythmic drugs (when left ventricular function is preserved). Patients with arrhythmic warm-up sustained by ischemic attacks may be stabilized after percutaneous or surgical revascularization. We report the cases of 2 ICD patients, in whom the correction of myocardial ischemia was successful in preventing further ICD discharges. In the first patient with known coronary artery disease (previous acute myocardial infarction and left ventricular ejection fraction 30%) a sudden arrhythmic warm-up was reported with 70 ICD discharges in 24 hours; the patient underwent coronary artery bypass surgery and only few isolated episodes of ventricular tachycardia were observed during the following 34 months. In the second patient with a history of dorsal acute myocardial infarction and two previous interventions of coronary artery bypass graft surgery, we observed a sudden and unexpected arrhythmic instabilization with several ICD discharges. After percutaneous transluminal angioplasty of a graft stenosis, the clinical situation was stabilized and no more ICD activations were observed during the follow-up. In selected patients arrhythmic warm-up can rely on an ischemic substrate, then a careful re-evaluation for ischemia is mandatory in order to resolve the situation.

[Role of stress myocardial perfusion scintigraphy in the follow-up of patients undergoing coronary angioplasty: comparison between qualitative and semi-quantitative analysis]. / Ruolo della scintigrafia miocardica da sforzo nel follow-up dei pazienti sottoposti ad angioplastica coronarcia: confronto fra analisi qualitativa e semiquantitativa.

In order to assess the diagnostic accuracy of stress/rest myocardial perfusion scintigraphy in the follow-up of patients undergoing percutaneous transluminal coronary angioplasty (PTCA) we studied 50 patients (pts) before and 6 months after PTCA. All patients underwent control coronary angiography and then were divided in 2 groups, according to angiographic evidence of restenosis (25 pts) or no restenosis (25 pts). Myocardial perfusion imaging was performed with 99mTc-methoxy-isobutyl-isonitrile (MIBI). For MIBI scans, both qualitative and semi-quantitative analysis were performed. SPECT images were displayed on a color monitor in random order and graded blindly by 2 experienced observers. Rest and stress MIBI uptake was scored using a 4-point scale (ranging from 0 = normal, to 3 = absence of uptake). Individual subjects' perfusion scores were calculated by adding the individual segments' scores. History of relapsing angina showed a sensitivity and specificity of 76 and 96%, respectively. Exercise testing and MIBI tomoscintigraphy exhibited sensitivity and specificity of 80 and 56%, and 92 and 44%, respectively. However, when considering semiquantitative data and comparing them with pre-PTCA studies, specificity of MIBI scan increased to 96%, while sensitivity decreased to 72%. The results of the present study confirm high sensitivity and low specificity for both exercise ECG and myocardial perfusion scintigraphy, in the detection of restenosis following PTCA. However, when performing semiquantitative analysis of perfusion scanning and comparison with pre-PTCA images, the specificity of MIBI tomoscintigraphy increases significantly. Therefore, when adopting myocardial perfusion scintigraphy for the follow-up of patients undergoing PTCA, a pre-revascularization scan should be obtained as often as possible. This approach, in the context of a positive test, makes feasible the assessment of often partial improvements in perfusion of the myocardium relative to the treated vessel, consequently avoiding many false positive results which invariably lead to coronary angiography.